Research ArticleDeveloping Dynamic Digital Image CorrelationTechnique to Monitor Structural Damage of OldBuildings under External Excitation

Ming-Hsiang Shih1 and Wen-Pei Sung2

1 Department of Civil Engineering National Chi Nan University Puli Nantou 545 Taiwan2Department of Landscape Architecture Integrated Research Center for Green Living Technologies National Chin-Yi UniversityTaichung 41170 Taiwan

Correspondence should be addressed to Wen-Pei Sung wpsncutedutw

Received 4 February 2014 Revised 11 June 2014 Accepted 15 June 2014 Published 15 July 2014

Academic Editor Longjun Dong

Copyright copy 2014 M-H Shih and W-P Sung This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The capacity of buildings to resist external excitation is an important factor to consider for the structural design of buildingsWhensubject to external excitation a buildingmay suffer a certain degree of damages and its residual capacity to resist external excitationcannot be evaluated In this research dynamic digital image correlation method combined with parameter evaluation available insystem identification is used to evaluate the structural capacity to resist external excitationThe results reveal possible building latentsafety problems so that timely structural reinforcement or dismantling of the building can be initiated to alleviate further damagesThe results of experiments using the proposed method conform to the results obtained using the conventional method but thismethod is more convenient and rapid than the latter in the subsequent procedure of data processing If only the frequency changeis used the damages suffered by the building can be detected but the damage location is not revealed The interstory drift modeshape (IDMS) based on the characteristic of story drift has higher sensitivity than the approximate story damage index (ADSI)method based on modal frequency and vibration type however both indices can be used to determine the degree and location ofbuilding damages

1 Introduction

The life cycle of a civil engineering structure includes thesteps of development and construction application andmaintenance and demolition and removal Enhancing thefunctional characteristics of materials and applying newconstruction technology during the construction period willimprove the quality the functions and the safety of thestructure However before a structure reaches its designedlife cycle its structural functions need to be evaluated duringthe various stages of application the results will be referencedfor conducting structuralmaintenance andor reinforcementIn recent years the record breaking earthquakes of RichterScale 9 and the aftermath tsunami such as those that have

occurred in Indonesia and Japan are profoundly impressive[1 2] The global warming will lead to more natural disastersin the future so that the evaluation of building capability toresist external excitation should be emphasized for the safetyof the occupants Although a building has been designed toresist external excitation of certain intensities it may suffer acertain degree of damage to weaken the building and reduceits quake-resisting capability In particular Taiwan is locatedin the Pacific seismic belt and there are many old buildingsin Taiwan constructed before 1970s Not only these kind ofold buildings are threatened by earthquake seriously but alsomany existed buildings are menaced the safety of structureby strong earthquake Hence conducting the evaluation ofthe capability of a building to resist external excitation will

Hindawi Publishing CorporationShock and VibrationVolume 2014 Article ID 954840 15 pageshttpdxdoiorg1011552014954840

2 Shock and Vibration

Moving object Computer

A

CameraCCD

Figure 1 The experimental setup for 2D digital image correlation method

allow timely remedies such as structural reinforcement oreven dismantling the building to alleviate damages to becaused by future quakeThe response of a building to externalvibration is extremely complicated its prediction must con-sider forecasting the quake characteristics and the buildingnonlinear responses to quake and theirmutual correlations inaddition to predicting erratic human factors Hence detailedestimation of the building quake-resisting capability of abuilding and its expected useful life is extremely difficultscholars and civil engineers in the world continually engagein developing quake-resisting buildings in order to safeguardlife and property of occupants

The technology for building diagnoses is mostly basedon the use of sensors (eg accelerometer speedometerstrainometer and global positioning system (GPS) amongmany others) to collect the building dynamic informationand data [3ndash12] Some noise signals from these dynamictest will affect the analysis precision of these kind of dataTherefore some de-noise methods such as a wavelet basedmultistep filtering method and improved particle filteringalgorithms are proposed to filter out the noise from dynamictest [13 14] Then the results are applied to develop math-ematical for example models for identifying the buildingdynamic parameters such as system matrices of structureor modal parameters of structures in a process known assystem identification [15ndash18] Pertinent structural featuressuch as natural frequency mode shape and damping ratiosamong many others can be isolated and identified usingthe above models to develop quantitative damage index Thetime-dependent variation of damage index is the basis forconducting building diagnoses

Some traditional measuring methods are applied todetect the building responses of dynamic parameters Thesemethods need to use many sensitive instruments to providethe needed information Nevertheless the cost involved istoo high to be practical The digital image correlation (DIC)method proposed by our research team is a new opticalmeasurement technique to offer low-cost strain distribu-tion with high precision In this study this DIC methodwill be developed based on developing and applying thedigital photographing technology to monitor the build-ing dynamic response under excitation of various externalearthquake records to test and verify the precision of thisproposed method in monitoring building deformation and

movement Therefore in this research the ldquodynamic digitalimage correlation DICrdquo method will be developed into atechnology for dynamic monitoring of structures based ondigital imagesThemeasurable data on characteristic buildingresponse data and features for example resonant frequenciesMAC COMAC mode shape curvatures dynamic flexibilitydamping and so forth will be excerpted to identify the degreeand location of building damages The results obtained usingthe proposed method will be compared with those reportedby previous researchers in order to verify the validity andapplicability of this dynamic method for timely diagnoses ofbuilding health

2 Methodology-Dynamic Digital ImageCorrelation Method

The dynamic digital image correlation method uses opticalequipment to record the process of the object deformationand movement in digital filmThese photographs can use theldquoFinding Algorithmrdquo to develop the technology of dynamicdigital image correlation method and dynamic DIC for com-paring the partial relativity of two images towards reflectionbefore and after structural deformation or movement theexperimental setup is shown in Figure 1 The comparisonresults can be used to analyze the relative displacement anddeformation of the object between the two moments Thisdynamic DIC technique is basically taken as the foundationof ldquosearch to perform mathematical calculationsrdquo The mainanalysis concept is based on the finite element methodthe images are divided into small mesh the total value ofthe mesh gray scale values of mesh in original image canbe compared with those in the image after transformationso that the corresponding location of a selected mesh inthe deformed image can be identified The two-dimensionalDIC method is suitable for the plane strain test or the testwithout obvious out-of-plane displacement [19] But somecharacteristics of structural dynamic response contain out-of-plane displacement or the specimen surface is not a planeTherefore the three-dimensional DIC method is necessaryfor the measurement Traditionally more than one cameraneeds to be installed to capture images to conduct three-dimensional image analysis process however the analyticalparameters of this method are correlated and excessive

Shock and Vibration 3

Lens center

b998400

a998400

b

a

O

q

pa pbABB

998400

e

A998400

Figure 2The parallax phenomenon caused by the difference objectdistance [20]

Therefore the simplest DIC method based on a single digitalcamera with 3D digital images is proposed by Shih et al [20]

21 A Single Digital Camera for 3D Digital Images [20] If thehorizontal distance for the camera tomove to the right (or theobject to move to the left) is ldquo119890rdquo the horizontal displacementson the photosensitive element are ldquo119860119860

1015840rdquo for a relatively closerpoint ldquo119886rdquo and ldquo1198611198611015840rdquo for a relatively farther point ldquo119887rdquo as shownin Figure 2

The geometric relationship is

1198601198601015840= (

119902

119901119886

) 119890

1198611198611015840= (

119902

119901119887

) 119890

(1)

where 119902119901119886 and119901

119887are the distance between center of lens and

photosensitive element point 119886 and point 119887 respectivelyThehorizontal movement on the sensing element is expressed inpixels thus

1198731198601198601015840 = 120574(

119902

119901119886

) 119890 (2)

where 120574 is the number of pixels of a unit sensing elementin pixelsmm and 119873

1198601198601015840 is the horizontal displacement of

ldquo119886rdquo in pixels Because the correct values of 120574 and 119902 areunknown these two parameters can be combined into asingle parameter ldquoΛrdquo Hence

Λ = 120574119902 (3)

Equation (4) can be rewritten as

Λ =

1198731198601198601015840119901119886

119890

(4)

Once the calibrated value of Λ can be found usingregression analyses the distance between two points can becalculated as follows

119901119887=

Λ

1198731198611198611015840

119890 (5)

Knowing the distance between the two points the hori-zontal and vertical distances of the object to the lens center(119909 119910) can be found Equation (5) can be used to calculate thedistance of any object ldquo119887rdquo and the theoretical error can beestimated by differentiating the equation

119889119901119887=

minusΛ119890

1198732

1198611198611015840

1198891198731198611198611015840 (6)

Equation (6) indicates that the error is inversed propor-tionally to the distance between the object and the cameradistance Hence a greater camera distance will lead to moreprecise results Therefore when the camera is horizontallymoved ldquo119890rdquo distance the horizontal displacement in pixels ofldquo119886rdquo on the sensing element is119873

1198601198601015840 based on the relationship

to approximate triangular form If the horizontal coordinateof 119886 with respect to the lens center is 119909

119886 its relationship

to the photohorizontal coordinate 119883119860

fits the followingrelationship

119909119886

119883119860

=

119890

1198731198601198601015840

(7)

Moving the terms one obtains

119909119886=

119883119860119890

1198731198601198601015840

(8)

Similarly

119910119886=

119884119860119890

1198731198601198601015840

(9)

22TheThree-Dimensional Dynamic DICMethod with Spine-Type Prism The principal of three-dimensional DIC forusing a single digital camera to photograph digital imagesis based on the plane geometrical images of the 3D objectphotographed from different angle displaying these twoimages at the same general appearance of a picture andthen assembling these two digital images in an analyticalgeometry as three-dimensional coordinates to be displayed asthree-dimensional images This measurement principle canbe accurately applied in static deformation test Neverthelessthis theory is not suitable for three-dimensional dynamictests A key point of three-dimensional DIC technique isapplied a camera to capture images of object movement inthe same position If the above-mentioned method is applieddirectly to measure dynamic response of structure it wouldresult in significant analysis errors

Therefore a spine-type prism is proposed to separatethe view axis of the digital camera into two axes which areinclined to each other in this research to conduct three-dimensional dynamic digital image correlation techniques In

4 Shock and Vibration

Object

Virtual image L Virtual image R

Image

Prism

CameraRL

Virtual camera Virtual camera

Figure 3 Principle of the spine-type prism for 3-dimensional DIC

the dynamic test digital cameras can receive two images withparallax in a single capture action These two images withparallax are stored in the right and left parts of the sensor ofthe cameraThe analysis principle of this proposedmethod isshown in Figure 3 The major advantage of this technology isthe maneuverability As long as the prism is installed on thecamera the camera can be used normally to capture imageswith parallax

In order to identify the three-dimensional dynamicresponse of structure under excitation of external force thehardware specifications of cameras must meet the require-ment of sensitive instruments and equipment with sufficientfrequency or sufficient readings for each recoding channelwithin a unit time Hence NexShot2C-2M CMOS industrialcamera with 12-inch CMOS active-pixel digital image sen-sor 1600 times 1200 dots per inch 41Hz capturing frequencysensitization 2 mega pixels and the highest sampling ratereaches to 53 fps (frames per seconds) is used to collect theuncompressed photographs with high quality in this studyBecause the recording frequency is insufficient the scanningnumbers of selecting images adjust 120 pieces and selectingimage reaches to 42 pictures per minute Then the collectedimages can be used to analyze the displacement reaction oftest object by the DIC method

3 Damage Index

31 Natural Frequency as Damage Index When building isexcited by external force the dynamic features can be easilyextracted from structural dynamic response such as naturalfrequency mode shape and damping ratios These dynamicfeatures can be used to establish damage index to diagnose thestructural health In this section natural frequency variationof structure under the excitation of external force to inducestructural injury is proposed to be damage index to monitorstructural health

The evaluation formula of damage index based on naturalfrequency is expressed as follows

120575119872

= 1 minus

(1198790)initial

(1198790)max

(10)

where (1198790)initial represents basic dynamic cycle of undamaged

structure (1198790)max is the maximum basic dynamic cycle of

time history of dynamic response The value of damageindex based on natural frequency is between 0 and 1 0 andrepresents undamaged of structure

32 Approximation Story Damage Index (ASDI) Story Dam-age Index (SDI) applied the participative parameters fromstructural system such as stiffness and mass to producestructural modal parameters (eigenvalue 120582(= 119908

2) and mode

shape 120601) and the relationship between mass of floor andstiffness to establish a Story Damage Index for assessingbuilding damage excited by earthquake Nevertheless themass of floor is hard to evaluate Therefore ApproximationStory Damage Index (ASDI) is proposed to ignore the massof floor This method requires only one modal parameterto assess story damage Wang et al [16] The main conceptof ASDI is applied to plane structure of shear frame Thetorsion coincidental effect must be considered for three-dimensional structure The damage index from frequencyand modal vector of the first mode shape has been transforminto summation inertia of floor to story drift mode Thenstory drift mode changes into story stiffness of structure toassess the decay of story stiffness after structural damage asan estimating index

The evaluation formula of Approximation Story DamageIndex (ASDI) is expressed as follows

ASDI119897= 1 minus

120596lowast2

119895sum119873

119894=1(120601lowast

119894119895Δ120601lowast

119894119895)

1205962

119895sum119873

119894=1(120601119894119895Δ120601lowast

119894119895)

(11)

where 119897is degree of freedom 119873 is total floor of structure 120596lowast119895

is the 119895th natural frequency after structural damage 120596119895is

the 119895th natural frequency before structural damage 120601lowast119894119895is the

mode shape of 119894th degree of freedom of the 119895th mode shapeafter structural damage 120601

119894119895is the mode shape of 119894th degree of

freedom of the 119895thmode shape before structural damageThevalue ofASDI is between 0 and 1 0 and represents undamagedof structure

33 Interstory Drift Mode Shape (IDMS) as Damage IndexWhen structural damage happens the stiffness of build-ing structure drops off affecting the displacement modereaction of structure Thus IDMS is proposed to probethe relationship of structural destructiveness and variationof displacement mode to judge the structural damage onbuilding The ratio of story drift of the first mode usedIDMS as a normalized datum value of roof before damagefor comparison with IDMS as a normalized datum value ofroof after damage When the sensitivity of IDMS is higherthe probability of structural damage is higher The definitionof story drift and sensitivity of IDMS is expressed as follows

Shock and Vibration 5

Figure 4 The completed five-story shearing steel structure

Story driftis as follows

120575119894= Max (Δ

119894minus Δ119894minus1

)

1205751= Max (Δ

1minus Δ119866)

(12)

where 120575119894is time history analysis of the maximum story

drift of the 119894th floor Δ119894is time history analysis of the

structural displacement history of the 119894th floor Δ119866is ground

displacement

Sensitivity of IDMS is as follows

119878119894=

119863119894minus 119861119894

119861119894

times 100 (13)

where 119878119894is the sensitivity() of the story drift variation after

damage of the 1st mode of the 119894th floor of building 119863119894is the

normalized story drift mode value after damage of the 119894thfloor of building 119861

119894is the normalized story drift mode value

before damage of the 119894th floor of building

4 Experimental Setup

The shaking table model test will be used in this research tocarry out all laboratory studies The shearing steel structuralmodel is a five-story steel framed structure using steel with 119864

value of 2times 1011 kgm2Thenet height of each story is 800mmwith a total building height of 5800mm width of 1520mmand depth of 400mm Each story weighs 242 kg and totalstructure has a designednatural frequency of 1076Hz and thenatural frequency of the second vibration mode of 321HzFigure 4 shows the photo of the completed five-story shearingsteel structure Figure 5 shows the installed camera andother relevant equipments Each element used in the modelstructure has been carefully evaluated to check whether itreaches the yield point If an element shows the sign of yieldit is immediately replaced in order to warrant the accuracy of

