Wakota Bridge Thermal Monitoring Program Part II: Data Analysis and Model Comparison

Abstract

In this work, a common refined design method is evaluated with respect to a recently constructed bridge. Two finite element models of the Wakota Bridge in South St. Paul, Minnesota were produced using a design level program (SAP2000). These models were analyzed and their results compared to the data collected from the bridge. The second half of this study concerned the comparison of the collected field data with the values produced by evaluating the design-level finite element models previously created in Phase I of the project, and calibrating these models to provide an accurate prediction of the future behavior of the bridge. This was done by calculating changes in axial force and moment from strain data collected from the Wakota Bridge and changing various parameters within the design level model (DLM) in order to calibrate the models to the field data. The model using the refined design method was shown to correlate to the superstructure field data to within 2 percent, while between 13 percent and 35 percent correlation was seen between the model deploying the gross section method and the field data. The pier behavior predicted by the two models showed much less correlation to the field data. After calibration, it was possible to predict the general trend of the pier behavior, but the values of changes in moment did not correspond to the field data. This was especially true in Pier 4. Further consideration of the model parameters is necessary to fully calibrate the models. The two temperature application methods (Procedure A and B in the AASHTO LRFD) were also compared. The internal concrete temperature ranges measured in the field were much closer to the range specified in Procedure A.