Baseline Model Updating During Bridge Construction Using Measured Strains

Instrumentation, structural modeling, and model updating are incorporated into the design and construction process of a multi-span bridge to change the paradigm of traditional bridge design to a long-term bridge design. A continuous three span composite steel stringer bridge in Barre, Massachusetts was used as a pilot bridge. A monitoring system was installed in order to capture structural behavior during construction and into the service life of the bridge. Strain data from the steel girders was collected during the concrete deck pour. Two finite element models were created using shell/solid elements and frame/shell elements. Both computer model responses are compared with field strain measurements of the full scale bridge during the concrete deck pour. Both the shell/solid and frame/shell FEMs produced close estimates of the measured strain data. Modeling assumptions for boundary conditions and temperature effects play a major role in magnitudes of the analytical responses. In the future, truck load tests will be used for baseline model updating of the completed bridge. The structural model that reflects the actual bridge 3D system behavior can be used for load rating and overload permitting