Post-Earthquake Fire Resistance of Circular Concrete-Filled Steel Tubular Columns

Abstract

An experimental study was conducted to investigate the mechanical behavior and residual capacity of concrete-filled steel tubular (CFST) columns subjected to a post-earthquake fire. Nine circular cantilever CFST columns, including two control specimens, were tested to investigate their post-earthquake fire resistance time. The residual seismic behavior and load carrying capacity of an additional four columns were also studied following post-earthquake fire. All specimens were first subjected to a reversed cyclic or simulated earthquake loading (to induce initial seismic damage) and were then heated to obtain the fire resistance time or were subjected to additional cyclic reversed loading after a post-earthquake fire. The experimental results indicate that the CFST columns generally performed well after a post-earthquake fire. Specimens with high compressive strength concrete exhibited longer post-earthquake fire resistance times, whereas the increase in tube wall thickness only had a marginal effect on improving post-earthquake fire resistance. More importantly, the presence of residual lateral drift at the end of the earthquake loading had a much more significant effect on the post-earthquake fire performance than specimens without residual deformation. Finally, it is recommended that the failure criterion for fire loading should possibly take into consideration lateral deformation limits during fire testing.