Abstract:

Proposed in this paper are two methods to select the input waves under seismic action,one is SRSS method and the other is dual period method.The two methods,fitting the target design response spectrum with the SRSS spectrum in the response spectra of two horizontal earthquake components,refer the notion of selecting input earthquake waves for three-dimension analysis in American codes ASCE/SEI 7-05 and FEMA 368,and integrate with the dual frequency interval method of two-dimension analysis used in China.Then,by taking three spatial frames as examples,and by using the maximum elastic base shear under frequent earthquake,as well as the maximum elasto-plastic top displacement and elasto-plastic inter-story drift angle under rare earthquake as the structural response indicators,the selecting and controlling effects of the two proposed methods are compared and analyzed.The results show that the deviation of the maximum elastic base shear obtained by the dual period method is lowest,that the deviations of the maximum elasto-plastic top displacement and the maximum elasto-plastic inter-story drift angle obtained by the SRSS method and the dual period method are lower than those obtained by the dual frequency interval method,and that the dual period method controls the structural response indicators more comprehensively and effectively.

Key words: three-dimension frame, seismic waves, bi-direction horizontal seismic motion, response spectrum, time-history analysis