Behaviour, design and performance of steel-concrete composite walls in fire

This paper utilizes finite element (FE) modelling in ABAQUS software to investigate the behaviour of steel-concrete composite (SCC) walls under combined mechanical and fire loadings, based on an existing database of SCC wall fire tests. An extensive parametric analysis of 234 FE models is implemented, which offers deep insight into the critical design parameters, comprising the initial eccentricity, wall slenderness, core concrete thickness, core load ratio, and a range of fire exposure conditions. The sequential coupled thermo-mechanical analysis of the FE models is conducted in one-minute intervals. It includes a heat transfer analysis to establish the temperature field, followed by an incremental static stress-strain analysis to determine the load-displacement response. The simulation results show that an initial eccentricity of 5 % of the core concrete thickness and its direction have a significant impact on the fire resistance period (FRP). Under one-sided fire exposure, the FRP for insulation correlates linearly with the core concrete thickness, and the wall exhibits longer FRP when compared with all-sided or two-sided fire cases. Moreover, the higher core load ratios and wall slenderness considerably lower the FRP. Through a detailed comparison of the modelling results with design standards, the limitations of prevailing standards for predicting the FRP of SCC walls are identified. Therefore, a series of new design equations derived from the best-fit analysis of the modelling results are proposed to offer more reliable estimates of the FRP. This paper will contribute to the future refinement of design guidelines for assessing the fire-resistance capacity of SCC walls.