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Research Abstracts Online
January - December 2011

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University of Minnesota Twin Cities
College of Science and Engineering
Department of Civil Engineering

PI: Catherine W. French

Instrumentation and Monitoring of I-35W St. Anthony Falls Bridge

After the collapse of the steel truss bridge crossing the Mississippi River on August 1, 2007, construction of the I-35W St. Anthony Falls replacement bridge was completed in September of 2008. Construction of the St. Anthony Falls Bridge incorporated a “smart-bridge” system, equipped with instrumentation for monitoring the behavior of the structures. The instrumentation consists of strain gauges in various cross sections of the bridge. These gauges measure strains and allow the computation of associated stresses in the instrumented cross sections. Thermistors have been placed to measure the thermal gradient through the depth of the box and through the thickness of the webs, bottom flange, and top flange at one of the sections. Accelerometers measure the dynamic bridge response to ambient and traffic forcing. The bridge has been modeled using the finite-element program Abaqus. The model will be extended to investigate time-dependent behavior, with the goal of predictive modeling of future behavior of the structure. Further bridge exploration involves parametric studies investigating the sensitivity of the structure to likely damage scenarios. Together, the goals of predictive modeling and sensitivity to damage would facilitate the implementation of a structural monitoring system on the physical bridge that, given sensor readings, could predict safe baseline structural behavior or identify anomalous, and potentially damaged, behavior.

Group Members

Ben Dymond, Graduate Student
Brock Hedegaard, Graduate Student
Carol K. Shield, Faculty Collaborator