Exploring risk-targeted ground motions and seismic design spectra for mainland China

Abstract

Seismic design under the paradigm of uniform hazard only considers the seismic hazard of building sites, which will lead to inconsistent collapse risks of buildings in different areas. To achieve uniform collapse risk, the paradigm of conventional seismic design with uniform hazard should be shifted to the new framework of uniform risk, which accounts for both seismic hazard of sites and collapse fragility of buildings. In this study, based on the principle of risk targeting, parametric sensitivity analyses of risk-targeted ground motions for mainland China are performed considering different risk categories and site classes. Then, the risk-targeted peak ground accelerations and the uniform-risk seismic design spectra are obtained for mainland China. Seismic risk assessment is conducted for an 8-story reinforced concrete frame structure using the ground motions selected based on the uniform-risk seismic design spectra. The results indicate that the influence of logarithmic standard deviation of the target collapse fragility function on the risk-targeted maximum considered earthquake gradually increases with risk category. The impact of target collapse risk on risk-targeted maximum considered earthquake of a hard site is more remarkable than that of other sites. The effects of the logarithmic standard deviation and the conditional collapse probability under the maximum considered earthquake on the collapse risk gradually increase with the site class. In addition, the construction of uniform-risk seismic design spectra takes into account both seismic hazard and structural fragility. It is reasonable to select ground motions based on uniform-risk seismic design spectra for conducting seismic risk assessment of structures.