Recently, the conditional mean spectrum (CMS) has become an important tool in ground-motion selection for seismic evaluation of structures. In the present numerical study, a 10-storey RC frame building is assumed to be situated on type-II soil and located in seismic zone V of India. The building is designed using the response spectrum analysis method of the Indian seismic code. Further, it is analysed using the nonlinear time history analysis method for three different CMS ground motions. The numerical study is performed for three cases: (1) fixed base with actual earthquake record; (2) fixed base with site-specific earthquake record considering soil amplification; and (3) flexible base considering soil–foundation flexibility and soil amplification. The results of the analysis are compared for the above-mentioned cases in terms of lateral displacement and storey drifts. It is observed that the displacement profile of the structure subjected to all the three considered ground motions is not the same, although they are matching to CMS. It is concluded that out of the two important soil effects, i.e. soil amplification and soil–foundation flexibility, soil amplification has a significant effect on the seismic response; however, the nature of response depends mainly on the ground-motion characteristics.

中文翻译：

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条件平均谱在考虑土壤影响的钢筋混凝土建筑抗震评价中的应用

近来，条件平均谱（CMS）已成为结构地震评价地震动选择的重要工具。在目前的数值研究中，假设一座 10 层高的钢筋混凝土框架建筑位于 II 类土壤上，位于印度的 V 地震带。该建筑采用印度地震规范的响应谱分析方法设计。进一步，使用非线性时程分析方法对三种不同的 CMS 地震动进行了分析。数值研究分三种情况进行：（1）有实际地震记录的固定基地；(2) 考虑土壤放大的具有特定地点地震记录的固定基地；(3) 考虑土-地基柔性和土壤放大的柔性地基。对上述案例的分析结果在横向位移和楼层漂移方面进行了比较。可以观察到，尽管它们与 CMS 相匹配，但在所有三种考虑的地面运动下，结构的位移剖面并不相同。得出的结论是，在土壤放大和地基柔性这两个重要的土壤效应中，土壤放大对地震响应有显着影响；然而，响应的性质主要取决于地面运动特性。土体放大和土基柔性，土体放大对地震响应有显着影响；然而，响应的性质主要取决于地面运动特性。土体放大和土基柔性，土体放大对地震响应有显着影响；然而，响应的性质主要取决于地面运动特性。