topic Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE in Robot Structural Analysis Forum

ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

tovarog23 — Sat, 22 May 2021 17:15:35 GMT

Hello!

I have been working on a steel structure model that I have already tested at other different structural analysis software (MIDAS Gen, ETABS) and for some reason, in the new 2022 RSA, when I run the model, the displacement values and deformed shape are almost non existent and way too small. I have a large cantilever that carries two levels, and, despite the fact that I was expecting to get a large value of deformation, the value turned out to be less than 1cm, without even using bracing and using very small steel sections. I have attached an image of the deformed shape which makes no sense. I have already checked everything and cannot find any error. I do get an instability of type 3 whenever I run the model, but not sure if that is somehow related.

Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

Stephane.kapetanovic — Sun, 28 Sep 2025 00:40:39 GMT

hi @tovarog23

Could you share your model ?

Best regards

Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

tovarog23 — Sat, 22 May 2021 20:17:11 GMT

The model is just consists of steel framing and cladding. Only secondary beams have pin-pin releases and all columns have a pinned support. In terms of loads, it has gravitational (Dead, Live) and a response spectrum analysis with 10% eccentricity for each direction. I would love to share the model in this platform, but not sure how to do it as files bigger than 71 MB are not allowed.

Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

Stephane.kapetanovic — Sun, 28 Sep 2025 00:42:40 GMT

Zip it before uploading. You can also send a download hyperlink.

Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

Krzysztof_Wasik — Sat, 22 May 2021 21:42:18 GMT

HI @tovarog23

Save file as RTD without results than zip it. Then it should be small enough to attach it to forum post.

Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

tovarog23 — Sun, 23 May 2021 03:47:07 GMT

Thanks for the advice, I have attached the model that I made.

Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

Krzysztof_Wasik — Sun, 23 May 2021 12:01:48 GMT

You have used full stiffening (rigid body) model for slab panels simulation. Change it to Partial stiffening (in XY).

Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

tovarog23 — Sun, 23 May 2021 16:34:30 GMT

Thanks a lot! I initially thought that full stiffening would provide me a rigid diaphragm behavior, and that the partial diaphragm would be more of a flexible option. If I wanted RSA to consider a flexible diaphragm, what should I use?

Re: ROBOT STRUCTURAL SMALL DISPLACEMENTS/DEFORMED SHAPE

Krzysztof_Wasik — Sun, 23 May 2021 20:56:09 GMT

Hi @tovarog23

In this case you should use Partial stiffening (in XY)..