震后火作用下钢筋混凝土框架基于火灾荷载密度的易损性分析

Vulnerability analysis of reinforced concrete frame under post-earthquakefire based on fire load density

针对钢筋混凝土框架的地震易损性分析已经较为成熟,但其震后火次生灾害作用下的易损性分析还尚未深入。采用ABAQUS软件分别建立3层和9层的钢筋混凝土框架有限元模型,选取火灾荷载密度(fire load density,FLD)作为火灾强度指标,对历经地震后损伤的混凝土框架结构进行火灾易损性分析。结果表明:随着地震动强度和火灾荷载密度的增大,钢筋混凝土框架的失效概率呈非线性增长;在相同火灾荷载密度下,历经多遇、设防、罕遇地震损伤后,9层钢筋混凝土框架发生不同程度破坏的超越概率高于3层钢筋混凝土框架;相对于顶层和中层受火,混凝土框架底层受火时发生不同破坏的超越概率相对较大,发生火灾的楼层越高,结构发生不同破坏的超越概率相对越小,可为钢筋混凝土框架的性能化抗火设计与评估提供研究参考。

The seismic vulnerability analysis of multistory reinforced concrete frame has been relatively mature,but the vulnerability analysis of post-earthquake fire secondary disaster has not been in-depth.In this paper,ABAQUS software is used to establish three-story and nine-story reinforced concrete frame finite element models,and fire load density(FLD)is selected as the fire intensity index to analyze the fire vulnerability of concrete frame structures damaged after earthquakes.The results show that the failure probability of reinforced concrete frame increases nonlinearly with the increase of ground motion intensity and fire load density.Under the same fire load density,the exceedance probability of different degrees of damage of 9-story reinforced concrete frame after frequent,fortification and rare earthquake damage is higher than that of 3-story reinforced concrete frame.Compared with the top and middle layers of concrete frame under fire,the surmounting probability of different damages in the bottom layer under fire is relatively large.The higher the fire floor,the smaller the exceedance probability of different structural damage.This paper can provide reference for the performance-based fire resistance design and evaluation of reinforced concrete frames.