Site response analysis: Uncertain motions propagating through uncertain elastoplastic soil

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Presented is a stochastic site response analysis of uncertain seismic motions propagating through uncertain elastoplastic soil. Time domain stochastic bedrock motions are simulated from GMPE of Fourier amplitude spectra and Fourier phase derivative. The uncertain motions are directly modeled as a non-stationary random process in the time domain, capturing all the important seismic characteristics. Uncertain heterogeneous parameters for the elastoplastic behavior of soils are also considered and modeled as random fields. Both uncertain motions and uncertain material parameters are discretized in the probabilistic space using orthogonal Hermite polynomial chaos basis. The probabilistic site response is efficiently solved using Galerkin stochastic elastoplastic finite element method, circumventing Monte Carlo simulations. The implication of the presented methodology for site-specific probabilistic seismic hazard analysis is discussed as well.