Optimum Performance of Bridge Isolation System under Parameter Uncertainty

This article deals with the study of optimum performance of isolated bridge systems under stochastic earthquake load considering uncertain system parameters. The conditional stochastic response quantities are obtained in random vibration framework using the state space formulation. Subsequently, with the aid of matrix perturbation theory using first order Taylor series expansion of dynamic response function and its interval extension, the vibration control problem is transformed to appropriate deterministic optimization problems. This requires two separate objective functions correspond to a lower and upper bound optimum solutions. A lead rubber bearing system for isolating a bridge deck from a pier is considered for numerical study to elucidate the optimum performance of isolated bridge deck system. Then a numerical study is performed to observe the effect of parameter uncertainty on the optimization of the isolator parameters and the response reduction efficiency. It is seen that neglecting the effect of system parameter uncertainty may overestimate the system performance.