Does ETABS calculate period according to UBC 97 eq. 30-8?
Answer: When the option for UBC 97 is selected, the structural period used for auto-seismic load calculation is determined through one of the following methods:
- Method A
- According to the mode with the largest participation factor along that orientation.
- User-defined parameters
While ETABS does not use UBC 97 eq. 30-10 to calculate structural period, a properly substantiated analysis model should produce a period suitable for drift calculations. The ETABS Lateral Loads Manual provides additional information.