Analytical modeling of high damping rubber bearings

Two analysis models for high damping rubber bearings are proposed based on the results of shaking table tests of a seismically isolated bridge deck. These analysis models are established using the modified Gauss-Newton system identification method and the fractional derivative Kelvin model based on sinusoidal test results. The tests produced a maximum shear strain in the bearing of approximately 100%. Two existing equivalent linear models specified by the American Association of State Highway and Transportation Officials and the Public Works Research Institute of the Japanese Ministry of Construction are also characterized using sinusoidal test results. The predicted seismic responses of the test structure by the proposed models and the two equivalent linear models are compared with the measured responses. It is concluded that the proposed models can predict the seismic responses of the bearing better than the two equivalent linear models. For practical applications, the fractional derivative Kelvin model is implemented into an iteration procedure adopted by the current design practice. An evaluation of the convergence of iteration and the accuracy of prediction is conducted.