applying moment to composite (steel-concrete) section

[AleksaBgd94]

Hi everyone,

I am trying to model a composite (steel-concrete) beam-to-column joint and to analyze its behaviour under concentrated moment.

I applied a moment at the end of the beam section, to act in the center of inertia of composite section. The center of inertia is defined as a reference point (reference point is a control point for the coupling constraint).

The results concern me because:

steel section and concrete above it deform together, but stresses only appear in the steel section.

Do you have any tips - how to 'activate' the concrete above steel section?

I used C3D8R elements for steel section and C3D4 for concrete part of the assembly. The only interaction between two parts is general contact (hard contact and friction are assigned).

If you need more information about the model and the joint, please write.

Thanks

 

[FEA way]

Just to be sure - is the beam made of steel and the column made of concrete ? Or are these parts made of reinforced concrete (with steel inside) ? In case of the latter how did you include interaction between both materials ?

Use tie constraint instead of general contact and see if it works. You can also try using contact pairs rather than GC.

 

[Erik Panos Kostson]

I think a couple of screenshots of the model and the relevant settings would be of help to understand, and so we can help.

 

[AleksaBgd94]

FEA Way and Erik, thanks for your willingness to help.

I have to disappoint you and say that this was a 'false alarm' because I made a mistake while I was looking at the results. Stresses in concrete part were not shown when it was displayed together with steel parts, but when I did that separately results seemed OK. The conclusion is that the concrete activated!

FEA way, also thanks for your advice. This model was just steel - concrete, with elastic materials.

I made a new model with reinforced concrete and steel, and defined the contact between reinforcement bars (which were defined as truss sections) and concrete using constraints (embedded region).

 

[AleksaBgd94]

And just to make it clear, here is the screenshot of the model.

Column is made of steel.
Beam acts as a composite section : I-beam is made of steel, while above it is a part of reinforced concrete slab. The composite behaviour should be provided by studs.

https://files.engineering.com/getfi...-4edf-bec8-867896f890b7&file=Abaqus-model.png