P-delta Analysis

[Fernandokis]

Could someone please explain me how to understand why a model does not converge? Is there any ouput file to look for?, to understand this. I have a model that works for first order effects. However, when I want to carry out a p-delta analysis I can't get the model to converge for certain load cases. For example, load case 1000, 1.35 D+1.5L does not converge. However, if I reduced this load to 0.6(1.35D+1.5L) then the model converge. What is it happening? Do the members need to become bigger?

I am attaching to this email the model described above.

Thank you

[Artur.Kosakowski]

You missed the file but you may be very right. P-Delta (or  just non-linear analysis which includes in Robot the 2nd order effects) may increase internal forces causing the structure to become unstable. Try to set non linear buckling analysis (without P-Delta) for 0.6(1.35D+1.5L) and check the value of the critical coefficient value.

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[Fernandokis]

Thanks Arthur for your reply. I am attaching the file this time. Could you please now answer my question?

Thank you

[Artur.Kosakowski]

You should increase the size of the columns.

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.