topic Re: Linear Buckling problem in Robot Structural Analysis Forum

Linear Buckling problem

ianrhale — Wed, 24 May 2017 14:57:55 GMT

Hi all,

I am trying to run a linear buckling analysis on the attached model, and it is all working. What i want to do is release the 'wing' braces, that is the diagonal brace at each level, to have a pinned joint at the junction with the tower. This wing brace has a horizontal fixed, vertical free support at its other end (ie a vertical roller). As soon as I release the brace at the tower end the analysis will not run. I think I am correct in releasing Z and Y at the end of this member so that torsion remains fixed, but I can't get the analysis to complete. I think the fixed joint might be giving me slightly high results.

Can someone give me a pointer why it wont run?

Thanks, Ian.

Re: Linear Buckling problem

Rafacascudo — Wed, 24 May 2017 21:34:01 GMT

I didn't check your model (on cellphone) but in the picture you sent you don't have vertical uz support outside the building for your braces. So , if you release the moments in the connection with the building , the braces will become unstable. Probably you are getting instabilities warnings for these horizontal brace supports in the Uz direction.
Try setting these braces as truss bars (geometry/additional atributes/advanced bar properties) and then set those brace supports as totally fixed supports

Re: Linear Buckling problem

Artur.Kosakowski — Fri, 26 May 2017 09:09:53 GMT

Hi @ianrhale

Has the solution proposed by @Rafacascudo (thank you) worked for you?

Re: Linear Buckling problem

ianrhale — Thu, 01 Jun 2017 08:30:16 GMT

Hi guys,

Sorry for not getting back to you, I have been away. I have a few more questions but will think it over in the next day or two and will report back. Thanks!

Re: Linear Buckling problem

ianrhale — Fri, 23 Jun 2017 10:01:32 GMT

Artur & Rafael,

It has taken me a while to get back to this, but I just wanted to say I have been through it and can see the issue, I have no more questions.

You help is appreciated as always.

Thanks,

Ian.