STATE OF THE ART OF GROUND MOTION INTENSITY MEASURES ACCOUNTING FOR THE INFLUENCE OF SPECTRAL SHAPE

Selecting and scaling ground motion records reasonably is one of very important issues to affect the reliability of elastic-plastic time history analysis results of a structure. In this paper, a six-storey planar reinforced concrete frame structure with three bays under 15 ground motion records was taken as case study. 15 ground motion records were selected and scaled by the intensity measure S_a(T₁), spectral acceleration at the fundamental period first. Then this frame was analyzed via incremental dynamic analysis (IDA). And the correlation of linear and nonlinear seismic responses of the structure, such as maximum inter-story drift ratio with the spectral acceleration values at different periods, was investigated. The results show that the correlation of seismic responses with the spectral acceleration values at different periods is different and the correlation level also depends on nonlinear level. This indicates that the variation of the dynamic analysis results must be larger if the ground motion records are just scaled based on the single intensity measure such as S_a(T₁) due to the higher-mode effect and elastic-plastic period elongation. Thusly, the development of intensity measures, which can account for the influence of ground motion spectral shape, is necessary for the improvement of seismic response analysis and seismic performance evaluation of structures. Furthermore, in order to provide the reference for conducting the further research on this issue in China, the state-of-the-art developments of the intensity measures accounting for the ground motion spectral shape and reasonable methods for selecting and scaling ground motion records are summarized comprehensively.