Research ArticleNew Bridge Weigh-in-Motion System Using Piezo-Bearing

Jinkyo F Choo 1 Dong-Ho Ha 2 Seok-Gi Chang3 Dong-Ho Lee2

and Chang-Beck Cho4

1Dept of Energy Engineering Konkuk University 120 Neundong-ro Gwangjin-gu Seoul 05029 Republic of Korea2Dept of Civil Engineering Konkuk University 120 Neundong-ro Gwangjin-gu Seoul 05029 Republic of Korea3Civil Structural Eng Business Division Jinwoo Engineering Korea 151 Gasan Digital 1-ro Geumcheon-gu Seoul 08506Republic of Korea4Korea Institute of Construction Engineering and Building Technology 283 Goyangdae-ro Ilsanseo-gu Gyeonggi-do 10223Republic of Korea

Correspondence should be addressed to Dong-Ho Ha hadonghokonkukackr

Received 27 July 2018 Revised 26 October 2018 Accepted 31 October 2018 Published 18 December 2018

Academic Editor Angelo Marcelo Tusset

Copyright copy 2018 Jinkyo F Choo et al -is 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 isproperly cited

-e traditional BWIM (bridge weigh-in-motion) system measures the deformation of the bridge by means of sensors and usesthese measurements to estimate the characteristics of passing traffic bymeans of dedicated algorithms However the application ofthe BWIM system is subordinated to the type of superstructure composition geometry materials and shape of the bridge thelocation of the strain sensors used in the system and the need to calibrate the measured strain curve and of a precise model of thestructure at hand In order to be free from these constraints this paper proposes a simpler BWIM system using the bridge bearingsas a weighing scale to measure the reaction forces at the supports resulting from the passing traffic To that goal the piezo-composite element known for its durability and responsiveness to external loading is embedded appropriately in the bridgebearing to achieve the piezo-bearing -is paper presents the BWIM system constituted by the so-called piezo-bearing the resultsof a series of tests conducted to verify the responsiveness of the system to external dynamic excitation and a numerical example tovalidate the feasibility of the proposed BWIM system-e numerical example shows that the identification of the characteristics ofthe vehicle crossing the bridge can be realized based simply upon the theory of mechanics using the time histories of the measuredreaction forces instead of the deformation of the bridge

1 Introduction

Traffic load is known to be the major cause of pavementdegradation Traffic is characterized by very different types ofvehicles varying in magnitude number of axles and axlegrouping Truck weight regulations were enacted becauseheavier loads accelerate the accumulation of damage inpavement and increase the costs spent to maintain thepavement in good condition [1 2] It is thus necessary tohave clear insight into the traffic by acquiring proper trafficdata that will help drawing adequate maintenance andcontrol strategies Knowing the actual traffic loads in termsof weight configuration and number is critical in assessingthe pavement lifetime and its integrity

As part of the road network monitoring traffic on bridgestructures is an attractive approach since it can reduce

uncertainties in the traffic load assessment and provide dataenabling to optimize bridge maintenance strategies Basedon the weigh-in-motion (WIM) Moses [3] was the first whointroduced the concept of BWIM to weigh the vehicles andtheir axles while traveling at full highway speed using thebridge itself as weigh-platform [4 5]

-e traditional BWIM (bridge weigh-in-motion) systemmeasures the deformation of the bridge by means of sensorsand uses these measurements to estimate the characteristicsof passing traffic by means of dedicated algorithms [6] -esensing hardware of a typical BWIM system includes strainsensors axle-detecting sensors data acquisition system andcomputer-e strain sensors installed on the bridge soffit aregenerally electrical-resistant strain gauges arranged in aWheatstone bridge configuration to amplify the very lowmeasured strain [7] Although current BWIM systems

HindawiShock and VibrationVolume 2018 Article ID 6185695 9 pageshttpsdoiorg10115520186185695

develop accuracy levels enabling to select vehicles to beweighed using static scales Richardson et al [6] reportedthat BWIM systems using such electrical-resistant straingauges could not achieve sufficient accuracy for enforcementof overloaded vehicles Besides axle-detecting sensors wereoriginally road surface sensors but considering the lack ofdurability of the system caused by damage under heavytraffic additional strain sensors are now installed on thebridge soffit to detect axle peaks [7]

-e sensor layout depends on several factors includingthe function and sensitivity-to-strain variations of thesensors the type of bridge and the expected strain levels-e sensors are usually installed at the midspan of thebridge which is characterized by the most pronouncedresponses to measure the bending strain generated by thevehicle loads Moreover the sensitivity of strain responses toaxle loads is specific to the bridge type and sensor layout [2]Lydon et al [7] also stressed this dependency on the bridgetype involving not only the structural type and materials ofthe bridge but also its alignment It is noteworthy thatBWIM systems have not been applied to prestressed con-crete bridges and skewed bridges despite their considerablepresence in the bridge stock of most countries

Concurrently with the hardware huge efforts are beingdevoted to the development of BWIM algorithms At thebeginning most of the algorithms were based on the Moses[3] algorithm which took root on the fact that the measuredchange in strain is related to the bending moment where therelation involves the dimensions and material properties ofthe bridge In such algorithms the identification isapproached as an optimization problemminimizing the errorbetween the measured response and the response computedusing the vehicle parameters Later moving force identifi-cation (MFI) was introduced successfully to account for thepresence of multiple vehicles on the bridge MFI methodsintended to obtain the time history of the wheel loads passingthrough the bridge but failed to achieve real-time identifi-cation due to expensive computational efforts [2]

From this review it appears that despite its high degreeof maturity the BWIM system has still drawbacks like thedependence on the type of superstructure compositiongeometry materials and shape of the bridge the location ofthe strain gauges used in the system and the need to cali-brate the measured strain curve and of a precise model of thestructure at hand [2 6ndash9]

Considering that the bearing is a natural component ofthe bridge a simpler and easy-to-implement BWIM systemin terms of both hardware and software would use thebearing as a weighing scale to measure the reaction forces atthe supports resulting from the passing traffic -is BWIMsystem would ease the identification of the wheel loadscrossing the bridge based simply upon the theory of me-chanics using the time histories of the measured reactionforces instead of the deformation of the bridge To that goalthe authors proposed to use piezoceramics instead of theconventional sensors owing to their responsiveness andsensitivity to dynamic loads However piezoceramics exhibitbrittleness and poor performance that make them imprac-ticable for sensing in civil structures characterized by large

loads and impacts -erefore a dedicated piezocompositeelectricity-generating element (PCGE) was designed todevelop a new BWIM system embedded in the bridgebearing to realize simple and cost-effective traffic moni-toring [8 10]

-is paper presents the BWIM system constituted by theso-called piezo-bearing the results of a series of tests con-ducted to grasp the responsiveness of the system underexternal dynamic excitation and a numerical example toshow the effectiveness of the proposed system

2 Piezo-Bearing with d33-Mode PCGE

21 PCGE for On-Bridge Traffic Monitoring -e piezoelec-tric effect is the ability of certain materials to generate anelectric charge in response to applied mechanical forceAmong these materials lead zirconate titanate (PZT)crystals can generate measurable piezoelectricity when theiroriginal dimension is deformed by about 01 Used ex-tensively for energy harvesting PZT is an electroceramicmaterial that is extremely fragile to shocks or impacts [11]Considering the environment in which the piezoelectricelement will be employed large pressure will be actingconstantly on the element together with regular impactsapplied by the rolling wheels -is implies that the piezo-electric element to be developed should be resistant topressure and impact while exhibiting sufficient sensitivity toproduce voltage large enough for the monitoring purpose

A fair solution to meet these requirements is provided bymultilayered piezocomposites (Figure 1) due to their higherelectromechanical coupling coefficients and higher piezo-electric voltage constants compared to conventional densematerials Moreover the material parameters of the piezo-composite can be accommodated by adjusting appropriatelythe ceramic-to-polymer volume fractions in the differentlayers to satisfy the specific performance for the purposedapplication [12 13] Accordingly multilayered d33-modepiezocomposite electricity-generating element (PCGE) wasconsidered since the pressure and wheel loads applied on thebridge bearing act only in the vertical direction

-e PCGE is fabricated according to the layup design bystacking several layers of selected materials over the bottomlayer made of glassepoxy fabric -e so-composed ceramicwafer is connected using two electrodes made of copperattached at its top and bottom (Figure 1) Curing is thenperformed as follows in an autoclave the temperature is firstincreased gradually during 1 hour from room temperatureto 177degC that is then maintained for 2 hours before coolingto the room temperature At the end of this process thePCGE develops thermal residual stresses throughout itsthickness because the different layers have different co-efficients of thermal expansion -e designed d33-modePCGE shown in Figure 2 presents six layers combining thepiezoceramic material glassepoxy composite and carbonepoxy composite [8 10]

22 Composition of the Piezo-Bearing -e widely used potbearing is selected for the implementation of the BWIM

2 Shock and Vibration

system As shown in Figure 3 the pot bearing is simply anelastomeric pad tightly confined in a steel cylinder -e loadis transferred downward via a piston attached on the upperbearing plate to the elastomeric pad which is the load-carrying medium with multidirectional rotational capacityNote that this configuration allows the generation of auniform compression inside the bearing when subjected toexternal loading -e PCGE with a size of 76 times 76mm2 isinstalled between the pot plate and the elastomeric discPrevious tests showed that this arrangement led the PCGE toproduce higher voltage output due to the difference betweenthe deformation of the elastomer and steel plate [14ndash16]

23 Performance Tests of the Piezo-Bearing -e durabilityand responsiveness to load of the proposed piezo-bearingwere evaluated experimentally First the cyclic loading testwas performed using the apparatus shown in Figure 4 toverify whether the d33-mode PCGE inserted in the potbearing would last as long as the bearing itself Note that inthe fatigue test the PCGE was not inserted in the pot bearingand was protected only by a thin rubber pad whichmade thePCGE exposed to harsher conditions that it would actuallybe -e PCGE was hit more than two million times and theresults showed that the PCGE kept its integrity under the lowstress level -is indicated that the selected PCGE wouldfulfill reliably its measuring role with durability comparableto that of the bearing [17]

Dynamic tests were also performed on the piezo-bearingto verify the responsiveness and relationship between the loadapplied on the bearing and the corresponding output voltageof the PCGE inserted in the bearing -e tested bearingcorresponds to the smallest commercially available pot bearingwith a load-bearing capacity of 500 kN Loading was appliedusing the 500 kN universal testing machine (UTM) of theKOCED Laboratory Facility at Keimyung University Korea

To provide various load cases and simulate as possiblethe load configurations of the bearing in a real bridgepermanent load was basically applied as the weight of thesuperstructure and live harmonic loading was additionallyapplied with different frequencies to simulate the vehiclesrunning at different speeds on the superstructure Consid-ering the limitations of the UTM the permanent load was setto 100 kN and 200 kN and live loads with amplitudes of30 kN 60 kN 90 kN 120 kN and 150 kN were applied atfrequencies of 05Hz 10Hz and 30Hz which correspondto vehicles spaced by about 10m running respectively at18 km 36 kmh and 108 kmh Each load case was repeatedthree times to secure consistency of the measurements Adata acquisition system (NI cDAQ-9178) connected to avoltmeter (NI-9225) and load cell (SM-500L CAS NI-9237)measured the output voltage and applied loads during thetests [18]

-e results of the dynamic tests shown in Figure 5 forloading frequencies of 05Hz 10Hz and 30Hz togetherwith their regression lines confirm that the PCGE maintainsa linear relationship between the applied load and its outputvoltage regardless of the permanent load sustained by thebearing -is indicates that the output voltage produced bythe PCGE can sufficiently become an indicator of the ve-hicular load crossing the bridge

It is also observed that the slope of the linear relationsvaries according to the speed of the vehicle -e problem is

CarbonepoxyGlassepoxyGlassepoxy

GlassepoxyGlassepoxy

Piezoceramic

009 mm0

71 m

m

Neutral axis

009 mm

025 mm

009 mm009 mm010 mm

047

4 m

m

Figure 2 Layup configuration of multilayered d33-mode PCGE

(5)

(4)

(3)

(2)

(1)

Figure 3 Composition of the proposed pot bearing-type BWIM(1) pot plate (2) elastomeric disc (3) brass sealing ring (4) pistonwith PTFE (5) upper sliding plate and PCGE installed in thebearing [14ndash16]

(b)(a)

(c)(d)

(e)

Figure 4 Motor-driven lever system (a) mass (b) sliding bar (c)spring (d) cam mechanism (e) motor [17]

Neutral surfacePZTlayer

Compressive load and pressure

Figure 1 Concept of multilayered d33-mode PCGE and manu-factured PCGE

Shock and Vibration 3

that it was practically impossible to perform the test at otherfrequencies due to the limitations in the testing equipmentand the large loads required to simulate the permanent loadand traffic load Accordingly as a first attempt and despitethe poor number of experimental data a fitting curve wascomputed using these 3 frequency cases to provide a re-lationship between the ratio of the load-to-output voltagedata (slope of voltage-load lines) and the loading frequencyunder the assumption that the slopes of the lines relating theoutput voltage to the load in Figure 5 depend only on thefrequency of the excitation (speed of the vehicle)

Considering the linear nature of the response of thePCGE to the applied load it seems reasonable to apply aleast-squares fit for the relation between this slope and thefrequency-e equation for the linear model for the 3 pointsrelating the exciting frequency f (05 10 and 30Hz) andthe slopes (WaxleV) of the data in Figure 5 is as follows andplotted in Figure 6

Waxle

V 108417minus 10409f (1)

where Waxle axle load of the vehicle (kN) V outputvoltage measured by the bearing (V) and f excitingfrequency (Hz)

Equation (1) of the least-square fitting line in Figure 6can be rewritten as follows by expressing the frequency usingthe speed of the vehicle (v) and the span length of the bridge(L) and matching the units

Waxle

V 108417minus 02892

v

L1113874 1113875 (2)

where L span length of the bridge (m) and v speed of thevehicle passing through the bridge (kmh)

Equation (2) provides a means of determining the axleload (Waxle) of the vehicle using the output voltage (V) of thePCGE when the speed (v) of the vehicle is known

3 On-Bridge Traffic Monitoring Using theProposed BWIM System with Piezo-Bearing

To demonstrate the applicability of the proposed BWIMsystem a numerical example is presented -e considered

bridge is a single-span bridge with a length of 40m and widthof 1098m of which slab is made of concrete and supportedby 4 steel girders -e bridge supports 3 one-way traffic lanesand the 3-dimensional model shown in Figure 7 is used forthe application It is assumed that each girder is supported atits ends by the proposed BWIM bearing of which positionsare indicated by the node numbers in Figure 7

-e considered vehicular load is the DB-24 truck load ofthe Korea Highway Bridge Design Code It is a three-axletruck with the characteristics shown in Figure 8 For thenumerical example the distance between the middle and rearaxles is set to 4200mmMoving load analysis is conducted forthe truck running at speeds of 20 kmh and 80 kmh on Lane2 It is assumed that the linear model of the piezo-bearingexpressed in equation (2) is applicable -is means that theaxle load can be identified once the span length of the bridgeand the speed of the passing vehicle are known

From amechanics perspective the time history of the loadmeasured by the bearing will show a peak whenever one axleof the vehicle passes over the bearing In Figures 9 and 10presenting the time histories of the loads measured by thebearings respectively at the entrance (joint 336) and exit(joint 344) of the vehicle the peaks corresponding to the accessor exit of each axle of the DB-24 truck running at a speed of20 kmh can be clearly distinguished in the graph provided bythe bearing closest to the lane on which the vehicle travels

For clarity Figure 11 plots concurrently the time his-tories of joints 336 (entrance) and 344 (exit) In the timehistories the peaks indicated by 1 2 and 3 correspondrespectively to the access or exit of the front middle andrear axles of the 3-axle truck on the bridge Applying thefirst-infirst-out (FIFO) principle peak 1 occurs at 019 s(entrance side) and 72 s (exit side) in Figure 11 -eseoccurrence times of peak 1 at the entrance and exit show thatit took 701 s (72 minus 019) for the truck to cross the bridge(40m) which gives a speed of 20542 kmh -e same cal-culation for peaks 2 and 3 gives speeds of 20574 kmh and20484 kmh respectively Compared to the running speedof 20 kmh considered in the analysis the speed obtainedusing this peak-to-peak time lapse appears to estimate ac-curately the actual speed of the vehicle Accordingly theassumption that equation (2) is applicable for identifying theaxle load once the speed of the vehicle is known appears to bereasonable

