I wanted to calculate the Story Drift for my model corresponding to the response spectrum seismic case. I have specified the CHECK STOREY DRFIT command after the Response Spectrum case. However, STAAD reports the following message in the output file. **WARNING: FLOOR LEVELS ARE NOT DEFINED. THERE WILL BE NO STORY DRIFT CHECKING.
To use this command the floor levels should be specified using the FLOOR HEIGHT command or by modelling the RIGID DIAPHRAGMS. You have not defined any of these in your model.