To establish relation between oblique incidence wave and design seismic component, and structure wave field which can result in non uniform ground motion, in this paper, design seismic component is regarded as result of oblique plane SV wave and oblique plane P wave. According to theory of wave propagating in solid, both incidence angles and amplitudes of the oblique waves have deterministic relation. Based on viscous-spring artificial boundary condition, the time-domain calculating method for dynamic interaction between soil and structure object to obliquely incident seismic waves is developed. Half space example with simple ground motion and Koyna seismic horizontal history proves that the method advised in this paper has good precision and can produce similar seismic response to the design seismic component. With general FEM software, the advised method can easily applied to the dynamic analysis of long span structure with non uniform ground motion.
