Thermo-mechanical behavior of composite beams with corrugated steel webs exposed to localized fire

Abstract

In this study, a one-way coupling methodology combining fire simulation based computational fluid dynamics (CFD) with finite element (FE) analysis is proposed to investigate the thermo-mechanical behaviors of composite beams with corrugated steel webs (CSWs) under localized fire exposure. Fire Dynamics Simulator (FDS) is used to simulate the local fire environment, and the adiabatic surface temperature (AST) data obtained in FDS are imported into the FE models in ABAQUS by the fds2ascii coupling tool. The validations of FDS models and the CFD-FE coupling method are verified by a localized fire test on a steel beam conducted by the National Institute of Standards and Technology (NIST). Then, the CFD-FE coupling method is applied to analyze the thermo-mechanical behaviors of composite beams with concrete flanges and CSWs exposed to localized fire. As the fire exposure time increases, the composite beam appears significant variation of the temperature gradient at elevated temperature, and induce the dynamic, uneven temperature field in the structural members. Due to the influences of the temperature gradient field, the traditional design assumptions for composite beams with CSWs are not valid when the structures suffered a localized fire. It found that the shear stress on the CSWs is no longer evenly distributed along the depth at elevated temperatures, and the concrete flange resists a considerable part of the sectional shear force, particularly of the fire-affect zone. This study hopes to provide a basis for the fire resistance design of composite girder bridges with CSWs.