Dist

Dist

Camels height

SONY height

Figure 5 The experimental setup of installed camera and otherrelevant equipment

the laboratory study results A series of dynamic experimentshave been planned the results are compared with thoseobtained using accelerometer But there are two factors (1)the maximum throw of this test shaking table is plusmn125mm(2) test structure should remain within linear elastic rangefor dynamic test and it needs to be considered in this studyTherefore the maximum acceleration should be scaled downto 15ndash20 gal Actually the purpose of this research is toobtain the modal frequencies and modes of test structurewithin linear elastic range Therefore the authenticities ofearthquake records do not provide sensitivity Otherwise ElCentro Kobe and TCU earthquake records are providedwith characteristic of far field and near-fault earthquakeThese records are applied to excite modal response of highfrequencies and low frequencies of test structureThen whitenoise study is carried out in order to investigate whetherthe shearing steel structure is subject to environmentalinterference thatwill adversely impact the practicability of theexperimental results Table 1 lists the study plan

41 System Identification Method In this research themethod of comparing images is implemented to reveal thetime-dependent variation of displacement so that using thesystem identification method can be used to measure theexternal force input and the resulting dynamic response ofthe structural degree of freedom for obtaining the structuralmode parameters for example frequency 120596 damping ratio120585 vibration mode 120601 and so forth The system realizationusing information matrix (SRIM) which uses the systemidentification matrix of the measured data is capable ofidentifying the system modes of multiple inputs and outputsin additional to identify the system dynamic structuralmatrices based on the structural system matrix The modeparameters including frequency (120596) damping ratio (120585) andvibration mode (120601) can then be extracted from the dynamicstructure of the identification of the two-stage system forevaluating the building damages The SRIM system used inthis system is based on the identification theory developed byJuang [21] to construct a broad Hankel matrix using impulseresponse data and to estimate the extendable observability

6 Shock and Vibration

Table 1 Study plan for laboratory experiment

Name of structure Experimental shearing steel structureShearing steel structure Reference set (width of column) Experimental set (width of column)Normal monitoringexperiment 400mm 380mm 360mm 280mm and 200mm

Data retrieving andrecording equipment

Equipment for dynamic DIC techniques(1) Dynamic digital device-industrial CCD(2) Dynamic digital device-handy video SONY andCannon EOS digital cameraTraditional acceleration detecting deviceACC Accelerometer

Location for installing thedata retrieving andrecording equipment

DICmethodThe experimental setup is shown in Figure 5 Alldynamic responses of test structure are recorded bylocal images of structural responseData retrieving form accelerometerAccelerometers are installed in each floor and base athorizontal direction

Input of earthquake dataand external force for thesteel structure

Natural earthquake record(1) Strong earthquake Kobe and El Centro 1940earthquake record(2) Strong earthquake TCU Chi-Chi earthquakerecord 1999(3) White noise(4) RAMP

and controllability matrices using singular value decompo-sition (SVD) for extracting a set of equivalent discrete timestate-space equations to extract the mode parameters for thestructural system matrix

5 Results and Discussions

The dynamic experimental procedures to be carried outin this study must be done by overcoming difficultiesencountered when implementing the traditional experimen-tal technique they must also be integrated with imagecapture and dynamic CCD transfer and analysis of imageinformation Additionally the quake loading to a building isof random nature the mode and frequency of the responsivebuilding vibration that causes damages to the building arealso of random nature Hence responses to external quakeloading inputs using free vibration method environmentaldisturbance method and forced oscillation method are usedas the inputs in order to investigate the variations of themode and frequency of vibration for the building when it isbeing gradually damaged Further variations of the first-storycolumn cross-sectional stiffness are investigated to simulatethe influence of column stiffness on the mode and frequencyof building vibration

The reference set with width of column is 400mm underexcitation of various earthquake records and the experimen-tal set with different widths of column is 380mm 360mm280mm and 200mmunder excitation of various earthquakerecords to obtain the dynamic responses respectively Thedetected typical dynamic responses from this proposed DICmethod that used the width of column 380mm as an

example are shown in Figure 6 Then all analysis resultsof natural frequencies damping ratio and mode shape ofsteel test building with width of column = 380mm underexcitation of free vibration Kobe earthquake record and ElCentro 1940 record detected from this proposedDICmethodand traditional accelerometers are listed in Table 2 as anexample respectively All detected dynamic responses fromDIC method and accelerometers are analyzed and comparedwith each other in Sections 51 52 and 53

The difference of natural frequencies between the test andanalysis results of this proposed DIC method and those ofaccelerometers is about 002ndash45 The relative errors ofthe 1st mode and 2nd mode are from 000 to 150 andfrom 000 to 12 respectively The test results reveal thatrelative errors of the 3rd and 4th modes are from 000to 2000 and from 000 to 1500 respectively There isa slight difference between these two methods at the 5thmode The maximum relative error of this mode happens atthe 3rd floor of shearing building under the excitation of ElCentro earthquake record Otherwise the comparison of testand analysis results of damping ratio between the structuraldynamic responses under excitation of various external forcesshows that when the test structure is under excitation offree vibration the damping ratio between these two methodsis slightly different But when the test structure is underexcitation of various earthquake records the difference ofdamping ratio at the 1st mode becomes large Although theerrors of the 3rdmode are higher than the othermodes all themode shapes and frequencies of the test and analysis results ofthis proposedmethod are close to the test and analysis resultsof the structural response records of acceleration recorded byaccelerometer

Shock and Vibration 7

Absolute displacement

minus150

minus100

minus50

Base-X

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

50

100

150

00 100 200 300 400 500 600

Disp

(pi

xel)

(a) Absolute displacement record

minus100

Relative displacement

minus400

minus300

minus200

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

100

200

300

400

00 100 200 300 400 500 600

Disp

(m

m)

(b) Relative displacement record

Time (s)

Story drift

minus100

minus80

minus60

minus40

minus20

Stor

y dr

ift (m

m)

1st story drift2nd story drift

4th story drift5th story drift

00

20

40

60

80

100

00 100 200 300 400 500 600

3rd story drift

(c) Story drift record

Figure 6 The typical dynamic responses detected from DIC method with width of column = 380mm under excitation of free vibration astypical responses records

51 Results of Analyses Using Natural Frequency as the Charac-teristic Damage Indices Figures 7 8 9 10 and 11 show com-parisons of the identified natural frequencies for columns ofvarious cross-sectional sizes subject to different earthquakerecords listed in Table 1 The result shown in Figure 7indicated that when the steel cross-sectional area is 400mmthe highmodenatural frequencies obtained using themethodproposed in this research and the traditional method havesome discrepancies mainly caused by differences betweenthe methods used for zeroing the reference line Howevervariations of the natural frequencies for buildings of differentstiffness subject to various earthquake records (Figure 10simFigure 11) indicate that the method proposed in this researchis capable of predicting the building natural frequency afterthe earthquake as precisely as the conventional methodResults of damage index analyses conducted on the aboveexperimental results shown in Figure 12 reveal that themethod proposed in this research and the conventionalmethod will yield similar damage indices Hence the exper-imental results confirm that the damage index that is basedon frequency can be used as a rapid method to evaluate theoverall health of a buildingWhen an earthquake damages the

building variations of the building stiffness that is graduallychanging can be monitored so that the degree of buildingdamage can be evaluated However this method is notcapable of determining the location of building damage

52 Analysis Results on Approximation Story Damage Index-(ASDI-) Based Damage Index Results of ApproximationStory Damage Index (ASDI) that is the damage index basedon characteristic modal type and frequency are shown inFigures 13ndash16 The free vibration ASDI for various buildingdimensions shown in Figure 13 reveals closer ASDI resultsbetween the method proposed in this research and theconventional method for lower ASDI levels and vice versathe sensitivity of the method proposed in this research ishigher than the conventional method Hence this method iscapable of detecting the degree of building damage based onASDI for building suffering from slight damages Figure 14reveals that when the EL Centro 1940 earthquake records aretested the ASDI are closer for these two methods becauseof the more serious damages at the cross-section Whenthe cross-section dimension is 380mm the ASDI for these

8 Shock and Vibration

Table 2 Test and analysis results of natural frequencies damping ratio andmode shape of steel test building with width of column = 380mmunder excitation of free vibration Kobe earthquake record and El Centro 1940 record

(a)

Test and analysis results of free vibration traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10743 32036 51060 65896 75249Damping ratio 05320 04916 04767 05022 04506Mode shape

Base 0 0 0 0 01F 03155 07997 1 09547 051272F 05912 1 01928 minus08875 minus089233F 07940 04850 minus09206 minus01499 14F 09499 minus03400 minus04162 1 minus082865F 1 minus08691 07326 minus06280 03532

Test and analysis results of free vibration proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10551 31610 50600 65700 75240Damping ratio 06270 06240 048931 04930 05860Mode shapeBase 0 0 0 0 0

1F 03160 08390 1 09120 044212F 05700 1 01650 minus09030 minus082603F 07780 04770 minus09550 minus01430 14F 09250 minus03740 minus04140 1 minus085135F 1 minus09220 08060 minus06520 04180

(b)

Test and analysis results of Kobe earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10317 30969 50368 66412 76884Damping ratio 06373 04574 46337 28685 55449Mode shape

Base 0 0 0 0 01F 03773 09008 1 08386 073902F 06365 1 01596 minus07806 minus13F 08256 04324 minus09755 minus02302 086204F 09710 minus03862 minus03910 1 minus058465F 1 minus08833 07546 minus06033 02264

Test and analysis results of Kobe earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 16292 31732 51040 65572 74244Damping ratio 05594 05271 3952 29022 59642Mode shape

Base 0 0 0 0 01F 03253 08001 09040 08371 079102F 05783 1 02295 minus09281 minus13F 07867 04750 minus1 minus02050 082324F 09320 minus03711 minus03954 1 minus05547

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

2 Shock and Vibration

Moving object Computer

A

CameraCCD

Figure 1 The experimental setup for 2D digital image correlation method

allow timely remedies such as structural reinforcement oreven dismantling the building to alleviate damages to becaused by future quakeThe response of a building to externalvibration is extremely complicated its prediction must con-sider forecasting the quake characteristics and the buildingnonlinear responses to quake and theirmutual correlations inaddition to predicting erratic human factors Hence detailedestimation of the building quake-resisting capability of abuilding and its expected useful life is extremely difficultscholars and civil engineers in the world continually engagein developing quake-resisting buildings in order to safeguardlife and property of occupants

The technology for building diagnoses is mostly basedon the use of sensors (eg accelerometer speedometerstrainometer and global positioning system (GPS) amongmany others) to collect the building dynamic informationand data [3ndash12] Some noise signals from these dynamictest will affect the analysis precision of these kind of dataTherefore some de-noise methods such as a wavelet basedmultistep filtering method and improved particle filteringalgorithms are proposed to filter out the noise from dynamictest [13 14] Then the results are applied to develop math-ematical for example models for identifying the buildingdynamic parameters such as system matrices of structureor modal parameters of structures in a process known assystem identification [15ndash18] Pertinent structural featuressuch as natural frequency mode shape and damping ratiosamong many others can be isolated and identified usingthe above models to develop quantitative damage index Thetime-dependent variation of damage index is the basis forconducting building diagnoses

Some traditional measuring methods are applied todetect the building responses of dynamic parameters Thesemethods need to use many sensitive instruments to providethe needed information Nevertheless the cost involved istoo high to be practical The digital image correlation (DIC)method proposed by our research team is a new opticalmeasurement technique to offer low-cost strain distribu-tion with high precision In this study this DIC methodwill be developed based on developing and applying thedigital photographing technology to monitor the build-ing dynamic response under excitation of various externalearthquake records to test and verify the precision of thisproposed method in monitoring building deformation and

movement Therefore in this research the ldquodynamic digitalimage correlation DICrdquo method will be developed into atechnology for dynamic monitoring of structures based ondigital imagesThemeasurable data on characteristic buildingresponse data and features for example resonant frequenciesMAC COMAC mode shape curvatures dynamic flexibilitydamping and so forth will be excerpted to identify the degreeand location of building damages The results obtained usingthe proposed method will be compared with those reportedby previous researchers in order to verify the validity andapplicability of this dynamic method for timely diagnoses ofbuilding health

2 Methodology-Dynamic Digital ImageCorrelation Method

The dynamic digital image correlation method uses opticalequipment to record the process of the object deformationand movement in digital filmThese photographs can use theldquoFinding Algorithmrdquo to develop the technology of dynamicdigital image correlation method and dynamic DIC for com-paring the partial relativity of two images towards reflectionbefore and after structural deformation or movement theexperimental setup is shown in Figure 1 The comparisonresults can be used to analyze the relative displacement anddeformation of the object between the two moments Thisdynamic DIC technique is basically taken as the foundationof ldquosearch to perform mathematical calculationsrdquo The mainanalysis concept is based on the finite element methodthe images are divided into small mesh the total value ofthe mesh gray scale values of mesh in original image canbe compared with those in the image after transformationso that the corresponding location of a selected mesh inthe deformed image can be identified The two-dimensionalDIC method is suitable for the plane strain test or the testwithout obvious out-of-plane displacement [19] But somecharacteristics of structural dynamic response contain out-of-plane displacement or the specimen surface is not a planeTherefore the three-dimensional DIC method is necessaryfor the measurement Traditionally more than one cameraneeds to be installed to capture images to conduct three-dimensional image analysis process however the analyticalparameters of this method are correlated and excessive

Shock and Vibration 3

Lens center

b998400

a998400

b

a

O

q

pa pbABB

998400

e

A998400

Figure 2The parallax phenomenon caused by the difference objectdistance [20]

Therefore the simplest DIC method based on a single digitalcamera with 3D digital images is proposed by Shih et al [20]

21 A Single Digital Camera for 3D Digital Images [20] If thehorizontal distance for the camera tomove to the right (or theobject to move to the left) is ldquo119890rdquo the horizontal displacementson the photosensitive element are ldquo119860119860

1015840rdquo for a relatively closerpoint ldquo119886rdquo and ldquo1198611198611015840rdquo for a relatively farther point ldquo119887rdquo as shownin Figure 2

The geometric relationship is

1198601198601015840= (

119902

119901119886

) 119890

1198611198611015840= (

119902

119901119887

) 119890

(1)

where 119902119901119886 and119901

119887are the distance between center of lens and

photosensitive element point 119886 and point 119887 respectivelyThehorizontal movement on the sensing element is expressed inpixels thus

1198731198601198601015840 = 120574(

119902

119901119886

) 119890 (2)

where 120574 is the number of pixels of a unit sensing elementin pixelsmm and 119873

1198601198601015840 is the horizontal displacement of

ldquo119886rdquo in pixels Because the correct values of 120574 and 119902 areunknown these two parameters can be combined into asingle parameter ldquoΛrdquo Hence

Λ = 120574119902 (3)

Equation (4) can be rewritten as

Λ =

1198731198601198601015840119901119886

119890

(4)

Once the calibrated value of Λ can be found usingregression analyses the distance between two points can becalculated as follows

119901119887=

Λ

1198731198611198611015840

119890 (5)

Knowing the distance between the two points the hori-zontal and vertical distances of the object to the lens center(119909 119910) can be found Equation (5) can be used to calculate thedistance of any object ldquo119887rdquo and the theoretical error can beestimated by differentiating the equation

