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

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. (C) 2020 American Society of Civil Engineers.