I am conducting a sequential heat transfer-stress analysis for a composite wall consisting of steel plates and a concrete core, similar to concrete-filled tubes or CFTs. My analysis involves heating the wall from one of its faces using a heat transfer analysis, which runs smoothly. However, when I perform the stress analysis by inputting the results from the previous analysis, the program fails to converge after a certain amount of computation time. This is because the steel expands more than the concrete core, leading to interaction problems in the program. This issue does not occur when the temperature is applied simultaneously on all faces. Due to the deformations resulting from being exposed on only one face, the core penetrates the steel plates. How can I prevent this from happening, disregarding the fact that I already have a hard contact between both surfaces?
The issue you are facing in your sequential heat transfer-stress analysis, where the concrete core penetrates the steel plates due to uneven expansion, is a common challenge in composite structures. One approach to prevent this is to use a technique called sub-modeling. This involves creating a more detailed model of the interface between the concrete core and the steel plates, allowing for a more accurate representation of the stress and strain distribution in this region. By incorporating the effects of the temperature gradient more accurately, sub-modeling can help mitigate the interaction problems that lead to the convergence issues in your analysis. For more connect with me on https://wa.me/+923440907874
@Engr.Tufail Thank you very much, I will try creating a submodel, I hope it works because I have been trying to create this model for a long time.
How is the connection between steel and concrete?
Some more details on the model (e.g. figure) would allow us to help more
Hi @Denis, I have tried many ways of surface-to-surface contact and general contact, here are a couple of images showing the model.
I am not an expert of steel-concrete structures, but as far as I understand, steel and concrete share the same displacements at their common interface.
Therefore, the structure can be modelled by using shared nodes at steel-concrete interface, rather than contact elements that usually make the analysis far more complicated.
Denis Benasciutti That only applies to steel bars in reinforced concrete; in this type of structure, the shear load at the interface is transmitted through friction, which is somewhat lesser, and through shear studs. Additionally, I need the plates to detach from the concrete when they buckle, so I cannot perform an analysis with rigid node-to-node contact, which forces me to use surface-to-surface or general contact.
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