SAP Pushover / Nonlinear Analysis not converging

[tpsk]

Hi,
It is my first post here, so I would like to thank you all for the answers I have already found here, and for the ones to come!

I am running across a problem while doing a nonlinear analysis on SAP2000. I am running the NL because I have tension-only bracing. I have different Load Combinations based on NL Load Cases.
Using the Multi-Thread solver, the analysis converges very quickly for the Load Cases based on the N/S direction of the wind. The combinations based on the E/W direction of wind do not converge at all...

The building is a simple 1950s steel warehouse, with one-way trusses.

Has anyone ever run across this?
Any tips?

thanks a lot,
Thomas.

 

[ishvaaag]

One can imagine this to be a case where accounting for the nonlinearities by present standards a safe situation is not found in the analysis. This may be found when any particular direction is particularly flexible, irrespective of if an old or new design. Try to ascertain if such can be the case or if your model lacks some stabilizing stiffness that may be really present and not modeled.

 

[tpsk]

Thanks a lot for your answer.
Actually, I eventually realized that I had a few instabilities in the model (due to several changes etc.).
I found them by re-running the model on a Linear Load Case with the standard solver. Then I turned back the multi-threaded solver, and the nonlinear Load Cases on, and it worked perfectly.
Have a good day.
Thomas.