System Identification of Base Isolated USC Hospital Building From Recorded Response, #359

The University of Southern California hospital (USC) base isolated building in Los Angeles experienced strong motion during the 1994 Northridge Earthquake. The recorded response of the building is available. Prior analytical studies of USC hospital have adopted stiffening of the superstructure to match the recorded and computed response. The objective of this study is to perform system identification of the USC hospital building using nonparametric and parametric methods and determine the actual periods and damping ratios existing during the earthquake. System identification is performed using recorded response. A detailed analytical model of the building is developed without stiffening of the superstructure. The results obtained from detailed analytical modeling are verified using results from system identification. It is shown that system identification can be used to reliably estimate the actual dynamic characteristics of base isolated structures, including the energy dissipation in the base isolation system, from the recorded earthquake response.