基于耐震时程分析法的高效地下结构地震易损性分析

Efficient seismic fragility of underground structures using endurance time analysis method

为研究基于耐震时程分析法对地铁车站进行高效地震易损性分析的可行性,选取Ⅲ类工程场地中典型两层三跨地铁车站作为研究对象进行地震易损性分析。为反映所构造的耐震时程曲线具有所选天然地震记录的离散特性,借鉴IDA分析中分位数回归统计方法,分别以所选实际天然地震记录反应谱的16%,50%,84%分位值作为目标反应谱,各自构造3条人工耐震时程曲线作为有限元模型输入,并基于耐震时程分析结果与IDA结果绘制各级性能水准下的地铁车站地震易损性曲线。结果表明:在Ⅲ类工程场地中两种方法计算得到的地下结构各级性能水准地震易损性曲线吻合良好。因此,考虑输入耐震时程曲线离散特性的耐震时程分析法能够显著降低地下结构进行地震易损性分析过程中的非线性动力时程计算次数,并保证较高的计算精度;同时也验证了基于地震记录反应谱的分位值构造一系列具有离散特性耐震时程曲线进行易损性分析的思路是可行的。

The feasibility of efficient seismic fragility analysis of underground structures using the endurance time analysis(ETA)method is investigated.A typical two-story three-span subway station embedded in the site class III is used as the prototype.To effectively consider the inherent dispersion of as-recorded earthquake ground motions during the simulation of endurance time acceleration functions,the 16%,50%and 84%quantiles of response spectra of the as-recorded ground motions at the engineering bedrock are used as the target response spectra to generate three endurance time acceleration functions using the quantile regression method in the incremental dynamic analysis(IDA)for reference as the input motions for the nonlinear soil-structure interaction system,respectively.The seismic fragility evaluation of the underground structures is performed based on the ETA results and the IDA results.It can be seen from the numerical results that the seismic fragility curves obtained by the ETA are in good agreement with those obtained by the IDA.Therefore,the proposed ETA with full consideration of the dispersion of ground motions can significantly reduce the number of nonlinear dynamic analyses,and ensure high accuracy of the computed results.Moreover,the proposed ETA using a series of discrete ETAFs by the quantiles of response spectra of the as-recorded ground motions is a feasible alternative for the seismic fragility analysis of underground structures.