Ok, thank you for your answer

The truth is that I tried what you mention about Base Excitation. However, the model would stay for hours at 20% with the Modal Expansion (it was tied to a previous modal analysis) and would not continue calculating.

Then I tried a much simpler and smaller model. With this model the Base Excitation did work. However, I had no actual graphs for that model with which to compare the FEM model to see if it was correct.