Performance-based testing specifications for seismic isolators

This paper presents a study that determines the conditions of testing for determining the bounding properties of seismic isolators for use in analysis and design in a test that is meant to be a replacement of tests Items 2(a) and 3 of ASCE/SEI-7. Then separately, the study determines the conditions of testing for determining the adequacy of isolators in the maximum considered earthquake in a test is meant to be a replacement of test Item 4 of ASCE/SEI-7. The test conditions are determined by performing analyses with models that account for the time-variant properties of the isolators and by computing the resultant isolator displacements. In performing the work, a large number of isolation systems (total of 96 systems, single friction pendulum, triple friction pendulum and lead-rubber), three different seismic hazards as measured by the spectral acceleration at the period of one second, and a large collection of bi-directional ground motions with short- and long-duration characteristics (71 pairs of each duration, 96 systems, three seismic hazards) were considered. Fundamental in this methodology is the use of analysis models in which the properties of the isolators (friction or characteristic strength) are dependent on the instantaneous temperature at the sliding interfaces or in the lead core.