Randel Ilumin

Suppose that I have a ground motion record having three components (North-South, East-West, and Up-Down). From the other forum that you shared, it says that I need to apply this motion to the whole body itself (using the accel command) while restricting or fixing the nodes on the base level. However, gravity is also an upward-downward component too, so do you mean that it is right to combine or add this gravity (9.81) to the vertical component considering the opposite direction that you have mentioned? Thank you.