Connection between steel modules

[Anonymous]

I am designing a steel superstructure which consists of steel container type modules. The modules between themselves are welded together in the column places. What would be the best way to model the connection between them if it is a welded steel plate 80x10 mm? If I put a steel section 80x10mm with no releases then after calculation I get type 3 instabilities. Maybe someone has made a steel module superstructure like this and can help me. Attached some pictures.

[Rafacascudo · Accepted solution]

You need to check if this instability can be ignored. Create a new load case and apply a unit load in the direction of the instability. If it is a translational (Ux Uy Uz) instability , apply a force on the reported direction.
If it is a rotation, apply a unit moment.
Run the model. If this node displacements are normal , then you can ignore this instability type 3 warning.
If not , can you send the model?

[Anonymous]

Thanks. The displacements ar normal after applying the force. Only why the programm reports an instability if the displacements are normal. What causes this instability?

[Artur.Kosakowski · Accepted solution]

Hi @Anonymous

Please check this article .

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