0

2

4

6

8

10

12

0 05 1 15 2 25 3 35

Load

vol

tage

(kN

V)

Exciting frequency (Hz)

Figure 6 Least-squares fitting between the slope of the outputvoltage-load lines and the loading frequency

Freq 05 Hzy = 11001xRsup2 = 09999

Freq 10 Hzy = 8951xRsup2 = 09999

Freq 30 Hzy = 78888xRsup2 = 09988

0

40

80

120

160

200

0 5 10 15 20

Load

(kN

)

Voltage (V)

Figure 5 Output voltage-load relation of the BWIM system atvarious dynamic load frequencies

4 Shock and Vibration

Figures 12 and 13 present the same time histories for theDB-24 truck running at a speed of 80 kmh Here also theentrance and exit of each axle of the load-train can be clearlyidentified in the time history of the load measured by thebearing closest to the lane crossed by the vehicle (joint 336 atthe entrance side and joint 344 at the exit side)

As done for the previous case Figure 14 plots con-currently the time histories of joints 336 (entrance) and344 (exit) In the time histories the peaks indicated by 12 and 3 correspond respectively to the access or exit ofthe front middle and rear axles of the 3-axle truck on thebridge -e occurrence times of peak 1 at the entrance andexit show that it took 167 s ( 181 minus 014) for the truck tocross the bridge (40m) which gives a speed of 86227 kmh -e same calculation for peaks 2 and 3 gives speeds of86227 kmh and 85207 kmh respectively Compared tothe running speed of 80 kmh considered in the analysisthe speed obtained using this peak-to-peak time gapappears to approximate the actual speed of the vehiclewith an error below 78 which is lower than the error of10 commonly allowed for traffic speedometers In thiscase also the assumption that equation (2) is applicable

for identifying the axle load once the speed of the vehicle isknown appears to be reasonable

Tables 1 and 2 arrange the values of the loads measuredby the piezo-bearings corresponding to the peaks togetherwith their occurrence time in Figures 9ndash14 Considering theequilibrium of forces the vehicle load applied on the bridgeis distributed to the underlying bearings Accordingly thesum of the values measured by the piezo-bearings at theentrance or exit of the bridge and picked at the time at whichthe peaks are identified shall be added together to providethe actual cumulated load of the axles accessing or exitingthe bridge -ese sums (Wtotal) are also listed in the lastcolumn of Tables 1 and 2

In Tables 1 and 2 the cases where all the axles are loadedon the bridge are at peak 3 at the entrance side and peak 1 atthe exit side -e three axles of the truck are loaded on thebridge but are not located above the bearings at the sametime-is means that the loads measured by the bearings areonly indicative of the axle loads and do not give the values ofthe axle loads themselves -e positions of the loads at peaks1 2 and 3 at the exit side are shown in Figure 15

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 9 Loads measured by BWIM bearings at the entrance side(speed 20 kmh)

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 10 Loads measured by BWIM bearings at the exit side(speed 20 kmh)

Front Middle Rear

4200 v = 4200~9000

01W

01W

04W

04W

04W

04W

1800

2 times 24kN 2 times 96kN 2 times 96kN

600

600

Figure 8 DB-24 truck load model (in mm)

Entra

nce

334

335336

337

342343 344

345

Lane 1Lane 2Lane 3

Figure 7 -ree-dimensional model of the example bridge

Shock and Vibration 5

Considering that the loads measured by the bearingscorrespond in fact to the support reactions oriented in theopposite direction these measured loads can be used tocalculate the axle loads by the influence caused by a series ofconcentrated loads using the influence lines (ILs) for thesupport reaction shown in Figure 16

Once the speed of the vehicle is known the time lapsebetween the peaks at the entrance side or exit side providesthe distance between the axles Based on the location of theloads for each peak at the exit side in Figure 15 the in-fluence for the support reaction (RB) at the exit side inFigure 16 can be used to calculate successively the loads ofthe rear middle and front axles as expressed in the fol-lowing equations

Wrear axle Wtotal( 1113857peak 3 exit (3)

where Wrear axle identified value of the rear axle load of thetruck and (Wtotal)peak 3 exit sum of loads measured byjoints 342 343 344 and 345 at occurrence of peak 3 at theexit side

Wmiddle axle Wtotal( 1113857peak 2 exitminusWrear axle 1minusd2

L1113888 1113889 (4)

where Wmiddle axle identified value of the rear axle load ofthe truck (Wtotal)peak 2 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 2 at the exit sideWrear axle value of the rear axle load of the truck providedby equation (3) and d2 distance between middle and rearaxles of the truck

Wfront axle Wtotal( 1113857peak 1 exitminusWmiddle axle 1minusd1

L1113888 1113889

minusWrear axle 1minusd1 + d2

L1113888 1113889

(5)

where Wfront axle identified value of the front axle load ofthe truck (Wtotal)peak 1 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 1 at the exit sideWmiddle axle value of the middle axle load of the truckprovided by equation (4) d1 distance between front andmiddle axles of the truck Wrear axle value of the rear axle

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 13 Loads measured by BWIM bearings at the exit side(speed 80 kmh)

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 2Peak 1

Peak 3

Peak 3

Peak 2

Peak 1

Figure 14 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 80 kmh

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 1

Peak 2

Peak 1

Peak 2

Peak 3

Peak 3

Figure 11 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 20 kmh

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 12 Loads measured by BWIM bearings at the entrance side(speed 80 kmh)

6 Shock and Vibration

load of the truck provided by equation (3) and d2 distancebetween middle and rear axles of the truck

Figure 17 shows the flowchart for the identification ofthe axle loads using the loads measured by the bearings

Note that in Figure 17 the identification of the numberof peaks will give information on the type of vehicle passingon the bridge based on the standardized vehicle classificationsystem -e vehicle classification system categorizes thevehicles into 13 classes from motorcycles passenger carsand buses to multiple-axle trucks according to the number ofaxles and the distance between consecutive axles

Using the flowchart in Figure 17 Table 3 arranges theidentified axle loads of the DB-24 truck running at 20 kmhand 80 kmh with the errors For the calculation of the errorthe estimated values are compared with the actual values ofthe DB-24 truck model (Figure 8) of the Korea HighwayBridge Design Code with the front axle load of 48 kN middleaxle load of 192 kN and rear axle load of 192 kN which givesa total load of 432 kN and the distance between the axles isd1 d2 4200 mm

As mentioned above the speed obtained using the peak-to-peak time gap approximates the actual speed of the

Table 1 Values of peaks identified in time histories of loads measured by BWIM bearings (20 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 019 minus023965 minus136519 2543254 2109958 44927282 097 minus295398 minus078127 1190154 1062699 22155013 172 minus1036348 1744544 18531005 19043366 3828257Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 720 minus1618517 4062979 15109605 19135729 36689802 797 minus666830 816733 18355975 17510131 36016013 875 040080 minus883196 1111157 8745885 1901434

Table 2 Values of peaks identified in time histories of loads measured by BWIM bearings (80 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 014 minus084606 00354 2100938 1918984 39388562 033 minus561803 484041 9905302 9702933 19530473 050 minus1380111 2230247 16227767 17895248 3497315Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 181 minus1911155 4599867 14047757 19121095 358575642 200 minus1118191 1709516 16991835 17735358 353185183 219 minus380146 minus396868 10125288 8811671 18159945

RearFront

Entrance ExitL = 40m

Middle

d1d2

(a)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(b)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(c)

Figure 15 Position of truck axles corresponding to peaks at the exit side of the bridge (a) Occurrence of peak 1 at the exit side (b)Occurrence of peak 2 at the exit side (c) Occurrence of peak 3 at the exit side

Shock and Vibration 7

vehicle with an error below 736 on the average which islower than the error of 10 commonly allowed for trafficspeedometers Recalling that the linear model in equation(2) relating the output voltage to the load was establishedusing data measured at excitation frequencies of 05Hz10 Hz and 30Hz (vehicles running respectively at18 km 36 kmh and 108 kmh) the linear model obtainedby the least-squares method is sufficiently applicableconsidering that the speed limits in Korea are 60 kmh inurban areas 80 kmh in highways and 100 kmh and110 kmh in expressways

-e error in the estimation of the distance between theaxles appears to increase with the speed of the vehicle butremains below 792 for the considered cases However thiserror had poor effect on the estimation of the axle loads ofwhich error remained below 542-e final total load of thetruck could be estimated with an error below 243 Since allthe trucks are characterized by their number of axles axledistance and axle loads the type of truck can thus beidentified and eventual overload can be captured

Based upon the simplest theory of mechanics theproposed BWIM system with built-in PCGE offers thus allthe functions required for the conventional BWIM that arecapturing and recording axle weights and distances andgross weights and velocities of vehicles regardless of the typematerial composition and shape of the bridge

4 Conclusions

-is paper presented a new BWIM system overcoming thedrawbacks of former systems -e proposed BWIM systemappears in the form of a piezo-bearing in which the PCGE isembedded To that goal a PCGEwas designed and fabricatedto offer all the advantages of piezoceramics while being freefrom their material brittleness A series of performance testsincluding fatigue test and dynamic test showed that thePCGE can be used to sustain the large load involved in thetraffic monitoring in civil structures Moving load analysiswas performed on a full three-dimensional model of a bridgeusing a typical truck load to verify the applicability of theproposed BWIM system for the on-bridge traffic monitor-ing-e following conclusions can be drawn from the resultsof the moving load analysis

(1) A linear model for converting the measured outputvoltage of the PCGE into loading was proposedconsidering its linear nature Further experimentsshall be implemented to verify the adequacy of themodel for a wider range of exciting frequencies

(2) -e time histories of the loads measured by thepiezo-bearings were used to distinguish the entranceor exit of the axle loads on the bridge -e passage ofeach axle load could be identified by the occurrenceof peaks in the time histories Based on the stan-dardized vehicle classification system the identifi-cation of the number of peaks can give informationon the type of vehicle passing on the bridge and inturn allowed the estimation of the speed of thevehicle and distances between the axles

Entrance

A B

IL for RB1

ExitL = 40m

xL

x40

1x

x

Figure 16 Influence lines for support reaction at the exit side

Start

Identification of vehicle type (number ofaxles) by measured peaks at entrance side

Identification of peaks at exit side

Calculation of vehicle speedusing peak-to-peak time gap between

entrance and exit sides

Conversion of output voltageinto load data using equation (2)

Calculation of axle distances (di) usingoccurrence time of peaks at exit side

Calculation of axle loads (Waxle) usinginfluence line for support reaction in

Figure 16 at exit side using equations (2)ndash(5)

End

Figure 17 Flowchart for the identification of axle loads using theproposed BWIM bearing

Table 3 Estimated vehiclersquos speed and axle loads using the pro-posed BWIM bearings

Estimated values Speed case20 kmh 80 kmh

Truck speed Average (kmh) 20532 85887Error () 267 736

Axle distance

d1 (mm) 439165 453295Error () 456 792d2 (mm) 444868 453295Error () 592 792

Axle loads

Front axle (kN) 48602 47747Error () 125 053

Middle axle (kN) 191164 192165Error () 043 0009

Rear axle (kN) 190143 181599Error () 097 542

Total load Total (kN) 429909 421512Error () 048 243

8 Shock and Vibration

(3) An algorithm based on the concept of influence linefor support reaction was established to calculate eachaxle load of the vehicle using the identified loadpeaks

(4) -e simulated data could estimate the speed of thevehicle passing the bridge as well as the axle weightsand distances and gross weights of the vehicle withgood accuracy regardless of the type materialcomposition and shape of the bridge purely basedon the theory of structural mechanics

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-e authors are thankful for funds provided by Korea In-stitute of Civil Engineering and Building Technology(KICT) Republic of Korea (Project No 2018-0255) -iswork was also supported by the Energy Efficiency amp Re-sources Core Technology Program of the Korea Institute ofEnergy Technology Evaluation and Planning (KETEP) andgranted financial resource from the Ministry of Trade In-dustry amp Energy Republic of Korea (No 20142020103979)

References

[1] J C Pais S I R Amorim and M J C Minhoto ldquoImpact oftraffic overload on road pavement performancerdquo Journal ofTransportation Engineering vol 139 no 9 pp 873ndash879 2013

[2] Y Yang C S Cai and D Lu ldquoState-of-the-art review onbridge weigh-in-motion technologyrdquo Advances in StructuralEngineering vol 19 no 9 pp 1514ndash1530 2016

[3] F Moses ldquoWeigh-in-motion system using instrumentedbridgesrdquo Journal of Transportation Engineering ASCEvol 105 no TE3 pp 233ndash249 1979

[4] Federal Highway Administration (FHWA) LTBP ProgramrsquosLiterature Review on Weigh-In-Motion Systems PublicationNo FHWA-HRT-16-024 FHWA Washington DC USA2016

[5] B Lechner M Lieschnegg O Mariani and M PiercherldquoDetection of vehicle data in a bridge weigh-in-motion sys-temrdquo Modern Traffic and Transportation Engineering Re-search vol 2 no 3 pp 153ndash161 2013

[6] J Richardson S Jones A Brown E J Orsquobrien andD Hajializadeh ldquoOn the use of bridge weigh-in-motion foroverweight truck enforcementrdquo International Journal ofHeavy Vehicle Systems vol 21 no 2 pp 83ndash104 2014

[7] M Lydon S E Taylor D Robinson A Mufti andE J O Brien ldquoRecent developments in bridge weigh inmotion (B-WIM)rdquo Journal of Civil Structural Health Moni-toring vol 6 no 1 pp 69ndash81 2015

[8] J F Choo V L Pham and N S Goo ldquoDesign of a d33-modepiezocomposite electricity generating element and its appli-cation to bridge monitoringrdquo Journal of Central South Uni-versity vol 21 no 7 pp 2572ndash2578 2014

[9] D G Yoo K S Kyung S J Lee H H Lee and J C Jeon ldquoAstudy on influencing factors in BWIM system and its fieldapplicabilityrdquo Journal of Korean Society of Steel Constructionvol 26 no 4 pp 251ndash262 2014

[10] J Zhao N S Goo and D-H Ha ldquoDesign and performanceevaluation of a d33-mode piezocomposite electricity gener-ating elementrdquo Journal of Mechanical Science and Technologyvol 28 no 1 pp 15ndash23 2014

[11] H A Sodano D J Inman and G Park ldquoComparison ofpiezoelectric energy harvesting devices for recharging bat-teriesrdquo Journal of Intelligent Material Systems and Structuresvol 16 no 10 pp 799ndash807 2016

[12] A Abrar and S Cochran ldquoMultilayer piezocompositestructures with piezoceramic volume fractions determined bymathematical optimisationrdquo Ultrasonics vol 42 no 1ndash9pp 259ndash265 2004

[13] R Ramesh H Kara and C R Bowen ldquoCharacteristics ofpiezoceramic and 3-3 piezocomposite hydrophones evaluatedby finite element modellingrdquo Computational Materials Sci-ence vol 30 no 3-4 pp 397ndash403 2004

[14] J F Choo D-H Ha N S Goo and W S Jang ldquoPreliminarytests for a multi-functional bridge bearing with built-in pie-zoelectric materialrdquo Advanced Science Letters vol 19 no 1pp 37ndash41 2013

[15] J F Choo D H Ha C H Lee andW S Jang ldquoExperimentalstudy on the optimal layering position of the piezocompositeelectricity generating element built-in an innovative trafficload-measuring bridge bearingrdquo Advanced Materials Re-search vol 811 pp 365ndash369 2013

[16] D H Ha J F Choo D Kim and N S Goo ldquoFeasibility of amulti-functional bridge bearing with built-in piezoelectricmaterialrdquo International Journal on Advances in InformationSciences and Service Sciences vol 4 no 11 pp 142ndash150 2012

[17] V L Pham N S Ha N S Goo and J F Choo ldquoEffects ofcyclic impacts on the performance of a piezo-compositeelectricity generating element in a d33 mode energy har-vestingrdquo Journal of Nanoscience and Nanotechnology vol 14no 10 pp 7410ndash7418 2014

[18] D H Ha J F Choo C H Lee W S Jang and N S GooldquoDynamic characteristics of a multi-functional bridge bearingwith built-in piezocomposite elementrdquo Applied Mechanicsand Materials vol 432 pp 275ndash280 2013

