Critical Buckling Load

[Anonymous]

Hi all

My question here is how ARSA determines the side to calculate the critical load

It takes the Imax instead to calculate the Imin to calculate the critical load, in fact this may lead to wrong results

See the attached *.rtd file

The critical Load for Iz is perfect (equals the Euler value), but the real critical load must be for the Iy side.

For Rafal and Pawel

The files send under this link

http://we.tl/eMjotXDF88

I want to calculate the critical load for this model, the smaller file ...1408s is a simplification of the another

(The shell elements are deleted, the beams are from the catalog and there is only one load case left)

I need some advice to avoid the error 5000

Defined a nonlinear combination for (Permanent + Live + Wind)

I set the buckling parameters for the 50 modes

Best Regards

Marcelo

[Artur.Kosakowski]

My question here is how ARSA determines the side to calculate the critical load

Please check: http://forums.autodesk.com/t5/robot-structural-analysis/help-with-buckling-analysis/m-p/3687172

It takes the Imax instead to calculate the Imin to calculate the critical load, in fact this may lead to wrong results

See the attached *.rtd file

No, it doesn't. As explained by Rafal in the thread indicated above it is hard to determine the mode which corresponds to the primary buckling shape of a particular column of a complex model and this is not the objective of this analysis. 

The critical Load for Iz is perfect (equals the Euler value), but the real critical load must be for the Iy side.

If you make a test for a single column (or look at the ones already "done" on this forum) you will see that the values are correct for both sides (provided you look at the right buckling shapes). 

I need some advice to avoid the error 5000

Could you atatch the model where you get it (I have calculated both models you attached with no issues) please?