topic Re: Separate structure error with geometric imperfections in Robot Structural Analysis Forum

Separate structure error with geometric imperfections

Anonymous — Wed, 13 Apr 2016 18:02:22 GMT

Hello

I got "Separate structure error" when tried to analyse model with geometric imperfections

If imperfections deleted from model analysis going fine without any instabilities or errors. Imperfections defined by default type "Automatic" to columns, bracings and stringers. After canceling analysis all nodes in model become separate.

Re: Separate structure error with geometric imperfections

Rafal.Gaweda — Thu, 14 Apr 2016 09:17:45 GMT

File please.

Re: Separate structure error with geometric imperfections

Anonymous — Thu, 14 Apr 2016 10:09:03 GMT

Here is the file

Re: Separate structure error with geometric imperfections

Anonymous — Mon, 18 Apr 2016 11:49:46 GMT

Interesting buckling mode

Re: Separate structure error with geometric imperfections

Rafal.Gaweda — Mon, 18 Apr 2016 13:52:53 GMT

I got warning about separate structure but nodal list is empty so I guess warning is irrelevant

Buckling mode - I suspect you are running buckling on model with imperfections. If so it can be hard to check buckling modes because members can go out of different planes

Re: Separate structure error with geometric imperfections

Anonymous — Mon, 18 Apr 2016 14:06:16 GMT

I tried to ignore this warnng, but got huge (billions of mm) displacements of columns when checking columns in steel design tab.
Also I tried to add local imperfections
- in one direction
- only to central columns
- by forces
It's not helped too.

I am running buckling analysis only to check value of critical force for model.

Re: Separate structure error with geometric imperfections

Rafal.Gaweda — Mon, 18 Apr 2016 14:19:27 GMT

Let's put it this way: model you sent had no imperfections and no buckling so I defined them by myself.
If you want us to check what you really got you have to send us up-to-date model with all settings you made.
Otherwise we will be still "walking as a blind man"

Re: Separate structure error with geometric imperfections

Anonymous — Tue, 19 Apr 2016 08:24:28 GMT

Here is the last version of file. It is without buckling analysis because of separate structure warning and some unreal reslts (look screenshots). Only local imperfections.

Re: Separate structure error with geometric imperfections

Rafal.Gaweda — Tue, 19 Apr 2016 11:48:01 GMT

I am afraid you have to delete imperfections from bars to get correct results.

Re: Separate structure error with geometric imperfections

Anonymous — Tue, 19 Apr 2016 12:59:39 GMT

😞 too bad... Anyhow, thank you for tried to help, Rafal. Best regards