wave propagation in the soil

[sreedharrao144]

Sir,
I'm working on soil-structure interaction problem.I'm giving ground motion to soil domain.I provided lysimer-dash pot boundary conditions (dash pots are provided in both X-and Y-directions).In the ground motion,it has P-wave,S-waves.P-wave will propagate first.Suppose we are giving ground motion in X-direction.Then in which directions P-wave and S-wave propagate? I guess P-wave in X-direction and S-wave in Y-direction.Is it correct? If P-wave is propagating in X-direction,then particle motion in Y-direction(i.e.perpendicular to wave propagation).If S-wave in Y-direction then particle motion in X-direction.Due to particle motion in X-direction bottom boundary in shear and lateral boundary in compression.Due to particle motion in Y-direction bottom boundary in compression and lateral boundary in shear.These are because of particle motion. But how do I know which wave is propagating in a particular direction .One more issue I want to discuss. Is it required to apply ground motion in both directions or ground motion in one direction is sufficient to analyze the above said problem.Please tell me,will opensees will take both the waves in a single ground motion or the same ground motion is to be applied in another direction.In opensees,in a particular ground motion will it consider both wave propagation or single wave propagation and directions of both waves? Please inform me in this regard.Your suggestion is extremely important for my thesis progress.