基于性能设计的钢筋混凝土框架结构易损性分析

Seismic vulnerability analysis of RC moment resisting frames complied with requirements of different performance in current seismic code

根据我国新抗震规范对7度区的钢筋混凝土框架进行基于性能的结构设计,采用OpenSees建立相应的结构非线性分析模型,进行多地震波作用下的结构增量动力分析和结构易损性分析。分析结果表明:在同一地震动强度作用下,性能要求越高的结构超越规定的极限状态的概率越小,其抗倒塌储备系数CMR值越大;大震作用下,结构的倒塌概率满足美国ATC关于"大震不倒"的设防要求,巨震作用下,高性能的结构倒塌概率明显比其他结构低;但用美国ATC单一的评价指标,本文七层框架按低性能水平设计的结构抗倒塌储备系数CMR值不能满足要求;因此如何针对我国规范的性能水平,建立对应的CMR评判多指标体系,应是当前亟待解决的问题之一。

RC frames in seismic zone of fortification intensity 7 have been designed using performance-based method recommended by Code for seismic design of buildings in China,and nonlinear analytical models have also been constructed using OpenSees software. Then the incremental dynamic analysis and seismic vulnerability analysis were performed under several ground motions. The conclusions were obtained from analysis results as following,under the same intensity measured earthquake,the higher the structural seismic performance requires,the lower the probability exceeding the limited state is and the bigger the value of Collapse Margin Ratio( CMR) is. The structures are satisfied with the requirements of collapse prevention under rare earthquake in ATC code evaluated by probability of collapse,and the probability of collapse for structures with higher performance is definitely lower than the ones with lower performance under huge earthquakes. The frames with 7 stories which were designed related to the low performance do not meet the limited CMR value required by ATC. Thus one of the most necessary research works is needed to establish the evaluation system using multi-index based on China seismic codes.