119889119901119887=

minusΛ119890

1198732

1198611198611015840

1198891198731198611198611015840 (6)

Equation (6) indicates that the error is inversed propor-tionally to the distance between the object and the cameradistance Hence a greater camera distance will lead to moreprecise results Therefore when the camera is horizontallymoved ldquo119890rdquo distance the horizontal displacement in pixels ofldquo119886rdquo on the sensing element is119873

1198601198601015840 based on the relationship

to approximate triangular form If the horizontal coordinateof 119886 with respect to the lens center is 119909

119886 its relationship

to the photohorizontal coordinate 119883119860

fits the followingrelationship

119909119886

119883119860

=

119890

1198731198601198601015840

(7)

Moving the terms one obtains

119909119886=

119883119860119890

1198731198601198601015840

(8)

Similarly

119910119886=

119884119860119890

1198731198601198601015840

(9)

22TheThree-Dimensional Dynamic DICMethod with Spine-Type Prism The principal of three-dimensional DIC forusing a single digital camera to photograph digital imagesis based on the plane geometrical images of the 3D objectphotographed from different angle displaying these twoimages at the same general appearance of a picture andthen assembling these two digital images in an analyticalgeometry as three-dimensional coordinates to be displayed asthree-dimensional images This measurement principle canbe accurately applied in static deformation test Neverthelessthis theory is not suitable for three-dimensional dynamictests A key point of three-dimensional DIC technique isapplied a camera to capture images of object movement inthe same position If the above-mentioned method is applieddirectly to measure dynamic response of structure it wouldresult in significant analysis errors

Therefore a spine-type prism is proposed to separatethe view axis of the digital camera into two axes which areinclined to each other in this research to conduct three-dimensional dynamic digital image correlation techniques In

4 Shock and Vibration

Object

Virtual image L Virtual image R

Image

Prism

CameraRL

Virtual camera Virtual camera

Figure 3 Principle of the spine-type prism for 3-dimensional DIC

the dynamic test digital cameras can receive two images withparallax in a single capture action These two images withparallax are stored in the right and left parts of the sensor ofthe cameraThe analysis principle of this proposedmethod isshown in Figure 3 The major advantage of this technology isthe maneuverability As long as the prism is installed on thecamera the camera can be used normally to capture imageswith parallax

In order to identify the three-dimensional dynamicresponse of structure under excitation of external force thehardware specifications of cameras must meet the require-ment of sensitive instruments and equipment with sufficientfrequency or sufficient readings for each recoding channelwithin a unit time Hence NexShot2C-2M CMOS industrialcamera with 12-inch CMOS active-pixel digital image sen-sor 1600 times 1200 dots per inch 41Hz capturing frequencysensitization 2 mega pixels and the highest sampling ratereaches to 53 fps (frames per seconds) is used to collect theuncompressed photographs with high quality in this studyBecause the recording frequency is insufficient the scanningnumbers of selecting images adjust 120 pieces and selectingimage reaches to 42 pictures per minute Then the collectedimages can be used to analyze the displacement reaction oftest object by the DIC method

3 Damage Index

31 Natural Frequency as Damage Index When building isexcited by external force the dynamic features can be easilyextracted from structural dynamic response such as naturalfrequency mode shape and damping ratios These dynamicfeatures can be used to establish damage index to diagnose thestructural health In this section natural frequency variationof structure under the excitation of external force to inducestructural injury is proposed to be damage index to monitorstructural health

The evaluation formula of damage index based on naturalfrequency is expressed as follows

120575119872

= 1 minus

(1198790)initial

(1198790)max

(10)

where (1198790)initial represents basic dynamic cycle of undamaged

structure (1198790)max is the maximum basic dynamic cycle of

time history of dynamic response The value of damageindex based on natural frequency is between 0 and 1 0 andrepresents undamaged of structure

32 Approximation Story Damage Index (ASDI) Story Dam-age Index (SDI) applied the participative parameters fromstructural system such as stiffness and mass to producestructural modal parameters (eigenvalue 120582(= 119908

2) and mode

shape 120601) and the relationship between mass of floor andstiffness to establish a Story Damage Index for assessingbuilding damage excited by earthquake Nevertheless themass of floor is hard to evaluate Therefore ApproximationStory Damage Index (ASDI) is proposed to ignore the massof floor This method requires only one modal parameterto assess story damage Wang et al [16] The main conceptof ASDI is applied to plane structure of shear frame Thetorsion coincidental effect must be considered for three-dimensional structure The damage index from frequencyand modal vector of the first mode shape has been transforminto summation inertia of floor to story drift mode Thenstory drift mode changes into story stiffness of structure toassess the decay of story stiffness after structural damage asan estimating index

The evaluation formula of Approximation Story DamageIndex (ASDI) is expressed as follows

ASDI119897= 1 minus

120596lowast2

119895sum119873

119894=1(120601lowast

119894119895Δ120601lowast

119894119895)

1205962

119895sum119873

119894=1(120601119894119895Δ120601lowast

119894119895)

(11)

where 119897is degree of freedom 119873 is total floor of structure 120596lowast119895

is the 119895th natural frequency after structural damage 120596119895is

the 119895th natural frequency before structural damage 120601lowast119894119895is the

mode shape of 119894th degree of freedom of the 119895th mode shapeafter structural damage 120601

119894119895is the mode shape of 119894th degree of

freedom of the 119895thmode shape before structural damageThevalue ofASDI is between 0 and 1 0 and represents undamagedof structure

33 Interstory Drift Mode Shape (IDMS) as Damage IndexWhen structural damage happens the stiffness of build-ing structure drops off affecting the displacement modereaction of structure Thus IDMS is proposed to probethe relationship of structural destructiveness and variationof displacement mode to judge the structural damage onbuilding The ratio of story drift of the first mode usedIDMS as a normalized datum value of roof before damagefor comparison with IDMS as a normalized datum value ofroof after damage When the sensitivity of IDMS is higherthe probability of structural damage is higher The definitionof story drift and sensitivity of IDMS is expressed as follows

Shock and Vibration 5

Figure 4 The completed five-story shearing steel structure

Story driftis as follows

120575119894= Max (Δ

119894minus Δ119894minus1

)

1205751= Max (Δ

1minus Δ119866)

(12)

where 120575119894is time history analysis of the maximum story

drift of the 119894th floor Δ119894is time history analysis of the

structural displacement history of the 119894th floor Δ119866is ground

displacement

Sensitivity of IDMS is as follows

119878119894=

119863119894minus 119861119894

119861119894

times 100 (13)

where 119878119894is the sensitivity() of the story drift variation after

damage of the 1st mode of the 119894th floor of building 119863119894is the

normalized story drift mode value after damage of the 119894thfloor of building 119861

119894is the normalized story drift mode value

before damage of the 119894th floor of building

4 Experimental Setup

The shaking table model test will be used in this research tocarry out all laboratory studies The shearing steel structuralmodel is a five-story steel framed structure using steel with 119864

value of 2times 1011 kgm2Thenet height of each story is 800mmwith a total building height of 5800mm width of 1520mmand depth of 400mm Each story weighs 242 kg and totalstructure has a designednatural frequency of 1076Hz and thenatural frequency of the second vibration mode of 321HzFigure 4 shows the photo of the completed five-story shearingsteel structure Figure 5 shows the installed camera andother relevant equipments Each element used in the modelstructure has been carefully evaluated to check whether itreaches the yield point If an element shows the sign of yieldit is immediately replaced in order to warrant the accuracy of

Dist

Dist

Camels height

SONY height

Figure 5 The experimental setup of installed camera and otherrelevant equipment

the laboratory study results A series of dynamic experimentshave been planned the results are compared with thoseobtained using accelerometer But there are two factors (1)the maximum throw of this test shaking table is plusmn125mm(2) test structure should remain within linear elastic rangefor dynamic test and it needs to be considered in this studyTherefore the maximum acceleration should be scaled downto 15ndash20 gal Actually the purpose of this research is toobtain the modal frequencies and modes of test structurewithin linear elastic range Therefore the authenticities ofearthquake records do not provide sensitivity Otherwise ElCentro Kobe and TCU earthquake records are providedwith characteristic of far field and near-fault earthquakeThese records are applied to excite modal response of highfrequencies and low frequencies of test structureThen whitenoise study is carried out in order to investigate whetherthe shearing steel structure is subject to environmentalinterference thatwill adversely impact the practicability of theexperimental results Table 1 lists the study plan

41 System Identification Method In this research themethod of comparing images is implemented to reveal thetime-dependent variation of displacement so that using thesystem identification method can be used to measure theexternal force input and the resulting dynamic response ofthe structural degree of freedom for obtaining the structuralmode parameters for example frequency 120596 damping ratio120585 vibration mode 120601 and so forth The system realizationusing information matrix (SRIM) which uses the systemidentification matrix of the measured data is capable ofidentifying the system modes of multiple inputs and outputsin additional to identify the system dynamic structuralmatrices based on the structural system matrix The modeparameters including frequency (120596) damping ratio (120585) andvibration mode (120601) can then be extracted from the dynamicstructure of the identification of the two-stage system forevaluating the building damages The SRIM system used inthis system is based on the identification theory developed byJuang [21] to construct a broad Hankel matrix using impulseresponse data and to estimate the extendable observability

6 Shock and Vibration

Table 1 Study plan for laboratory experiment

Name of structure Experimental shearing steel structureShearing steel structure Reference set (width of column) Experimental set (width of column)Normal monitoringexperiment 400mm 380mm 360mm 280mm and 200mm

Data retrieving andrecording equipment

Equipment for dynamic DIC techniques(1) Dynamic digital device-industrial CCD(2) Dynamic digital device-handy video SONY andCannon EOS digital cameraTraditional acceleration detecting deviceACC Accelerometer

Location for installing thedata retrieving andrecording equipment

DICmethodThe experimental setup is shown in Figure 5 Alldynamic responses of test structure are recorded bylocal images of structural responseData retrieving form accelerometerAccelerometers are installed in each floor and base athorizontal direction

Input of earthquake dataand external force for thesteel structure

Natural earthquake record(1) Strong earthquake Kobe and El Centro 1940earthquake record(2) Strong earthquake TCU Chi-Chi earthquakerecord 1999(3) White noise(4) RAMP

and controllability matrices using singular value decompo-sition (SVD) for extracting a set of equivalent discrete timestate-space equations to extract the mode parameters for thestructural system matrix

5 Results and Discussions

The dynamic experimental procedures to be carried outin this study must be done by overcoming difficultiesencountered when implementing the traditional experimen-tal technique they must also be integrated with imagecapture and dynamic CCD transfer and analysis of imageinformation Additionally the quake loading to a building isof random nature the mode and frequency of the responsivebuilding vibration that causes damages to the building arealso of random nature Hence responses to external quakeloading inputs using free vibration method environmentaldisturbance method and forced oscillation method are usedas the inputs in order to investigate the variations of themode and frequency of vibration for the building when it isbeing gradually damaged Further variations of the first-storycolumn cross-sectional stiffness are investigated to simulatethe influence of column stiffness on the mode and frequencyof building vibration

The reference set with width of column is 400mm underexcitation of various earthquake records and the experimen-tal set with different widths of column is 380mm 360mm280mm and 200mmunder excitation of various earthquakerecords to obtain the dynamic responses respectively Thedetected typical dynamic responses from this proposed DICmethod that used the width of column 380mm as an

example are shown in Figure 6 Then all analysis resultsof natural frequencies damping ratio and mode shape ofsteel test building with width of column = 380mm underexcitation of free vibration Kobe earthquake record and ElCentro 1940 record detected from this proposedDICmethodand traditional accelerometers are listed in Table 2 as anexample respectively All detected dynamic responses fromDIC method and accelerometers are analyzed and comparedwith each other in Sections 51 52 and 53

The difference of natural frequencies between the test andanalysis results of this proposed DIC method and those ofaccelerometers is about 002ndash45 The relative errors ofthe 1st mode and 2nd mode are from 000 to 150 andfrom 000 to 12 respectively The test results reveal thatrelative errors of the 3rd and 4th modes are from 000to 2000 and from 000 to 1500 respectively There isa slight difference between these two methods at the 5thmode The maximum relative error of this mode happens atthe 3rd floor of shearing building under the excitation of ElCentro earthquake record Otherwise the comparison of testand analysis results of damping ratio between the structuraldynamic responses under excitation of various external forcesshows that when the test structure is under excitation offree vibration the damping ratio between these two methodsis slightly different But when the test structure is underexcitation of various earthquake records the difference ofdamping ratio at the 1st mode becomes large Although theerrors of the 3rdmode are higher than the othermodes all themode shapes and frequencies of the test and analysis results ofthis proposedmethod are close to the test and analysis resultsof the structural response records of acceleration recorded byaccelerometer

Shock and Vibration 7

Absolute displacement

minus150

minus100

minus50

Base-X

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

50

100

150

00 100 200 300 400 500 600

Disp

(pi

xel)

(a) Absolute displacement record

minus100

Relative displacement

minus400

minus300

minus200

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

100

200

300

400

00 100 200 300 400 500 600

Disp

(m

m)

(b) Relative displacement record

Time (s)

Story drift

minus100

minus80

minus60

minus40

minus20

Stor

y dr

ift (m

m)

1st story drift2nd story drift

4th story drift5th story drift

00

20

40

60

80

100

00 100 200 300 400 500 600

3rd story drift

(c) Story drift record

Figure 6 The typical dynamic responses detected from DIC method with width of column = 380mm under excitation of free vibration astypical responses records

51 Results of Analyses Using Natural Frequency as the Charac-teristic Damage Indices Figures 7 8 9 10 and 11 show com-parisons of the identified natural frequencies for columns ofvarious cross-sectional sizes subject to different earthquakerecords listed in Table 1 The result shown in Figure 7indicated that when the steel cross-sectional area is 400mmthe highmodenatural frequencies obtained using themethodproposed in this research and the traditional method havesome discrepancies mainly caused by differences betweenthe methods used for zeroing the reference line Howevervariations of the natural frequencies for buildings of differentstiffness subject to various earthquake records (Figure 10simFigure 11) indicate that the method proposed in this researchis capable of predicting the building natural frequency afterthe earthquake as precisely as the conventional methodResults of damage index analyses conducted on the aboveexperimental results shown in Figure 12 reveal that themethod proposed in this research and the conventionalmethod will yield similar damage indices Hence the exper-imental results confirm that the damage index that is basedon frequency can be used as a rapid method to evaluate theoverall health of a buildingWhen an earthquake damages the

building variations of the building stiffness that is graduallychanging can be monitored so that the degree of buildingdamage can be evaluated However this method is notcapable of determining the location of building damage

52 Analysis Results on Approximation Story Damage Index-(ASDI-) Based Damage Index Results of ApproximationStory Damage Index (ASDI) that is the damage index basedon characteristic modal type and frequency are shown inFigures 13ndash16 The free vibration ASDI for various buildingdimensions shown in Figure 13 reveals closer ASDI resultsbetween the method proposed in this research and theconventional method for lower ASDI levels and vice versathe sensitivity of the method proposed in this research ishigher than the conventional method Hence this method iscapable of detecting the degree of building damage based onASDI for building suffering from slight damages Figure 14reveals that when the EL Centro 1940 earthquake records aretested the ASDI are closer for these two methods becauseof the more serious damages at the cross-section Whenthe cross-section dimension is 380mm the ASDI for these

8 Shock and Vibration

Table 2 Test and analysis results of natural frequencies damping ratio andmode shape of steel test building with width of column = 380mmunder excitation of free vibration Kobe earthquake record and El Centro 1940 record

