Structural Stiffness Identification of Bridge Superstructures: Final Report

About the report:

Accurate measures of bridge stiffness are important when determining structural integrity. This information should be an integral part of any comprehensive bridge maintenance program, especially considering the nation's aging infrastructure. Informed decisions regarding the placement or repair of an existing bridge require knowledge of the in-situ structural state. Although static and dynamic field tests can provide accurate measures of in-situ stiffness, the instrumentation necessary to conduct such tests is time consuming and labor intensive. A need exists for an accurate, cost-effective, and time-efficient method of measuring aggregate bridge stiffness. The falling weight deflectometer (FWD) is an instrument that may provide accurate measures of aggregate bridge stiffness in a timely fashion. The purpose of this study was to determine the feasibility of using the FWD to measure bridge stiffness. Aggregate bridge stiffness in two bridges was measured using the FWD. These stiffness values were compared to values obtained from finite element models. A static field test was conducted on one of the bridges, and the stiffness values obtained were compared with the FWD results. The FWD has the potential to be an effective tool for measuring structural stiffness in certain circumstances and may be capable of providing bridge engineers with crucial information in a timely, cost-efficient fashion. Further calibration of the FWD is necessary before it can be used in a comprehensive bridge maintenance program.

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