Risk‐based seismic design of base‐isolated structures with single surface friction sliders

Abstract

AbstractChoosing friction pendulum isolators to avoid problems with device displacement capacity or boundary wall collision is a critical part of the seismic design of base isolation systems. This paper developed a probabilistic method to quantify the risk of failure in single friction pendulum bearing (FPB) devices. This was done by calibrating a demand‐intensity model for FPBs from numerical analysis for several device property combinations. These properties encompassed the dynamic friction coefficient and effective radius of curvature—key parameters impacting these FPB devices’ seismic response. Through this demand‐intensity model, a closed‐form and relatively simple approach to quantify the mean annual frequency of exceeding a given device displacement threshold, or risk of failure, was proposed. By applying this simplified method to several case study structures and comparing it with a more extensive assessment involving multiple stripe analysis (MSA) using hazard‐consistent ground motions, the proposed simplified approach could provide very accurate estimates of displacement‐based failure risk in FPB devices under the assumption of no non‐linear behaviour in the superstructure. This proposed approach implies that structural engineers can now quickly assess the actual failure rates of different FPB device combinations used in practice to give a more uniform level of safety or reliability when designing and assessing FPB‐isolated systems. It is also arguably much simpler, direct and accurate than currently available code‐based approaches.