Abstract
It is important to consider the spatial variability of soil properties to evaluate the uncertainty of dynamic response of subsurface structures subjected to earthquakes. Although there are many proposed models for generation of stochastic fields, few researches have been conducted to understand the basic feature of the response variability of the system having those stochastic fields. This paper examines the response variability of the underground structures and surrounding ground subjected to the earthquake ground motion, modeled with random fields. Series of Monte-Carlo simulations were conducted for linear and nonlinear models under various conditions, e.g. shear wave velocity Vs, thickness H, correlation length of the ground shear stiffness θ, and so on. From those results, it turned out that the response variability can be estimated with the variance function proposed by Vanmarcke for liner model with choosing appropriate local averaging lengh, while for nonlinear model, the variance of the response becomes much larger than estimated by variance function when the ratio of local averaging length and correlation length takes a certain value corresponding to each response to be examined.
