Performance of steel moment-resisting frames in post-earthquake horizontally traveling fire

Abstract

PurposeThe study investigates the performance of a three-story unprotected steel moment-resisting frame (SMRF) designed for high seismic demand in the fire-only (FO) and post-earthquake uniform and traveling fires (PEF). The primary objective is to investigate the effects of seismic residual deformation on the structure's performance in horizontally traveling fires. The traveling fire methodology, unlike conventional fire models, considers a spatially varying temperature environment.Design/methodology/approachMulti-step finite element simulations were carried out on undamaged and damaged frames to provide insight into the effects of the earthquake-initiated fires on the local and global behavior of SMRF. The earthquake simulations were conducted using nonlinear time history analysis, whereas the structure in the fire was investigated by sequential thermal-structural analysis procedure in ABAQUS. The frame was subjected to a suite of seven ground motions. In total, four horizontal traveling fire sizes were considered along with the Eurocode (EC) parametric fire for a comparison. The deformation history, axial force and moment variation in the critical beams and columns of affected compartments in the fire heating and cooling regimes were examined. The global structural performance in terms of inter-story drifts in FO and PEF scenarios was investigated.FindingsIt was observed that the larger traveling fires (25 and 48%) are more detrimental to the case study frame than the uniform EC parametric fire. Besides, no appreciable difference was observed in time and modes of failure of the structure in FO and PEF scenarios within the study's parameters.Originality/valueThe present study considers improved traveling fire methodology as an alternate design fire for the first time for the PEF performance of SMRF. The analysis results add to the much needed database on structures' performance in a wide range of fire scenarios.