Efficient Estimation of Seismic Response of Large-Span Structures Considering the Effect of Multiple-Support Excitation

For the seismic design of structures in which the respective supports are located at long distances from each other, the assumption of uniform ground motion may be inadequate. In this study, an efficient time domain method is proposed to determine seismic structural response considering the effect of stochastic multiple-support excitation (MSE). This method improves the Markov vector method by considering the frequency-dependent coherence function of the excitations, proposing a new modeling framework and solving strategy. The location of the time-modulating function is studied theoretically, the and the calculation method of the time-modulating function for an arbitrary excitation envelope of the MSE is studied. A natural way of calculating support damping is given. Based on the principle that a model built in absolute coordinates should be consistent with a model built in relative coordinates, the formulation of a damping matrix in absolute coordinates was studied. The nonstationary response variances were obtained by solving the governing ordinary differential equations. The results were compared with extensive Monte Carlo simulation, demonstrating that the proposed method is efficient and accurate for analysis of stochastically structures considering multiple-support excitation. (C) 2019 American Society of Civil Engineers.