Seismosoft | Earthquake Engineering Solutions

I am performing a Nonlinear Dynamic Time History Analysis on a 20-storey building model. However, I frequently encounter an error message regarding elm_ite on elements modeled as elfrmh (Inelastic Plastic Hinge Frame Elements).

Currently, to get the analysis to run, I have to manually adjust the Element Iterative Strategy parameters for every single earthquake record I run.

Could you please assist me with the following questions?

What is the main cause of this elm_ite convergence issue on elfrmh elements?

What are the recommended settings or standard values for Global Iterative Strategy and Element Iterative Strategy to ensure stability without sacrificing accuracy?

Additionally, I have tried resetting all parameters to their default values, but the analysis still failed to converge. However, when I relaxed the Element Loop Convergence Tolerance to 0.0005, the analysis ran successfully. I would like to know if 0.0005 is an acceptable and appropriate tolerance for this type of analysis, or if it might be too loose and compromise the accuracy of the results?

Thank you very much for your support and guidance.

Best regards,

A value of the norm equal to 0.0005 is relatively loose, but usually it does not lead to inaccurate values. However using this with the automatic adaptation of the norm should be used with caution. There is not a single answer for all structural models.

Furthermore, there is not a single set of parameters that fit to all cases. One good way to determine if you have inaccuracies in your model is to carry out sensitivity studies.
Some remarks:
- there are numerous posts in convergence problems in this forum. Carry out a search and you will find plenty of resources.
- In the Convergence Details page of the post-processor you will see which are the problematic members of locations in the structure that lead to divergence problems.
- in the help of the program you will find detailed description of the divergence flags and guidelines on how to overcome them.

Kind Regards,
Seismosoft Support