Temperature-Driven Assessment of a Cantilever Truss Bridge

Temperature-driven assessment has the potential to advance our understanding of long-span bridge behavior. The novel approach researched as part of this study is the identification and monitoring of a long-span cantilever truss bridge using the input-output temperature relationship. The goal is to use this relationship to identify and monitor unknown quantifiable information with regard to an existing structure using the structural identification process (e.g. boundary conditions, continuity conditions, force distribution, etc.). Since many structural parameters on long-span bridges are highly sensitive to temperature loads, a structure such as the Hurricane Bridge is a prime candidate for this type of monitoring. The Hurricane Bridge is a four-span, cantilever truss bridge over the Caney Fork River in DeKalb County, Tennessee, with a total length of approximately 1787 feet. It was built in 1949 and rehabilitated in 2011. The rehabilitation included widening the deck, strengthening various truss members, and installing a “catch system” consisting of four stainless steel rods around each vertical at the cantilever locations. This critical structure has a great deal of uncertainty related to performance and remaining service life. Therefore, a temperature-driven monitoring system has been designed and implemented to reduce the uncertainty associated with the: “catch system”, pin and hanger effects at cantilever locations, and bearing mechanisms. The sensing technology of this system is comprised of fifty-six vibrating wire strain gages, eight vibrating wire displacement gages, and sixty-four thermistors. Long-term data collection is on-going; however, preliminary results are presented and tasks for future research are explored.