Shock and Vibration 9

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system As shown in Figure 3 the pot bearing is simply anelastomeric pad tightly confined in a steel cylinder -e loadis transferred downward via a piston attached on the upperbearing plate to the elastomeric pad which is the load-carrying medium with multidirectional rotational capacityNote that this configuration allows the generation of auniform compression inside the bearing when subjected toexternal loading -e PCGE with a size of 76 times 76mm2 isinstalled between the pot plate and the elastomeric discPrevious tests showed that this arrangement led the PCGE toproduce higher voltage output due to the difference betweenthe deformation of the elastomer and steel plate [14ndash16]

23 Performance Tests of the Piezo-Bearing -e durabilityand responsiveness to load of the proposed piezo-bearingwere evaluated experimentally First the cyclic loading testwas performed using the apparatus shown in Figure 4 toverify whether the d33-mode PCGE inserted in the potbearing would last as long as the bearing itself Note that inthe fatigue test the PCGE was not inserted in the pot bearingand was protected only by a thin rubber pad whichmade thePCGE exposed to harsher conditions that it would actuallybe -e PCGE was hit more than two million times and theresults showed that the PCGE kept its integrity under the lowstress level -is indicated that the selected PCGE wouldfulfill reliably its measuring role with durability comparableto that of the bearing [17]

Dynamic tests were also performed on the piezo-bearingto verify the responsiveness and relationship between the loadapplied on the bearing and the corresponding output voltageof the PCGE inserted in the bearing -e tested bearingcorresponds to the smallest commercially available pot bearingwith a load-bearing capacity of 500 kN Loading was appliedusing the 500 kN universal testing machine (UTM) of theKOCED Laboratory Facility at Keimyung University Korea

To provide various load cases and simulate as possiblethe load configurations of the bearing in a real bridgepermanent load was basically applied as the weight of thesuperstructure and live harmonic loading was additionallyapplied with different frequencies to simulate the vehiclesrunning at different speeds on the superstructure Consid-ering the limitations of the UTM the permanent load was setto 100 kN and 200 kN and live loads with amplitudes of30 kN 60 kN 90 kN 120 kN and 150 kN were applied atfrequencies of 05Hz 10Hz and 30Hz which correspondto vehicles spaced by about 10m running respectively at18 km 36 kmh and 108 kmh Each load case was repeatedthree times to secure consistency of the measurements Adata acquisition system (NI cDAQ-9178) connected to avoltmeter (NI-9225) and load cell (SM-500L CAS NI-9237)measured the output voltage and applied loads during thetests [18]

-e results of the dynamic tests shown in Figure 5 forloading frequencies of 05Hz 10Hz and 30Hz togetherwith their regression lines confirm that the PCGE maintainsa linear relationship between the applied load and its outputvoltage regardless of the permanent load sustained by thebearing -is indicates that the output voltage produced bythe PCGE can sufficiently become an indicator of the ve-hicular load crossing the bridge

It is also observed that the slope of the linear relationsvaries according to the speed of the vehicle -e problem is

CarbonepoxyGlassepoxyGlassepoxy

GlassepoxyGlassepoxy

Piezoceramic

009 mm0

71 m

m

Neutral axis

009 mm

025 mm

009 mm009 mm010 mm

047

4 m

m

Figure 2 Layup configuration of multilayered d33-mode PCGE

(5)

(4)

(3)

(2)

(1)

Figure 3 Composition of the proposed pot bearing-type BWIM(1) pot plate (2) elastomeric disc (3) brass sealing ring (4) pistonwith PTFE (5) upper sliding plate and PCGE installed in thebearing [14ndash16]

(b)(a)

(c)(d)

(e)

Figure 4 Motor-driven lever system (a) mass (b) sliding bar (c)spring (d) cam mechanism (e) motor [17]

Neutral surfacePZTlayer

Compressive load and pressure

Figure 1 Concept of multilayered d33-mode PCGE and manu-factured PCGE

Shock and Vibration 3

that it was practically impossible to perform the test at otherfrequencies due to the limitations in the testing equipmentand the large loads required to simulate the permanent loadand traffic load Accordingly as a first attempt and despitethe poor number of experimental data a fitting curve wascomputed using these 3 frequency cases to provide a re-lationship between the ratio of the load-to-output voltagedata (slope of voltage-load lines) and the loading frequencyunder the assumption that the slopes of the lines relating theoutput voltage to the load in Figure 5 depend only on thefrequency of the excitation (speed of the vehicle)

Considering the linear nature of the response of thePCGE to the applied load it seems reasonable to apply aleast-squares fit for the relation between this slope and thefrequency-e equation for the linear model for the 3 pointsrelating the exciting frequency f (05 10 and 30Hz) andthe slopes (WaxleV) of the data in Figure 5 is as follows andplotted in Figure 6

Waxle

V 108417minus 10409f (1)

where Waxle axle load of the vehicle (kN) V outputvoltage measured by the bearing (V) and f excitingfrequency (Hz)

Equation (1) of the least-square fitting line in Figure 6can be rewritten as follows by expressing the frequency usingthe speed of the vehicle (v) and the span length of the bridge(L) and matching the units

Waxle

V 108417minus 02892

v

L1113874 1113875 (2)

where L span length of the bridge (m) and v speed of thevehicle passing through the bridge (kmh)

Equation (2) provides a means of determining the axleload (Waxle) of the vehicle using the output voltage (V) of thePCGE when the speed (v) of the vehicle is known

3 On-Bridge Traffic Monitoring Using theProposed BWIM System with Piezo-Bearing

To demonstrate the applicability of the proposed BWIMsystem a numerical example is presented -e considered

bridge is a single-span bridge with a length of 40m and widthof 1098m of which slab is made of concrete and supportedby 4 steel girders -e bridge supports 3 one-way traffic lanesand the 3-dimensional model shown in Figure 7 is used forthe application It is assumed that each girder is supported atits ends by the proposed BWIM bearing of which positionsare indicated by the node numbers in Figure 7

-e considered vehicular load is the DB-24 truck load ofthe Korea Highway Bridge Design Code It is a three-axletruck with the characteristics shown in Figure 8 For thenumerical example the distance between the middle and rearaxles is set to 4200mmMoving load analysis is conducted forthe truck running at speeds of 20 kmh and 80 kmh on Lane2 It is assumed that the linear model of the piezo-bearingexpressed in equation (2) is applicable -is means that theaxle load can be identified once the span length of the bridgeand the speed of the passing vehicle are known

From amechanics perspective the time history of the loadmeasured by the bearing will show a peak whenever one axleof the vehicle passes over the bearing In Figures 9 and 10presenting the time histories of the loads measured by thebearings respectively at the entrance (joint 336) and exit(joint 344) of the vehicle the peaks corresponding to the accessor exit of each axle of the DB-24 truck running at a speed of20 kmh can be clearly distinguished in the graph provided bythe bearing closest to the lane on which the vehicle travels

For clarity Figure 11 plots concurrently the time his-tories of joints 336 (entrance) and 344 (exit) In the timehistories the peaks indicated by 1 2 and 3 correspondrespectively to the access or exit of the front middle andrear axles of the 3-axle truck on the bridge Applying thefirst-infirst-out (FIFO) principle peak 1 occurs at 019 s(entrance side) and 72 s (exit side) in Figure 11 -eseoccurrence times of peak 1 at the entrance and exit show thatit took 701 s (72 minus 019) for the truck to cross the bridge(40m) which gives a speed of 20542 kmh -e same cal-culation for peaks 2 and 3 gives speeds of 20574 kmh and20484 kmh respectively Compared to the running speedof 20 kmh considered in the analysis the speed obtainedusing this peak-to-peak time lapse appears to estimate ac-curately the actual speed of the vehicle Accordingly theassumption that equation (2) is applicable for identifying theaxle load once the speed of the vehicle is known appears to bereasonable

0

2

4

6

8

10

12

0 05 1 15 2 25 3 35

Load

vol

tage

(kN

V)

Exciting frequency (Hz)

Figure 6 Least-squares fitting between the slope of the outputvoltage-load lines and the loading frequency

Freq 05 Hzy = 11001xRsup2 = 09999

Freq 10 Hzy = 8951xRsup2 = 09999

Freq 30 Hzy = 78888xRsup2 = 09988

0

40

80

120

160

200

0 5 10 15 20

Load

(kN

)

Voltage (V)

Figure 5 Output voltage-load relation of the BWIM system atvarious dynamic load frequencies

4 Shock and Vibration

Figures 12 and 13 present the same time histories for theDB-24 truck running at a speed of 80 kmh Here also theentrance and exit of each axle of the load-train can be clearlyidentified in the time history of the load measured by thebearing closest to the lane crossed by the vehicle (joint 336 atthe entrance side and joint 344 at the exit side)

As done for the previous case Figure 14 plots con-currently the time histories of joints 336 (entrance) and344 (exit) In the time histories the peaks indicated by 12 and 3 correspond respectively to the access or exit ofthe front middle and rear axles of the 3-axle truck on thebridge -e occurrence times of peak 1 at the entrance andexit show that it took 167 s ( 181 minus 014) for the truck tocross the bridge (40m) which gives a speed of 86227 kmh -e same calculation for peaks 2 and 3 gives speeds of86227 kmh and 85207 kmh respectively Compared tothe running speed of 80 kmh considered in the analysisthe speed obtained using this peak-to-peak time gapappears to approximate the actual speed of the vehiclewith an error below 78 which is lower than the error of10 commonly allowed for traffic speedometers In thiscase also the assumption that equation (2) is applicable

for identifying the axle load once the speed of the vehicle isknown appears to be reasonable

Tables 1 and 2 arrange the values of the loads measuredby the piezo-bearings corresponding to the peaks togetherwith their occurrence time in Figures 9ndash14 Considering theequilibrium of forces the vehicle load applied on the bridgeis distributed to the underlying bearings Accordingly thesum of the values measured by the piezo-bearings at theentrance or exit of the bridge and picked at the time at whichthe peaks are identified shall be added together to providethe actual cumulated load of the axles accessing or exitingthe bridge -ese sums (Wtotal) are also listed in the lastcolumn of Tables 1 and 2

In Tables 1 and 2 the cases where all the axles are loadedon the bridge are at peak 3 at the entrance side and peak 1 atthe exit side -e three axles of the truck are loaded on thebridge but are not located above the bearings at the sametime-is means that the loads measured by the bearings areonly indicative of the axle loads and do not give the values ofthe axle loads themselves -e positions of the loads at peaks1 2 and 3 at the exit side are shown in Figure 15

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 9 Loads measured by BWIM bearings at the entrance side(speed 20 kmh)

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 10 Loads measured by BWIM bearings at the exit side(speed 20 kmh)

Front Middle Rear

4200 v = 4200~9000

01W

01W

04W

04W

04W

04W

1800

2 times 24kN 2 times 96kN 2 times 96kN

600

600

Figure 8 DB-24 truck load model (in mm)

Entra

nce

334

335336

337

342343 344

345

Lane 1Lane 2Lane 3

Figure 7 -ree-dimensional model of the example bridge

Shock and Vibration 5

Considering that the loads measured by the bearingscorrespond in fact to the support reactions oriented in theopposite direction these measured loads can be used tocalculate the axle loads by the influence caused by a series ofconcentrated loads using the influence lines (ILs) for thesupport reaction shown in Figure 16

Once the speed of the vehicle is known the time lapsebetween the peaks at the entrance side or exit side providesthe distance between the axles Based on the location of theloads for each peak at the exit side in Figure 15 the in-fluence for the support reaction (RB) at the exit side inFigure 16 can be used to calculate successively the loads ofthe rear middle and front axles as expressed in the fol-lowing equations

Wrear axle Wtotal( 1113857peak 3 exit (3)

where Wrear axle identified value of the rear axle load of thetruck and (Wtotal)peak 3 exit sum of loads measured byjoints 342 343 344 and 345 at occurrence of peak 3 at theexit side

Wmiddle axle Wtotal( 1113857peak 2 exitminusWrear axle 1minusd2

L1113888 1113889 (4)

where Wmiddle axle identified value of the rear axle load ofthe truck (Wtotal)peak 2 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 2 at the exit sideWrear axle value of the rear axle load of the truck providedby equation (3) and d2 distance between middle and rearaxles of the truck

Wfront axle Wtotal( 1113857peak 1 exitminusWmiddle axle 1minusd1

L1113888 1113889

minusWrear axle 1minusd1 + d2

L1113888 1113889

(5)

where Wfront axle identified value of the front axle load ofthe truck (Wtotal)peak 1 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 1 at the exit sideWmiddle axle value of the middle axle load of the truckprovided by equation (4) d1 distance between front andmiddle axles of the truck Wrear axle value of the rear axle

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 13 Loads measured by BWIM bearings at the exit side(speed 80 kmh)

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 2Peak 1

Peak 3

Peak 3

Peak 2

Peak 1

Figure 14 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 80 kmh

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 1

Peak 2

Peak 1

Peak 2

Peak 3

Peak 3

Figure 11 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 20 kmh

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 12 Loads measured by BWIM bearings at the entrance side(speed 80 kmh)

6 Shock and Vibration

load of the truck provided by equation (3) and d2 distancebetween middle and rear axles of the truck

Figure 17 shows the flowchart for the identification ofthe axle loads using the loads measured by the bearings

Note that in Figure 17 the identification of the numberof peaks will give information on the type of vehicle passingon the bridge based on the standardized vehicle classificationsystem -e vehicle classification system categorizes thevehicles into 13 classes from motorcycles passenger carsand buses to multiple-axle trucks according to the number ofaxles and the distance between consecutive axles

Using the flowchart in Figure 17 Table 3 arranges theidentified axle loads of the DB-24 truck running at 20 kmhand 80 kmh with the errors For the calculation of the errorthe estimated values are compared with the actual values ofthe DB-24 truck model (Figure 8) of the Korea HighwayBridge Design Code with the front axle load of 48 kN middleaxle load of 192 kN and rear axle load of 192 kN which givesa total load of 432 kN and the distance between the axles isd1 d2 4200 mm

As mentioned above the speed obtained using the peak-to-peak time gap approximates the actual speed of the

Table 1 Values of peaks identified in time histories of loads measured by BWIM bearings (20 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 019 minus023965 minus136519 2543254 2109958 44927282 097 minus295398 minus078127 1190154 1062699 22155013 172 minus1036348 1744544 18531005 19043366 3828257Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 720 minus1618517 4062979 15109605 19135729 36689802 797 minus666830 816733 18355975 17510131 36016013 875 040080 minus883196 1111157 8745885 1901434

Table 2 Values of peaks identified in time histories of loads measured by BWIM bearings (80 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 014 minus084606 00354 2100938 1918984 39388562 033 minus561803 484041 9905302 9702933 19530473 050 minus1380111 2230247 16227767 17895248 3497315Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 181 minus1911155 4599867 14047757 19121095 358575642 200 minus1118191 1709516 16991835 17735358 353185183 219 minus380146 minus396868 10125288 8811671 18159945

RearFront

Entrance ExitL = 40m

Middle

d1d2

(a)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(b)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(c)

Figure 15 Position of truck axles corresponding to peaks at the exit side of the bridge (a) Occurrence of peak 1 at the exit side (b)Occurrence of peak 2 at the exit side (c) Occurrence of peak 3 at the exit side

Shock and Vibration 7

vehicle with an error below 736 on the average which islower than the error of 10 commonly allowed for trafficspeedometers Recalling that the linear model in equation(2) relating the output voltage to the load was establishedusing data measured at excitation frequencies of 05Hz10 Hz and 30Hz (vehicles running respectively at18 km 36 kmh and 108 kmh) the linear model obtainedby the least-squares method is sufficiently applicableconsidering that the speed limits in Korea are 60 kmh inurban areas 80 kmh in highways and 100 kmh and110 kmh in expressways

-e error in the estimation of the distance between theaxles appears to increase with the speed of the vehicle butremains below 792 for the considered cases However thiserror had poor effect on the estimation of the axle loads ofwhich error remained below 542-e final total load of thetruck could be estimated with an error below 243 Since allthe trucks are characterized by their number of axles axledistance and axle loads the type of truck can thus beidentified and eventual overload can be captured

Based upon the simplest theory of mechanics theproposed BWIM system with built-in PCGE offers thus allthe functions required for the conventional BWIM that arecapturing and recording axle weights and distances andgross weights and velocities of vehicles regardless of the typematerial composition and shape of the bridge

