This paper describes a novel probabilistic fire following earthquake (FFE) framework to develop FFE fragility functions for steel braced frames. In particular, an 8-storey steel braced frame, located in a high seismic area, was used to demonstrate the framework. An algorithm was formulated to generate fire scenarios based on seismic damage. Damage caused by the earthquake was expressed in terms of inter-storey drift ratio (IDR) and peak floor acceleration (PFA). Damage was captured in structural and non-structural components, such as glazing and partition walls. In particular, floors with IDR and PFA that exceeded pre-defined thresholds were considered to experience ignition after an earthquake. More than 1100 nonlinear FFE analyses were performed by randomly generating values of window widths, fire load densities, earthquake intensities, and yield strength of steel at ambient and at high temperatures. Historic ground motions and natural fire curves were employed to characterize the hazards. Thermomechanical analyses were completed and failure criteria based on displacement and displacement rate were applied to the girders (primary beams) and columns. The results of simulations were processed to generate FFE fragility curves and surfaces for girder and column failures with respect to the time to failure in the FFE scenario and grouped based on spectral acceleration intervals. The results showed that the girder always failed first given the low structural redundancy due to the end conditions. Moreover, the higher the spectral acceleration, the more uniform the damage across the structure with a lower time to reach failure. It was finally found that the fire load density did not have a significant effect on the probability of failure for the case study under consideration.

本文描述了一种新颖的地震后概率火灾 (FFE) 框架，用于开发钢支撑框架的 FFE 脆弱性函数。特别是，使用位于高地震区的 8 层钢支撑框架来演示该框架。制定了一种算法来根据地震损坏生成火灾场景。地震造成的损坏用层间位移比（IDR）和峰值楼层加速度（PFA）来表示。结构和非结构部件（例如玻璃和隔墙）受到损坏。特别是，IDR 和 PFA 超过预定义阈值的楼层被认为在地震后发生着火。通过随机生成窗户宽度、火灾荷载密度、地震强度、以及钢在环境温度和高温下的屈服强度。利用历史地面运动和自然火灾曲线来描述危险特征。热机械分析已完成，基于位移和位移速率的失效标准已应用于梁（主梁）和柱。对模拟结果进行处理，生成梁和柱失效相对于 FFE 场景中失效时间的 FFE 脆性曲线和曲面，并根据谱加速间隔进行分组。结果表明，由于最终条件导致结构冗余度较低，梁总是首先失效。此外，谱加速度越高，整个结构的损伤越均匀，达到失效的时间越短。