Answer:
Yes, it is possible using the load generator.
In the "Tools" menu, you can find the "From Motion…" command under "Generate Loads".
In the "Generate Loads From Motion" dialog box, you can define acceleration a in [m/s²], which can be used to determine a load, depending on the mass of the structure.
In RSTAB, it is thus possible to generate a load on a member. In RFEM, on a member, surface, or solid.
Important: The program uses the dead load of the structure. The mass of a specific load case cannot be applied here.