Abstract: Under random seismic excitations, the precision of results with the scope of soil region in seismic response of soil layer and soil-structure interaction was analyzed. In this paper, with the bedrock white noise spectrum and Du Xiuli modified bedrock spectrum as excitations, random seismic response of soil layer was analyzed; and the effect of random seismic response of soil layer with three artificial boundaries(free boundary, fixed boundary and viscous-spring boundary), damp coefficient and the ratio of width to depth (L/H) was discussed. Based on the above basis, suggestions of reasonable scope of lateral artificial boundary were given. At the same time, with the bedrock white noise spectrum, Du Xiuli modified bedrock spectrum and the power spectrum of seismic waves records as excitations, the random seismic response of soil-structure interaction was analyzed after the reasonable scope of soil selected and the model of soil-structure interaction established. The results show that the scope of lateral artificial boundary is satisfied for random seismic response of soil-structure interaction analysis

Key words: random seismic excitations, random seismic response of soil layer, soil-structure interaction, lateral artificial boundary