4 Conclusions

-is paper presented a new BWIM system overcoming thedrawbacks of former systems -e proposed BWIM systemappears in the form of a piezo-bearing in which the PCGE isembedded To that goal a PCGEwas designed and fabricatedto offer all the advantages of piezoceramics while being freefrom their material brittleness A series of performance testsincluding fatigue test and dynamic test showed that thePCGE can be used to sustain the large load involved in thetraffic monitoring in civil structures Moving load analysiswas performed on a full three-dimensional model of a bridgeusing a typical truck load to verify the applicability of theproposed BWIM system for the on-bridge traffic monitor-ing-e following conclusions can be drawn from the resultsof the moving load analysis

(1) A linear model for converting the measured outputvoltage of the PCGE into loading was proposedconsidering its linear nature Further experimentsshall be implemented to verify the adequacy of themodel for a wider range of exciting frequencies

(2) -e time histories of the loads measured by thepiezo-bearings were used to distinguish the entranceor exit of the axle loads on the bridge -e passage ofeach axle load could be identified by the occurrenceof peaks in the time histories Based on the stan-dardized vehicle classification system the identifi-cation of the number of peaks can give informationon the type of vehicle passing on the bridge and inturn allowed the estimation of the speed of thevehicle and distances between the axles

Entrance

A B

IL for RB1

ExitL = 40m

xL

x40

1x

x

Figure 16 Influence lines for support reaction at the exit side

Start

Identification of vehicle type (number ofaxles) by measured peaks at entrance side

Identification of peaks at exit side

Calculation of vehicle speedusing peak-to-peak time gap between

entrance and exit sides

Conversion of output voltageinto load data using equation (2)

Calculation of axle distances (di) usingoccurrence time of peaks at exit side

Calculation of axle loads (Waxle) usinginfluence line for support reaction in

Figure 16 at exit side using equations (2)ndash(5)

End

Figure 17 Flowchart for the identification of axle loads using theproposed BWIM bearing

Table 3 Estimated vehiclersquos speed and axle loads using the pro-posed BWIM bearings

Estimated values Speed case20 kmh 80 kmh

Truck speed Average (kmh) 20532 85887Error () 267 736

Axle distance

d1 (mm) 439165 453295Error () 456 792d2 (mm) 444868 453295Error () 592 792

Axle loads

Front axle (kN) 48602 47747Error () 125 053

Middle axle (kN) 191164 192165Error () 043 0009

Rear axle (kN) 190143 181599Error () 097 542

Total load Total (kN) 429909 421512Error () 048 243

8 Shock and Vibration

(3) An algorithm based on the concept of influence linefor support reaction was established to calculate eachaxle load of the vehicle using the identified loadpeaks

(4) -e simulated data could estimate the speed of thevehicle passing the bridge as well as the axle weightsand distances and gross weights of the vehicle withgood accuracy regardless of the type materialcomposition and shape of the bridge purely basedon the theory of structural mechanics

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-e authors are thankful for funds provided by Korea In-stitute of Civil Engineering and Building Technology(KICT) Republic of Korea (Project No 2018-0255) -iswork was also supported by the Energy Efficiency amp Re-sources Core Technology Program of the Korea Institute ofEnergy Technology Evaluation and Planning (KETEP) andgranted financial resource from the Ministry of Trade In-dustry amp Energy Republic of Korea (No 20142020103979)

References

[1] J C Pais S I R Amorim and M J C Minhoto ldquoImpact oftraffic overload on road pavement performancerdquo Journal ofTransportation Engineering vol 139 no 9 pp 873ndash879 2013

[2] Y Yang C S Cai and D Lu ldquoState-of-the-art review onbridge weigh-in-motion technologyrdquo Advances in StructuralEngineering vol 19 no 9 pp 1514ndash1530 2016

[3] F Moses ldquoWeigh-in-motion system using instrumentedbridgesrdquo Journal of Transportation Engineering ASCEvol 105 no TE3 pp 233ndash249 1979

[4] Federal Highway Administration (FHWA) LTBP ProgramrsquosLiterature Review on Weigh-In-Motion Systems PublicationNo FHWA-HRT-16-024 FHWA Washington DC USA2016

[5] B Lechner M Lieschnegg O Mariani and M PiercherldquoDetection of vehicle data in a bridge weigh-in-motion sys-temrdquo Modern Traffic and Transportation Engineering Re-search vol 2 no 3 pp 153ndash161 2013

[6] J Richardson S Jones A Brown E J Orsquobrien andD Hajializadeh ldquoOn the use of bridge weigh-in-motion foroverweight truck enforcementrdquo International Journal ofHeavy Vehicle Systems vol 21 no 2 pp 83ndash104 2014

[7] M Lydon S E Taylor D Robinson A Mufti andE J O Brien ldquoRecent developments in bridge weigh inmotion (B-WIM)rdquo Journal of Civil Structural Health Moni-toring vol 6 no 1 pp 69ndash81 2015

[8] J F Choo V L Pham and N S Goo ldquoDesign of a d33-modepiezocomposite electricity generating element and its appli-cation to bridge monitoringrdquo Journal of Central South Uni-versity vol 21 no 7 pp 2572ndash2578 2014

[9] D G Yoo K S Kyung S J Lee H H Lee and J C Jeon ldquoAstudy on influencing factors in BWIM system and its fieldapplicabilityrdquo Journal of Korean Society of Steel Constructionvol 26 no 4 pp 251ndash262 2014

[10] J Zhao N S Goo and D-H Ha ldquoDesign and performanceevaluation of a d33-mode piezocomposite electricity gener-ating elementrdquo Journal of Mechanical Science and Technologyvol 28 no 1 pp 15ndash23 2014

[11] H A Sodano D J Inman and G Park ldquoComparison ofpiezoelectric energy harvesting devices for recharging bat-teriesrdquo Journal of Intelligent Material Systems and Structuresvol 16 no 10 pp 799ndash807 2016

[12] A Abrar and S Cochran ldquoMultilayer piezocompositestructures with piezoceramic volume fractions determined bymathematical optimisationrdquo Ultrasonics vol 42 no 1ndash9pp 259ndash265 2004

[13] R Ramesh H Kara and C R Bowen ldquoCharacteristics ofpiezoceramic and 3-3 piezocomposite hydrophones evaluatedby finite element modellingrdquo Computational Materials Sci-ence vol 30 no 3-4 pp 397ndash403 2004

[14] J F Choo D-H Ha N S Goo and W S Jang ldquoPreliminarytests for a multi-functional bridge bearing with built-in pie-zoelectric materialrdquo Advanced Science Letters vol 19 no 1pp 37ndash41 2013

[15] J F Choo D H Ha C H Lee andW S Jang ldquoExperimentalstudy on the optimal layering position of the piezocompositeelectricity generating element built-in an innovative trafficload-measuring bridge bearingrdquo Advanced Materials Re-search vol 811 pp 365ndash369 2013

[16] D H Ha J F Choo D Kim and N S Goo ldquoFeasibility of amulti-functional bridge bearing with built-in piezoelectricmaterialrdquo International Journal on Advances in InformationSciences and Service Sciences vol 4 no 11 pp 142ndash150 2012

[17] V L Pham N S Ha N S Goo and J F Choo ldquoEffects ofcyclic impacts on the performance of a piezo-compositeelectricity generating element in a d33 mode energy har-vestingrdquo Journal of Nanoscience and Nanotechnology vol 14no 10 pp 7410ndash7418 2014

[18] D H Ha J F Choo C H Lee W S Jang and N S GooldquoDynamic characteristics of a multi-functional bridge bearingwith built-in piezocomposite elementrdquo Applied Mechanicsand Materials vol 432 pp 275ndash280 2013

Shock and Vibration 9

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

that it was practically impossible to perform the test at otherfrequencies due to the limitations in the testing equipmentand the large loads required to simulate the permanent loadand traffic load Accordingly as a first attempt and despitethe poor number of experimental data a fitting curve wascomputed using these 3 frequency cases to provide a re-lationship between the ratio of the load-to-output voltagedata (slope of voltage-load lines) and the loading frequencyunder the assumption that the slopes of the lines relating theoutput voltage to the load in Figure 5 depend only on thefrequency of the excitation (speed of the vehicle)

Considering the linear nature of the response of thePCGE to the applied load it seems reasonable to apply aleast-squares fit for the relation between this slope and thefrequency-e equation for the linear model for the 3 pointsrelating the exciting frequency f (05 10 and 30Hz) andthe slopes (WaxleV) of the data in Figure 5 is as follows andplotted in Figure 6

Waxle

V 108417minus 10409f (1)

where Waxle axle load of the vehicle (kN) V outputvoltage measured by the bearing (V) and f excitingfrequency (Hz)

Equation (1) of the least-square fitting line in Figure 6can be rewritten as follows by expressing the frequency usingthe speed of the vehicle (v) and the span length of the bridge(L) and matching the units

Waxle

V 108417minus 02892

v

L1113874 1113875 (2)

where L span length of the bridge (m) and v speed of thevehicle passing through the bridge (kmh)

Equation (2) provides a means of determining the axleload (Waxle) of the vehicle using the output voltage (V) of thePCGE when the speed (v) of the vehicle is known

3 On-Bridge Traffic Monitoring Using theProposed BWIM System with Piezo-Bearing

To demonstrate the applicability of the proposed BWIMsystem a numerical example is presented -e considered

bridge is a single-span bridge with a length of 40m and widthof 1098m of which slab is made of concrete and supportedby 4 steel girders -e bridge supports 3 one-way traffic lanesand the 3-dimensional model shown in Figure 7 is used forthe application It is assumed that each girder is supported atits ends by the proposed BWIM bearing of which positionsare indicated by the node numbers in Figure 7

-e considered vehicular load is the DB-24 truck load ofthe Korea Highway Bridge Design Code It is a three-axletruck with the characteristics shown in Figure 8 For thenumerical example the distance between the middle and rearaxles is set to 4200mmMoving load analysis is conducted forthe truck running at speeds of 20 kmh and 80 kmh on Lane2 It is assumed that the linear model of the piezo-bearingexpressed in equation (2) is applicable -is means that theaxle load can be identified once the span length of the bridgeand the speed of the passing vehicle are known

From amechanics perspective the time history of the loadmeasured by the bearing will show a peak whenever one axleof the vehicle passes over the bearing In Figures 9 and 10presenting the time histories of the loads measured by thebearings respectively at the entrance (joint 336) and exit(joint 344) of the vehicle the peaks corresponding to the accessor exit of each axle of the DB-24 truck running at a speed of20 kmh can be clearly distinguished in the graph provided bythe bearing closest to the lane on which the vehicle travels

For clarity Figure 11 plots concurrently the time his-tories of joints 336 (entrance) and 344 (exit) In the timehistories the peaks indicated by 1 2 and 3 correspondrespectively to the access or exit of the front middle andrear axles of the 3-axle truck on the bridge Applying thefirst-infirst-out (FIFO) principle peak 1 occurs at 019 s(entrance side) and 72 s (exit side) in Figure 11 -eseoccurrence times of peak 1 at the entrance and exit show thatit took 701 s (72 minus 019) for the truck to cross the bridge(40m) which gives a speed of 20542 kmh -e same cal-culation for peaks 2 and 3 gives speeds of 20574 kmh and20484 kmh respectively Compared to the running speedof 20 kmh considered in the analysis the speed obtainedusing this peak-to-peak time lapse appears to estimate ac-curately the actual speed of the vehicle Accordingly theassumption that equation (2) is applicable for identifying theaxle load once the speed of the vehicle is known appears to bereasonable

0

2

4

6

8

10

12

0 05 1 15 2 25 3 35

Load

vol

tage

(kN

V)

Exciting frequency (Hz)

Figure 6 Least-squares fitting between the slope of the outputvoltage-load lines and the loading frequency

Freq 05 Hzy = 11001xRsup2 = 09999

Freq 10 Hzy = 8951xRsup2 = 09999

Freq 30 Hzy = 78888xRsup2 = 09988

0

40

80

120

160

200

0 5 10 15 20

Load

(kN

)

Voltage (V)

Figure 5 Output voltage-load relation of the BWIM system atvarious dynamic load frequencies

4 Shock and Vibration

Figures 12 and 13 present the same time histories for theDB-24 truck running at a speed of 80 kmh Here also theentrance and exit of each axle of the load-train can be clearlyidentified in the time history of the load measured by thebearing closest to the lane crossed by the vehicle (joint 336 atthe entrance side and joint 344 at the exit side)

As done for the previous case Figure 14 plots con-currently the time histories of joints 336 (entrance) and344 (exit) In the time histories the peaks indicated by 12 and 3 correspond respectively to the access or exit ofthe front middle and rear axles of the 3-axle truck on thebridge -e occurrence times of peak 1 at the entrance andexit show that it took 167 s ( 181 minus 014) for the truck tocross the bridge (40m) which gives a speed of 86227 kmh -e same calculation for peaks 2 and 3 gives speeds of86227 kmh and 85207 kmh respectively Compared tothe running speed of 80 kmh considered in the analysisthe speed obtained using this peak-to-peak time gapappears to approximate the actual speed of the vehiclewith an error below 78 which is lower than the error of10 commonly allowed for traffic speedometers In thiscase also the assumption that equation (2) is applicable

for identifying the axle load once the speed of the vehicle isknown appears to be reasonable

Tables 1 and 2 arrange the values of the loads measuredby the piezo-bearings corresponding to the peaks togetherwith their occurrence time in Figures 9ndash14 Considering theequilibrium of forces the vehicle load applied on the bridgeis distributed to the underlying bearings Accordingly thesum of the values measured by the piezo-bearings at theentrance or exit of the bridge and picked at the time at whichthe peaks are identified shall be added together to providethe actual cumulated load of the axles accessing or exitingthe bridge -ese sums (Wtotal) are also listed in the lastcolumn of Tables 1 and 2

In Tables 1 and 2 the cases where all the axles are loadedon the bridge are at peak 3 at the entrance side and peak 1 atthe exit side -e three axles of the truck are loaded on thebridge but are not located above the bearings at the sametime-is means that the loads measured by the bearings areonly indicative of the axle loads and do not give the values ofthe axle loads themselves -e positions of the loads at peaks1 2 and 3 at the exit side are shown in Figure 15

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 9 Loads measured by BWIM bearings at the entrance side(speed 20 kmh)

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 10 Loads measured by BWIM bearings at the exit side(speed 20 kmh)

Front Middle Rear

4200 v = 4200~9000

01W

01W

04W

04W

04W

04W

1800

2 times 24kN 2 times 96kN 2 times 96kN

600

600

Figure 8 DB-24 truck load model (in mm)

Entra

nce

334

335336

337

342343 344

345

Lane 1Lane 2Lane 3

Figure 7 -ree-dimensional model of the example bridge

Shock and Vibration 5

Considering that the loads measured by the bearingscorrespond in fact to the support reactions oriented in theopposite direction these measured loads can be used tocalculate the axle loads by the influence caused by a series ofconcentrated loads using the influence lines (ILs) for thesupport reaction shown in Figure 16

Once the speed of the vehicle is known the time lapsebetween the peaks at the entrance side or exit side providesthe distance between the axles Based on the location of theloads for each peak at the exit side in Figure 15 the in-fluence for the support reaction (RB) at the exit side inFigure 16 can be used to calculate successively the loads ofthe rear middle and front axles as expressed in the fol-lowing equations

Wrear axle Wtotal( 1113857peak 3 exit (3)

where Wrear axle identified value of the rear axle load of thetruck and (Wtotal)peak 3 exit sum of loads measured byjoints 342 343 344 and 345 at occurrence of peak 3 at theexit side

Wmiddle axle Wtotal( 1113857peak 2 exitminusWrear axle 1minusd2

L1113888 1113889 (4)

where Wmiddle axle identified value of the rear axle load ofthe truck (Wtotal)peak 2 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 2 at the exit sideWrear axle value of the rear axle load of the truck providedby equation (3) and d2 distance between middle and rearaxles of the truck

Wfront axle Wtotal( 1113857peak 1 exitminusWmiddle axle 1minusd1

L1113888 1113889

minusWrear axle 1minusd1 + d2

L1113888 1113889

(5)

where Wfront axle identified value of the front axle load ofthe truck (Wtotal)peak 1 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 1 at the exit sideWmiddle axle value of the middle axle load of the truckprovided by equation (4) d1 distance between front andmiddle axles of the truck Wrear axle value of the rear axle

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 13 Loads measured by BWIM bearings at the exit side(speed 80 kmh)

