考虑倒塌概率修正的钢筋混凝土框架结构地震易损性分析

Modified seismic fragility analysis of reinforced concrete frame structures in consideration of collapse probability

为研究倒塌概率对非倒塌极限状态的影响,提出了考虑倒塌概率修正的结构地震易损性分析方法。基于全概率定理,将结构极限状态划分为倒塌状态和非倒塌状态两类,若结构发生倒塌则认为结构发生非倒塌极限状态破坏的概率为100%。考虑倒塌概率修正的地震易损性分析方法包含直接方法和间接方法,其中,直接方法是直接对传统地震易损性函数进行修正,而间接方法仅修正地震易损性函数中的概率地震需求参数。以4榀不同高度不同设防烈度的钢筋混凝土平面框架结构作为研究对象,选择100条实际地震动记录作为输入,分别采用直接方法和间接方法开展考虑倒塌概率修正的地震易损性分析。结果表明:倒塌概率对轻微破坏和中等破坏极限状态的影响较小,而对严重破坏极限状态的影响较大;在地震动强度较小时,两种方法对地震易损性的修正结果相差较小;随着地震动强度的提高,两种方法对地震易损性修正结果的差距逐渐增大。

A modified seismic fragility analysis method was presented to examine the effect of collapse probability on non-collapse limit states. This method, based on the total-probability theory, divided structural limit states into two categories as collapse limit states and non-collapse limit states. When the structure occurring collapse, the exceeding probability of non-collapse limit states were taken as 100%. Both a direct method and an indirect method were included in the presented method, where the direct one modified the parameters of fragility functions directly, while the indirect one only modified probabilistie seismic demand parameters. Four reinforced concrete frame structures designed for different heights and different earthquake fortification levels were taken as the study cases. A suite of 100 real ground motion records were selected as the earthquake inputs, and the modified seismic fragility analysis using the direct method and the indirect method was conducted. The results show that the collapse probability has ignorable effect on the limit states of slight damage and moderate damage, where it has a significant effect on the limit state of server damage. The two methods for modifying seismic fragility values result in similar results under small earthquake intensities. With increasing earthquake intensities, the seismic fragility values modified by different strategies are becoming significantly different.