A simulation-based investigation on thermal responses of suspension bridge towers under different fire scenarios

Fire is one of the most severe dynamic loads with low probability and high impacts. The bridge fire incidents, such as the Oakland maze collapse, resulted in catastrophic consequences to both economy and people. Hence, the consideration of fire load needs to be an integral part of bridge structural design, especially in more complex bridge structures such as steel suspension bridges. One of the important considerations in bridge fire structural analysis is finding the fire source impact on the important load-carrying elements such as suspension bridge towers. Considering the importance of the topic, this study simulates fire exposure to a bridge tower, using Fire Dynamic Simulator (FDS), followed by heat transfer analysis, with ABAQUS finite element software, for evaluating its failure status. For this, the Bosphorus bridge, one of the iconic bridges in the world, is selected as a case study to evaluate the most critical fire scenarios that arise from different combinations of influential parameters. Accordingly, this study is performed in three main steps; firstly 12 fire scenarios are simulated using different vehicle types, exposure durations, and distances between the tower and fire source along with considering wind effect; secondly, heat transfer analysis is performed over the 12 simulated fire scenarios to obtain the temperature distribution within the tower section; thirdly, the damage level of bridge tower is evaluated based on peak temperature of steel.