(a)

Test and analysis results of free vibration traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10743 32036 51060 65896 75249Damping ratio 05320 04916 04767 05022 04506Mode shape

Base 0 0 0 0 01F 03155 07997 1 09547 051272F 05912 1 01928 minus08875 minus089233F 07940 04850 minus09206 minus01499 14F 09499 minus03400 minus04162 1 minus082865F 1 minus08691 07326 minus06280 03532

Test and analysis results of free vibration proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10551 31610 50600 65700 75240Damping ratio 06270 06240 048931 04930 05860Mode shapeBase 0 0 0 0 0

1F 03160 08390 1 09120 044212F 05700 1 01650 minus09030 minus082603F 07780 04770 minus09550 minus01430 14F 09250 minus03740 minus04140 1 minus085135F 1 minus09220 08060 minus06520 04180

(b)

Test and analysis results of Kobe earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10317 30969 50368 66412 76884Damping ratio 06373 04574 46337 28685 55449Mode shape

Base 0 0 0 0 01F 03773 09008 1 08386 073902F 06365 1 01596 minus07806 minus13F 08256 04324 minus09755 minus02302 086204F 09710 minus03862 minus03910 1 minus058465F 1 minus08833 07546 minus06033 02264

Test and analysis results of Kobe earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 16292 31732 51040 65572 74244Damping ratio 05594 05271 3952 29022 59642Mode shape

Base 0 0 0 0 01F 03253 08001 09040 08371 079102F 05783 1 02295 minus09281 minus13F 07867 04750 minus1 minus02050 082324F 09320 minus03711 minus03954 1 minus05547

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 3

Lens center

b998400

a998400

b

a

O

q

pa pbABB

998400

e

A998400

Figure 2The parallax phenomenon caused by the difference objectdistance [20]

Therefore the simplest DIC method based on a single digitalcamera with 3D digital images is proposed by Shih et al [20]

21 A Single Digital Camera for 3D Digital Images [20] If thehorizontal distance for the camera tomove to the right (or theobject to move to the left) is ldquo119890rdquo the horizontal displacementson the photosensitive element are ldquo119860119860

1015840rdquo for a relatively closerpoint ldquo119886rdquo and ldquo1198611198611015840rdquo for a relatively farther point ldquo119887rdquo as shownin Figure 2

The geometric relationship is

1198601198601015840= (

119902

119901119886

) 119890

1198611198611015840= (

119902

119901119887

) 119890

(1)

where 119902119901119886 and119901

119887are the distance between center of lens and

photosensitive element point 119886 and point 119887 respectivelyThehorizontal movement on the sensing element is expressed inpixels thus

1198731198601198601015840 = 120574(

119902

119901119886

) 119890 (2)

where 120574 is the number of pixels of a unit sensing elementin pixelsmm and 119873

1198601198601015840 is the horizontal displacement of

ldquo119886rdquo in pixels Because the correct values of 120574 and 119902 areunknown these two parameters can be combined into asingle parameter ldquoΛrdquo Hence

Λ = 120574119902 (3)

Equation (4) can be rewritten as

Λ =

1198731198601198601015840119901119886

119890

(4)

Once the calibrated value of Λ can be found usingregression analyses the distance between two points can becalculated as follows

119901119887=

Λ

1198731198611198611015840

119890 (5)

Knowing the distance between the two points the hori-zontal and vertical distances of the object to the lens center(119909 119910) can be found Equation (5) can be used to calculate thedistance of any object ldquo119887rdquo and the theoretical error can beestimated by differentiating the equation

119889119901119887=

minusΛ119890

1198732

1198611198611015840

1198891198731198611198611015840 (6)

Equation (6) indicates that the error is inversed propor-tionally to the distance between the object and the cameradistance Hence a greater camera distance will lead to moreprecise results Therefore when the camera is horizontallymoved ldquo119890rdquo distance the horizontal displacement in pixels ofldquo119886rdquo on the sensing element is119873

1198601198601015840 based on the relationship

to approximate triangular form If the horizontal coordinateof 119886 with respect to the lens center is 119909

119886 its relationship

to the photohorizontal coordinate 119883119860

fits the followingrelationship

119909119886

119883119860

=

119890

1198731198601198601015840

(7)

Moving the terms one obtains

119909119886=

119883119860119890

1198731198601198601015840

(8)

Similarly

119910119886=

119884119860119890

1198731198601198601015840

(9)

22TheThree-Dimensional Dynamic DICMethod with Spine-Type Prism The principal of three-dimensional DIC forusing a single digital camera to photograph digital imagesis based on the plane geometrical images of the 3D objectphotographed from different angle displaying these twoimages at the same general appearance of a picture andthen assembling these two digital images in an analyticalgeometry as three-dimensional coordinates to be displayed asthree-dimensional images This measurement principle canbe accurately applied in static deformation test Neverthelessthis theory is not suitable for three-dimensional dynamictests A key point of three-dimensional DIC technique isapplied a camera to capture images of object movement inthe same position If the above-mentioned method is applieddirectly to measure dynamic response of structure it wouldresult in significant analysis errors

Therefore a spine-type prism is proposed to separatethe view axis of the digital camera into two axes which areinclined to each other in this research to conduct three-dimensional dynamic digital image correlation techniques In

4 Shock and Vibration

Object

Virtual image L Virtual image R

Image

Prism

CameraRL

Virtual camera Virtual camera

Figure 3 Principle of the spine-type prism for 3-dimensional DIC

the dynamic test digital cameras can receive two images withparallax in a single capture action These two images withparallax are stored in the right and left parts of the sensor ofthe cameraThe analysis principle of this proposedmethod isshown in Figure 3 The major advantage of this technology isthe maneuverability As long as the prism is installed on thecamera the camera can be used normally to capture imageswith parallax

In order to identify the three-dimensional dynamicresponse of structure under excitation of external force thehardware specifications of cameras must meet the require-ment of sensitive instruments and equipment with sufficientfrequency or sufficient readings for each recoding channelwithin a unit time Hence NexShot2C-2M CMOS industrialcamera with 12-inch CMOS active-pixel digital image sen-sor 1600 times 1200 dots per inch 41Hz capturing frequencysensitization 2 mega pixels and the highest sampling ratereaches to 53 fps (frames per seconds) is used to collect theuncompressed photographs with high quality in this studyBecause the recording frequency is insufficient the scanningnumbers of selecting images adjust 120 pieces and selectingimage reaches to 42 pictures per minute Then the collectedimages can be used to analyze the displacement reaction oftest object by the DIC method

3 Damage Index

31 Natural Frequency as Damage Index When building isexcited by external force the dynamic features can be easilyextracted from structural dynamic response such as naturalfrequency mode shape and damping ratios These dynamicfeatures can be used to establish damage index to diagnose thestructural health In this section natural frequency variationof structure under the excitation of external force to inducestructural injury is proposed to be damage index to monitorstructural health

The evaluation formula of damage index based on naturalfrequency is expressed as follows

120575119872

= 1 minus

(1198790)initial

(1198790)max

(10)

where (1198790)initial represents basic dynamic cycle of undamaged

structure (1198790)max is the maximum basic dynamic cycle of

time history of dynamic response The value of damageindex based on natural frequency is between 0 and 1 0 andrepresents undamaged of structure

32 Approximation Story Damage Index (ASDI) Story Dam-age Index (SDI) applied the participative parameters fromstructural system such as stiffness and mass to producestructural modal parameters (eigenvalue 120582(= 119908

2) and mode

shape 120601) and the relationship between mass of floor andstiffness to establish a Story Damage Index for assessingbuilding damage excited by earthquake Nevertheless themass of floor is hard to evaluate Therefore ApproximationStory Damage Index (ASDI) is proposed to ignore the massof floor This method requires only one modal parameterto assess story damage Wang et al [16] The main conceptof ASDI is applied to plane structure of shear frame Thetorsion coincidental effect must be considered for three-dimensional structure The damage index from frequencyand modal vector of the first mode shape has been transforminto summation inertia of floor to story drift mode Thenstory drift mode changes into story stiffness of structure toassess the decay of story stiffness after structural damage asan estimating index

The evaluation formula of Approximation Story DamageIndex (ASDI) is expressed as follows

ASDI119897= 1 minus

120596lowast2

119895sum119873

119894=1(120601lowast

119894119895Δ120601lowast

119894119895)

1205962

119895sum119873

119894=1(120601119894119895Δ120601lowast

119894119895)

(11)

where 119897is degree of freedom 119873 is total floor of structure 120596lowast119895

is the 119895th natural frequency after structural damage 120596119895is

the 119895th natural frequency before structural damage 120601lowast119894119895is the

mode shape of 119894th degree of freedom of the 119895th mode shapeafter structural damage 120601

119894119895is the mode shape of 119894th degree of

freedom of the 119895thmode shape before structural damageThevalue ofASDI is between 0 and 1 0 and represents undamagedof structure

33 Interstory Drift Mode Shape (IDMS) as Damage IndexWhen structural damage happens the stiffness of build-ing structure drops off affecting the displacement modereaction of structure Thus IDMS is proposed to probethe relationship of structural destructiveness and variationof displacement mode to judge the structural damage onbuilding The ratio of story drift of the first mode usedIDMS as a normalized datum value of roof before damagefor comparison with IDMS as a normalized datum value ofroof after damage When the sensitivity of IDMS is higherthe probability of structural damage is higher The definitionof story drift and sensitivity of IDMS is expressed as follows

Shock and Vibration 5

Figure 4 The completed five-story shearing steel structure

Story driftis as follows

120575119894= Max (Δ

119894minus Δ119894minus1

)

1205751= Max (Δ

1minus Δ119866)

(12)

where 120575119894is time history analysis of the maximum story

drift of the 119894th floor Δ119894is time history analysis of the

structural displacement history of the 119894th floor Δ119866is ground

displacement

Sensitivity of IDMS is as follows

119878119894=

119863119894minus 119861119894

119861119894

times 100 (13)

where 119878119894is the sensitivity() of the story drift variation after

damage of the 1st mode of the 119894th floor of building 119863119894is the

normalized story drift mode value after damage of the 119894thfloor of building 119861

119894is the normalized story drift mode value

before damage of the 119894th floor of building

4 Experimental Setup

The shaking table model test will be used in this research tocarry out all laboratory studies The shearing steel structuralmodel is a five-story steel framed structure using steel with 119864

value of 2times 1011 kgm2Thenet height of each story is 800mmwith a total building height of 5800mm width of 1520mmand depth of 400mm Each story weighs 242 kg and totalstructure has a designednatural frequency of 1076Hz and thenatural frequency of the second vibration mode of 321HzFigure 4 shows the photo of the completed five-story shearingsteel structure Figure 5 shows the installed camera andother relevant equipments Each element used in the modelstructure has been carefully evaluated to check whether itreaches the yield point If an element shows the sign of yieldit is immediately replaced in order to warrant the accuracy of

Dist

Dist

Camels height

SONY height

Figure 5 The experimental setup of installed camera and otherrelevant equipment

the laboratory study results A series of dynamic experimentshave been planned the results are compared with thoseobtained using accelerometer But there are two factors (1)the maximum throw of this test shaking table is plusmn125mm(2) test structure should remain within linear elastic rangefor dynamic test and it needs to be considered in this studyTherefore the maximum acceleration should be scaled downto 15ndash20 gal Actually the purpose of this research is toobtain the modal frequencies and modes of test structurewithin linear elastic range Therefore the authenticities ofearthquake records do not provide sensitivity Otherwise ElCentro Kobe and TCU earthquake records are providedwith characteristic of far field and near-fault earthquakeThese records are applied to excite modal response of highfrequencies and low frequencies of test structureThen whitenoise study is carried out in order to investigate whetherthe shearing steel structure is subject to environmentalinterference thatwill adversely impact the practicability of theexperimental results Table 1 lists the study plan

41 System Identification Method In this research themethod of comparing images is implemented to reveal thetime-dependent variation of displacement so that using thesystem identification method can be used to measure theexternal force input and the resulting dynamic response ofthe structural degree of freedom for obtaining the structuralmode parameters for example frequency 120596 damping ratio120585 vibration mode 120601 and so forth The system realizationusing information matrix (SRIM) which uses the systemidentification matrix of the measured data is capable ofidentifying the system modes of multiple inputs and outputsin additional to identify the system dynamic structuralmatrices based on the structural system matrix The modeparameters including frequency (120596) damping ratio (120585) andvibration mode (120601) can then be extracted from the dynamicstructure of the identification of the two-stage system forevaluating the building damages The SRIM system used inthis system is based on the identification theory developed byJuang [21] to construct a broad Hankel matrix using impulseresponse data and to estimate the extendable observability

6 Shock and Vibration

Table 1 Study plan for laboratory experiment

Name of structure Experimental shearing steel structureShearing steel structure Reference set (width of column) Experimental set (width of column)Normal monitoringexperiment 400mm 380mm 360mm 280mm and 200mm

Data retrieving andrecording equipment

Equipment for dynamic DIC techniques(1) Dynamic digital device-industrial CCD(2) Dynamic digital device-handy video SONY andCannon EOS digital cameraTraditional acceleration detecting deviceACC Accelerometer

Location for installing thedata retrieving andrecording equipment

DICmethodThe experimental setup is shown in Figure 5 Alldynamic responses of test structure are recorded bylocal images of structural responseData retrieving form accelerometerAccelerometers are installed in each floor and base athorizontal direction

Input of earthquake dataand external force for thesteel structure

Natural earthquake record(1) Strong earthquake Kobe and El Centro 1940earthquake record(2) Strong earthquake TCU Chi-Chi earthquakerecord 1999(3) White noise(4) RAMP

and controllability matrices using singular value decompo-sition (SVD) for extracting a set of equivalent discrete timestate-space equations to extract the mode parameters for thestructural system matrix

5 Results and Discussions

The dynamic experimental procedures to be carried outin this study must be done by overcoming difficultiesencountered when implementing the traditional experimen-tal technique they must also be integrated with imagecapture and dynamic CCD transfer and analysis of imageinformation Additionally the quake loading to a building isof random nature the mode and frequency of the responsivebuilding vibration that causes damages to the building arealso of random nature Hence responses to external quakeloading inputs using free vibration method environmentaldisturbance method and forced oscillation method are usedas the inputs in order to investigate the variations of themode and frequency of vibration for the building when it isbeing gradually damaged Further variations of the first-storycolumn cross-sectional stiffness are investigated to simulatethe influence of column stiffness on the mode and frequencyof building vibration

The reference set with width of column is 400mm underexcitation of various earthquake records and the experimen-tal set with different widths of column is 380mm 360mm280mm and 200mmunder excitation of various earthquakerecords to obtain the dynamic responses respectively Thedetected typical dynamic responses from this proposed DICmethod that used the width of column 380mm as an

example are shown in Figure 6 Then all analysis resultsof natural frequencies damping ratio and mode shape ofsteel test building with width of column = 380mm underexcitation of free vibration Kobe earthquake record and ElCentro 1940 record detected from this proposedDICmethodand traditional accelerometers are listed in Table 2 as anexample respectively All detected dynamic responses fromDIC method and accelerometers are analyzed and comparedwith each other in Sections 51 52 and 53

