Nonlinear analysis for compression-only soil spring 1

[JasonGeng]

If a sap model has involved compressioin-only soil spring, does it need to run non-linear analysis for every primary load case and all load-combination cases as well?

I have modeled an underground tunnel in SAP, and there are quite a lot of soil spring (compression-only) defined. I appreciate if any comments.

Thanks.

 

[WillisV]

Yes. Anytime non-linear analysis is involved it needs to be performed on each load combination as linear superposition is not valid.

 

[JasonGeng]

Thanks very much for your reply. If I want to look at the results just from one primary load case, do i need to run this load case nonlinearly as well?
Thanks.

 

[WillisV]

In your specific case where the actual analysis results of a single load case require non-linear analysis (compression only springs), then yes each load case would need to be run non-linear as well to view their specific results.

You should be able to easily see this in the output of the model (the compression-only springs will be taking tension if you don't run non-linear).