Good day,
I am currently creating a type static analysis for a special steel connection using FE.
For this, I initially modeled all components that could be modeled using the Steeljoints addon and then continued working within the submodel. Since the model is quite large, the calculation time is relatively long for my investigations, which is why I am considering changing the analysis settings. Although I calculate several load steps, I do this manually using many load cases that I create myself and therefore wonder to what extent the settings of the 4 load steps, which are automatically preset after downloading the submodel, are really necessary? Do these load steps effectively affect the material or geometric stiffness matrix? (According to my assumption, these should already be covered by the Newton iterations alone regardless of setting multiple load steps, but I am not deeply familiar with this or do not have reliable information on this matter). I would be very grateful for feedback with a detailed answer regarding the background of the default settings of 4 load steps for the submodels of the steel connection addon.
Best regards, Nick
Hello @DeflectionPerfection 
,
The 4 load steps have several reasons. On the one hand, the model includes nonlinear contact conditions, and on the other hand, we expect plastic redistributions in most cases. Both factors are load-path dependent, because, for example, with plastic strains, it is crucial whether the neighboring elements are also already yielding.
With load steps, one tries to keep the deformations in the system small enough so that the solver can reliably map the correct load path. If you try to calculate everything with only one load step, you will encounter significant convergence problems because many elements influence each other. With smaller load steps, the probability that these converge is significantly higher, making the calculation more stable and robust.
In principle, for nonlinear calculations, it always applies: the more load steps, the better. This is a discretization, and a discretization study can never hurt. The 4 load steps have proven in tests to be a good compromise between accuracy and calculation time. But it is no coincidence that this value is a setting in the load-bearing capacity or stiffness analysis configuration. So it may also be that you get a very similar result with fewer load steps.
If you have any further questions or want to learn more about the load steps and configurations, I am happy to help! 
Best regards,
Fabian
2 Likes