条件均值谱选取记录的结构抗倒塌易损性分析

以抗倒塌易损性分析方法中的强震记录选取环节为研究对象,为了更好体现不同场址的地震动危险性差异,利用目标地区地震概率危险性分析的设定地震解耦结果构建条件均值谱（CMS）,进而将其进行多次调幅得到对应的目标谱,将匹配选波结果作为增量动力分析方法（IDA）的输入.以自振周期为0.5、1.0和1.5 s的3个平面框架为算例,在中国两个城市的地震安全性评价工作的基础上构建CMS谱,进行IDA分析,并将与当地一致概率谱、罕遇地震规范谱以及ATC63数据集得到的结果进行对比讨论,结果表明基于规范目标谱得到的抗倒塌易损性概率曲线最陡峭,基于一致概率谱与ATC63数据集得到的抗倒塌易损性概率曲线次之,CMS对应的抗倒塌易损性概率曲线最平缓.同时,对于较长周期的1.5 s结构,本文建议采用包络CMS谱来考虑多阶振型的影响,否则采用单点周期CMS谱会使得倒塌易损性计算结果显著低估实际的倒塌超越概率.

Structural collapse fragility analysis based on strong ground-motion records selection using conditional mean spectrum

The strong ground-motion records selection in structural collapse fragility analysis was studied. To consider the seismic hazard difference within target sites, the conditional mean spectrum (CMS) was used as the target spectrum for ground-motion records selection in the increment dynamic analysis (IDA) method. The CMS was constructed through the China seismic deaggregation and probability seismic hazard analysis. Taking three different 2D structures as examples and based on the seismic safety evaluation of two cities in China, the CMS was constructed to analyze the collapse fragility curves with IDA method, and the results were compared with the results obtained from the uniform hazard spectrum, the code spectrum, and recommended recordings in ATC63. The results indicate that the collapse fragility curve using code spectrum is the steepest, the results of the uniform hazard spectrum and ATC63 are the next, and the suggested method is the flattest. Meanwhile, for the long period 1.5 s structure, the envelope CMS is implemented to consider the influence of the multiple model period effect instead of the single period CMS which underestimates the collapse fragility calculation result significantly for the long period structures.