Post-earthquake fire performance of partially encased composite steel and concrete columns

Abstract

Considering the potential severity of losses caused by post-earthquake fires compared to earthquakes alone, this study employed a three-dimensional Finite Element (FE) model established in ABAQUS to investigate the response of partially encased composite (PEC) steel and concrete columns under post-earthquake fire, serving as preliminary analysis for subsequent experimental studies. The validity of the FE model was verified using results from existing seismic and fire loading tests. In simulating the hysteresis behavior of PEC columns, this study evaluated the impacts of concrete discrete cracking and mechanical models on the simulation outcomes, thereby refining the modeling technique. A typical PEC column was selected as the focus of this investigation. Sequential earthquake-fire simulations were conducted using a data transfer technique to assess the fire resistance performance of different seismic damaged columns with different axial compression load ratios. The results indicate that the behavior of damaged PEC columns evolves based on initial damage, and the failure exhibits overall bending accompanied by local buckling of the steel flange. As the axial load ratio increases, the fire resistance time of seismic-damaged PEC columns significantly decreases. When the axial compression ratio is increased from 0.2 to 0.5, the fire resistance time of columns with damage factor D within 0.6 decreases by 59.07% on average. This sensitivity to axial pressure is particularly pronounced when earthquake damage is severe. Moreover, it finds that the lateral drift ratio under seismic action should be controlled within 2% to ensure that the post-earthquake fire resistance will not be significantly reduced.