MODELATION OF SOIL PRESSURE ON MODAL SPECTRUM ANALYSIS

[3JC]

Dear friends,

As I comment on the subject,I am evaluatin the structural performance of a steel structure sopported on walls. Due to the complexity of the design, I am using the modal spectral analysis to evaluate the seismic actions. But my question is the next: How can I consider on this type of analysis the soil pressure on walls?
Thank you very much for your attention.
Regards,
3JC

 

[stressed]

If you model the soil as an assigned load load, define a load case which includes selfweight and pressure load and change that load case to nonlinear P-Delta. Next, definee a modal dynamic case using "Stiffness at end of nonlinear case" and select the nonlinear load case with selfweight and pressure. You can run multiple modal analyses in the same run to compare fundamental periods to see how the pressure load affects it.

The "stressed" modal cases can be used in response spectrum or modal time history analysis.