The use of base isolation systems to achieve complex seismic performance objectives

To investigate possible improvements to the design of isolated structures, an extensive research program was conducted. Analytical and experimental investigations are presented to characterize multistage spherical sliding isolation bearings capable of progressively exhibiting different hysteretic properties at different stages of response. A newly developed analytical model is implemented as part of a parametric study of single- and multistory buildings incorporating a wide class of isolation systems. Behavior of the new triple pendulum bearing is compared with that of linear isolation systems with both nonlinear viscous and bilinear hysteretic energy dissipation mechanisms. The results of parametric analyses are used to develop a design framework based on targeting a multi-objective Seismic Performance Classification (SPC). This SPC is introduced to describe satisfaction of a complex seismic performance objective, defined as aggregate damage state limitation over multiple levels of seismic hazard. The probability of satisfying specific SPCs is computed for three- and nine-story buildings on all classes of isolators investigated.