Evaluation of the In-Servic Performance of the Tom's Creek Bridge

The Tom's Creek Bridge is a small-scale demonstration project involving the use of fiber-reinforced polymer (FRP) composite girders as the main load carrying members. The project is intended to serve two purposes. First, by calculating bridge design parameters such as the dynamic load allowance, transverse wheel load distribution and deflections under service loading, the Tom's Creek Bridge will aid in modifying current AASHTO bridge design standards for use with FRP composite materials. Second, by evaluating the FRP girders after being exposed to service conditions, the project will begin to answer questions about the long-term performance of these advanced composite material beams when used in bridge design.

This thesis details the In-Service analysis of the Tom's Creek Bridge. Five load tests, at six month intervals, were conducted on the bridge. Using mid-span strain and deflection data gathered from the FRP composite girders during these tests the above mentioned bridge design parameters have been determined. The Tom's Creek Bridge was determined to have a dynamic load allowance, IM, of 0.90, a transverse wheel load distribution factor, g, of 0.101 and a maximum deflection of L/488.

Two bridge girders were removed from the Tom's Creek Bridge after fifteen months of service loading. These FRP composite girders were tested at the Structures and Materials Research Laboratory at Virginia Tech for stiffness and ultimate strength and compared to pre-service values for the same beams. This analysis indicates that after fifteen months of service, the FRP composite girders have not lost a significant amount of either stiffness or ultimate strength.