Evaluating fire resistance of steel girders in bridges

In current practice, no special measures are applied for enhancing structural fire safety of steel bridge girders. Further, there is very limited information and research data in the literature on the fire resistance of structural members in bridges. In this paper, the fire response of a steel bridge girder under different conditions is evaluated using the FEM computer program ANSYS. In the analysis, the critical factors that influence fire resistance, namely, fire scenario, fire insulation, and composite action arising from steel-concrete interaction, are accounted for. Results from numerical studies show that the composite action arising from steel-girder-concrete-slab interaction significantly enhances the structural performance (and fire resistance) of a steel bridge girder under fire conditions. Other significant factors that influence fire resistance of steel bridge girders are fire insulation and type of fire scenario.