1. The procedure seems fine.
2. Unless your masses are restrained in a particular direction and cannot vibrate in that direction, you should always apply the masses in ALL 3 directions no matter whether your dynamic load is a seismic load or a vibrating machine.
3. Can you please upload the model ?
2. Unless your masses are restrained in a particular direction and cannot vibrate in that direction, you should always apply the masses in ALL 3 directions no matter whether your dynamic load is a seismic load or a vibrating machine.
3. Can you please upload the model ?