The difference of natural frequencies between the test andanalysis results of this proposed DIC method and those ofaccelerometers is about 002ndash45 The relative errors ofthe 1st mode and 2nd mode are from 000 to 150 andfrom 000 to 12 respectively The test results reveal thatrelative errors of the 3rd and 4th modes are from 000to 2000 and from 000 to 1500 respectively There isa slight difference between these two methods at the 5thmode The maximum relative error of this mode happens atthe 3rd floor of shearing building under the excitation of ElCentro earthquake record Otherwise the comparison of testand analysis results of damping ratio between the structuraldynamic responses under excitation of various external forcesshows that when the test structure is under excitation offree vibration the damping ratio between these two methodsis slightly different But when the test structure is underexcitation of various earthquake records the difference ofdamping ratio at the 1st mode becomes large Although theerrors of the 3rdmode are higher than the othermodes all themode shapes and frequencies of the test and analysis results ofthis proposedmethod are close to the test and analysis resultsof the structural response records of acceleration recorded byaccelerometer

Shock and Vibration 7

Absolute displacement

minus150

minus100

minus50

Base-X

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

50

100

150

00 100 200 300 400 500 600

Disp

(pi

xel)

(a) Absolute displacement record

minus100

Relative displacement

minus400

minus300

minus200

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

100

200

300

400

00 100 200 300 400 500 600

Disp

(m

m)

(b) Relative displacement record

Time (s)

Story drift

minus100

minus80

minus60

minus40

minus20

Stor

y dr

ift (m

m)

1st story drift2nd story drift

4th story drift5th story drift

00

20

40

60

80

100

00 100 200 300 400 500 600

3rd story drift

(c) Story drift record

Figure 6 The typical dynamic responses detected from DIC method with width of column = 380mm under excitation of free vibration astypical responses records

51 Results of Analyses Using Natural Frequency as the Charac-teristic Damage Indices Figures 7 8 9 10 and 11 show com-parisons of the identified natural frequencies for columns ofvarious cross-sectional sizes subject to different earthquakerecords listed in Table 1 The result shown in Figure 7indicated that when the steel cross-sectional area is 400mmthe highmodenatural frequencies obtained using themethodproposed in this research and the traditional method havesome discrepancies mainly caused by differences betweenthe methods used for zeroing the reference line Howevervariations of the natural frequencies for buildings of differentstiffness subject to various earthquake records (Figure 10simFigure 11) indicate that the method proposed in this researchis capable of predicting the building natural frequency afterthe earthquake as precisely as the conventional methodResults of damage index analyses conducted on the aboveexperimental results shown in Figure 12 reveal that themethod proposed in this research and the conventionalmethod will yield similar damage indices Hence the exper-imental results confirm that the damage index that is basedon frequency can be used as a rapid method to evaluate theoverall health of a buildingWhen an earthquake damages the

building variations of the building stiffness that is graduallychanging can be monitored so that the degree of buildingdamage can be evaluated However this method is notcapable of determining the location of building damage

52 Analysis Results on Approximation Story Damage Index-(ASDI-) Based Damage Index Results of ApproximationStory Damage Index (ASDI) that is the damage index basedon characteristic modal type and frequency are shown inFigures 13ndash16 The free vibration ASDI for various buildingdimensions shown in Figure 13 reveals closer ASDI resultsbetween the method proposed in this research and theconventional method for lower ASDI levels and vice versathe sensitivity of the method proposed in this research ishigher than the conventional method Hence this method iscapable of detecting the degree of building damage based onASDI for building suffering from slight damages Figure 14reveals that when the EL Centro 1940 earthquake records aretested the ASDI are closer for these two methods becauseof the more serious damages at the cross-section Whenthe cross-section dimension is 380mm the ASDI for these

8 Shock and Vibration

Table 2 Test and analysis results of natural frequencies damping ratio andmode shape of steel test building with width of column = 380mmunder excitation of free vibration Kobe earthquake record and El Centro 1940 record

(a)

Test and analysis results of free vibration traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10743 32036 51060 65896 75249Damping ratio 05320 04916 04767 05022 04506Mode shape

Base 0 0 0 0 01F 03155 07997 1 09547 051272F 05912 1 01928 minus08875 minus089233F 07940 04850 minus09206 minus01499 14F 09499 minus03400 minus04162 1 minus082865F 1 minus08691 07326 minus06280 03532

Test and analysis results of free vibration proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10551 31610 50600 65700 75240Damping ratio 06270 06240 048931 04930 05860Mode shapeBase 0 0 0 0 0

1F 03160 08390 1 09120 044212F 05700 1 01650 minus09030 minus082603F 07780 04770 minus09550 minus01430 14F 09250 minus03740 minus04140 1 minus085135F 1 minus09220 08060 minus06520 04180

(b)

Test and analysis results of Kobe earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10317 30969 50368 66412 76884Damping ratio 06373 04574 46337 28685 55449Mode shape

Base 0 0 0 0 01F 03773 09008 1 08386 073902F 06365 1 01596 minus07806 minus13F 08256 04324 minus09755 minus02302 086204F 09710 minus03862 minus03910 1 minus058465F 1 minus08833 07546 minus06033 02264

Test and analysis results of Kobe earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 16292 31732 51040 65572 74244Damping ratio 05594 05271 3952 29022 59642Mode shape

Base 0 0 0 0 01F 03253 08001 09040 08371 079102F 05783 1 02295 minus09281 minus13F 07867 04750 minus1 minus02050 082324F 09320 minus03711 minus03954 1 minus05547

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

4 Shock and Vibration

Object

Virtual image L Virtual image R

Image

Prism

CameraRL

Virtual camera Virtual camera

Figure 3 Principle of the spine-type prism for 3-dimensional DIC

the dynamic test digital cameras can receive two images withparallax in a single capture action These two images withparallax are stored in the right and left parts of the sensor ofthe cameraThe analysis principle of this proposedmethod isshown in Figure 3 The major advantage of this technology isthe maneuverability As long as the prism is installed on thecamera the camera can be used normally to capture imageswith parallax

In order to identify the three-dimensional dynamicresponse of structure under excitation of external force thehardware specifications of cameras must meet the require-ment of sensitive instruments and equipment with sufficientfrequency or sufficient readings for each recoding channelwithin a unit time Hence NexShot2C-2M CMOS industrialcamera with 12-inch CMOS active-pixel digital image sen-sor 1600 times 1200 dots per inch 41Hz capturing frequencysensitization 2 mega pixels and the highest sampling ratereaches to 53 fps (frames per seconds) is used to collect theuncompressed photographs with high quality in this studyBecause the recording frequency is insufficient the scanningnumbers of selecting images adjust 120 pieces and selectingimage reaches to 42 pictures per minute Then the collectedimages can be used to analyze the displacement reaction oftest object by the DIC method

3 Damage Index

31 Natural Frequency as Damage Index When building isexcited by external force the dynamic features can be easilyextracted from structural dynamic response such as naturalfrequency mode shape and damping ratios These dynamicfeatures can be used to establish damage index to diagnose thestructural health In this section natural frequency variationof structure under the excitation of external force to inducestructural injury is proposed to be damage index to monitorstructural health

The evaluation formula of damage index based on naturalfrequency is expressed as follows

120575119872

= 1 minus

(1198790)initial

(1198790)max

(10)

where (1198790)initial represents basic dynamic cycle of undamaged

structure (1198790)max is the maximum basic dynamic cycle of

time history of dynamic response The value of damageindex based on natural frequency is between 0 and 1 0 andrepresents undamaged of structure

32 Approximation Story Damage Index (ASDI) Story Dam-age Index (SDI) applied the participative parameters fromstructural system such as stiffness and mass to producestructural modal parameters (eigenvalue 120582(= 119908

2) and mode

shape 120601) and the relationship between mass of floor andstiffness to establish a Story Damage Index for assessingbuilding damage excited by earthquake Nevertheless themass of floor is hard to evaluate Therefore ApproximationStory Damage Index (ASDI) is proposed to ignore the massof floor This method requires only one modal parameterto assess story damage Wang et al [16] The main conceptof ASDI is applied to plane structure of shear frame Thetorsion coincidental effect must be considered for three-dimensional structure The damage index from frequencyand modal vector of the first mode shape has been transforminto summation inertia of floor to story drift mode Thenstory drift mode changes into story stiffness of structure toassess the decay of story stiffness after structural damage asan estimating index

The evaluation formula of Approximation Story DamageIndex (ASDI) is expressed as follows

ASDI119897= 1 minus

120596lowast2

119895sum119873

119894=1(120601lowast

119894119895Δ120601lowast

119894119895)

1205962

119895sum119873

119894=1(120601119894119895Δ120601lowast

119894119895)

(11)

where 119897is degree of freedom 119873 is total floor of structure 120596lowast119895

is the 119895th natural frequency after structural damage 120596119895is

the 119895th natural frequency before structural damage 120601lowast119894119895is the

mode shape of 119894th degree of freedom of the 119895th mode shapeafter structural damage 120601

119894119895is the mode shape of 119894th degree of

freedom of the 119895thmode shape before structural damageThevalue ofASDI is between 0 and 1 0 and represents undamagedof structure

33 Interstory Drift Mode Shape (IDMS) as Damage IndexWhen structural damage happens the stiffness of build-ing structure drops off affecting the displacement modereaction of structure Thus IDMS is proposed to probethe relationship of structural destructiveness and variationof displacement mode to judge the structural damage onbuilding The ratio of story drift of the first mode usedIDMS as a normalized datum value of roof before damagefor comparison with IDMS as a normalized datum value ofroof after damage When the sensitivity of IDMS is higherthe probability of structural damage is higher The definitionof story drift and sensitivity of IDMS is expressed as follows

Shock and Vibration 5

Figure 4 The completed five-story shearing steel structure

Story driftis as follows

120575119894= Max (Δ

119894minus Δ119894minus1

)

1205751= Max (Δ

1minus Δ119866)

(12)

where 120575119894is time history analysis of the maximum story

drift of the 119894th floor Δ119894is time history analysis of the

structural displacement history of the 119894th floor Δ119866is ground

displacement

Sensitivity of IDMS is as follows

119878119894=

119863119894minus 119861119894

119861119894

times 100 (13)

where 119878119894is the sensitivity() of the story drift variation after

damage of the 1st mode of the 119894th floor of building 119863119894is the

normalized story drift mode value after damage of the 119894thfloor of building 119861

119894is the normalized story drift mode value

before damage of the 119894th floor of building

4 Experimental Setup

The shaking table model test will be used in this research tocarry out all laboratory studies The shearing steel structuralmodel is a five-story steel framed structure using steel with 119864

value of 2times 1011 kgm2Thenet height of each story is 800mmwith a total building height of 5800mm width of 1520mmand depth of 400mm Each story weighs 242 kg and totalstructure has a designednatural frequency of 1076Hz and thenatural frequency of the second vibration mode of 321HzFigure 4 shows the photo of the completed five-story shearingsteel structure Figure 5 shows the installed camera andother relevant equipments Each element used in the modelstructure has been carefully evaluated to check whether itreaches the yield point If an element shows the sign of yieldit is immediately replaced in order to warrant the accuracy of

Dist

Dist

Camels height

SONY height

Figure 5 The experimental setup of installed camera and otherrelevant equipment

the laboratory study results A series of dynamic experimentshave been planned the results are compared with thoseobtained using accelerometer But there are two factors (1)the maximum throw of this test shaking table is plusmn125mm(2) test structure should remain within linear elastic rangefor dynamic test and it needs to be considered in this studyTherefore the maximum acceleration should be scaled downto 15ndash20 gal Actually the purpose of this research is toobtain the modal frequencies and modes of test structurewithin linear elastic range Therefore the authenticities ofearthquake records do not provide sensitivity Otherwise ElCentro Kobe and TCU earthquake records are providedwith characteristic of far field and near-fault earthquakeThese records are applied to excite modal response of highfrequencies and low frequencies of test structureThen whitenoise study is carried out in order to investigate whetherthe shearing steel structure is subject to environmentalinterference thatwill adversely impact the practicability of theexperimental results Table 1 lists the study plan

41 System Identification Method In this research themethod of comparing images is implemented to reveal thetime-dependent variation of displacement so that using thesystem identification method can be used to measure theexternal force input and the resulting dynamic response ofthe structural degree of freedom for obtaining the structuralmode parameters for example frequency 120596 damping ratio120585 vibration mode 120601 and so forth The system realizationusing information matrix (SRIM) which uses the systemidentification matrix of the measured data is capable ofidentifying the system modes of multiple inputs and outputsin additional to identify the system dynamic structuralmatrices based on the structural system matrix The modeparameters including frequency (120596) damping ratio (120585) andvibration mode (120601) can then be extracted from the dynamicstructure of the identification of the two-stage system forevaluating the building damages The SRIM system used inthis system is based on the identification theory developed byJuang [21] to construct a broad Hankel matrix using impulseresponse data and to estimate the extendable observability

6 Shock and Vibration

Table 1 Study plan for laboratory experiment

Name of structure Experimental shearing steel structureShearing steel structure Reference set (width of column) Experimental set (width of column)Normal monitoringexperiment 400mm 380mm 360mm 280mm and 200mm

Data retrieving andrecording equipment

Equipment for dynamic DIC techniques(1) Dynamic digital device-industrial CCD(2) Dynamic digital device-handy video SONY andCannon EOS digital cameraTraditional acceleration detecting deviceACC Accelerometer

Location for installing thedata retrieving andrecording equipment

DICmethodThe experimental setup is shown in Figure 5 Alldynamic responses of test structure are recorded bylocal images of structural responseData retrieving form accelerometerAccelerometers are installed in each floor and base athorizontal direction

Input of earthquake dataand external force for thesteel structure

Natural earthquake record(1) Strong earthquake Kobe and El Centro 1940earthquake record(2) Strong earthquake TCU Chi-Chi earthquakerecord 1999(3) White noise(4) RAMP

and controllability matrices using singular value decompo-sition (SVD) for extracting a set of equivalent discrete timestate-space equations to extract the mode parameters for thestructural system matrix

5 Results and Discussions

The dynamic experimental procedures to be carried outin this study must be done by overcoming difficultiesencountered when implementing the traditional experimen-tal technique they must also be integrated with imagecapture and dynamic CCD transfer and analysis of imageinformation Additionally the quake loading to a building isof random nature the mode and frequency of the responsivebuilding vibration that causes damages to the building arealso of random nature Hence responses to external quakeloading inputs using free vibration method environmentaldisturbance method and forced oscillation method are usedas the inputs in order to investigate the variations of themode and frequency of vibration for the building when it isbeing gradually damaged Further variations of the first-storycolumn cross-sectional stiffness are investigated to simulatethe influence of column stiffness on the mode and frequencyof building vibration

The reference set with width of column is 400mm underexcitation of various earthquake records and the experimen-tal set with different widths of column is 380mm 360mm280mm and 200mmunder excitation of various earthquakerecords to obtain the dynamic responses respectively Thedetected typical dynamic responses from this proposed DICmethod that used the width of column 380mm as an

example are shown in Figure 6 Then all analysis resultsof natural frequencies damping ratio and mode shape ofsteel test building with width of column = 380mm underexcitation of free vibration Kobe earthquake record and ElCentro 1940 record detected from this proposedDICmethodand traditional accelerometers are listed in Table 2 as anexample respectively All detected dynamic responses fromDIC method and accelerometers are analyzed and comparedwith each other in Sections 51 52 and 53

