In the 'Load Cases & Combinations' dialog box, go to the Response Spectrum tab to define the parameters of the response spectrum.
Activate the X and Y directions to assign the default response spectra according to ASCE 7 | 2022. The diagram below then will show the relationship between acceleration and time.
The default maximum acceleration 0.333 of "g" is rather high. To apply the values valid for the geographical location of the model, click one of the
buttons next to the 'Response spectrum' list. The 'Edit Response Spectrum' dialog box is opened.
The 'Definition Type' list includes several possibilities how to define the response spectrum. Make sure that the According to Standard - ASCE 7 | 2022 option is set.
The MCER at Short Periods (SS) and at a Period of 1 sec. S1 are set to 50% and 20% respectfully. As the model is situated in San Francisco, California, it is recommended to apply the value specific to that location. If you do not have it at hand, you can use the tool provided by Dlubal Software. Open the Dlubal Online Services.
A map is opened where you can select the snow loads, wind speed, and seismic loads. Select the Seismic option (1).
In the 'Enter a Location' box, type San Francisco (2) and select the San Francisco, CA, USA option from the list (3). The data for this location is read in.
The Short and 1 Sec Periods (SS and S1) are 150% and 60%. Copy those values and return to the 'Edit Response Spectrum' dialog box. There, paste the values of "150%" and "60%" to the 'MCER at short periods' and 'MCER at a period of 1 sec.' boxes.
When you click some other box next to apply the modification, you will see in the diagram that the maximum acceleration now is 1.00.
You can check some other parameters in the table, such as the ground type or importance class. They are not to be modified for the example, however. Click OK to apply the modified spectrum and return to the 'Load Cases & Combinations' dialog box.