System identification of rubber-bearing isolators based on experimental tests

Rubber-bearing isolation systems have been used in buildings and bridges. These base isolation systems will become more popular in the future due to their ability to reduce significantly the structural responses induced by earthquakes and other dynamic loads. To ensure the integrity and safety of these base isolation systems, a structural health monitoring system is needed. One important problem in the structural health monitoring is the identification of the system and the detection of damages. This problem is more challenging for the rubber-bearing isolation systems because of their nonlinear behavior. In this paper, experimental studies have been conducted for the system identification of nonlinear hysteretic rubber-bearings. Experimental tests of a rubber-bearing isolator under El Centro and Kobe earthquakes have been performed. The Bouc-Wen models with 3, 5 and 6 unknown parameters, respectively, have been investigated to represent the hysteretic behavior of rubber-bearing isolators. The extended Kalman filter (EKF) approach has been used to identify the nonlinear parameters of the Bouc-Wen models for the rubber-bearing isolators. Our experimental studies demonstrate that the Bouc-Wen models are capable of describing the nonlinear behavior of rubber-bearing isolators, and that the EKF approach is effective in identifying nonlinear hysteretic parameters.