Large Deflection Warning in RAM Concept

RE: Large Deflection Warning in RAM Concept

Seth Guthrie — Tue, 06 Dec 2022 16:23:14 GMT

Yes, exactly. I don't know exactly what the threshold is for large displacement warnings, but it's pretty small (maybe as a percentage of the model size).

RE: Large Deflection Warning in RAM Concept

Chris Gerding — Tue, 06 Dec 2022 16:14:02 GMT

Thanks for the quick response Seth. Lateral deflections for the model with the warning message are 0.00106" and 0.00152" for the x and y directions, respectively. The lateral deflections for the other mat foundation model without the warning are 0.00219" and -0.00305" for x and y directions, respectively.

I varied the area springs KFr and KFs values from 0.1 to 0.15 and the warning went away. Is it possible that this warning is indicating the mat foundation is sliding?

RE: Large Deflection Warning in RAM Concept

Seth Guthrie — Tue, 06 Dec 2022 15:49:19 GMT

Did you check the lateral deflection, and if so how much is it? Surely your 2 models are different in several ways; the shape of the mat, the magnitude of the lateral load, etc.

RE: Large Deflection Warning in RAM Concept

Chris Gerding — Tue, 06 Dec 2022 15:17:21 GMT

I am also having receiving this warning message. I modeled and analyzed one mat foundation by importing through RAM SS, where I did not receive this warning message. As I am now analyzing a second mat foundation from this same model, I am receiving this warning. The mat foundations have area springs set up, and have very similar vertical and lateral deflections between the two concept models.

RE: Large Deflection Warning in RAM Concept

Seth Guthrie — Mon, 01 Oct 2018 14:58:31 GMT

You can plot lateral deflection (plan X or Y directions) for any load case or combination.

RE: Large Deflection Warning in RAM Concept

Karthik Madhur — Fri, 28 Sep 2018 22:52:54 GMT

Seth Thank you! But I don't have any lateral loads applied in the model. Is there a way to check the sliding of the mat ?

RE: Large Deflection Warning in RAM Concept

Seth Guthrie — Fri, 28 Sep 2018 22:38:50 GMT

If you only provide vertical supports and have any lateral loads the entire mat can slide. This can result in instability or large lateral deformations. https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/3038/ram-instability-in-finite-element-analysis-tn#mat