Seismic Response of Stochastic Ground

Abstract

The spatial variation of seismic ground motions is an important factor that should be carefully considered in the seismic design of buried lifelines such as tunnels and pipelines. The consideration of the spatial variation of ground motions may also have significant effects on the seismic response of structures with spatially extended foundations or multiple supports. The temporal and spatial variability of seismic ground motions has been inferred experimentally using data from closely spaced seismograph arrays. In this paper, the seismic ground motions varying in time and space domain are described analytically by the stochastic waves filtered by a surface soil layer, with random thickness, resting on rigid bedrock. The seismic wave, being assumed by a single plane wave, is transmitted to the soil layer from the rigid bedrock. The stochastic waves from the model possess the characteristics of both the coherent and incoherent components of ground motions. The analytic expressions of the frequency- wavenumber spectra of the stochastic waves at ground surface are then derived.