Selecting hazard-consistent ground motions for seismic risk analysis: an equivalent earthquake-based methodology

Seismic risk analysis is crucial for assessing and mitigating the impacts of earthquakes on infrastructure. A fundamental component of this analysis involves the selection of hazard-consistent ground motions that exhibit good consistency with seismic hazard curves over various periods and encompass a wide range of hazard levels. Traditional methods for selecting such hazard-consistent ground motions often have limitations, typically maintaining consistency at only a limited number of periods and using discrete intensity levels, potentially leading to inaccurate risk assessments. This study proposes an innovative methodology that overcomes these limitations by employing equivalent earthquakes, which are derived from specialized seismic hazard disaggregation techniques. Unlike traditional methods that focus on a target response spectrum corresponding to a specified hazard level, this new method utilizes seismic hazard curves at multiple periods as the primary targets. The ground motions selected using this method cover a wide range of seismic hazard levels, with particular emphasis on higher hazard levels associated with rare events. Numerical examples in the study demonstrate that ground motions selected by the proposed method maintain robust consistency with the site-specific seismic hazard curves over various periods. Importantly, the proposed method is independent of the fundamental periods of specific structures, allowing for its application in accurate seismic risk analyses for various buildings at the same site. This comprehensive methodology is expected to enhance the field of seismic risk analysis by improving the accuracy and applicability of hazard-consistent ground motion selection. However, it is important to note that the proposed method is designed for risk-based applications, where a larger number of ground motions are selected. One limitation of the method is that it may not be as practical for intensity-based assessments.