Performance Evaluation of Fire Exposed RC Structure Using Pushover Analysis

Abstract

A rise in concern is observed to determine capacity of RC Framed structure to resist seismic forces, fire effect, along with gravity loads. The analysis of structure by considering fire effect requires consideration of thermal degradation and material non-linearity. In general, a finite element program is adopted to conduct structural fire analysis. However, application of finite element software is time consuming. Hence, in the present work, post-fire performance of structure to seismic forces is determined using ETAB software. The post-fire properties of structural elements are obtained using Wickström’s empirical relationships. In the present work, RC building frame is designed as per Indian standard guidelines using linear static method by adopting gravity load, wind load, and seismic load. Further, the pushover analysis is carried out to RC framed structure by adopting displacement controlled methods until peak roof displacement is reached. Later, RC members are subjected to standard fire using Wickström’s empirical relationship to obtain temperature isotherms. Further, 500 °C isotherm is used to obtain reduced cross section of the RC Frame members. Various fire spread scenarios were considered to determine the criticality of fire and seismic effect. It is observed that fire on the ground floor will greatly affect the structural performance of seismic loads.