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 2Peak 1

Peak 3

Peak 3

Peak 2

Peak 1

Figure 14 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 80 kmh

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 1

Peak 2

Peak 1

Peak 2

Peak 3

Peak 3

Figure 11 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 20 kmh

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 12 Loads measured by BWIM bearings at the entrance side(speed 80 kmh)

6 Shock and Vibration

load of the truck provided by equation (3) and d2 distancebetween middle and rear axles of the truck

Figure 17 shows the flowchart for the identification ofthe axle loads using the loads measured by the bearings

Note that in Figure 17 the identification of the numberof peaks will give information on the type of vehicle passingon the bridge based on the standardized vehicle classificationsystem -e vehicle classification system categorizes thevehicles into 13 classes from motorcycles passenger carsand buses to multiple-axle trucks according to the number ofaxles and the distance between consecutive axles

Using the flowchart in Figure 17 Table 3 arranges theidentified axle loads of the DB-24 truck running at 20 kmhand 80 kmh with the errors For the calculation of the errorthe estimated values are compared with the actual values ofthe DB-24 truck model (Figure 8) of the Korea HighwayBridge Design Code with the front axle load of 48 kN middleaxle load of 192 kN and rear axle load of 192 kN which givesa total load of 432 kN and the distance between the axles isd1 d2 4200 mm

As mentioned above the speed obtained using the peak-to-peak time gap approximates the actual speed of the

Table 1 Values of peaks identified in time histories of loads measured by BWIM bearings (20 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 019 minus023965 minus136519 2543254 2109958 44927282 097 minus295398 minus078127 1190154 1062699 22155013 172 minus1036348 1744544 18531005 19043366 3828257Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 720 minus1618517 4062979 15109605 19135729 36689802 797 minus666830 816733 18355975 17510131 36016013 875 040080 minus883196 1111157 8745885 1901434

Table 2 Values of peaks identified in time histories of loads measured by BWIM bearings (80 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 014 minus084606 00354 2100938 1918984 39388562 033 minus561803 484041 9905302 9702933 19530473 050 minus1380111 2230247 16227767 17895248 3497315Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 181 minus1911155 4599867 14047757 19121095 358575642 200 minus1118191 1709516 16991835 17735358 353185183 219 minus380146 minus396868 10125288 8811671 18159945

RearFront

Entrance ExitL = 40m

Middle

d1d2

(a)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(b)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(c)

Figure 15 Position of truck axles corresponding to peaks at the exit side of the bridge (a) Occurrence of peak 1 at the exit side (b)Occurrence of peak 2 at the exit side (c) Occurrence of peak 3 at the exit side

Shock and Vibration 7

vehicle with an error below 736 on the average which islower than the error of 10 commonly allowed for trafficspeedometers Recalling that the linear model in equation(2) relating the output voltage to the load was establishedusing data measured at excitation frequencies of 05Hz10 Hz and 30Hz (vehicles running respectively at18 km 36 kmh and 108 kmh) the linear model obtainedby the least-squares method is sufficiently applicableconsidering that the speed limits in Korea are 60 kmh inurban areas 80 kmh in highways and 100 kmh and110 kmh in expressways

-e error in the estimation of the distance between theaxles appears to increase with the speed of the vehicle butremains below 792 for the considered cases However thiserror had poor effect on the estimation of the axle loads ofwhich error remained below 542-e final total load of thetruck could be estimated with an error below 243 Since allthe trucks are characterized by their number of axles axledistance and axle loads the type of truck can thus beidentified and eventual overload can be captured

Based upon the simplest theory of mechanics theproposed BWIM system with built-in PCGE offers thus allthe functions required for the conventional BWIM that arecapturing and recording axle weights and distances andgross weights and velocities of vehicles regardless of the typematerial composition and shape of the bridge

4 Conclusions

-is paper presented a new BWIM system overcoming thedrawbacks of former systems -e proposed BWIM systemappears in the form of a piezo-bearing in which the PCGE isembedded To that goal a PCGEwas designed and fabricatedto offer all the advantages of piezoceramics while being freefrom their material brittleness A series of performance testsincluding fatigue test and dynamic test showed that thePCGE can be used to sustain the large load involved in thetraffic monitoring in civil structures Moving load analysiswas performed on a full three-dimensional model of a bridgeusing a typical truck load to verify the applicability of theproposed BWIM system for the on-bridge traffic monitor-ing-e following conclusions can be drawn from the resultsof the moving load analysis

(1) A linear model for converting the measured outputvoltage of the PCGE into loading was proposedconsidering its linear nature Further experimentsshall be implemented to verify the adequacy of themodel for a wider range of exciting frequencies

(2) -e time histories of the loads measured by thepiezo-bearings were used to distinguish the entranceor exit of the axle loads on the bridge -e passage ofeach axle load could be identified by the occurrenceof peaks in the time histories Based on the stan-dardized vehicle classification system the identifi-cation of the number of peaks can give informationon the type of vehicle passing on the bridge and inturn allowed the estimation of the speed of thevehicle and distances between the axles

Entrance

A B

IL for RB1

ExitL = 40m

xL

x40

1x

x

Figure 16 Influence lines for support reaction at the exit side

Start

Identification of vehicle type (number ofaxles) by measured peaks at entrance side

Identification of peaks at exit side

Calculation of vehicle speedusing peak-to-peak time gap between

entrance and exit sides

Conversion of output voltageinto load data using equation (2)

Calculation of axle distances (di) usingoccurrence time of peaks at exit side

Calculation of axle loads (Waxle) usinginfluence line for support reaction in

Figure 16 at exit side using equations (2)ndash(5)

End

Figure 17 Flowchart for the identification of axle loads using theproposed BWIM bearing

Table 3 Estimated vehiclersquos speed and axle loads using the pro-posed BWIM bearings

Estimated values Speed case20 kmh 80 kmh

Truck speed Average (kmh) 20532 85887Error () 267 736

Axle distance

d1 (mm) 439165 453295Error () 456 792d2 (mm) 444868 453295Error () 592 792

Axle loads

Front axle (kN) 48602 47747Error () 125 053

Middle axle (kN) 191164 192165Error () 043 0009

Rear axle (kN) 190143 181599Error () 097 542

Total load Total (kN) 429909 421512Error () 048 243

8 Shock and Vibration

(3) An algorithm based on the concept of influence linefor support reaction was established to calculate eachaxle load of the vehicle using the identified loadpeaks

(4) -e simulated data could estimate the speed of thevehicle passing the bridge as well as the axle weightsand distances and gross weights of the vehicle withgood accuracy regardless of the type materialcomposition and shape of the bridge purely basedon the theory of structural mechanics

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-e authors are thankful for funds provided by Korea In-stitute of Civil Engineering and Building Technology(KICT) Republic of Korea (Project No 2018-0255) -iswork was also supported by the Energy Efficiency amp Re-sources Core Technology Program of the Korea Institute ofEnergy Technology Evaluation and Planning (KETEP) andgranted financial resource from the Ministry of Trade In-dustry amp Energy Republic of Korea (No 20142020103979)

References

[1] J C Pais S I R Amorim and M J C Minhoto ldquoImpact oftraffic overload on road pavement performancerdquo Journal ofTransportation Engineering vol 139 no 9 pp 873ndash879 2013

[2] Y Yang C S Cai and D Lu ldquoState-of-the-art review onbridge weigh-in-motion technologyrdquo Advances in StructuralEngineering vol 19 no 9 pp 1514ndash1530 2016

[3] F Moses ldquoWeigh-in-motion system using instrumentedbridgesrdquo Journal of Transportation Engineering ASCEvol 105 no TE3 pp 233ndash249 1979

[4] Federal Highway Administration (FHWA) LTBP ProgramrsquosLiterature Review on Weigh-In-Motion Systems PublicationNo FHWA-HRT-16-024 FHWA Washington DC USA2016

[5] B Lechner M Lieschnegg O Mariani and M PiercherldquoDetection of vehicle data in a bridge weigh-in-motion sys-temrdquo Modern Traffic and Transportation Engineering Re-search vol 2 no 3 pp 153ndash161 2013

[6] J Richardson S Jones A Brown E J Orsquobrien andD Hajializadeh ldquoOn the use of bridge weigh-in-motion foroverweight truck enforcementrdquo International Journal ofHeavy Vehicle Systems vol 21 no 2 pp 83ndash104 2014

[7] M Lydon S E Taylor D Robinson A Mufti andE J O Brien ldquoRecent developments in bridge weigh inmotion (B-WIM)rdquo Journal of Civil Structural Health Moni-toring vol 6 no 1 pp 69ndash81 2015

[8] J F Choo V L Pham and N S Goo ldquoDesign of a d33-modepiezocomposite electricity generating element and its appli-cation to bridge monitoringrdquo Journal of Central South Uni-versity vol 21 no 7 pp 2572ndash2578 2014

[9] D G Yoo K S Kyung S J Lee H H Lee and J C Jeon ldquoAstudy on influencing factors in BWIM system and its fieldapplicabilityrdquo Journal of Korean Society of Steel Constructionvol 26 no 4 pp 251ndash262 2014

[10] J Zhao N S Goo and D-H Ha ldquoDesign and performanceevaluation of a d33-mode piezocomposite electricity gener-ating elementrdquo Journal of Mechanical Science and Technologyvol 28 no 1 pp 15ndash23 2014

[11] H A Sodano D J Inman and G Park ldquoComparison ofpiezoelectric energy harvesting devices for recharging bat-teriesrdquo Journal of Intelligent Material Systems and Structuresvol 16 no 10 pp 799ndash807 2016

[12] A Abrar and S Cochran ldquoMultilayer piezocompositestructures with piezoceramic volume fractions determined bymathematical optimisationrdquo Ultrasonics vol 42 no 1ndash9pp 259ndash265 2004

[13] R Ramesh H Kara and C R Bowen ldquoCharacteristics ofpiezoceramic and 3-3 piezocomposite hydrophones evaluatedby finite element modellingrdquo Computational Materials Sci-ence vol 30 no 3-4 pp 397ndash403 2004

[14] J F Choo D-H Ha N S Goo and W S Jang ldquoPreliminarytests for a multi-functional bridge bearing with built-in pie-zoelectric materialrdquo Advanced Science Letters vol 19 no 1pp 37ndash41 2013

[15] J F Choo D H Ha C H Lee andW S Jang ldquoExperimentalstudy on the optimal layering position of the piezocompositeelectricity generating element built-in an innovative trafficload-measuring bridge bearingrdquo Advanced Materials Re-search vol 811 pp 365ndash369 2013

[16] D H Ha J F Choo D Kim and N S Goo ldquoFeasibility of amulti-functional bridge bearing with built-in piezoelectricmaterialrdquo International Journal on Advances in InformationSciences and Service Sciences vol 4 no 11 pp 142ndash150 2012

[17] V L Pham N S Ha N S Goo and J F Choo ldquoEffects ofcyclic impacts on the performance of a piezo-compositeelectricity generating element in a d33 mode energy har-vestingrdquo Journal of Nanoscience and Nanotechnology vol 14no 10 pp 7410ndash7418 2014

[18] D H Ha J F Choo C H Lee W S Jang and N S GooldquoDynamic characteristics of a multi-functional bridge bearingwith built-in piezocomposite elementrdquo Applied Mechanicsand Materials vol 432 pp 275ndash280 2013

Shock and Vibration 9

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

Figures 12 and 13 present the same time histories for theDB-24 truck running at a speed of 80 kmh Here also theentrance and exit of each axle of the load-train can be clearlyidentified in the time history of the load measured by thebearing closest to the lane crossed by the vehicle (joint 336 atthe entrance side and joint 344 at the exit side)

As done for the previous case Figure 14 plots con-currently the time histories of joints 336 (entrance) and344 (exit) In the time histories the peaks indicated by 12 and 3 correspond respectively to the access or exit ofthe front middle and rear axles of the 3-axle truck on thebridge -e occurrence times of peak 1 at the entrance andexit show that it took 167 s ( 181 minus 014) for the truck tocross the bridge (40m) which gives a speed of 86227 kmh -e same calculation for peaks 2 and 3 gives speeds of86227 kmh and 85207 kmh respectively Compared tothe running speed of 80 kmh considered in the analysisthe speed obtained using this peak-to-peak time gapappears to approximate the actual speed of the vehiclewith an error below 78 which is lower than the error of10 commonly allowed for traffic speedometers In thiscase also the assumption that equation (2) is applicable

for identifying the axle load once the speed of the vehicle isknown appears to be reasonable

Tables 1 and 2 arrange the values of the loads measuredby the piezo-bearings corresponding to the peaks togetherwith their occurrence time in Figures 9ndash14 Considering theequilibrium of forces the vehicle load applied on the bridgeis distributed to the underlying bearings Accordingly thesum of the values measured by the piezo-bearings at theentrance or exit of the bridge and picked at the time at whichthe peaks are identified shall be added together to providethe actual cumulated load of the axles accessing or exitingthe bridge -ese sums (Wtotal) are also listed in the lastcolumn of Tables 1 and 2

In Tables 1 and 2 the cases where all the axles are loadedon the bridge are at peak 3 at the entrance side and peak 1 atthe exit side -e three axles of the truck are loaded on thebridge but are not located above the bearings at the sametime-is means that the loads measured by the bearings areonly indicative of the axle loads and do not give the values ofthe axle loads themselves -e positions of the loads at peaks1 2 and 3 at the exit side are shown in Figure 15

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 9 Loads measured by BWIM bearings at the entrance side(speed 20 kmh)

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 10 Loads measured by BWIM bearings at the exit side(speed 20 kmh)

Front Middle Rear

4200 v = 4200~9000

01W

01W

04W

04W

04W

04W

1800

2 times 24kN 2 times 96kN 2 times 96kN

600

600

Figure 8 DB-24 truck load model (in mm)

Entra

nce

334

335336

337

342343 344

345

Lane 1Lane 2Lane 3

Figure 7 -ree-dimensional model of the example bridge

Shock and Vibration 5

Considering that the loads measured by the bearingscorrespond in fact to the support reactions oriented in theopposite direction these measured loads can be used tocalculate the axle loads by the influence caused by a series ofconcentrated loads using the influence lines (ILs) for thesupport reaction shown in Figure 16

Once the speed of the vehicle is known the time lapsebetween the peaks at the entrance side or exit side providesthe distance between the axles Based on the location of theloads for each peak at the exit side in Figure 15 the in-fluence for the support reaction (RB) at the exit side inFigure 16 can be used to calculate successively the loads ofthe rear middle and front axles as expressed in the fol-lowing equations

Wrear axle Wtotal( 1113857peak 3 exit (3)

where Wrear axle identified value of the rear axle load of thetruck and (Wtotal)peak 3 exit sum of loads measured byjoints 342 343 344 and 345 at occurrence of peak 3 at theexit side

Wmiddle axle Wtotal( 1113857peak 2 exitminusWrear axle 1minusd2

L1113888 1113889 (4)

where Wmiddle axle identified value of the rear axle load ofthe truck (Wtotal)peak 2 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 2 at the exit sideWrear axle value of the rear axle load of the truck providedby equation (3) and d2 distance between middle and rearaxles of the truck

Wfront axle Wtotal( 1113857peak 1 exitminusWmiddle axle 1minusd1

L1113888 1113889

minusWrear axle 1minusd1 + d2

L1113888 1113889

(5)

where Wfront axle identified value of the front axle load ofthe truck (Wtotal)peak 1 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 1 at the exit sideWmiddle axle value of the middle axle load of the truckprovided by equation (4) d1 distance between front andmiddle axles of the truck Wrear axle value of the rear axle

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 13 Loads measured by BWIM bearings at the exit side(speed 80 kmh)

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 2Peak 1

Peak 3

Peak 3

Peak 2

Peak 1

Figure 14 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 80 kmh

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 1

Peak 2

Peak 1

Peak 2

Peak 3

Peak 3

Figure 11 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 20 kmh

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 12 Loads measured by BWIM bearings at the entrance side(speed 80 kmh)

6 Shock and Vibration

load of the truck provided by equation (3) and d2 distancebetween middle and rear axles of the truck

Figure 17 shows the flowchart for the identification ofthe axle loads using the loads measured by the bearings

Note that in Figure 17 the identification of the numberof peaks will give information on the type of vehicle passingon the bridge based on the standardized vehicle classificationsystem -e vehicle classification system categorizes thevehicles into 13 classes from motorcycles passenger carsand buses to multiple-axle trucks according to the number ofaxles and the distance between consecutive axles

Using the flowchart in Figure 17 Table 3 arranges theidentified axle loads of the DB-24 truck running at 20 kmhand 80 kmh with the errors For the calculation of the errorthe estimated values are compared with the actual values ofthe DB-24 truck model (Figure 8) of the Korea HighwayBridge Design Code with the front axle load of 48 kN middleaxle load of 192 kN and rear axle load of 192 kN which givesa total load of 432 kN and the distance between the axles isd1 d2 4200 mm

As mentioned above the speed obtained using the peak-to-peak time gap approximates the actual speed of the

Table 1 Values of peaks identified in time histories of loads measured by BWIM bearings (20 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 019 minus023965 minus136519 2543254 2109958 44927282 097 minus295398 minus078127 1190154 1062699 22155013 172 minus1036348 1744544 18531005 19043366 3828257Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 720 minus1618517 4062979 15109605 19135729 36689802 797 minus666830 816733 18355975 17510131 36016013 875 040080 minus883196 1111157 8745885 1901434

Table 2 Values of peaks identified in time histories of loads measured by BWIM bearings (80 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 014 minus084606 00354 2100938 1918984 39388562 033 minus561803 484041 9905302 9702933 19530473 050 minus1380111 2230247 16227767 17895248 3497315Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 181 minus1911155 4599867 14047757 19121095 358575642 200 minus1118191 1709516 16991835 17735358 353185183 219 minus380146 minus396868 10125288 8811671 18159945

RearFront

Entrance ExitL = 40m

Middle

d1d2

(a)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(b)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(c)

Figure 15 Position of truck axles corresponding to peaks at the exit side of the bridge (a) Occurrence of peak 1 at the exit side (b)Occurrence of peak 2 at the exit side (c) Occurrence of peak 3 at the exit side

Shock and Vibration 7

vehicle with an error below 736 on the average which islower than the error of 10 commonly allowed for trafficspeedometers Recalling that the linear model in equation(2) relating the output voltage to the load was establishedusing data measured at excitation frequencies of 05Hz10 Hz and 30Hz (vehicles running respectively at18 km 36 kmh and 108 kmh) the linear model obtainedby the least-squares method is sufficiently applicableconsidering that the speed limits in Korea are 60 kmh inurban areas 80 kmh in highways and 100 kmh and110 kmh in expressways

-e error in the estimation of the distance between theaxles appears to increase with the speed of the vehicle butremains below 792 for the considered cases However thiserror had poor effect on the estimation of the axle loads ofwhich error remained below 542-e final total load of thetruck could be estimated with an error below 243 Since allthe trucks are characterized by their number of axles axledistance and axle loads the type of truck can thus beidentified and eventual overload can be captured

Based upon the simplest theory of mechanics theproposed BWIM system with built-in PCGE offers thus allthe functions required for the conventional BWIM that arecapturing and recording axle weights and distances andgross weights and velocities of vehicles regardless of the typematerial composition and shape of the bridge

4 Conclusions

-is paper presented a new BWIM system overcoming thedrawbacks of former systems -e proposed BWIM systemappears in the form of a piezo-bearing in which the PCGE isembedded To that goal a PCGEwas designed and fabricatedto offer all the advantages of piezoceramics while being freefrom their material brittleness A series of performance testsincluding fatigue test and dynamic test showed that thePCGE can be used to sustain the large load involved in thetraffic monitoring in civil structures Moving load analysiswas performed on a full three-dimensional model of a bridgeusing a typical truck load to verify the applicability of theproposed BWIM system for the on-bridge traffic monitor-ing-e following conclusions can be drawn from the resultsof the moving load analysis

(1) A linear model for converting the measured outputvoltage of the PCGE into loading was proposedconsidering its linear nature Further experimentsshall be implemented to verify the adequacy of themodel for a wider range of exciting frequencies

(2) -e time histories of the loads measured by thepiezo-bearings were used to distinguish the entranceor exit of the axle loads on the bridge -e passage ofeach axle load could be identified by the occurrenceof peaks in the time histories Based on the stan-dardized vehicle classification system the identifi-cation of the number of peaks can give informationon the type of vehicle passing on the bridge and inturn allowed the estimation of the speed of thevehicle and distances between the axles

Entrance

A B

IL for RB1

ExitL = 40m

xL

x40

1x

x

Figure 16 Influence lines for support reaction at the exit side

Start

Identification of vehicle type (number ofaxles) by measured peaks at entrance side

Identification of peaks at exit side

Calculation of vehicle speedusing peak-to-peak time gap between

entrance and exit sides

Conversion of output voltageinto load data using equation (2)

Calculation of axle distances (di) usingoccurrence time of peaks at exit side

Calculation of axle loads (Waxle) usinginfluence line for support reaction in

Figure 16 at exit side using equations (2)ndash(5)

End

Figure 17 Flowchart for the identification of axle loads using theproposed BWIM bearing

Table 3 Estimated vehiclersquos speed and axle loads using the pro-posed BWIM bearings

Estimated values Speed case20 kmh 80 kmh

Truck speed Average (kmh) 20532 85887Error () 267 736

Axle distance

d1 (mm) 439165 453295Error () 456 792d2 (mm) 444868 453295Error () 592 792

Axle loads

Front axle (kN) 48602 47747Error () 125 053

Middle axle (kN) 191164 192165Error () 043 0009

Rear axle (kN) 190143 181599Error () 097 542

Total load Total (kN) 429909 421512Error () 048 243

8 Shock and Vibration

(3) An algorithm based on the concept of influence linefor support reaction was established to calculate eachaxle load of the vehicle using the identified loadpeaks

(4) -e simulated data could estimate the speed of thevehicle passing the bridge as well as the axle weightsand distances and gross weights of the vehicle withgood accuracy regardless of the type materialcomposition and shape of the bridge purely basedon the theory of structural mechanics

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-e authors are thankful for funds provided by Korea In-stitute of Civil Engineering and Building Technology(KICT) Republic of Korea (Project No 2018-0255) -iswork was also supported by the Energy Efficiency amp Re-sources Core Technology Program of the Korea Institute ofEnergy Technology Evaluation and Planning (KETEP) andgranted financial resource from the Ministry of Trade In-dustry amp Energy Republic of Korea (No 20142020103979)

References

[1] J C Pais S I R Amorim and M J C Minhoto ldquoImpact oftraffic overload on road pavement performancerdquo Journal ofTransportation Engineering vol 139 no 9 pp 873ndash879 2013

[2] Y Yang C S Cai and D Lu ldquoState-of-the-art review onbridge weigh-in-motion technologyrdquo Advances in StructuralEngineering vol 19 no 9 pp 1514ndash1530 2016

[3] F Moses ldquoWeigh-in-motion system using instrumentedbridgesrdquo Journal of Transportation Engineering ASCEvol 105 no TE3 pp 233ndash249 1979

[4] Federal Highway Administration (FHWA) LTBP ProgramrsquosLiterature Review on Weigh-In-Motion Systems PublicationNo FHWA-HRT-16-024 FHWA Washington DC USA2016

[5] B Lechner M Lieschnegg O Mariani and M PiercherldquoDetection of vehicle data in a bridge weigh-in-motion sys-temrdquo Modern Traffic and Transportation Engineering Re-search vol 2 no 3 pp 153ndash161 2013

[6] J Richardson S Jones A Brown E J Orsquobrien andD Hajializadeh ldquoOn the use of bridge weigh-in-motion foroverweight truck enforcementrdquo International Journal ofHeavy Vehicle Systems vol 21 no 2 pp 83ndash104 2014

[7] M Lydon S E Taylor D Robinson A Mufti andE J O Brien ldquoRecent developments in bridge weigh inmotion (B-WIM)rdquo Journal of Civil Structural Health Moni-toring vol 6 no 1 pp 69ndash81 2015

[8] J F Choo V L Pham and N S Goo ldquoDesign of a d33-modepiezocomposite electricity generating element and its appli-cation to bridge monitoringrdquo Journal of Central South Uni-versity vol 21 no 7 pp 2572ndash2578 2014

[9] D G Yoo K S Kyung S J Lee H H Lee and J C Jeon ldquoAstudy on influencing factors in BWIM system and its fieldapplicabilityrdquo Journal of Korean Society of Steel Constructionvol 26 no 4 pp 251ndash262 2014

[10] J Zhao N S Goo and D-H Ha ldquoDesign and performanceevaluation of a d33-mode piezocomposite electricity gener-ating elementrdquo Journal of Mechanical Science and Technologyvol 28 no 1 pp 15ndash23 2014

[11] H A Sodano D J Inman and G Park ldquoComparison ofpiezoelectric energy harvesting devices for recharging bat-teriesrdquo Journal of Intelligent Material Systems and Structuresvol 16 no 10 pp 799ndash807 2016

[12] A Abrar and S Cochran ldquoMultilayer piezocompositestructures with piezoceramic volume fractions determined bymathematical optimisationrdquo Ultrasonics vol 42 no 1ndash9pp 259ndash265 2004

[13] R Ramesh H Kara and C R Bowen ldquoCharacteristics ofpiezoceramic and 3-3 piezocomposite hydrophones evaluatedby finite element modellingrdquo Computational Materials Sci-ence vol 30 no 3-4 pp 397ndash403 2004

[14] J F Choo D-H Ha N S Goo and W S Jang ldquoPreliminarytests for a multi-functional bridge bearing with built-in pie-zoelectric materialrdquo Advanced Science Letters vol 19 no 1pp 37ndash41 2013

[15] J F Choo D H Ha C H Lee andW S Jang ldquoExperimentalstudy on the optimal layering position of the piezocompositeelectricity generating element built-in an innovative trafficload-measuring bridge bearingrdquo Advanced Materials Re-search vol 811 pp 365ndash369 2013

[16] D H Ha J F Choo D Kim and N S Goo ldquoFeasibility of amulti-functional bridge bearing with built-in piezoelectricmaterialrdquo International Journal on Advances in InformationSciences and Service Sciences vol 4 no 11 pp 142ndash150 2012

[17] V L Pham N S Ha N S Goo and J F Choo ldquoEffects ofcyclic impacts on the performance of a piezo-compositeelectricity generating element in a d33 mode energy har-vestingrdquo Journal of Nanoscience and Nanotechnology vol 14no 10 pp 7410ndash7418 2014

[18] D H Ha J F Choo C H Lee W S Jang and N S GooldquoDynamic characteristics of a multi-functional bridge bearingwith built-in piezocomposite elementrdquo Applied Mechanicsand Materials vol 432 pp 275ndash280 2013

Shock and Vibration 9

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Considering that the loads measured by the bearingscorrespond in fact to the support reactions oriented in theopposite direction these measured loads can be used tocalculate the axle loads by the influence caused by a series ofconcentrated loads using the influence lines (ILs) for thesupport reaction shown in Figure 16

Once the speed of the vehicle is known the time lapsebetween the peaks at the entrance side or exit side providesthe distance between the axles Based on the location of theloads for each peak at the exit side in Figure 15 the in-fluence for the support reaction (RB) at the exit side inFigure 16 can be used to calculate successively the loads ofthe rear middle and front axles as expressed in the fol-lowing equations

Wrear axle Wtotal( 1113857peak 3 exit (3)

where Wrear axle identified value of the rear axle load of thetruck and (Wtotal)peak 3 exit sum of loads measured byjoints 342 343 344 and 345 at occurrence of peak 3 at theexit side

Wmiddle axle Wtotal( 1113857peak 2 exitminusWrear axle 1minusd2

L1113888 1113889 (4)

where Wmiddle axle identified value of the rear axle load ofthe truck (Wtotal)peak 2 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 2 at the exit sideWrear axle value of the rear axle load of the truck providedby equation (3) and d2 distance between middle and rearaxles of the truck

Wfront axle Wtotal( 1113857peak 1 exitminusWmiddle axle 1minusd1

L1113888 1113889

minusWrear axle 1minusd1 + d2

L1113888 1113889

(5)

where Wfront axle identified value of the front axle load ofthe truck (Wtotal)peak 1 exit sum of loadsmeasured by joints342 343 344 and 345 at occurrence of peak 1 at the exit sideWmiddle axle value of the middle axle load of the truckprovided by equation (4) d1 distance between front andmiddle axles of the truck Wrear axle value of the rear axle

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 342Joint 343

Joint 344Joint 345

Figure 13 Loads measured by BWIM bearings at the exit side(speed 80 kmh)

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 2Peak 1

Peak 3

Peak 3

Peak 2

Peak 1

Figure 14 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 80 kmh

ndash50

0

50

100

150

200

0 2 4 6 8 10

Load

(kN

)

Time (sec)

Joint 336Joint 344

Peak 1

Peak 2

Peak 1

Peak 2

Peak 3

Peak 3

Figure 11 Loads measured at joints 336 (entrance) and 344 (exit)for the vehicle running at a speed of 20 kmh

ndash50

0

50

100

150

200

0 1 2 3 4

Load

(kN

)

Time (sec)

Joint 334Joint 335

Joint 336Joint 337

Figure 12 Loads measured by BWIM bearings at the entrance side(speed 80 kmh)

6 Shock and Vibration

load of the truck provided by equation (3) and d2 distancebetween middle and rear axles of the truck

Figure 17 shows the flowchart for the identification ofthe axle loads using the loads measured by the bearings

Note that in Figure 17 the identification of the numberof peaks will give information on the type of vehicle passingon the bridge based on the standardized vehicle classificationsystem -e vehicle classification system categorizes thevehicles into 13 classes from motorcycles passenger carsand buses to multiple-axle trucks according to the number ofaxles and the distance between consecutive axles

Using the flowchart in Figure 17 Table 3 arranges theidentified axle loads of the DB-24 truck running at 20 kmhand 80 kmh with the errors For the calculation of the errorthe estimated values are compared with the actual values ofthe DB-24 truck model (Figure 8) of the Korea HighwayBridge Design Code with the front axle load of 48 kN middleaxle load of 192 kN and rear axle load of 192 kN which givesa total load of 432 kN and the distance between the axles isd1 d2 4200 mm

As mentioned above the speed obtained using the peak-to-peak time gap approximates the actual speed of the

Table 1 Values of peaks identified in time histories of loads measured by BWIM bearings (20 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 019 minus023965 minus136519 2543254 2109958 44927282 097 minus295398 minus078127 1190154 1062699 22155013 172 minus1036348 1744544 18531005 19043366 3828257Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 720 minus1618517 4062979 15109605 19135729 36689802 797 minus666830 816733 18355975 17510131 36016013 875 040080 minus883196 1111157 8745885 1901434

Table 2 Values of peaks identified in time histories of loads measured by BWIM bearings (80 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 014 minus084606 00354 2100938 1918984 39388562 033 minus561803 484041 9905302 9702933 19530473 050 minus1380111 2230247 16227767 17895248 3497315Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 181 minus1911155 4599867 14047757 19121095 358575642 200 minus1118191 1709516 16991835 17735358 353185183 219 minus380146 minus396868 10125288 8811671 18159945

RearFront

Entrance ExitL = 40m

Middle

d1d2

(a)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(b)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(c)

Figure 15 Position of truck axles corresponding to peaks at the exit side of the bridge (a) Occurrence of peak 1 at the exit side (b)Occurrence of peak 2 at the exit side (c) Occurrence of peak 3 at the exit side

Shock and Vibration 7

vehicle with an error below 736 on the average which islower than the error of 10 commonly allowed for trafficspeedometers Recalling that the linear model in equation(2) relating the output voltage to the load was establishedusing data measured at excitation frequencies of 05Hz10 Hz and 30Hz (vehicles running respectively at18 km 36 kmh and 108 kmh) the linear model obtainedby the least-squares method is sufficiently applicableconsidering that the speed limits in Korea are 60 kmh inurban areas 80 kmh in highways and 100 kmh and110 kmh in expressways

-e error in the estimation of the distance between theaxles appears to increase with the speed of the vehicle butremains below 792 for the considered cases However thiserror had poor effect on the estimation of the axle loads ofwhich error remained below 542-e final total load of thetruck could be estimated with an error below 243 Since allthe trucks are characterized by their number of axles axledistance and axle loads the type of truck can thus beidentified and eventual overload can be captured

Based upon the simplest theory of mechanics theproposed BWIM system with built-in PCGE offers thus allthe functions required for the conventional BWIM that arecapturing and recording axle weights and distances andgross weights and velocities of vehicles regardless of the typematerial composition and shape of the bridge

4 Conclusions

-is paper presented a new BWIM system overcoming thedrawbacks of former systems -e proposed BWIM systemappears in the form of a piezo-bearing in which the PCGE isembedded To that goal a PCGEwas designed and fabricatedto offer all the advantages of piezoceramics while being freefrom their material brittleness A series of performance testsincluding fatigue test and dynamic test showed that thePCGE can be used to sustain the large load involved in thetraffic monitoring in civil structures Moving load analysiswas performed on a full three-dimensional model of a bridgeusing a typical truck load to verify the applicability of theproposed BWIM system for the on-bridge traffic monitor-ing-e following conclusions can be drawn from the resultsof the moving load analysis

(1) A linear model for converting the measured outputvoltage of the PCGE into loading was proposedconsidering its linear nature Further experimentsshall be implemented to verify the adequacy of themodel for a wider range of exciting frequencies

(2) -e time histories of the loads measured by thepiezo-bearings were used to distinguish the entranceor exit of the axle loads on the bridge -e passage ofeach axle load could be identified by the occurrenceof peaks in the time histories Based on the stan-dardized vehicle classification system the identifi-cation of the number of peaks can give informationon the type of vehicle passing on the bridge and inturn allowed the estimation of the speed of thevehicle and distances between the axles

Entrance

A B

IL for RB1

ExitL = 40m

xL

x40

1x

x

Figure 16 Influence lines for support reaction at the exit side

Start

Identification of vehicle type (number ofaxles) by measured peaks at entrance side

Identification of peaks at exit side

Calculation of vehicle speedusing peak-to-peak time gap between

entrance and exit sides

Conversion of output voltageinto load data using equation (2)

Calculation of axle distances (di) usingoccurrence time of peaks at exit side

Calculation of axle loads (Waxle) usinginfluence line for support reaction in

Figure 16 at exit side using equations (2)ndash(5)

End

Figure 17 Flowchart for the identification of axle loads using theproposed BWIM bearing

Table 3 Estimated vehiclersquos speed and axle loads using the pro-posed BWIM bearings

Estimated values Speed case20 kmh 80 kmh

Truck speed Average (kmh) 20532 85887Error () 267 736

Axle distance

d1 (mm) 439165 453295Error () 456 792d2 (mm) 444868 453295Error () 592 792

Axle loads

Front axle (kN) 48602 47747Error () 125 053

Middle axle (kN) 191164 192165Error () 043 0009

Rear axle (kN) 190143 181599Error () 097 542

Total load Total (kN) 429909 421512Error () 048 243

8 Shock and Vibration

(3) An algorithm based on the concept of influence linefor support reaction was established to calculate eachaxle load of the vehicle using the identified loadpeaks

(4) -e simulated data could estimate the speed of thevehicle passing the bridge as well as the axle weightsand distances and gross weights of the vehicle withgood accuracy regardless of the type materialcomposition and shape of the bridge purely basedon the theory of structural mechanics

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-e authors are thankful for funds provided by Korea In-stitute of Civil Engineering and Building Technology(KICT) Republic of Korea (Project No 2018-0255) -iswork was also supported by the Energy Efficiency amp Re-sources Core Technology Program of the Korea Institute ofEnergy Technology Evaluation and Planning (KETEP) andgranted financial resource from the Ministry of Trade In-dustry amp Energy Republic of Korea (No 20142020103979)

References

[1] J C Pais S I R Amorim and M J C Minhoto ldquoImpact oftraffic overload on road pavement performancerdquo Journal ofTransportation Engineering vol 139 no 9 pp 873ndash879 2013

[2] Y Yang C S Cai and D Lu ldquoState-of-the-art review onbridge weigh-in-motion technologyrdquo Advances in StructuralEngineering vol 19 no 9 pp 1514ndash1530 2016

[3] F Moses ldquoWeigh-in-motion system using instrumentedbridgesrdquo Journal of Transportation Engineering ASCEvol 105 no TE3 pp 233ndash249 1979

[4] Federal Highway Administration (FHWA) LTBP ProgramrsquosLiterature Review on Weigh-In-Motion Systems PublicationNo FHWA-HRT-16-024 FHWA Washington DC USA2016

[5] B Lechner M Lieschnegg O Mariani and M PiercherldquoDetection of vehicle data in a bridge weigh-in-motion sys-temrdquo Modern Traffic and Transportation Engineering Re-search vol 2 no 3 pp 153ndash161 2013

[6] J Richardson S Jones A Brown E J Orsquobrien andD Hajializadeh ldquoOn the use of bridge weigh-in-motion foroverweight truck enforcementrdquo International Journal ofHeavy Vehicle Systems vol 21 no 2 pp 83ndash104 2014

[7] M Lydon S E Taylor D Robinson A Mufti andE J O Brien ldquoRecent developments in bridge weigh inmotion (B-WIM)rdquo Journal of Civil Structural Health Moni-toring vol 6 no 1 pp 69ndash81 2015

[8] J F Choo V L Pham and N S Goo ldquoDesign of a d33-modepiezocomposite electricity generating element and its appli-cation to bridge monitoringrdquo Journal of Central South Uni-versity vol 21 no 7 pp 2572ndash2578 2014

[9] D G Yoo K S Kyung S J Lee H H Lee and J C Jeon ldquoAstudy on influencing factors in BWIM system and its fieldapplicabilityrdquo Journal of Korean Society of Steel Constructionvol 26 no 4 pp 251ndash262 2014

[10] J Zhao N S Goo and D-H Ha ldquoDesign and performanceevaluation of a d33-mode piezocomposite electricity gener-ating elementrdquo Journal of Mechanical Science and Technologyvol 28 no 1 pp 15ndash23 2014

[11] H A Sodano D J Inman and G Park ldquoComparison ofpiezoelectric energy harvesting devices for recharging bat-teriesrdquo Journal of Intelligent Material Systems and Structuresvol 16 no 10 pp 799ndash807 2016

[12] A Abrar and S Cochran ldquoMultilayer piezocompositestructures with piezoceramic volume fractions determined bymathematical optimisationrdquo Ultrasonics vol 42 no 1ndash9pp 259ndash265 2004

[13] R Ramesh H Kara and C R Bowen ldquoCharacteristics ofpiezoceramic and 3-3 piezocomposite hydrophones evaluatedby finite element modellingrdquo Computational Materials Sci-ence vol 30 no 3-4 pp 397ndash403 2004

[14] J F Choo D-H Ha N S Goo and W S Jang ldquoPreliminarytests for a multi-functional bridge bearing with built-in pie-zoelectric materialrdquo Advanced Science Letters vol 19 no 1pp 37ndash41 2013

[15] J F Choo D H Ha C H Lee andW S Jang ldquoExperimentalstudy on the optimal layering position of the piezocompositeelectricity generating element built-in an innovative trafficload-measuring bridge bearingrdquo Advanced Materials Re-search vol 811 pp 365ndash369 2013

[16] D H Ha J F Choo D Kim and N S Goo ldquoFeasibility of amulti-functional bridge bearing with built-in piezoelectricmaterialrdquo International Journal on Advances in InformationSciences and Service Sciences vol 4 no 11 pp 142ndash150 2012

[17] V L Pham N S Ha N S Goo and J F Choo ldquoEffects ofcyclic impacts on the performance of a piezo-compositeelectricity generating element in a d33 mode energy har-vestingrdquo Journal of Nanoscience and Nanotechnology vol 14no 10 pp 7410ndash7418 2014

[18] D H Ha J F Choo C H Lee W S Jang and N S GooldquoDynamic characteristics of a multi-functional bridge bearingwith built-in piezocomposite elementrdquo Applied Mechanicsand Materials vol 432 pp 275ndash280 2013

Shock and Vibration 9

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

load of the truck provided by equation (3) and d2 distancebetween middle and rear axles of the truck

Figure 17 shows the flowchart for the identification ofthe axle loads using the loads measured by the bearings

Note that in Figure 17 the identification of the numberof peaks will give information on the type of vehicle passingon the bridge based on the standardized vehicle classificationsystem -e vehicle classification system categorizes thevehicles into 13 classes from motorcycles passenger carsand buses to multiple-axle trucks according to the number ofaxles and the distance between consecutive axles

Using the flowchart in Figure 17 Table 3 arranges theidentified axle loads of the DB-24 truck running at 20 kmhand 80 kmh with the errors For the calculation of the errorthe estimated values are compared with the actual values ofthe DB-24 truck model (Figure 8) of the Korea HighwayBridge Design Code with the front axle load of 48 kN middleaxle load of 192 kN and rear axle load of 192 kN which givesa total load of 432 kN and the distance between the axles isd1 d2 4200 mm

As mentioned above the speed obtained using the peak-to-peak time gap approximates the actual speed of the

Table 1 Values of peaks identified in time histories of loads measured by BWIM bearings (20 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 019 minus023965 minus136519 2543254 2109958 44927282 097 minus295398 minus078127 1190154 1062699 22155013 172 minus1036348 1744544 18531005 19043366 3828257Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 720 minus1618517 4062979 15109605 19135729 36689802 797 minus666830 816733 18355975 17510131 36016013 875 040080 minus883196 1111157 8745885 1901434

Table 2 Values of peaks identified in time histories of loads measured by BWIM bearings (80 kmh)Entrance side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 334 Joint 335 Joint 336 Joint 337

1 014 minus084606 00354 2100938 1918984 39388562 033 minus561803 484041 9905302 9702933 19530473 050 minus1380111 2230247 16227767 17895248 3497315Exit side

Peak Occurrence time (s) Measured load (kN)Wtotal (kN)Joint 342 Joint 343 Joint 344 Joint 345

1 181 minus1911155 4599867 14047757 19121095 358575642 200 minus1118191 1709516 16991835 17735358 353185183 219 minus380146 minus396868 10125288 8811671 18159945

RearFront

Entrance ExitL = 40m

Middle

d1d2

(a)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(b)

Front

Entrance ExitL = 40m

Rear Middle

d1d2

(c)

Figure 15 Position of truck axles corresponding to peaks at the exit side of the bridge (a) Occurrence of peak 1 at the exit side (b)Occurrence of peak 2 at the exit side (c) Occurrence of peak 3 at the exit side

Shock and Vibration 7

vehicle with an error below 736 on the average which islower than the error of 10 commonly allowed for trafficspeedometers Recalling that the linear model in equation(2) relating the output voltage to the load was establishedusing data measured at excitation frequencies of 05Hz10 Hz and 30Hz (vehicles running respectively at18 km 36 kmh and 108 kmh) the linear model obtainedby the least-squares method is sufficiently applicableconsidering that the speed limits in Korea are 60 kmh inurban areas 80 kmh in highways and 100 kmh and110 kmh in expressways

-e error in the estimation of the distance between theaxles appears to increase with the speed of the vehicle butremains below 792 for the considered cases However thiserror had poor effect on the estimation of the axle loads ofwhich error remained below 542-e final total load of thetruck could be estimated with an error below 243 Since allthe trucks are characterized by their number of axles axledistance and axle loads the type of truck can thus beidentified and eventual overload can be captured

Based upon the simplest theory of mechanics theproposed BWIM system with built-in PCGE offers thus allthe functions required for the conventional BWIM that arecapturing and recording axle weights and distances andgross weights and velocities of vehicles regardless of the typematerial composition and shape of the bridge

4 Conclusions

-is paper presented a new BWIM system overcoming thedrawbacks of former systems -e proposed BWIM systemappears in the form of a piezo-bearing in which the PCGE isembedded To that goal a PCGEwas designed and fabricatedto offer all the advantages of piezoceramics while being freefrom their material brittleness A series of performance testsincluding fatigue test and dynamic test showed that thePCGE can be used to sustain the large load involved in thetraffic monitoring in civil structures Moving load analysiswas performed on a full three-dimensional model of a bridgeusing a typical truck load to verify the applicability of theproposed BWIM system for the on-bridge traffic monitor-ing-e following conclusions can be drawn from the resultsof the moving load analysis

(1) A linear model for converting the measured outputvoltage of the PCGE into loading was proposedconsidering its linear nature Further experimentsshall be implemented to verify the adequacy of themodel for a wider range of exciting frequencies

(2) -e time histories of the loads measured by thepiezo-bearings were used to distinguish the entranceor exit of the axle loads on the bridge -e passage ofeach axle load could be identified by the occurrenceof peaks in the time histories Based on the stan-dardized vehicle classification system the identifi-cation of the number of peaks can give informationon the type of vehicle passing on the bridge and inturn allowed the estimation of the speed of thevehicle and distances between the axles

Entrance

A B

IL for RB1

ExitL = 40m

xL

x40

1x

x

Figure 16 Influence lines for support reaction at the exit side

Start

Identification of vehicle type (number ofaxles) by measured peaks at entrance side

Identification of peaks at exit side

Calculation of vehicle speedusing peak-to-peak time gap between

entrance and exit sides

Conversion of output voltageinto load data using equation (2)

Calculation of axle distances (di) usingoccurrence time of peaks at exit side

Calculation of axle loads (Waxle) usinginfluence line for support reaction in

Figure 16 at exit side using equations (2)ndash(5)

End

Figure 17 Flowchart for the identification of axle loads using theproposed BWIM bearing

Table 3 Estimated vehiclersquos speed and axle loads using the pro-posed BWIM bearings

Estimated values Speed case20 kmh 80 kmh

Truck speed Average (kmh) 20532 85887Error () 267 736

Axle distance

d1 (mm) 439165 453295Error () 456 792d2 (mm) 444868 453295Error () 592 792

Axle loads

Front axle (kN) 48602 47747Error () 125 053

Middle axle (kN) 191164 192165Error () 043 0009

Rear axle (kN) 190143 181599Error () 097 542

Total load Total (kN) 429909 421512Error () 048 243

8 Shock and Vibration

(3) An algorithm based on the concept of influence linefor support reaction was established to calculate eachaxle load of the vehicle using the identified loadpeaks

(4) -e simulated data could estimate the speed of thevehicle passing the bridge as well as the axle weightsand distances and gross weights of the vehicle withgood accuracy regardless of the type materialcomposition and shape of the bridge purely basedon the theory of structural mechanics

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-e authors are thankful for funds provided by Korea In-stitute of Civil Engineering and Building Technology(KICT) Republic of Korea (Project No 2018-0255) -iswork was also supported by the Energy Efficiency amp Re-sources Core Technology Program of the Korea Institute ofEnergy Technology Evaluation and Planning (KETEP) andgranted financial resource from the Ministry of Trade In-dustry amp Energy Republic of Korea (No 20142020103979)

References

[1] J C Pais S I R Amorim and M J C Minhoto ldquoImpact oftraffic overload on road pavement performancerdquo Journal ofTransportation Engineering vol 139 no 9 pp 873ndash879 2013

[2] Y Yang C S Cai and D Lu ldquoState-of-the-art review onbridge weigh-in-motion technologyrdquo Advances in StructuralEngineering vol 19 no 9 pp 1514ndash1530 2016

[3] F Moses ldquoWeigh-in-motion system using instrumentedbridgesrdquo Journal of Transportation Engineering ASCEvol 105 no TE3 pp 233ndash249 1979

[4] Federal Highway Administration (FHWA) LTBP ProgramrsquosLiterature Review on Weigh-In-Motion Systems PublicationNo FHWA-HRT-16-024 FHWA Washington DC USA2016

[5] B Lechner M Lieschnegg O Mariani and M PiercherldquoDetection of vehicle data in a bridge weigh-in-motion sys-temrdquo Modern Traffic and Transportation Engineering Re-search vol 2 no 3 pp 153ndash161 2013

[6] J Richardson S Jones A Brown E J Orsquobrien andD Hajializadeh ldquoOn the use of bridge weigh-in-motion foroverweight truck enforcementrdquo International Journal ofHeavy Vehicle Systems vol 21 no 2 pp 83ndash104 2014

[7] M Lydon S E Taylor D Robinson A Mufti andE J O Brien ldquoRecent developments in bridge weigh inmotion (B-WIM)rdquo Journal of Civil Structural Health Moni-toring vol 6 no 1 pp 69ndash81 2015

[8] J F Choo V L Pham and N S Goo ldquoDesign of a d33-modepiezocomposite electricity generating element and its appli-cation to bridge monitoringrdquo Journal of Central South Uni-versity vol 21 no 7 pp 2572ndash2578 2014

[9] D G Yoo K S Kyung S J Lee H H Lee and J C Jeon ldquoAstudy on influencing factors in BWIM system and its fieldapplicabilityrdquo Journal of Korean Society of Steel Constructionvol 26 no 4 pp 251ndash262 2014

