Bridge Monitoring – Security and Smart Bridges

Bridge Monitoring Bridge Monitoring –– Security Security and Smart Bridgesand Smart Bridges

Brent Phares and Terry WipfIowa State University

National Center for Wood Transportation Structures and

Bridge Engineering Center

Mike RitterUSDA Forest Products Laboratory

Bridge SecurityBridge SecurityBridge Security

l Cooperative research project initiated by the USDA Forest Product Laboratory and Iowa State University.

l A critical need identified – provide a level of protection to historic covered bridges.– Vandalism– Arson

The Need in Madison County, IAThe Need in Madison County, IAThe Need in Madison County, IA

Initial GoalsInitial GoalsInitial Goals

l Develop & demonstrate a prototype remote security system

l Assist in the preservation of important timber bridges

l “Fill” a gap in the FHWA Covered Bridge Manual.

First Generation System ConfigurationFirst Generation System First Generation System ConfigurationConfiguration

l Three types of sensing systems:– Infrared camera– Flame detector– Fiber optic temperature sensors

l Data collected and processed on-site.l Alarms sent via text message and e-

mail to ISU and emergency responders.

Infrared CameraInfrared CameraInfrared Cameral Detects both people

and firel Mounted on utility

polel “Sees” IR spectrum

rather than visible light

Flame DetectorFlame DetectorFlame Detector

l Detects presence of a flame using:– infrared– ultraviolet– visual technologies

(flicker rate, etc.)l Probability of false

alarm is very small

Fiber OpticsFiber OpticsFiber Optics

l Measures temperature changes

l Length of sensor changes with temperature

l Installed in bridge behind trusses

On-site SystemOnOn--site Systemsite System

l Data transmitted from sensors using onsite wireless network

l Software processes data from all sensors

l Records data (including images) for use by law enforcement when alert issued

NotificationsNotificationsNotifications

Current ActivitiesCurrent ActivitiesCurrent Activities

l Second generation system currently being deployed on an additional 5 bridges.

l A covered bridge security manual is currently being developed.

Development of a Smart Timber Bridge SystemDevelopment of a Smart Timber Development of a Smart Timber Bridge SystemBridge System

l Concept: A holistic approach to timber bridge management through the integration of sensors and on-board computing.

l Initially developed the scope of research needed for full development.

l Currently in the first phase of that work.

Current Objective and ScopeCurrent Objective and ScopeCurrent Objective and Scopel Objective

– Develop methods for embedding in and attaching sensors to wood members.

l Scope– Design two types of sensors packages:

» One for structural adhesion.» One to isolate the sensor from structural response.

– Construction of small scale glulam specimens that are internally and externally instrumented.

– Laboratory testing of the specimens under different loading and temperature conditions.

– Selection of the best sensor packages.– Construction of a full scale beam specimen using selected packages

and test under laboratory conditions.

Small Scale Laboratory TestingSmall Scale Laboratory TestingSmall Scale Laboratory Testing

Nine specimens tested under:l Bendingl Sustained loadingl Fast loadingl Pseudo cyclic loadingl Heat and sustained loadingl Cold and sustained loading

Structural Response PackagesStructural Response PackagesStructural Response PackagesExternal Packages:External Packages:

CC--FRP Loctite 426 RSFRP Loctite 426 RS--SS Loctite 426SS Loctite 426

ISIS--SS Loctite 4212 72HSS Loctite 4212 72H--SS Loctite 426SS Loctite 426

Internal Packages:Internal Packages:AMAM--SS Loctite 454 RSSS Loctite 454 RS--SS Loctite 426SS Loctite 426

812"

78"

812" 7

8"

212"

12"1

2"

34"

812" 81

2"

112"

14"

12"1

4" on center

18" on center

812"

112"

2"

1"

812" 7

8"

Small Scale Test SetupSmall Scale Test SetupSmall Scale Test Setup

CL

Pin connection

Roller connection

GLULAM Specimen

SATEC Table

SATEC head

Direction ofloading

12"

36"

2500 lbs2500 lbs2500 lbs

Full Scale BeamFull Scale BeamFull Scale Beam

Full Scale Beam TestingFull Scale Beam TestingFull Scale Beam TestingMid Span

31'

West End

East End

N.A.

30'

Load Location

Girder length = Span length =

DCDT on the bottom

DCDT at neutral axis

7" typical 4'-6" 4'-6" Sensors

Typical ResultsTypical ResultsTypical Results

0 100 200 300 4000

1000

2000

3000

-300

-200

-100

0

100

200

300

-300

-200

-100

0

100

200

300

[N]

Load

[lbs]

Time [sec]

Load on Side 1 West Frame East Frame0.0

4448.2

8896.4

13344.6

MOE 1600 ksi Compressive lateral Compressive midspan Tensile lateral Tensile midspan

[με] Stra

ins

[με]

Strain Sensors Side 1 West End Side 1 Mid Span Side 1 East Ead Side 2 West End Side 2 Mid Span Side 2 East End:

Typical ResultsTypical ResultsTypical Results

0 250 500 750 10000

2500

5000

7500

10000

12500

15000

-1200

-900

-600

-300

0

300

600

900

1200

-1200

-900

-600

-300

0

300

600

900

1200

[N]

Load

[lbs]

Time [sec]

Load on Side 1 West Frame East Frame

0.0

11120.5

22241.0

33361.5

44482.0

55602.5

66723.0

MOE 1600 ksi Compressive Tensile

[με] Stra

ins

[ με]

Strain SensorsSide 1

West C-FRP Loctite 426 Mid Span C-FRP Loctite 426 Est 72H-SS Loctite 4212

Side 2 West RS-SS Loctite 426 Mid Span RS-SS Loctite 426 East IS-SS Loctite 4212

Questions?Questions?Questions?

Thank you!

www.woodcenter.orgwww.bec.iastate.edu