Fires Following Earthquake Fragility Functions of Steel Braced Frames

The paper describes the outcomes of the analysis of a steel braced frame subjected to fires following earthquake (FFE). Nonlinear time-history analyses were performed in order to evaluate the seismic response. Then, based on the damage suffered by the structure, which was estimated according to the interstorey drift ratio (IDR) and floor acceleration, the post-earthquake fire ignitions within selected compartments were considered. Natural fire curves were determined by means of zone models. Thus, compartmentation and opening characteristics were included in the analysis. Finally, thermomechanical analyses were run and failure criteria based on the column and beam displacement and rate of displacement were applied. The results of the probabilistic analyses were used to produce fragility functions to evaluate the probability of exceeding a limit state conditioned on an intensity measure in the context of FFE.