General Theory for Torsional Warping

Most beam engineering problems worldwide are solved using 6 DOF (degrees of freedom) beam models. These beam models are generally very close to reality, but they have two important weaknesses.
First, 6 DOF beam models cannot correctly predict torsional behavior in most real-world cases. Second, they cannot simulate torsion-related stability loss modes such as lateral-torsional buckling, torsional buckling, or combined buckling modes.

For these reasons, beam models require seven degrees of freedom: the traditional bending, shear, and torsion DOFs, plus an additional DOF that represents cross-sectional warping.

So-called 7 DOF (torsional warping) beam models have existed for several years, but their underlying theory has limitations. They are applicable only to thin-walled open sections. Contrary to a common misconception, torsional warping can be found everywhere: in closed box sections, thick-walled sections, and arbitrary cross-sections. