Multiphysics Analysis of a Steel-Concrete Composite Bridge Under Fire Conditions

Abstract

In this study, numerical results on the behavior of a three-dimensional steel-concrete composite bridge under fire conditions are discussed based on multiphysics simulations. In particular, a procedure combining fire-driven flow simulation and thermal-stress analysis of structures is presented to investigate the mechanical behavior and the safety of a fire-exposed bridge structure. First of all, fire analysis is conducted using Fire Dynamics Simulator (FDS) in a rectangular parallelepiped domain containing the bridge structure. The FDS simulation can yield the temporal variation of temperature on the surface of the bridge structure under fire condition. Second, mechanical responses of the fire-exposed bridge structure with respect to prescribed dead and live loads can be calculated by a fully-coupled thermal-stress analysis using the time-varying surface temperatures as boundary conditions. The material nonlinearities of steel and concrete have been considered in the thermo-structural analysis. A series of numerical results are presented to demonstrate the feasibility of the multiphysics fire analysis for investigating the structural behavior of bridge girders under extreme fire conditions