The new I-35W Bridge was instrumented incorporating "smart bridge technology" by Figg Engineering Group in
conjunction with Flatiron-Manson. The purpose of the instrumentation was to monitor the structure during service,
and to use this information to investigate the design and performance of the bridge. Instrumentation included static
sensors (vibrating wire strain gages, resistive strain gages and thermistors in the foundation, bridge piers, and
superstructure, as well as fiber optic sensors and string potentiometers in the superstructure) and dynamic sensors
(accelerometers in the superstructure). Finite element models were constructed, taking into account measured
material properties, to further explore the behavior of the bridge. The bridge was tested using static and dynamic
truck load tests, which were used, along with continually collected ambient data under changing environmental
conditions, to validate the finite element models. These models were applied to gain a better understanding of the
structural behavior, and to evaluate the design assumptions presented in the Load Rating Manual for the structure.
This report documents the bridge instrumentation scheme, the material testing, finite element model construction
methodology, the methodology and results of the truck tests, validation of the models with respect to gravity loads
and thermal effects, measured and modeled dynamic modal characteristics of the structure, and documentation of
the investigated assumptions from the Load Rating Manual. It was found that the models accurately recreated the
response from the instrumented bridge, and that the bridge had behaved as expected during the monitoring period.
Department of Civil Engineering, University of Minnesota; Minnesota Department of Transportation
French, Catherine E.W.; Shield, Carol K.; Stolarski, Henryk K; Hedegaard, Brock D.; Jilk, Ben J..
Instrumentation, Monitoring, and Modeling of the I-35W Bridge.
Minnesota Department of Transportation.
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