The performance of HDRB devices in base isolation: A stochastic sensitivity analysis

In this paper the seismic response of base isolated structures with high damping laminated rubber bearings is evaluated. The analysis is based on a stochastic approach and the seismic acceleration is modelled through a Gaussian zero mean non stationary stochastic process. More precisely, the recent generalized Kanai-Tajimi model proposed by Fan and Ahmadi for the El Centro 1940 N00W and Mexico City 1985 N90W earthquakes is used to preserve the non stationary amplitude and frequency characteristics of the seismic motion. The non linear constitutive behaviour of the base isolator is represented by the hysteretic differential Bouc-Wen model. The stochastic linearization method in the time domain is used to evaluate the statistical moments of the system response in the state space. The non linear differential equation of the response covariance matrix is solved by using an iterative procedure which at each step updates the coefficients of the equivalent linear system and searches for the solution of the response covariance matrix equation. To assess the accuracy of the results, these are compared with the non linear response obtained by using seismic accelerations generated with Monte Carlo simulation. Finally, the peaks of the system response variance are estimated and a sensitivity analysis is performed.