[10] J Zhao N S Goo and D-H Ha ldquoDesign and performanceevaluation of a d33-mode piezocomposite electricity gener-ating elementrdquo Journal of Mechanical Science and Technologyvol 28 no 1 pp 15ndash23 2014

[11] H A Sodano D J Inman and G Park ldquoComparison ofpiezoelectric energy harvesting devices for recharging bat-teriesrdquo Journal of Intelligent Material Systems and Structuresvol 16 no 10 pp 799ndash807 2016

[12] A Abrar and S Cochran ldquoMultilayer piezocompositestructures with piezoceramic volume fractions determined bymathematical optimisationrdquo Ultrasonics vol 42 no 1ndash9pp 259ndash265 2004

[13] R Ramesh H Kara and C R Bowen ldquoCharacteristics ofpiezoceramic and 3-3 piezocomposite hydrophones evaluatedby finite element modellingrdquo Computational Materials Sci-ence vol 30 no 3-4 pp 397ndash403 2004

[14] J F Choo D-H Ha N S Goo and W S Jang ldquoPreliminarytests for a multi-functional bridge bearing with built-in pie-zoelectric materialrdquo Advanced Science Letters vol 19 no 1pp 37ndash41 2013

[15] J F Choo D H Ha C H Lee andW S Jang ldquoExperimentalstudy on the optimal layering position of the piezocompositeelectricity generating element built-in an innovative trafficload-measuring bridge bearingrdquo Advanced Materials Re-search vol 811 pp 365ndash369 2013

[16] D H Ha J F Choo D Kim and N S Goo ldquoFeasibility of amulti-functional bridge bearing with built-in piezoelectricmaterialrdquo International Journal on Advances in InformationSciences and Service Sciences vol 4 no 11 pp 142ndash150 2012

[17] V L Pham N S Ha N S Goo and J F Choo ldquoEffects ofcyclic impacts on the performance of a piezo-compositeelectricity generating element in a d33 mode energy har-vestingrdquo Journal of Nanoscience and Nanotechnology vol 14no 10 pp 7410ndash7418 2014

[18] D H Ha J F Choo C H Lee W S Jang and N S GooldquoDynamic characteristics of a multi-functional bridge bearingwith built-in piezocomposite elementrdquo Applied Mechanicsand Materials vol 432 pp 275ndash280 2013

Shock and Vibration 9

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

vehicle with an error below 736 on the average which islower than the error of 10 commonly allowed for trafficspeedometers Recalling that the linear model in equation(2) relating the output voltage to the load was establishedusing data measured at excitation frequencies of 05Hz10 Hz and 30Hz (vehicles running respectively at18 km 36 kmh and 108 kmh) the linear model obtainedby the least-squares method is sufficiently applicableconsidering that the speed limits in Korea are 60 kmh inurban areas 80 kmh in highways and 100 kmh and110 kmh in expressways

-e error in the estimation of the distance between theaxles appears to increase with the speed of the vehicle butremains below 792 for the considered cases However thiserror had poor effect on the estimation of the axle loads ofwhich error remained below 542-e final total load of thetruck could be estimated with an error below 243 Since allthe trucks are characterized by their number of axles axledistance and axle loads the type of truck can thus beidentified and eventual overload can be captured

Based upon the simplest theory of mechanics theproposed BWIM system with built-in PCGE offers thus allthe functions required for the conventional BWIM that arecapturing and recording axle weights and distances andgross weights and velocities of vehicles regardless of the typematerial composition and shape of the bridge

4 Conclusions

-is paper presented a new BWIM system overcoming thedrawbacks of former systems -e proposed BWIM systemappears in the form of a piezo-bearing in which the PCGE isembedded To that goal a PCGEwas designed and fabricatedto offer all the advantages of piezoceramics while being freefrom their material brittleness A series of performance testsincluding fatigue test and dynamic test showed that thePCGE can be used to sustain the large load involved in thetraffic monitoring in civil structures Moving load analysiswas performed on a full three-dimensional model of a bridgeusing a typical truck load to verify the applicability of theproposed BWIM system for the on-bridge traffic monitor-ing-e following conclusions can be drawn from the resultsof the moving load analysis

(1) A linear model for converting the measured outputvoltage of the PCGE into loading was proposedconsidering its linear nature Further experimentsshall be implemented to verify the adequacy of themodel for a wider range of exciting frequencies

(2) -e time histories of the loads measured by thepiezo-bearings were used to distinguish the entranceor exit of the axle loads on the bridge -e passage ofeach axle load could be identified by the occurrenceof peaks in the time histories Based on the stan-dardized vehicle classification system the identifi-cation of the number of peaks can give informationon the type of vehicle passing on the bridge and inturn allowed the estimation of the speed of thevehicle and distances between the axles

Entrance

A B

IL for RB1

ExitL = 40m

xL

x40

1x

x

Figure 16 Influence lines for support reaction at the exit side

Start

Identification of vehicle type (number ofaxles) by measured peaks at entrance side

Identification of peaks at exit side

Calculation of vehicle speedusing peak-to-peak time gap between

entrance and exit sides

Conversion of output voltageinto load data using equation (2)

Calculation of axle distances (di) usingoccurrence time of peaks at exit side

Calculation of axle loads (Waxle) usinginfluence line for support reaction in

Figure 16 at exit side using equations (2)ndash(5)

End

Figure 17 Flowchart for the identification of axle loads using theproposed BWIM bearing

Table 3 Estimated vehiclersquos speed and axle loads using the pro-posed BWIM bearings

Estimated values Speed case20 kmh 80 kmh

Truck speed Average (kmh) 20532 85887Error () 267 736

Axle distance

d1 (mm) 439165 453295Error () 456 792d2 (mm) 444868 453295Error () 592 792

Axle loads

Front axle (kN) 48602 47747Error () 125 053

Middle axle (kN) 191164 192165Error () 043 0009

Rear axle (kN) 190143 181599Error () 097 542

Total load Total (kN) 429909 421512Error () 048 243

8 Shock and Vibration

(3) An algorithm based on the concept of influence linefor support reaction was established to calculate eachaxle load of the vehicle using the identified loadpeaks

(4) -e simulated data could estimate the speed of thevehicle passing the bridge as well as the axle weightsand distances and gross weights of the vehicle withgood accuracy regardless of the type materialcomposition and shape of the bridge purely basedon the theory of structural mechanics

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-e authors are thankful for funds provided by Korea In-stitute of Civil Engineering and Building Technology(KICT) Republic of Korea (Project No 2018-0255) -iswork was also supported by the Energy Efficiency amp Re-sources Core Technology Program of the Korea Institute ofEnergy Technology Evaluation and Planning (KETEP) andgranted financial resource from the Ministry of Trade In-dustry amp Energy Republic of Korea (No 20142020103979)

References

[1] J C Pais S I R Amorim and M J C Minhoto ldquoImpact oftraffic overload on road pavement performancerdquo Journal ofTransportation Engineering vol 139 no 9 pp 873ndash879 2013

[2] Y Yang C S Cai and D Lu ldquoState-of-the-art review onbridge weigh-in-motion technologyrdquo Advances in StructuralEngineering vol 19 no 9 pp 1514ndash1530 2016

[3] F Moses ldquoWeigh-in-motion system using instrumentedbridgesrdquo Journal of Transportation Engineering ASCEvol 105 no TE3 pp 233ndash249 1979

[4] Federal Highway Administration (FHWA) LTBP ProgramrsquosLiterature Review on Weigh-In-Motion Systems PublicationNo FHWA-HRT-16-024 FHWA Washington DC USA2016

[5] B Lechner M Lieschnegg O Mariani and M PiercherldquoDetection of vehicle data in a bridge weigh-in-motion sys-temrdquo Modern Traffic and Transportation Engineering Re-search vol 2 no 3 pp 153ndash161 2013

[6] J Richardson S Jones A Brown E J Orsquobrien andD Hajializadeh ldquoOn the use of bridge weigh-in-motion foroverweight truck enforcementrdquo International Journal ofHeavy Vehicle Systems vol 21 no 2 pp 83ndash104 2014

[7] M Lydon S E Taylor D Robinson A Mufti andE J O Brien ldquoRecent developments in bridge weigh inmotion (B-WIM)rdquo Journal of Civil Structural Health Moni-toring vol 6 no 1 pp 69ndash81 2015

[8] J F Choo V L Pham and N S Goo ldquoDesign of a d33-modepiezocomposite electricity generating element and its appli-cation to bridge monitoringrdquo Journal of Central South Uni-versity vol 21 no 7 pp 2572ndash2578 2014

[9] D G Yoo K S Kyung S J Lee H H Lee and J C Jeon ldquoAstudy on influencing factors in BWIM system and its fieldapplicabilityrdquo Journal of Korean Society of Steel Constructionvol 26 no 4 pp 251ndash262 2014

[10] J Zhao N S Goo and D-H Ha ldquoDesign and performanceevaluation of a d33-mode piezocomposite electricity gener-ating elementrdquo Journal of Mechanical Science and Technologyvol 28 no 1 pp 15ndash23 2014

[11] H A Sodano D J Inman and G Park ldquoComparison ofpiezoelectric energy harvesting devices for recharging bat-teriesrdquo Journal of Intelligent Material Systems and Structuresvol 16 no 10 pp 799ndash807 2016

[12] A Abrar and S Cochran ldquoMultilayer piezocompositestructures with piezoceramic volume fractions determined bymathematical optimisationrdquo Ultrasonics vol 42 no 1ndash9pp 259ndash265 2004

[13] R Ramesh H Kara and C R Bowen ldquoCharacteristics ofpiezoceramic and 3-3 piezocomposite hydrophones evaluatedby finite element modellingrdquo Computational Materials Sci-ence vol 30 no 3-4 pp 397ndash403 2004

[14] J F Choo D-H Ha N S Goo and W S Jang ldquoPreliminarytests for a multi-functional bridge bearing with built-in pie-zoelectric materialrdquo Advanced Science Letters vol 19 no 1pp 37ndash41 2013

[15] J F Choo D H Ha C H Lee andW S Jang ldquoExperimentalstudy on the optimal layering position of the piezocompositeelectricity generating element built-in an innovative trafficload-measuring bridge bearingrdquo Advanced Materials Re-search vol 811 pp 365ndash369 2013

[16] D H Ha J F Choo D Kim and N S Goo ldquoFeasibility of amulti-functional bridge bearing with built-in piezoelectricmaterialrdquo International Journal on Advances in InformationSciences and Service Sciences vol 4 no 11 pp 142ndash150 2012

[17] V L Pham N S Ha N S Goo and J F Choo ldquoEffects ofcyclic impacts on the performance of a piezo-compositeelectricity generating element in a d33 mode energy har-vestingrdquo Journal of Nanoscience and Nanotechnology vol 14no 10 pp 7410ndash7418 2014

[18] D H Ha J F Choo C H Lee W S Jang and N S GooldquoDynamic characteristics of a multi-functional bridge bearingwith built-in piezocomposite elementrdquo Applied Mechanicsand Materials vol 432 pp 275ndash280 2013

Shock and Vibration 9

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

(3) An algorithm based on the concept of influence linefor support reaction was established to calculate eachaxle load of the vehicle using the identified loadpeaks

(4) -e simulated data could estimate the speed of thevehicle passing the bridge as well as the axle weightsand distances and gross weights of the vehicle withgood accuracy regardless of the type materialcomposition and shape of the bridge purely basedon the theory of structural mechanics

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-e authors are thankful for funds provided by Korea In-stitute of Civil Engineering and Building Technology(KICT) Republic of Korea (Project No 2018-0255) -iswork was also supported by the Energy Efficiency amp Re-sources Core Technology Program of the Korea Institute ofEnergy Technology Evaluation and Planning (KETEP) andgranted financial resource from the Ministry of Trade In-dustry amp Energy Republic of Korea (No 20142020103979)

References

[1] J C Pais S I R Amorim and M J C Minhoto ldquoImpact oftraffic overload on road pavement performancerdquo Journal ofTransportation Engineering vol 139 no 9 pp 873ndash879 2013

[2] Y Yang C S Cai and D Lu ldquoState-of-the-art review onbridge weigh-in-motion technologyrdquo Advances in StructuralEngineering vol 19 no 9 pp 1514ndash1530 2016

[3] F Moses ldquoWeigh-in-motion system using instrumentedbridgesrdquo Journal of Transportation Engineering ASCEvol 105 no TE3 pp 233ndash249 1979

[4] Federal Highway Administration (FHWA) LTBP ProgramrsquosLiterature Review on Weigh-In-Motion Systems PublicationNo FHWA-HRT-16-024 FHWA Washington DC USA2016

[5] B Lechner M Lieschnegg O Mariani and M PiercherldquoDetection of vehicle data in a bridge weigh-in-motion sys-temrdquo Modern Traffic and Transportation Engineering Re-search vol 2 no 3 pp 153ndash161 2013

[6] J Richardson S Jones A Brown E J Orsquobrien andD Hajializadeh ldquoOn the use of bridge weigh-in-motion foroverweight truck enforcementrdquo International Journal ofHeavy Vehicle Systems vol 21 no 2 pp 83ndash104 2014

[7] M Lydon S E Taylor D Robinson A Mufti andE J O Brien ldquoRecent developments in bridge weigh inmotion (B-WIM)rdquo Journal of Civil Structural Health Moni-toring vol 6 no 1 pp 69ndash81 2015

[8] J F Choo V L Pham and N S Goo ldquoDesign of a d33-modepiezocomposite electricity generating element and its appli-cation to bridge monitoringrdquo Journal of Central South Uni-versity vol 21 no 7 pp 2572ndash2578 2014

[9] D G Yoo K S Kyung S J Lee H H Lee and J C Jeon ldquoAstudy on influencing factors in BWIM system and its fieldapplicabilityrdquo Journal of Korean Society of Steel Constructionvol 26 no 4 pp 251ndash262 2014

[10] J Zhao N S Goo and D-H Ha ldquoDesign and performanceevaluation of a d33-mode piezocomposite electricity gener-ating elementrdquo Journal of Mechanical Science and Technologyvol 28 no 1 pp 15ndash23 2014

[11] H A Sodano D J Inman and G Park ldquoComparison ofpiezoelectric energy harvesting devices for recharging bat-teriesrdquo Journal of Intelligent Material Systems and Structuresvol 16 no 10 pp 799ndash807 2016

[12] A Abrar and S Cochran ldquoMultilayer piezocompositestructures with piezoceramic volume fractions determined bymathematical optimisationrdquo Ultrasonics vol 42 no 1ndash9pp 259ndash265 2004

[13] R Ramesh H Kara and C R Bowen ldquoCharacteristics ofpiezoceramic and 3-3 piezocomposite hydrophones evaluatedby finite element modellingrdquo Computational Materials Sci-ence vol 30 no 3-4 pp 397ndash403 2004

[14] J F Choo D-H Ha N S Goo and W S Jang ldquoPreliminarytests for a multi-functional bridge bearing with built-in pie-zoelectric materialrdquo Advanced Science Letters vol 19 no 1pp 37ndash41 2013

[15] J F Choo D H Ha C H Lee andW S Jang ldquoExperimentalstudy on the optimal layering position of the piezocompositeelectricity generating element built-in an innovative trafficload-measuring bridge bearingrdquo Advanced Materials Re-search vol 811 pp 365ndash369 2013

[16] D H Ha J F Choo D Kim and N S Goo ldquoFeasibility of amulti-functional bridge bearing with built-in piezoelectricmaterialrdquo International Journal on Advances in InformationSciences and Service Sciences vol 4 no 11 pp 142ndash150 2012

[17] V L Pham N S Ha N S Goo and J F Choo ldquoEffects ofcyclic impacts on the performance of a piezo-compositeelectricity generating element in a d33 mode energy har-vestingrdquo Journal of Nanoscience and Nanotechnology vol 14no 10 pp 7410ndash7418 2014

[18] D H Ha J F Choo C H Lee W S Jang and N S GooldquoDynamic characteristics of a multi-functional bridge bearingwith built-in piezocomposite elementrdquo Applied Mechanicsand Materials vol 432 pp 275ndash280 2013

Shock and Vibration 9

International Journal of

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Hindawiwwwhindawicom Volume 2018

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Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Active and Passive Electronic Components

VLSI Design

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Shock and Vibration

Hindawiwwwhindawicom Volume 2018

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom

Journal ofEngineeringVolume 2018

SensorsJournal of

Hindawiwwwhindawicom Volume 2018

International Journal of

RotatingMachinery

Hindawiwwwhindawicom Volume 2018

Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Navigation and Observation

International Journal of

Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom