Response of base-isolated USC hospital building in Northridge earthquake

The base-isolated University of Southern California (USC) hospital building experienced strong motion during the 1994 Northridge earthquake. Californi a Strong Motion Instrumentation Program data of the response are available for performance evaluation. The objective of this study is to evaluate the seismic performance of the base-isolated USC hospital building during the 1 994 Northridge earthquake. A nonlinear analytical model of the USC hospital building is developed and verified using system identification. The respon se computed, using the presented analytical modeling techniques, is verifie d using recorded data. Structural behavior during the Northridge earthquake is evaluated in detail. The base-isolated USC hospital building performed well and reduced the response when compared to a fixed-base structure. The free-field acceleration was 0.49g and peak foundation/ground acceleration w as 0.37g. The peak roof acceleration was reduced to 0.21g, nearly 50% of th e peak ground acceleration. The peak drift was <30% of the code specificati on. The bearings yielded and dissipated energy (20%). The superstructure wa s elastic due to the effectiveness of base isolation. The building is expec ted to perform well in future earthquakes similar to those used in the orig inal design.