Iterations failed to converge

[Anonymous]

Hello all,

I am trying to find out the capacity of a reinforced concrete section, but i when i carry out the capacity calculation for Y moment and Axial under both SLS and ULS, the "iteration has failed to converge" message dialog pops up.

Apart from adjusting the convergence tolerance, does anyone know how the "control iterations" form works?

[david.geeves]

Hi Benjamin,

This looks to be a very large and interesting section which will have a very large bending and axial capacity, so the first thing I would do is to ensure the convergence tolerance is set sufficiently high.  It sound like you have already tried this so the next thing I would try is to rotate the section by 90 degrees and try that. This is done from the overview window in pre-2016 versions and from the toolbar in the navigation window for 2016 onward and not only rotates the section but rotates the reinforcement and resolves any applied loading into the new orientation.  I would also suggest setting the iteration parameters back to the default of 20 for "Step Change in NA angle" and 3 for the "iterations between NA change".

This is by no means a guaranteed solution but it may get you there.  If this still fails please attach the data file for your section and I will have a closer look to get a solution for you.

Kind regards

[Anonymous]

Thanks for the advice David, unfortunately only rotating the section didn't work.

Is it possible to manually adjust the figures on the "control iterations" form to get a converged solution?

I have attached the .sam file if you could have a look.

Thanks!