Performance of Earthquake Isolation Systems

A comparison of the performances of three different base-isolation systems, the laminated rubber bearing system, the New Zealand system, and the resilient-friction base isolator system, is made under the same set of criteria. Conclusions pertaining to the ranges of the applicability of the systems for three earthquake sizes, M 6.0, 6.7, and 7.3, are obtained for a site located in the vicinity of the earthquake source (nominal source-to-site distance=10km). Two different seismological models of the earthquake source were used in modeling the spectral content of the earthquake input. The stochastic response of one-story and five-story base isolated structures is computed. The equivalent linearization technique is used to linearize the equations that govern those systems that are nonlinear. This study confirms the conclusions reached in previous studies by demonstrating again that friction plays an important role in energy absorption. This is the reason for the apparent superior performance of the resilient-friction base isolator; system. However, more studies are needed to assess the feasibility of this system and to better understand its behavior by testing.