Ground motions for FEMA P-695 application in subduction zones

Abstract

The FEMA P-695 report presents a methodology for the rational quantification of seismic performance factors for use in seismic design. Despite the fact that the methodology is comprehensive and covers a wide range of possible applications, it only provides ground motion sets recorded from shallow crustal earthquakes. Therefore, this paper presents a new set of ground motions aimed at extending the scope of the FEMA P-695 methodology to zones prone to subduction earthquakes. To consider the effect of spectral shapes on collapse capacities, the spectral shape factors SSF were also computed. Four light-frame buildings were analyzed to study the impact of using the new ground motion set. Results showed a decrease in collapse capacities of 12.4%, an increase in peak floor accelerations of 31.7%, and an increase in the dissipated hysteretic energy of 15.7%. Additionally, the number of ground motions and the intensity levels of the set proved to be robust enough to provide the same reliability that can be obtained when employing a much larger ground motion set. The ground motions and the information provided in this paper have been designed to be fully consistent with the FEMA P-695 guidelines. However, their application can be extended to other analyses that evaluate the seismic performance of structural systems in subduction areas. A database that includes the proposed ground motion set is available online.