The difference of natural frequencies between the test andanalysis results of this proposed DIC method and those ofaccelerometers is about 002ndash45 The relative errors ofthe 1st mode and 2nd mode are from 000 to 150 andfrom 000 to 12 respectively The test results reveal thatrelative errors of the 3rd and 4th modes are from 000to 2000 and from 000 to 1500 respectively There isa slight difference between these two methods at the 5thmode The maximum relative error of this mode happens atthe 3rd floor of shearing building under the excitation of ElCentro earthquake record Otherwise the comparison of testand analysis results of damping ratio between the structuraldynamic responses under excitation of various external forcesshows that when the test structure is under excitation offree vibration the damping ratio between these two methodsis slightly different But when the test structure is underexcitation of various earthquake records the difference ofdamping ratio at the 1st mode becomes large Although theerrors of the 3rdmode are higher than the othermodes all themode shapes and frequencies of the test and analysis results ofthis proposedmethod are close to the test and analysis resultsof the structural response records of acceleration recorded byaccelerometer

Shock and Vibration 7

Absolute displacement

minus150

minus100

minus50

Base-X

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

50

100

150

00 100 200 300 400 500 600

Disp

(pi

xel)

(a) Absolute displacement record

minus100

Relative displacement

minus400

minus300

minus200

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

100

200

300

400

00 100 200 300 400 500 600

Disp

(m

m)

(b) Relative displacement record

Time (s)

Story drift

minus100

minus80

minus60

minus40

minus20

Stor

y dr

ift (m

m)

1st story drift2nd story drift

4th story drift5th story drift

00

20

40

60

80

100

00 100 200 300 400 500 600

3rd story drift

(c) Story drift record

Figure 6 The typical dynamic responses detected from DIC method with width of column = 380mm under excitation of free vibration astypical responses records

51 Results of Analyses Using Natural Frequency as the Charac-teristic Damage Indices Figures 7 8 9 10 and 11 show com-parisons of the identified natural frequencies for columns ofvarious cross-sectional sizes subject to different earthquakerecords listed in Table 1 The result shown in Figure 7indicated that when the steel cross-sectional area is 400mmthe highmodenatural frequencies obtained using themethodproposed in this research and the traditional method havesome discrepancies mainly caused by differences betweenthe methods used for zeroing the reference line Howevervariations of the natural frequencies for buildings of differentstiffness subject to various earthquake records (Figure 10simFigure 11) indicate that the method proposed in this researchis capable of predicting the building natural frequency afterthe earthquake as precisely as the conventional methodResults of damage index analyses conducted on the aboveexperimental results shown in Figure 12 reveal that themethod proposed in this research and the conventionalmethod will yield similar damage indices Hence the exper-imental results confirm that the damage index that is basedon frequency can be used as a rapid method to evaluate theoverall health of a buildingWhen an earthquake damages the

building variations of the building stiffness that is graduallychanging can be monitored so that the degree of buildingdamage can be evaluated However this method is notcapable of determining the location of building damage

52 Analysis Results on Approximation Story Damage Index-(ASDI-) Based Damage Index Results of ApproximationStory Damage Index (ASDI) that is the damage index basedon characteristic modal type and frequency are shown inFigures 13ndash16 The free vibration ASDI for various buildingdimensions shown in Figure 13 reveals closer ASDI resultsbetween the method proposed in this research and theconventional method for lower ASDI levels and vice versathe sensitivity of the method proposed in this research ishigher than the conventional method Hence this method iscapable of detecting the degree of building damage based onASDI for building suffering from slight damages Figure 14reveals that when the EL Centro 1940 earthquake records aretested the ASDI are closer for these two methods becauseof the more serious damages at the cross-section Whenthe cross-section dimension is 380mm the ASDI for these

8 Shock and Vibration

Table 2 Test and analysis results of natural frequencies damping ratio andmode shape of steel test building with width of column = 380mmunder excitation of free vibration Kobe earthquake record and El Centro 1940 record

(a)

Test and analysis results of free vibration traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10743 32036 51060 65896 75249Damping ratio 05320 04916 04767 05022 04506Mode shape

Base 0 0 0 0 01F 03155 07997 1 09547 051272F 05912 1 01928 minus08875 minus089233F 07940 04850 minus09206 minus01499 14F 09499 minus03400 minus04162 1 minus082865F 1 minus08691 07326 minus06280 03532

Test and analysis results of free vibration proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10551 31610 50600 65700 75240Damping ratio 06270 06240 048931 04930 05860Mode shapeBase 0 0 0 0 0

1F 03160 08390 1 09120 044212F 05700 1 01650 minus09030 minus082603F 07780 04770 minus09550 minus01430 14F 09250 minus03740 minus04140 1 minus085135F 1 minus09220 08060 minus06520 04180

(b)

Test and analysis results of Kobe earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10317 30969 50368 66412 76884Damping ratio 06373 04574 46337 28685 55449Mode shape

Base 0 0 0 0 01F 03773 09008 1 08386 073902F 06365 1 01596 minus07806 minus13F 08256 04324 minus09755 minus02302 086204F 09710 minus03862 minus03910 1 minus058465F 1 minus08833 07546 minus06033 02264

Test and analysis results of Kobe earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 16292 31732 51040 65572 74244Damping ratio 05594 05271 3952 29022 59642Mode shape

Base 0 0 0 0 01F 03253 08001 09040 08371 079102F 05783 1 02295 minus09281 minus13F 07867 04750 minus1 minus02050 082324F 09320 minus03711 minus03954 1 minus05547

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 5

Figure 4 The completed five-story shearing steel structure

Story driftis as follows

120575119894= Max (Δ

119894minus Δ119894minus1

)

1205751= Max (Δ

1minus Δ119866)

(12)

where 120575119894is time history analysis of the maximum story

drift of the 119894th floor Δ119894is time history analysis of the

structural displacement history of the 119894th floor Δ119866is ground

displacement

Sensitivity of IDMS is as follows

119878119894=

119863119894minus 119861119894

119861119894

times 100 (13)

where 119878119894is the sensitivity() of the story drift variation after

damage of the 1st mode of the 119894th floor of building 119863119894is the

normalized story drift mode value after damage of the 119894thfloor of building 119861

119894is the normalized story drift mode value

before damage of the 119894th floor of building

4 Experimental Setup

The shaking table model test will be used in this research tocarry out all laboratory studies The shearing steel structuralmodel is a five-story steel framed structure using steel with 119864

value of 2times 1011 kgm2Thenet height of each story is 800mmwith a total building height of 5800mm width of 1520mmand depth of 400mm Each story weighs 242 kg and totalstructure has a designednatural frequency of 1076Hz and thenatural frequency of the second vibration mode of 321HzFigure 4 shows the photo of the completed five-story shearingsteel structure Figure 5 shows the installed camera andother relevant equipments Each element used in the modelstructure has been carefully evaluated to check whether itreaches the yield point If an element shows the sign of yieldit is immediately replaced in order to warrant the accuracy of

Dist

Dist

Camels height

SONY height

Figure 5 The experimental setup of installed camera and otherrelevant equipment

the laboratory study results A series of dynamic experimentshave been planned the results are compared with thoseobtained using accelerometer But there are two factors (1)the maximum throw of this test shaking table is plusmn125mm(2) test structure should remain within linear elastic rangefor dynamic test and it needs to be considered in this studyTherefore the maximum acceleration should be scaled downto 15ndash20 gal Actually the purpose of this research is toobtain the modal frequencies and modes of test structurewithin linear elastic range Therefore the authenticities ofearthquake records do not provide sensitivity Otherwise ElCentro Kobe and TCU earthquake records are providedwith characteristic of far field and near-fault earthquakeThese records are applied to excite modal response of highfrequencies and low frequencies of test structureThen whitenoise study is carried out in order to investigate whetherthe shearing steel structure is subject to environmentalinterference thatwill adversely impact the practicability of theexperimental results Table 1 lists the study plan

41 System Identification Method In this research themethod of comparing images is implemented to reveal thetime-dependent variation of displacement so that using thesystem identification method can be used to measure theexternal force input and the resulting dynamic response ofthe structural degree of freedom for obtaining the structuralmode parameters for example frequency 120596 damping ratio120585 vibration mode 120601 and so forth The system realizationusing information matrix (SRIM) which uses the systemidentification matrix of the measured data is capable ofidentifying the system modes of multiple inputs and outputsin additional to identify the system dynamic structuralmatrices based on the structural system matrix The modeparameters including frequency (120596) damping ratio (120585) andvibration mode (120601) can then be extracted from the dynamicstructure of the identification of the two-stage system forevaluating the building damages The SRIM system used inthis system is based on the identification theory developed byJuang [21] to construct a broad Hankel matrix using impulseresponse data and to estimate the extendable observability

6 Shock and Vibration

Table 1 Study plan for laboratory experiment

Name of structure Experimental shearing steel structureShearing steel structure Reference set (width of column) Experimental set (width of column)Normal monitoringexperiment 400mm 380mm 360mm 280mm and 200mm

Data retrieving andrecording equipment

Equipment for dynamic DIC techniques(1) Dynamic digital device-industrial CCD(2) Dynamic digital device-handy video SONY andCannon EOS digital cameraTraditional acceleration detecting deviceACC Accelerometer

Location for installing thedata retrieving andrecording equipment

DICmethodThe experimental setup is shown in Figure 5 Alldynamic responses of test structure are recorded bylocal images of structural responseData retrieving form accelerometerAccelerometers are installed in each floor and base athorizontal direction

Input of earthquake dataand external force for thesteel structure

Natural earthquake record(1) Strong earthquake Kobe and El Centro 1940earthquake record(2) Strong earthquake TCU Chi-Chi earthquakerecord 1999(3) White noise(4) RAMP

and controllability matrices using singular value decompo-sition (SVD) for extracting a set of equivalent discrete timestate-space equations to extract the mode parameters for thestructural system matrix

5 Results and Discussions

The dynamic experimental procedures to be carried outin this study must be done by overcoming difficultiesencountered when implementing the traditional experimen-tal technique they must also be integrated with imagecapture and dynamic CCD transfer and analysis of imageinformation Additionally the quake loading to a building isof random nature the mode and frequency of the responsivebuilding vibration that causes damages to the building arealso of random nature Hence responses to external quakeloading inputs using free vibration method environmentaldisturbance method and forced oscillation method are usedas the inputs in order to investigate the variations of themode and frequency of vibration for the building when it isbeing gradually damaged Further variations of the first-storycolumn cross-sectional stiffness are investigated to simulatethe influence of column stiffness on the mode and frequencyof building vibration

The reference set with width of column is 400mm underexcitation of various earthquake records and the experimen-tal set with different widths of column is 380mm 360mm280mm and 200mmunder excitation of various earthquakerecords to obtain the dynamic responses respectively Thedetected typical dynamic responses from this proposed DICmethod that used the width of column 380mm as an

example are shown in Figure 6 Then all analysis resultsof natural frequencies damping ratio and mode shape ofsteel test building with width of column = 380mm underexcitation of free vibration Kobe earthquake record and ElCentro 1940 record detected from this proposedDICmethodand traditional accelerometers are listed in Table 2 as anexample respectively All detected dynamic responses fromDIC method and accelerometers are analyzed and comparedwith each other in Sections 51 52 and 53

The difference of natural frequencies between the test andanalysis results of this proposed DIC method and those ofaccelerometers is about 002ndash45 The relative errors ofthe 1st mode and 2nd mode are from 000 to 150 andfrom 000 to 12 respectively The test results reveal thatrelative errors of the 3rd and 4th modes are from 000to 2000 and from 000 to 1500 respectively There isa slight difference between these two methods at the 5thmode The maximum relative error of this mode happens atthe 3rd floor of shearing building under the excitation of ElCentro earthquake record Otherwise the comparison of testand analysis results of damping ratio between the structuraldynamic responses under excitation of various external forcesshows that when the test structure is under excitation offree vibration the damping ratio between these two methodsis slightly different But when the test structure is underexcitation of various earthquake records the difference ofdamping ratio at the 1st mode becomes large Although theerrors of the 3rdmode are higher than the othermodes all themode shapes and frequencies of the test and analysis results ofthis proposedmethod are close to the test and analysis resultsof the structural response records of acceleration recorded byaccelerometer

Shock and Vibration 7

Absolute displacement

minus150

minus100

minus50

Base-X

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

50

100

150

00 100 200 300 400 500 600

Disp

(pi

xel)

(a) Absolute displacement record

minus100

Relative displacement

minus400

minus300

minus200

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

100

200

300

400

00 100 200 300 400 500 600

Disp

(m

m)

(b) Relative displacement record

Time (s)

Story drift

minus100

minus80

minus60

minus40

minus20

Stor

y dr

ift (m

m)

1st story drift2nd story drift

4th story drift5th story drift

00

20

40

60

80

100

00 100 200 300 400 500 600

3rd story drift

(c) Story drift record

Figure 6 The typical dynamic responses detected from DIC method with width of column = 380mm under excitation of free vibration astypical responses records

51 Results of Analyses Using Natural Frequency as the Charac-teristic Damage Indices Figures 7 8 9 10 and 11 show com-parisons of the identified natural frequencies for columns ofvarious cross-sectional sizes subject to different earthquakerecords listed in Table 1 The result shown in Figure 7indicated that when the steel cross-sectional area is 400mmthe highmodenatural frequencies obtained using themethodproposed in this research and the traditional method havesome discrepancies mainly caused by differences betweenthe methods used for zeroing the reference line Howevervariations of the natural frequencies for buildings of differentstiffness subject to various earthquake records (Figure 10simFigure 11) indicate that the method proposed in this researchis capable of predicting the building natural frequency afterthe earthquake as precisely as the conventional methodResults of damage index analyses conducted on the aboveexperimental results shown in Figure 12 reveal that themethod proposed in this research and the conventionalmethod will yield similar damage indices Hence the exper-imental results confirm that the damage index that is basedon frequency can be used as a rapid method to evaluate theoverall health of a buildingWhen an earthquake damages the

building variations of the building stiffness that is graduallychanging can be monitored so that the degree of buildingdamage can be evaluated However this method is notcapable of determining the location of building damage

52 Analysis Results on Approximation Story Damage Index-(ASDI-) Based Damage Index Results of ApproximationStory Damage Index (ASDI) that is the damage index basedon characteristic modal type and frequency are shown inFigures 13ndash16 The free vibration ASDI for various buildingdimensions shown in Figure 13 reveals closer ASDI resultsbetween the method proposed in this research and theconventional method for lower ASDI levels and vice versathe sensitivity of the method proposed in this research ishigher than the conventional method Hence this method iscapable of detecting the degree of building damage based onASDI for building suffering from slight damages Figure 14reveals that when the EL Centro 1940 earthquake records aretested the ASDI are closer for these two methods becauseof the more serious damages at the cross-section Whenthe cross-section dimension is 380mm the ASDI for these

8 Shock and Vibration

Table 2 Test and analysis results of natural frequencies damping ratio andmode shape of steel test building with width of column = 380mmunder excitation of free vibration Kobe earthquake record and El Centro 1940 record

(a)

Test and analysis results of free vibration traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10743 32036 51060 65896 75249Damping ratio 05320 04916 04767 05022 04506Mode shape

Base 0 0 0 0 01F 03155 07997 1 09547 051272F 05912 1 01928 minus08875 minus089233F 07940 04850 minus09206 minus01499 14F 09499 minus03400 minus04162 1 minus082865F 1 minus08691 07326 minus06280 03532

Test and analysis results of free vibration proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10551 31610 50600 65700 75240Damping ratio 06270 06240 048931 04930 05860Mode shapeBase 0 0 0 0 0

1F 03160 08390 1 09120 044212F 05700 1 01650 minus09030 minus082603F 07780 04770 minus09550 minus01430 14F 09250 minus03740 minus04140 1 minus085135F 1 minus09220 08060 minus06520 04180

(b)

Test and analysis results of Kobe earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10317 30969 50368 66412 76884Damping ratio 06373 04574 46337 28685 55449Mode shape

