Instrumented Bridge

TTI’s Instrumented Bridge is an innovative bridge design at TTI’s Proving Grounds Research Facility that is appropriate for spans of 50 feet or less. The bridge uses a new concrete spread slab beam bridge design. Conventional slab beam bridges have precast concrete slab beams placed immediately adjacent to one another with a cast-in-place (CIP) topping slab. While these bridges are used extensively, they are more expensive than traditional prestressed I-beam structures on a per-square-foot basis. This project investigated the use of precast concrete slab beams that are spread apart with precast concrete panel (PCP) stay-in-place forms between beams and a CIP concrete deck. Using fewer beams is expected to reduce construction costs. The test bridge was instrumented with multiple load cells, and strain gages and string potentiometers are installed during testing. The load cells are located at each beam end to determine how the load is distributed.

The full-scale test bridge was tested under static and dynamic truck loads to obtain important insight into its structural performance and live load distribution behavior for design, while also providing data to guide analytical and computational modeling. Static and dynamic load tests can be conducted with heavy vehicles, including loaded dump trucks and water tankers. Researchers can then measure the vertical deflections of the bridge girders and the girder end reactions under heavy loading. Data obtained from these tests are used for computer modeling and development of design guidelines.

The results have allowed the Texas Department of Transportation to use this new bridge design method as a viable alternative to the conventional side-by-side slab beam technique. The new system provides a cost-effective approach for short-span bridges, providing safe, long-lasting bridges that save scarce highway construction dollars. The instrumented bridge provides a test bed that can be used for evaluating measurement technologies that can then be deployed to the field.