During strong ground motion

the shear wave velocity of soil often decreases greatly which exhibits a great deal of nonlinearity.In this article

with the introduction of the pseudo-excitation method and the equivalent linearization approach into numerical simulation techniques of wave motions considering scattering problem

a nonlinear stochastic wave motion analysis method is presented in which the consistent excitation can be substituted by pseudo—incident waves in terms of the power spectrum density of random excitations

the effective shear strain of nonlinear soil is evaluated by mean peak shear which is computed in terms of its standard deviation and peak factor.The reliability and accuracy of the proposed method is examined through the comparison with results by Monte—Carlo simulation method and is used to estimate the spatial incoherence of earthquake ground motion.The results indicate that the local site conditions have great effects on the seismic ground motion under consistent excitations.The nonlinearity of the soil changes the structure of power spectra of the studied engineering site

this leads to the variation of spectral ratio at observation points and eventually change the spatial incoherence of the site.