Base 0 0 0 0 01F 03773 09008 1 08386 073902F 06365 1 01596 minus07806 minus13F 08256 04324 minus09755 minus02302 086204F 09710 minus03862 minus03910 1 minus058465F 1 minus08833 07546 minus06033 02264

Test and analysis results of Kobe earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 16292 31732 51040 65572 74244Damping ratio 05594 05271 3952 29022 59642Mode shape

Base 0 0 0 0 01F 03253 08001 09040 08371 079102F 05783 1 02295 minus09281 minus13F 07867 04750 minus1 minus02050 082324F 09320 minus03711 minus03954 1 minus05547

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

6 Shock and Vibration

Table 1 Study plan for laboratory experiment

Name of structure Experimental shearing steel structureShearing steel structure Reference set (width of column) Experimental set (width of column)Normal monitoringexperiment 400mm 380mm 360mm 280mm and 200mm

Data retrieving andrecording equipment

Equipment for dynamic DIC techniques(1) Dynamic digital device-industrial CCD(2) Dynamic digital device-handy video SONY andCannon EOS digital cameraTraditional acceleration detecting deviceACC Accelerometer

Location for installing thedata retrieving andrecording equipment

DICmethodThe experimental setup is shown in Figure 5 Alldynamic responses of test structure are recorded bylocal images of structural responseData retrieving form accelerometerAccelerometers are installed in each floor and base athorizontal direction

Input of earthquake dataand external force for thesteel structure

Natural earthquake record(1) Strong earthquake Kobe and El Centro 1940earthquake record(2) Strong earthquake TCU Chi-Chi earthquakerecord 1999(3) White noise(4) RAMP

and controllability matrices using singular value decompo-sition (SVD) for extracting a set of equivalent discrete timestate-space equations to extract the mode parameters for thestructural system matrix

5 Results and Discussions

The dynamic experimental procedures to be carried outin this study must be done by overcoming difficultiesencountered when implementing the traditional experimen-tal technique they must also be integrated with imagecapture and dynamic CCD transfer and analysis of imageinformation Additionally the quake loading to a building isof random nature the mode and frequency of the responsivebuilding vibration that causes damages to the building arealso of random nature Hence responses to external quakeloading inputs using free vibration method environmentaldisturbance method and forced oscillation method are usedas the inputs in order to investigate the variations of themode and frequency of vibration for the building when it isbeing gradually damaged Further variations of the first-storycolumn cross-sectional stiffness are investigated to simulatethe influence of column stiffness on the mode and frequencyof building vibration

The reference set with width of column is 400mm underexcitation of various earthquake records and the experimen-tal set with different widths of column is 380mm 360mm280mm and 200mmunder excitation of various earthquakerecords to obtain the dynamic responses respectively Thedetected typical dynamic responses from this proposed DICmethod that used the width of column 380mm as an

example are shown in Figure 6 Then all analysis resultsof natural frequencies damping ratio and mode shape ofsteel test building with width of column = 380mm underexcitation of free vibration Kobe earthquake record and ElCentro 1940 record detected from this proposedDICmethodand traditional accelerometers are listed in Table 2 as anexample respectively All detected dynamic responses fromDIC method and accelerometers are analyzed and comparedwith each other in Sections 51 52 and 53

The difference of natural frequencies between the test andanalysis results of this proposed DIC method and those ofaccelerometers is about 002ndash45 The relative errors ofthe 1st mode and 2nd mode are from 000 to 150 andfrom 000 to 12 respectively The test results reveal thatrelative errors of the 3rd and 4th modes are from 000to 2000 and from 000 to 1500 respectively There isa slight difference between these two methods at the 5thmode The maximum relative error of this mode happens atthe 3rd floor of shearing building under the excitation of ElCentro earthquake record Otherwise the comparison of testand analysis results of damping ratio between the structuraldynamic responses under excitation of various external forcesshows that when the test structure is under excitation offree vibration the damping ratio between these two methodsis slightly different But when the test structure is underexcitation of various earthquake records the difference ofdamping ratio at the 1st mode becomes large Although theerrors of the 3rdmode are higher than the othermodes all themode shapes and frequencies of the test and analysis results ofthis proposedmethod are close to the test and analysis resultsof the structural response records of acceleration recorded byaccelerometer

Shock and Vibration 7

Absolute displacement

minus150

minus100

minus50

Base-X

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

50

100

150

00 100 200 300 400 500 600

Disp

(pi

xel)

(a) Absolute displacement record

minus100

Relative displacement

minus400

minus300

minus200

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

100

200

300

400

00 100 200 300 400 500 600

Disp

(m

m)

(b) Relative displacement record

Time (s)

Story drift

minus100

minus80

minus60

minus40

minus20

Stor

y dr

ift (m

m)

1st story drift2nd story drift

4th story drift5th story drift

00

20

40

60

80

100

00 100 200 300 400 500 600

3rd story drift

(c) Story drift record

Figure 6 The typical dynamic responses detected from DIC method with width of column = 380mm under excitation of free vibration astypical responses records

51 Results of Analyses Using Natural Frequency as the Charac-teristic Damage Indices Figures 7 8 9 10 and 11 show com-parisons of the identified natural frequencies for columns ofvarious cross-sectional sizes subject to different earthquakerecords listed in Table 1 The result shown in Figure 7indicated that when the steel cross-sectional area is 400mmthe highmodenatural frequencies obtained using themethodproposed in this research and the traditional method havesome discrepancies mainly caused by differences betweenthe methods used for zeroing the reference line Howevervariations of the natural frequencies for buildings of differentstiffness subject to various earthquake records (Figure 10simFigure 11) indicate that the method proposed in this researchis capable of predicting the building natural frequency afterthe earthquake as precisely as the conventional methodResults of damage index analyses conducted on the aboveexperimental results shown in Figure 12 reveal that themethod proposed in this research and the conventionalmethod will yield similar damage indices Hence the exper-imental results confirm that the damage index that is basedon frequency can be used as a rapid method to evaluate theoverall health of a buildingWhen an earthquake damages the

building variations of the building stiffness that is graduallychanging can be monitored so that the degree of buildingdamage can be evaluated However this method is notcapable of determining the location of building damage

52 Analysis Results on Approximation Story Damage Index-(ASDI-) Based Damage Index Results of ApproximationStory Damage Index (ASDI) that is the damage index basedon characteristic modal type and frequency are shown inFigures 13ndash16 The free vibration ASDI for various buildingdimensions shown in Figure 13 reveals closer ASDI resultsbetween the method proposed in this research and theconventional method for lower ASDI levels and vice versathe sensitivity of the method proposed in this research ishigher than the conventional method Hence this method iscapable of detecting the degree of building damage based onASDI for building suffering from slight damages Figure 14reveals that when the EL Centro 1940 earthquake records aretested the ASDI are closer for these two methods becauseof the more serious damages at the cross-section Whenthe cross-section dimension is 380mm the ASDI for these

8 Shock and Vibration

Table 2 Test and analysis results of natural frequencies damping ratio andmode shape of steel test building with width of column = 380mmunder excitation of free vibration Kobe earthquake record and El Centro 1940 record

(a)

Test and analysis results of free vibration traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10743 32036 51060 65896 75249Damping ratio 05320 04916 04767 05022 04506Mode shape

Base 0 0 0 0 01F 03155 07997 1 09547 051272F 05912 1 01928 minus08875 minus089233F 07940 04850 minus09206 minus01499 14F 09499 minus03400 minus04162 1 minus082865F 1 minus08691 07326 minus06280 03532

Test and analysis results of free vibration proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10551 31610 50600 65700 75240Damping ratio 06270 06240 048931 04930 05860Mode shapeBase 0 0 0 0 0

1F 03160 08390 1 09120 044212F 05700 1 01650 minus09030 minus082603F 07780 04770 minus09550 minus01430 14F 09250 minus03740 minus04140 1 minus085135F 1 minus09220 08060 minus06520 04180

(b)

Test and analysis results of Kobe earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10317 30969 50368 66412 76884Damping ratio 06373 04574 46337 28685 55449Mode shape

Base 0 0 0 0 01F 03773 09008 1 08386 073902F 06365 1 01596 minus07806 minus13F 08256 04324 minus09755 minus02302 086204F 09710 minus03862 minus03910 1 minus058465F 1 minus08833 07546 minus06033 02264

Test and analysis results of Kobe earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 16292 31732 51040 65572 74244Damping ratio 05594 05271 3952 29022 59642Mode shape

Base 0 0 0 0 01F 03253 08001 09040 08371 079102F 05783 1 02295 minus09281 minus13F 07867 04750 minus1 minus02050 082324F 09320 minus03711 minus03954 1 minus05547

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 7

Absolute displacement

minus150

minus100

minus50

Base-X

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

50

100

150

00 100 200 300 400 500 600

Disp

(pi

xel)

(a) Absolute displacement record

minus100

Relative displacement

minus400

minus300

minus200

Time (s)

5F-X4F-X3F-X

2F-X1F-X

00

100

200

300

400

00 100 200 300 400 500 600

Disp

(m

m)

(b) Relative displacement record

Time (s)

Story drift

minus100

minus80

minus60

minus40

minus20

Stor

y dr

ift (m

m)

1st story drift2nd story drift

4th story drift5th story drift

00

20

40

60

80

100

00 100 200 300 400 500 600

3rd story drift

(c) Story drift record

Figure 6 The typical dynamic responses detected from DIC method with width of column = 380mm under excitation of free vibration astypical responses records

51 Results of Analyses Using Natural Frequency as the Charac-teristic Damage Indices Figures 7 8 9 10 and 11 show com-parisons of the identified natural frequencies for columns ofvarious cross-sectional sizes subject to different earthquakerecords listed in Table 1 The result shown in Figure 7indicated that when the steel cross-sectional area is 400mmthe highmodenatural frequencies obtained using themethodproposed in this research and the traditional method havesome discrepancies mainly caused by differences betweenthe methods used for zeroing the reference line Howevervariations of the natural frequencies for buildings of differentstiffness subject to various earthquake records (Figure 10simFigure 11) indicate that the method proposed in this researchis capable of predicting the building natural frequency afterthe earthquake as precisely as the conventional methodResults of damage index analyses conducted on the aboveexperimental results shown in Figure 12 reveal that themethod proposed in this research and the conventionalmethod will yield similar damage indices Hence the exper-imental results confirm that the damage index that is basedon frequency can be used as a rapid method to evaluate theoverall health of a buildingWhen an earthquake damages the

building variations of the building stiffness that is graduallychanging can be monitored so that the degree of buildingdamage can be evaluated However this method is notcapable of determining the location of building damage

52 Analysis Results on Approximation Story Damage Index-(ASDI-) Based Damage Index Results of ApproximationStory Damage Index (ASDI) that is the damage index basedon characteristic modal type and frequency are shown inFigures 13ndash16 The free vibration ASDI for various buildingdimensions shown in Figure 13 reveals closer ASDI resultsbetween the method proposed in this research and theconventional method for lower ASDI levels and vice versathe sensitivity of the method proposed in this research ishigher than the conventional method Hence this method iscapable of detecting the degree of building damage based onASDI for building suffering from slight damages Figure 14reveals that when the EL Centro 1940 earthquake records aretested the ASDI are closer for these two methods becauseof the more serious damages at the cross-section Whenthe cross-section dimension is 380mm the ASDI for these

8 Shock and Vibration

Table 2 Test and analysis results of natural frequencies damping ratio andmode shape of steel test building with width of column = 380mmunder excitation of free vibration Kobe earthquake record and El Centro 1940 record

(a)

Test and analysis results of free vibration traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10743 32036 51060 65896 75249Damping ratio 05320 04916 04767 05022 04506Mode shape

Base 0 0 0 0 01F 03155 07997 1 09547 051272F 05912 1 01928 minus08875 minus089233F 07940 04850 minus09206 minus01499 14F 09499 minus03400 minus04162 1 minus082865F 1 minus08691 07326 minus06280 03532

Test and analysis results of free vibration proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10551 31610 50600 65700 75240Damping ratio 06270 06240 048931 04930 05860Mode shapeBase 0 0 0 0 0

1F 03160 08390 1 09120 044212F 05700 1 01650 minus09030 minus082603F 07780 04770 minus09550 minus01430 14F 09250 minus03740 minus04140 1 minus085135F 1 minus09220 08060 minus06520 04180

(b)

Test and analysis results of Kobe earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10317 30969 50368 66412 76884Damping ratio 06373 04574 46337 28685 55449Mode shape

Base 0 0 0 0 01F 03773 09008 1 08386 073902F 06365 1 01596 minus07806 minus13F 08256 04324 minus09755 minus02302 086204F 09710 minus03862 minus03910 1 minus058465F 1 minus08833 07546 minus06033 02264

Test and analysis results of Kobe earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 16292 31732 51040 65572 74244Damping ratio 05594 05271 3952 29022 59642Mode shape

Base 0 0 0 0 01F 03253 08001 09040 08371 079102F 05783 1 02295 minus09281 minus13F 07867 04750 minus1 minus02050 082324F 09320 minus03711 minus03954 1 minus05547

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

8 Shock and Vibration

Table 2 Test and analysis results of natural frequencies damping ratio andmode shape of steel test building with width of column = 380mmunder excitation of free vibration Kobe earthquake record and El Centro 1940 record

(a)

Test and analysis results of free vibration traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10743 32036 51060 65896 75249Damping ratio 05320 04916 04767 05022 04506Mode shape

Base 0 0 0 0 01F 03155 07997 1 09547 051272F 05912 1 01928 minus08875 minus089233F 07940 04850 minus09206 minus01499 14F 09499 minus03400 minus04162 1 minus082865F 1 minus08691 07326 minus06280 03532

Test and analysis results of free vibration proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10551 31610 50600 65700 75240Damping ratio 06270 06240 048931 04930 05860Mode shapeBase 0 0 0 0 0

1F 03160 08390 1 09120 044212F 05700 1 01650 minus09030 minus082603F 07780 04770 minus09550 minus01430 14F 09250 minus03740 minus04140 1 minus085135F 1 minus09220 08060 minus06520 04180

(b)

Test and analysis results of Kobe earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10317 30969 50368 66412 76884Damping ratio 06373 04574 46337 28685 55449Mode shape

Base 0 0 0 0 01F 03773 09008 1 08386 073902F 06365 1 01596 minus07806 minus13F 08256 04324 minus09755 minus02302 086204F 09710 minus03862 minus03910 1 minus058465F 1 minus08833 07546 minus06033 02264

Test and analysis results of Kobe earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 16292 31732 51040 65572 74244Damping ratio 05594 05271 3952 29022 59642Mode shape

Base 0 0 0 0 01F 03253 08001 09040 08371 079102F 05783 1 02295 minus09281 minus13F 07867 04750 minus1 minus02050 082324F 09320 minus03711 minus03954 1 minus05547

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 9

(b) Continued

5F 1 minus09490 06543 minus04450 02641

(c)

Test and analysis results of El Centro 1940 earthquake record traditional accelerometerItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10319 30975 50211 65905 76536Damping ratio 06953 03928 07949 15966 36372Mode shape

Base 0 0 0 0 01F 03777 09028 1 09123 052052F 06374 1 00868 minus09088 minus092083F 08274 04325 minus09507 minus01363 14F 09721 minus03865 minus03792 1 minus080755F 1 minus08820 07432 minus06229 03449

