Good day,
As part of my master's thesis, I would like to model an experimental setup using RFEM 6.
It concerns the load distribution (through load application in the z-axis) in a composite column with a steel hollow profile filled with concrete. Due to the distribution of the load on the profile and the concrete cross-section, theoretically different deformations will occur, as well as a confinement effect from the steel profile. I modeled the profile with quadrangular surfaces and defined the concrete core as a volumetric body using thicknessless surfaces. How do I create a contact between the curved surfaces?
Thank you very much in advance.
Attached is a screenshot of the setup.
Hi mmontero120,
the contact between the concrete volume and the steel surface can be modeled via a contact volume. 
A detailed description of the modeling can be found in the online manual for RFEM 6 at the following link:
https://www.dlubal.com/de/downloads-und-infos/dokumente/online-handbuecher/rfem-6/000066
Important note on modeling
When creating the contact volume, you should observe the following:
- The two opposing surfaces must be constructed based on concentric circles.
- This means the surfaces differ only in their size, not in their geometry.
- Otherwise, error messages may occur, as in this case a correct meshing of the volume is not possible.
If this condition is met, the contact volume can usually be created and meshed without problems.
Best regards
Marco Nikoleizig