Performance evaluation of seismically isolated buildings near active faults

This paper investigates the collapse risk of seismically isolated buildings that are designed by the procedures of the ASCE/SEI 7-16 standard for sites within 5 km of the active fault that controls the hazard. The study is based on six-story perimeter frame buildings designed with special concentrically braced frames for a location in California. The seismic isolation systems considered in this study are comprised of either: (i) triple friction pendulum bearings with high friction coefficients at the sliding interfaces, (ii) triple friction pendulum bearings with low friction coefficient at the sliding surfaces and enhanced with fluid viscous dampers, or (iii) triple friction pendulum bearings with low friction coefficients at the sliding surfaces. The paper demonstrates that the seismically isolated buildings designed per Section 17.3.3 in ASCE/SEI 7-16 standard, but with either increased isolator displacement capacity or increased superstructure strength by comparison to the minimum required, can achieve an acceptable collapse risk. It is also demonstrated that the seismic isolation systems that have the best collapse performance for far-field motions are not necessarily the best for the near-field pulse-like ground motions.