基于易损性的基础隔震结构地震动选取方法研究

A method of ground motion selection for base-isolated structures based on vulnerability analysis

对基础隔震结构进行动力弹塑性时程分析时,地震记录的选择是关键。提出基于基础隔震结构弹塑性动力放大系数谱进行地震记录选取的方法:首先采用动力弹塑性时程分析方法对基础隔震结构的两自由度简化模型进行分析,得到结构的动力放大系数谱;然后采用谱匹配的方法选取地震记录,对一8层混凝土框架结构的基础隔震结构进行增量动力分析、地震易损性分析和倒塌能力分析;最后,从分析结果的精度和离散性方面对规范谱匹配选波和动力放大系数谱匹配选波两种地震记录选取方法进行对比。结果表明,采用动力放大系数谱进行谱匹配选取地震记录时,其计算精度与传统选波方法相差不大,但在减小结构地震响应离散性和地震记录数量方面表现出一定的优越性。

As the selection of seismic records is very important for dynamic elasto-plastic time-history analysis of base isolated structures,a method for selecting seismic records based on the elasto-plastic dynamic amplification factor spectrum of base-isolated structures was proposed.The dynamic elasto-plastic time-history analysis method was first used to analyze the two degree of freedom simplified model of the base-isolated structure,and the dynamic amplification coefficient spectrum of the structure was obtained.Then,the seismic records were selected by the spectral matching method,and used to carry out the incremental dynamic analysis,seismic vulnerability analysis,and collapse capacity analysis of an 8-story base isolated structure.Finally,the two selection methods of seismic records were compared from the accuracy and discreteness of the analysis results.The results showed that the calculation accuracy of the proposed method for selecting seismic records is not much different from that of traditional methods,but it shows some advantages in reducing the discreteness of structural seismic response and the number of seismic records.