The necessity to better understand how a steel structure behaves under re loading has gained signicance, since a large number of recent events have proved the vulnerability of steel structures under such hazard. Older concentrically braced frames have been widely used in buildings, which had been formerly designed without observing seismic provisions and details. Although the vulnerability of this type of structural systems, here referred to as non-seismic braced frames, under earthquake loading has already been studied, its behavior under re loading has not been investigated yet. Therefore, this study aims to investigate the behavior of global and local responses of the mentioned structural system under various uniform re scenarios. The heating and cooling phases of re were taken into account for dierent building stories using the nite element method. The results of the conducted analyses demonstrated that the braces buckled at high temperatures due to large compressive axial forces and expansion of lateral constraints. This phenomenon led to early loss of the lateral resistance of stories, which, in turn, resulted in the failure of columns. Consequently, the underlying oor collapsed under re. The analysis results contributed to a better understanding of the behavior of steel braced frames under re conditions.

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