STOCHASTIC FINITE-ELEMENT METHODS FOR THE SEISMIC RESPONSE OF SOILS

Some of the available stochastic finite element methods are adapted an d evaluated for the analyses of response of soils with uncertain prope rties subjected to earthquake induced random ground motion. In this st udy, the dynamic response of a soil mass, with finite element discreti zation, is formulated in the frequency domain. The spectral density fu nction of the response variables are obtained from which the evaluatio n of the root-mean-squared and the most probable extreme values of the response are made. The material non-linearities are incorporated by u sing strain compatible moduli and damping of soils using an equivalent linear model for stress-strain behaviour of soils and an iterative so lution of the response. The spatial variability of the shear modulus i s described through a random field model and the earthquake included m otion is treated as a stochastic process. The available formulations o f direct Monte-Carlo simulation, first-order perturbation method, a sp ectral decomposition method with Neumann expansion and a spectral deco mposition method with Polynomial Chaos are used to develop stochastic finite element analyses of the seismic response of soils. The numerica l results from these approaches are compared with respect to their acc uracy and computational efficiency. (C) 1998 John Wiley & Sons, Ltd.