Design Ground Motion Selecting Method for Nonlinear Time History Analysis by Correlating Fundamental Period and Mean Period

Nonlinear time history analysis (NTHA) has become a considerable option for seismic design. For complex and irregular structures, a NTHA derives realistic displacement that leads to efficient seismic design. However, regions without sufficient earthquake records face issues when determining which earthquake is most suitable for their site condition. In this study, a selection method for design ground motion used in the nonlinear time history analysis was developed by correlating the fundamental period of buildings and the mean period of ground motions. From existing literature, the relationship between the maximum displacement and the fundamental period normalized to the mean period was determined. A total of 200 NTHA was performed to establish the relationship of reinforced concrete (RC) piloti-type structures by statistically correlating them between the fundamental period and the mean period with the maximum displacement. By statistical means from RC piloti structure’s NTHA distribution, the regression curve and the 70% confidence interval were derived. This correlation determined the period ratio range category where the earthquake’s NTHA displacements were compared to the pseudo displacement of the design spectrum method. For the suggested piloti prototype model, it was concluded that the period ratio of 0.75-1.5 was a category that could determine whether the earthquake’s NTHA displacement was greater or less than the linear elastic response spectrum method.