Test and analysis results of El Centro 1940 earthquake record proposed DIC methodItems 1st mode 2nd mode 3rd mode 4th mode 5th modeNatural frequency 10623 31751 50911 69047 76536Damping ratio 05852 04331 08391 16671 36372Mode shape

Base 0 0 0 0 01F 03210 08380 09830 09225 052052F 05784 1 01070 minus09183 minus092083F 07860 04683 minus1 minus01465 14F 09321 minus03702 minus03341 1 minus081115F 1 minus09210 08300 minus06914 03501

two methods are slightly different but the difference is notsignificant

The analysis results shown in Figures 15 and 16 forstructural cross-sectional dimensions of 360mm400mmand 280mm400mm subject to various types of earthquakesthe ASDI values obtained by using these two methods arenot much differentThis confirms that as long as the buildingdamage reaches a certain level the method proposed in thisresearch is capable of revealing the damage characteristics ofthe building subject to earthquake

The white noise shown in Figure 17 shows the white noisefor the ASDI obtained using the free vibration digital imagemethod and the accelerometer method confirms that thismethod can really reveal the damage characteristics for thebuilding subject to earthquake

Figures 13ndash17 show that using the proposed index indiceswill clearly indicate the building damages and their sensitivityis dependent on the cross-sectional dimensions When thecolumn cross-sectional dimension is reduced by 80mm thedamage value is shown to increase obviously If the columncross-sectional dimension is reduced by 20mm the buildingdamage characteristics cannot be shown These figures alsoreveal that the damage index based on the natural vibrationidentifies modal parameter is not capable of deciding thelocation of building damage however the predicted degreeof building damage due to external earthquake force isconsistent The damage indices obtained using the methodproposed in this research and the conventional method have

good correlations for the various column cross-sectionaldimensions

53 Analysis Results on IDMS-Based Damage Index TheInterstory Drift Mode Shape (IDMS) damage index is theinterstory drift ratio before and after the earthquake (minus 1)for the first vibration mode that is based on the normalizedvalue for a designated building story as the reference In otherwords the ratio of the normalized interstory drift versus thesensitivities before and after the damage is used as the basismore damages correspond to higher sensitivities Figures 18and 19 show the sensitivity difference of this index for the datacollected using the digital imagemethod used in this researchand the conventional accelerometer method In Figure 18when the degree of damage is 240mm400mm the freevibration IDMS using the method proposed in this researchis 60 than that for the data collected using the traditionalaccelerometer Comparing the data shown in Figure 18 withthose shown in Figure 19 reveals that when the structure issubject to the EL Centro 1940 earthquake records the IDMSdamage values obtained using both methods reach 60 forthe damage level of 240mm400m hence the sensitivityof the proposed method can be confirmed AdditionallyFigure 18 also shows that the conventional accelerometermethod has worse sensitivity for lower degree of buildingdamage However Figure 19 reveals that when the buildingis subject to the EL Centro 1940 earthquake records and

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

10 Shock and Vibration

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 7 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 400mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

RAMP DIC

Figure 8 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 380mm

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)White noise ACCWhite noise DIC

Figure 9 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 360mm

00

10

20

30

40

50

60

70

80

Mode

Free ACCFree DICKobe ACCKobe DICEL Centro ACCEL Centro DIC

TCU ACCTCU DIC

RAMP ACCRAMP DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

White noise ACCWhite noise DIC

Figure 10 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 280mm

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 11

00

10

20

30

40

50

60

70

80

90

Mode

Free ACCFree DICKobe ACCKobe DIC

TCU ACCTCU DIC

1st 2nd 3rd 4th 5th

Nat

ural

freq

uenc

y (H

z)

EL Centro ACCEL Centro DIC

RAMP ACCRAMP DIC

White noise ACCWhite noise DIC

Figure 11 Comparisons of the identified building natural frequen-cies obtained using the method proposed in this research and theconventional method for cross-sectional dimensions of 200mm

00

50

100

150

200

250

Damage degree identified by DIC

Dam

age c

ontro

l (

)

Damage degree identified by ACC

400 380 360 280 200

Damage index frequency (mm)

Figure 12 Damage index that is based on natural frequency forvarious stiffness

the degree of damage is 380mm400mm this method haspoor sensitivity Hence when the IDMS damage index isused to evaluate the building health using different sensorsto collect data will lead to the difference of sensitivity levelsand the results of building health evaluation However thisdamage index is still capable of identifying the location ofbuilding story that suffers the damage For various damages

1F

380mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

ASDI index

DIC free

ACC free

Figure 13 Comparisons of the ASDI-based damage indices for freevibration digital image method proposed in this research and theconventional accelerometer method

1F

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

00 01 02 03 04 05 06 07 08 09 10

ASDI index

DIC-EL1940

1940

ACC-EL

Damage index ASDI

Figure 14 Comparisons of the ASDI-based damage indices usingEL Centrol 1940 earthquake data as input for free vibration digitalimage method proposed in this research and the conventionalaccelerometer method

of even less than 20mm column cross-sectional reductionthe sensitivity difference can still be compared only if thesensor has certain accuracy for monitoring the displacementHence the IDMSdamage index ismore suitable for the digitalimage method than the conventional accelerometer method

Differences of the IDMS values for the building subjectto EL Centro 1940 TCU white noise and RAMP with360mm400mm of damage are evaluated in this researchin order to understand the IDMS sensitivity when thebuilding is subject to various modes of earthquake butsuffers slight damages it is shown in Figure 20 Under the

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

12 Shock and Vibration1

F

00 01 02 03 04 05 06 07 08 09 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 15 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 360mm and 400mm)

1F

00 02 04 06 08 10

DIC

ACC

TCU

ASDI index

EL 1940 White noise

Damage index ASDI

RAMP

Figure 16 Comparisons of the ASDI-based damage indices for thefree vibration digital image method as proposed in this researchand the conventional accelerometermethod (cross-sectional dimen-sions of 280mm and 400mm)

influence of EL Centro 1940 and white noise this methodhas lower sensitivity than the conventional accelerometermethod when the building is subject to TCU and RAMPearthquakes both methods have comparable sensitivities orthis method sometimes has better sensitivity than the con-ventional method Figure 21 shows that when the structureis subject to EL Centro 1940 TCU white noise and RAMPtypes of earthquake with 280mm400mm of damage theIDMS sensitivity for the this method is higher than that forthe conventional method These observations confirm thatwhen IDMS is used as the damage index for buildings withmore serious damages the method proposed in this research

1F 2F 3F 4F 5F

Deg

ree o

f bui

ldin

g da

mag

e

Floor

200mm400mm

280mm400mm

200mm400mm

280mm400mm

380mm400mm

00

02

04

06

08

10Damage index ASDI

DIC white noise

ACC white noise

DIC white noise

ACC white noise

ACC white noise

Figure 17 Comparisons of the white noise for the ASDI obtainedusing the digital image method and the accelerometer method

1F

380mm400mm360mm400mm

0 10 20 30 40 50 60 70 80 90 100

IDMS index

DIC free

ACC free

Damage index IDMS ()

Figure 18 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to different damage scales

has a higher sensitivity to indicate the degree of buildingdamage

Comparisons of the ADSI and IDMS damage indicesfor buildings subject to EL Centro 1940 type earthquakewith various degrees of damages are shown in Figures 22and 23 In Figure 22 the ADSI damage indices are closefor both digital image method and accelerometer methodfor various degrees of building damages but there existobvious differences between these two damage indices for the

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 13

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

0 10 20 30 40 50 60 70 80 90

IDMS index

1F

DIC-EL1940

1940

ACC-EL

Damage index IDMS ()

Figure 19 Comparisons of the IDMS damage indices based on thefree vibration digital image method and the accelerometer methodfor building stories subject to the EL Centro 1940 earthquake data

fifth story when the degree of damage is 200mm400mmFigure 23 shows that the IDMS damage index is capable ofshowing the degree of damage for the first story and similardegree of damage for other stories However for the 5thstory the IDMS is higher for the conventional accelerometermethod than the digital image method These two methodsshow similar IDMS values for the 3rd and the 4th storiesTherefore the above observations indicate that the IDMSindex has higher sensitivity than the ADSI damage index andboth indices are capable of showing the location of damage

6 Conclusions

Results of this research confirm that the dynamic digitalimage analysis technology is capable of taking and analyzingdynamic images by way of detecting dynamic images toanalyze the mechanical behavior of building under exci-tation of external force and the integrated technique fordynamic digital image devices Laboratory studies confirmthe accuracy and feasibility of the proposed method Itsimplementation will assist in revealing the damage index ofthe building after it is subject to earthquake suffering fromdamages The following conclusions are obtained as a resultof a series of experimental studies

(1) Improving the method to zero the reference line willlead to good correlations between the results obtainedusing the method proposed in this research and theaccelerometer method

(2) The frequency variation is capable of predicting thebuilding damages but is incapable of predicting thelocation of damage

(3) The analysis results on ASDI-based damage indexreveal that ASDI based on natural vibration identifies

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

360mm400mm damage index IDMS ()

Figure 20 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 360mm400mm of damages

1F

0 10 20 30 40 50 60 70 80 90 100

DIC

ACC

TCUEL 1940 White noise

IDMS index

RAMP

280mm400mm damage index IDMS ()

Figure 21 Comparisons of IDMS values using the digital imagemethod and the accelerometer methods for building subject tovarious types of earthquakes with 280mm400mm of damages

that the modal parameter is not capable of decidingthe location of building damage Nevertheless thisproposed method can be used to predict the degreeof building damage due to external forces

(4) Using IDMS damage index will lead to reveal thebuilding story that suffers damagesHowever the sen-sitivity becomes obvious when the structural cross-section becomes obviously thinner to increase the

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

14 Shock and Vibration

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

380mm400mm360mm400mm280mm400mm

240mm400mm200mm400mm

Floo

r

Floo

r

minus47170

minus12551

minus4696

minus0152

0606

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

minus500 minus400 minus300 minus200 minus100 00 100 minus500 minus400 minus300 minus200 minus100 00 100

0608

minus77905

minus13097

minus4651

minus0164

DIC-EL 1940 ACC-EL 1940

Damage index ASDIDamage index ASDI

Figure 22 Comparisons of the ADSI damage index of various building stories based on the digital image method and the accelerometermethod for building subject to the EL Centro 1940 earthquake data

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

380mm400mm360mm400mm

280mm400mm240mm400mm200mm400mm

0 50 0 50

Floo

r

Floo

r

5F

4F

3F

2F

1F

5F

4F

3F

2F

1F

100100 minus100 minus50minus100 minus50 minus150

DIC-EL 1940 ACC-EL 1940

Damage index IDMS () Damage index IDMS ()

Figure 23 Comparisons of the IDMS damage index of various building stories based on the digital image method and the accelerometermethod for the building subject to the EL Centro 1940 earthquake data

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 15

damage value If the building column cross-sectionbecomes slightly thinner the damage index is notcapable of revealing the building damage character-istics

(5) If coped with the IDMS damage index this methodis capable of expressing the degree of damage causedwhen the building suffers a higher degree of damagecaused by earthquake

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge the support of TaiwanNational Science Council through Grant no NSC-100-2625-M-260-001

References

[1] httpenwikipediaorgwiki2004 Indian Ocean earthquakeand tsunami

[2] httptranslategooglecomtwtranslatehl=zh-TWamplangpair=en7Czh-TWampu=httpenwikipediaorgwiki2011 T25C5258Dhoku earthquake and tsunami

[3] S N Pakzad G L Fenves S Kim and D E Culler ldquoDesignand implementation of scalable wireless sensor network forstructuralmonitoringrdquo Journal of Infrastructure Systems vol 14no 1 pp 89ndash101 2008

[4] M J Whelan and K D Janoyan ldquoDesign of a robust high-ratewireless sensor network for static and dynamic structural mon-itoringrdquo Journal of Intelligent Material Systems and Structuresvol 20 no 7 pp 849ndash863 2009

[5] MKrommerMZellhofer andK-HHeilbrunner ldquoStrain-typesensor networks for structural monitoring of beam-type struc-turesrdquo Journal of Intelligent Material Systems and Structures vol20 no 15 pp 1875ndash1888 2009

[6] B Chen and W Liu ldquoMobile agent computing paradigmfor building a flexible structural health monitoring sensornetworkrdquo Computer-Aided Civil and Infrastructure Engineeringvol 25 no 7 pp 504ndash516 2010

[7] Z Qiu J Wu and S Yuan ldquoA wireless sensor network designand evaluation for large structural strain field monitoringrdquoMeasurement Science and Technology vol 22 no 7 Article ID075205 2011

[8] S K T Grattan S E Taylor P M A Basheer T Sun and KT V Grattan ldquoSensors systems especially fibre optic sensors instructural monitoring applications in concrete an overviewrdquo inNew Developments in Sensing Technology for Structural HealthMonitoring vol 96 of Lecture Notes in Electrical Engineering pp359ndash425 2011

[9] V A Tran S T Quek and W H Duan ldquoSensor validation indamage locating vector method for structural health monitor-ingrdquo International Journal of Structural Stability and Dynamicsvol 11 no 1 pp 149ndash180 2011

[10] F Federici F Graziosi M Faccio et al ldquoAn integrated approachto the design of wireless sensor networks for structural health

monitoringrdquo International Journal of Distributed Sensor Net-works vol 2012 Article ID 594842 16 pages 2012

[11] S K Ghorai and D Ranjan Roy ldquoSensor development life cycleof embedded fiber bragg grating sensor for structural healthmonitoringrdquo Journal of Structural Engineering vol 38 no 5 pp428ndash438 2011

[12] T Yi H Li and M Gu ldquoRecent research and applicationsof GPS-based monitoring technology for high-rise structuresrdquoStructural Control andHealthMonitoring vol 20 no 5 pp 649ndash670 2013

[13] T Yi H Li and M Gu ldquoWavelet based multi-step filteringmethod for bridge healthmonitoring usingGPS and accelerom-eterrdquo Smart Structures and Systems vol 11 no 4 pp 331ndash3482013

[14] T Yi H Li and M Gu ldquoCharacterization and extraction ofglobal positioning system multipath signals using an improvedparticle-filtering algorithmrdquoMeasurement Science and Technol-ogy vol 22 no 7 Article ID 075101 2011

[15] W Sung V C Matzen and M Shih ldquoTime domain systemidentification of unknown initial conditionsrdquo Journal of Zhe-jiang University Science vol 5 no 9 pp 1035ndash1044 2004

[16] J Wang C Lin and S Yen ldquoA story damage index ofseismically-excited buildings based on modal frequency andmode shaperdquo Engineering Structures vol 29 no 9 pp 2143ndash2157 2007

[17] P G Bakir ldquoThe combined deterministic stochastic subspacebased system identification in buildingsrdquo Structural Engineeringand Mechanics vol 38 no 3 pp 315ndash332 2011

[18] E Reynders ldquoSystem identification methods for (operational)modal analysis review and comparisonrdquo Archives of Computa-tional Methods in Engineering State of the Art Reviews vol 19no 1 pp 51ndash124 2012

[19] S Tung M Shih and W Sung ldquoDevelopment of digital imagecorrelationmethod to analyse crack variations ofmasonrywallrdquoSadhana vol 33 no 6 pp 767ndash779 2008

[20] M H Shih W P Sung S H Tung D Bacinskas andG Kaklauskas ldquoDeveloping three-dimensional digital imagecorrelation techniques to detect the surface smoothness ofconstruction materialsrdquo International Journal of Materials andProduct Technology vol 42 no 3-4 pp 234ndash246 2011

[21] J N Juang Applied System Identification Prentice-Hall Engle-wood Cliffs NJ USA 1994

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of