Instability caused by having cladding in a model

[e2009355]

Dear all,

I'm modelling steel building for car parking. the instability (type 3) has appeared during calculation in 1st order analysis and even in 2nd order analysis (I use Direct Analysis Method). I try to find solution in your webinar (Video: Instability), but i cannot fixed it. 

How can i do or i ignore theses instability?

Thanks very much!

@e2009355 Artur Kosakowski edited the topic for better findability 

[Artur.Kosakowski]

Hi @e2009355

My assumption is that cladding divide bar elements into very small calculation elements which causes large difference in values of elements of the stiffness matrix as when you delete them no instability is reported. 

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[e2009355]

Thanks sir, but how could i do? i try to change cladding to panel slab, but it doesn't work. It woks when i put load on beam (kn/m) and transfer to girder. So what your recommendation, I should use load panel (kn/m2) or load on beam (kn/m) then transfer to girder? 

[Artur.Kosakowski · Accepted solution]

Hi @e2009355

I'd ignore the warning and carefully check the obtained results. You may also apply init force/moment on the direction and the location of the reported instability. You mat find the relevant information in the 16th Robot webinar on the instability subject.  

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[e2009355]

Thank you very much, sir.