A new algorithm for ground motion selection based on target smooth spectrum using spectral shape parameters

Abstract

Ground motion selection is a pivotal step in the performance-based seismic design and assessments, because it bridges the gap between seismic hazard and structural response. Presently one prevalent practice involves constructing target spectra for the selection of ground motion records. This paper introduces a novel method to construct the target spectrum, transformed the acceleration response spectrum into a normalized spectrum β multiplied by PGA where β = Sa/PGA. The normalized spectrum is smoothed to obtain the spectral shape parameters used to construct the target smooth spectrum for ground motion selection. Two sets of ground motions, selected using the proposed method and CS, are subsequently employed in the analysis of a six-story, five-span building model to assess the structural fragility and the associated seismic risk to examine the efficiency of the proposed method. Results indicated that the probability of exceeding the Life Safety (LS) performance level is lower for CS compared to the proposed approach. Seismic risk curve derived from the proposed methodology, however, is close to those obtained through CS. In conclusion, the proposed methodology effectively mitigates the limitations inherent in the conventional ground motion selection approaches and allow the performance of structures to be determined at a more realistic scale.