Stochastic analysis of base-isolated liquid storage tanks with uncertain isolator parameters under random excitation

Stochastic response of base-isolated liquid storage tanks is presented herein, considering uncertainty in the characteristic isolator parameters, under random base excitation. The liquid storage tank is modeled using lumped mass mechanical analog, along with laminated rubber bearing (LRB) as the base isolator. The non-sampling stochastic simulation method based on the generalized polynomial chaos (gPC) expansion technique is used for numerical dynamic simulation of the base-isolated liquid storage tanks. The uncertain isolator parameters, the random base excitation and the system response quantities are represented by the truncated gPC expansions. The stochastic discrete model of the system, involving these expansions, is projected to an equivalent deterministic model by using the stochastic Galerkin method. Non-intrusive solution of the projected system is preformed, at a set of collocation points, for calculation of the gPC coefficients of the system response. The analyses are carried out for two different configurations of the liquid storage tanks, i.e. broad and slender tank configurations. It is observed that the uncertainty in the isolation parameters and in the excitation force affect the response of slender tanks more as compared to broad tanks. The statistics of the response quantities are examined, and the effectiveness of the procedure is compared with the results from the Monte Carlo simulations. It is further observed that uncertainty in the isolation damping has insignificant effect on the distribution of peak response quantities. It is also concluded that for specific uncertainties in the isolator parameters and excitation, the response calculated for the base-isolated liquid storage tank may be similar to that of fixed-base tank. (C) 2013 Elsevier Ltd. All rights reserved.