I would like to kindly ask for your assistance. I am currently using the RFEM 6 7-DOF module for my master’s thesis project, and I need to describe in detail the theoretical background of how this module works.
In particular, I am looking for information on the theoretical formulation and numerical method used in this feature (e.g. whether it is based on Vlasov beam theory or another formulation for non-uniform torsion and warping effects).
So far, I have only found user manuals and application-oriented documentation explaining how to use the module. However, I have not been able to find any detailed theoretical description of the implemented model.
Could you please provide me with any available theoretical documentation on this topic, or alternatively indicate a source where I can study the underlying formulation?
We appreciate your interest in learning more about Torsional Warping in RFEM 6. While we don't have specific written documentation on the theoretical background for torsional warping in RFEM 6, we're happy to provide you with some key insights:
Theoretical Background
Torsional warping in RFEM 6 is an extension of the standard Finite Element Method (FEM), built on deformation shape assumptions and a finite number of degrees of freedom. Specifically, for torsional warping, an additional axial deformation mode is introduced in the form of a warping function. This mode generates additional elastic energy, which is then included in the total elastic energy of the system. To achieve equilibrium, the principle of minimum potential energy is applied to construct the equilibrium equations.
Warping Magnitude Models
It's important to highlight the two different models for warping magnitude:
Vlasov Theory (Classical Model):
This model assumes that the warping deformation is directly proportional to the first derivative of member twist. However, it neglects the shear deformation effect from the secondary torsion moment in the case of warping-restrained torsion. This model is typically suitable for open thin-walled sections.
General Section Model:
For general sections, the shear deformation effect of the secondary torsion moment is considered. This model introduces an additional variable for warping magnitude, which is coupled with torsion through the shear strain energy corresponding to the secondary torsion moment. Additionally, this model applies a secondary torsion constant and incorporates the warping stiffness cross-section constant. The RSTAB solver utilizes this approach.
Additional Resources
While this information serves as an overview of torsional warping, you can explore general RFEM 6 background knowledge in our online manual. Although it doesn’t cover torsional warping in detail, it provides a valuable foundation for FEM and general calculation methods. You can access the manual here:
