基于耐震时程法的高拱坝地震易损性分析

Seismic fragility analysis of high arch dams based on endurance time analysis method

基于耐震时程分析方法(ETA),建立了三维坝体-库水-地基动力相互作用模型,进行高拱坝抗震性能评价。以基于目标反应谱合成的10条耐震加速度时程曲线为地震输入,选取坝体损伤体积比、坝顶坝踵顺河向相对位移和拱冠梁横缝开度作为结构性能指标,通过对结构不同性能水准的定义,建立了极限状态与结构性能指标之间的关系,以此为基础绘制易损性曲线。结果表明:随着耐震时程输入时间的增加,拱坝的各项响应值随之增大,不同响应指标对地震强度的敏感性不同,且ETA法与增量动力分析法(IDA)得到的响应结果基本一致,在同一性能水平下采用不同评价指标时对应的超越概率也不相同。因此,在进行结构的抗震性能评价时应综合考虑不同结构响应指标,选取不同性能下超越概率最大的结构响应指标进行分析。

A three-dimensional dam-reservoir-foundation dynamic interaction model is developed to evaluate the seismic performance of high arch dams,based on the endurance time analysis method(ETA).It takes inputs of 10 seismic acceleration time history curves synthesized using the target response spectra,and adopts structural performance indexes:the damage volume ratio of dam body,the relative streamwise displacements at the dam crest and heel,and the joint opening of crown cantilever.We formulate a relationship between the limit state and structural performance index by defining different performance levels of the dam-foundation system,so that we can draw its vulnerability curves.The results show that with an increasing input time of the seismic time history,the dam responses intensify,and the sensitivity of different response indexes to seismic intensity is different.And the responses calculated using the ETA method and the incremental dynamic analysis method(IDA)are nearly the same.When different evaluation indexes are used at the same performance level,the corresponding probabilities of exceedance will be different.Therefore,different structural response indexes should be considered comprehensively in evaluation of the seismic structure performance,and the index with the largest probability of exceedance at different performance levels should be selected for analysis.