The soil is linear elastic. This is the displacement in x direction. There is PML layer around but I did some analysis without the PML and the results was the same. if you zoom in you see that the opensees result is a nice smooth curve while in LSDYNA, I could get almost the same results but the curve is not smooth and is like step-wise. I applied acceleration here. Do you believe that I need to change the INTERFACE-SSI to static in order to get the better results? There is no gravity initialization here.