Pipe buckling

Andrea

I had a problem with a 100x100x3 square pipe collapse. See attached picture and static scheme. The problem is referred to understand the failure mode: resistance or local buckling. The pipe is undersized but, designing the new one (maybe 100x100x6 or 8 thickness - Outer dimenions shall be 100x100) I want to be sure that there will not be problem referred to local buckling.
What kind of analysis will be more near to the real conditions? I think non-linear buckling.
Other problem is related to the loads because they are transmitted by a contact

Mishal

@Andrea, The system can be checked using hand calculations. Closed sections acting isolation will not experience lateral torsional buckling, so general stress checks will be fine. If you look into the EN, AISC, SANS etc... there are equations to check the smaller components of the hollow sections, these equations are small and simple to implement.

If you send me the loads I can give some guidance on the equations.

Andrea

obviously is not due to lateral torsional buckling. It is a closed section. I intended local buckling due to compressive forces

Victor

Nonlinear quasi-static with an initial imperfection can be more accurate than linear buckling and allows you to include contact and explore the sensitivity to imperfections.