peteroznewman
Subscriber

In Workbench, create a Modal analysis and use Fixed Supports for the connection of the structure to ground.

Then drag a Response Spectrum analysis and drop it on the Solution cell of the Modal analysis. You can then use the Input Spectrum in this analysis as a Base Excitation.

Take some courses to learn Modal Analysis and other Dynamic Analyses such as Response Spectrum.

https://courses.ansys.com/index.php/courses/modal-analysis-in-ansys-mechanical/

https://courses.ansys.com/index.php/courses/single-point-response-spectrum-analysis-using-ansys-mechanical/