Seismic Performance Assessment of Seismically Isolated Buildings Designed by the Procedures of ASCE/SEI 7

Keywords: Earthquake engineering, Seismic isolation, ASCE/SEI 7, Collapse performance, Risk assessment, Probabilistic analysis

Abstract: This report presents an analytical study of the seismic performance of seismically isolated buildings and comparable non-isolated buildings designed by the procedures of ASCE/SEI 7-10 and -16 at a particular location in California. The study concludes that seismically isolated buildings designed to the minimum criteria of either ASCE/SEI 7-10 or 7-16 at the considered location may have unacceptable probability of collapse in the maximum considered earthquake. The probability of collapse in the maximum considered earthquake becomes acceptable and the design may also meet criteria of improved performance in terms of story drift, residual drift and floor acceleration when they are designed with enhanced criteria of RI=1.0 and with isolators having a displacement capacity at initiation of stiffening equal to 1.5 times the average demand in the maximum considered earthquake. It is also observed that designs that meet the minimum criteria of ASCE/SEI 7-10 or 7-16 and without a displacement restrainer have unacceptably high probabilities of collapse. The study finds that seismically isolated structures designed by the enhanced criteria offer lower mean annual frequencies of exceeding important limits on story rift ratio, residual story drift ratio and peak floor acceleration than comparable non-isolated structures.