Imperfection - Buckling mode from load case - "Too complex structure"

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1

Hello RFEM community,

I am performing an nonlinear analysis of a laterally loaded pile using the RFEM 6 API for my thesis project. My goal is to incorporate nonlinear spring stiffness, second-order effects, and imperfections based on a buckling mode derived from either a load case or a load combination.

I am able to run the analysis successfully with nonlinear springs and second-order effects. However, when I include imperfections, I encounter the error shown in the attached image.

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image1123×839 18.3 KB

I have tried the following without success:

  • Changing the imperfection source type between load case (only axial load V) and load combination
  • Adjusting imperfection magnitudes
  • Switching the material model from reinforced concrete to steel

The same error persists in all cases.

I have also performed a separate stability analysis to determine the buckling mode, which completed successfully. However, I am unable to apply this buckling mode as an imperfection in my load case.

Any guidance on how to correctly implement buckling-based imperfections or any workarounds would be greatly appreciated.

Best regards

3

Hello studentlnu11,

I’m afraid I need the model to check the problem. Can you please provide it?
BR Thomas

4

pile_model.rf6 (1.1 MB)

5

Thank you but I still need more information. How do you apply the imperfection and when does the warning appear?

Thank you in advance.

7

Hello again,

Im trying to apply the imperfection via load case or load combination. Once I press apply, I get this error.

I might had Stucture Stability Addon off in the model I sent. I have activated this addon.

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image3501×2112 250 KB

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image3222×1984 290 KB