Error of 'ForceBeamColumn' element

[mskim]

I received a cable bridge structure model built with Opensees, but the problem is that only the linear behavior is applied and the displacement is very small.

So I used the 'ForceBeamColumn' element to take into account the material nonlinearity only in the pylon, but only the part of the changed element is an error that failed to get compatible element forces&deformations for element.

I'd appreciate it if you could tell me why this error occurred.

Thank you.

[leomsilva]

Hello,

The ForceBeamColumn is harder to obtain convergence in general. That happens because the analysis must correct the elements response at every step to assure compatibility. And if it fails to do so within the tolerance, then an error is returned.

You may:
a) Add more iterations and a more allowable tolerance, with these tags added at the end of the ForceBeamColumn: " -iter $MaxIters $Tolerance".
b) Change your elements to the DispBeamColumn, and improve your mesh where the nonlinearity is expected. If you mesh is refined enough, it will return you accurate results.

[mskim]

Thank you for answer.

As you have mentioned, I have applied the 'displacementBeamColumn'.
But it continue to stop working on the opensees, can you tell us why?

Thank you

[leomsilva]

Then the problem could be a lot of things.
I would make make small models with each component isolated and test them.
If in your case the only problem is the line element, you could test it in a Moment-Curvature procedure and/or cantilever pushover simple model, just to see what you get.