Structural Health MonitoringPilot Project

Iowa Falls Arch Bridge

MAASTO 2013Milwaukee, WI

July 16-19, 2013

Background

• Iowa DOT investigations of new High Performance Materials, Design Concepts, Construction Methods and Maintenance Methods.

• Develop a Structural Health Monitoring (SHM) system to determine real time structural and continuous condition of a bridge.

Concept

• Develop a Structural Health Monitoring System that can be used on critical structures.

• Demonstrate the technology on a smaller project.

• Iowa Falls arch bridge was identified due to bridge type similarities and complexities.

Existing Bridge

• Built in 1928

• 255-foot open spandrel concrete arch

Constraints and Constructability Issues• Historic church

– NW corner of bridge– Listed on the National Register of Historic Places

Photo by: iafalls.com

Constraints and Constructability Issues• Dam

– Maintain water level for power generation

Foundation Issues• Existing bridge undermining

Demolition Concerns

Constructed a system to protect the sanitary sewer lines

Demolished the bridge using the causeway

Monitoring Components

• Environmental

• Structural

• Construction

• Security

Environmental

• Alert for high wind events

• More efficient use of de-icing chemicals thus reducing bridge deterioration and impact to environment

• Increase public safety due to timely application

• Wind speed and direction

• Bridge deck potential icing conditions

• Temperature and humidity

Structural

• Apply preventive maintenance based on early detection of deterioration

• Prevent failure of critical members • Use in updating rating and permitting• Detection of heavy loads• Fatigue life assessment

• Corrosion potential in deck, substructure at expansion joints, and micro piles and concrete anchors foundation

• Arch and hanger forces

• Collect data from bridge superstructure

Construction

• Monitor erection stresses during critical construction stages

• Work with contractors to make timely adjustments

• Avoid structural damage due to overstress during erection

Security

• Monitor activities on bridge

• Monitor stresses in hangers in case of breaks

• Send alerts of possible threats

Infrared Camera• Detects both people and fire

• Mounted on utility pole SW of bridge

• “Sees” IR spectrum rather than visible light

IR camera – research team detection

Data Collection

• Data sent via internet connection to InTrans servers once per minute (fast read) and once per 10 minutes (slow read)

• Cameras viewable real-timeIowa Falls

Data Collection PC

BECData Storage

ArrayFTP

Synchronization

MS SQL Database

Video

InternetAnemometer

33 ft

Satellite

Transceiver

UPS

Data

Storage

Server10 ft

Modem

Wireless

Router

CR9000C

WAP

(Bridge)

B E C

Remote Monitoring

Web Interface

Select Sensor to View Real-time Data

Real-time Video

Questions?

Norm McDonald

Director, Office of Bridges and Structures

Iowa Department of Transportation

Norman.mcdonald@dot.iowa.gov