Diagnostic Load Tests of Two Prestressed Concrete Bridges

Many of the state’s bridges are designed for loads that are lower than the current design loads set by the American Association of State Highway and Transportation Officials (AASHTO). The economic impact of load posting, closing, or replacing bridges across the entire state has led the Texas Department of Transportation to sponsor a series of research projects to investigate the actual performance of different types of bridges. Diagnostic load tests have been used in the past to demonstrate that the actual performance of most bridges is better than assumed by simplifying design procedures also used in the load rating. This thesis addresses the possibility of load testing prestressed concrete I-beam bridges to measure their response and evaluate their actual behavior based on the measurements. Differences between the expected behavior and the measured response are examined. An assessment of the rating of the structures based on the findings of the diagnostic load tests is also made.