Sensor-assisted Condition Evaluation of Steel and Prestressed Concrete Girder Bridges Subjected to Fire – Phase II

The overarching goal of this multi-phase study is to develop and validate a post-fire condition evaluation method for steel- and prestressed concrete-girder bridges (overpasses or viaducts) based on material and structural data, a fire scenario (e.g., a fuel tank on highway), and environmental factors (e.g., moisture and wind). The proposed method involves fire dynamics simulation underneath a bridge, thermomechanical analysis of the structure, and structural condition assessment against material strengths. One of the key challenges to achieve this goal is to measure strains in steel members on fire in order to validate various computational models. The first phase aimed to understand and validate the performance of distributed fiber optic sensors for temperature and strain measurements, and validate a fire dynamics simulator and a thermomechanical model with measured data. Large-scale composite specimens were tested in a controlled compartment fire. The second phase aims to improve the deployment scheme and data quality of distributed fiber optic sensors embedded in concrete and attached on steel members, understand and quantify the effect of multiple steel girders on the aerodynamics and heat distribution of a fire, and develop and validate fire dynamics and thermomechanical models with the testing of small-scale multi-girder bridge superstructures. Each specimen will be composed of a reinforced concrete (RC) deck on three steel girders with shear studs and evaluated in three steps. First, the fire dynamics surrounding structural elements will be predicted based on the capacity of a fuel tank in representative vehicles. Second, heat will be transferred from the surface to inside the elements. Third and finally, the behavior and condition of the bridge elements under gravity loads are evaluated during and after a fire scenario as a result of fuel tank spilling on highway bridges.

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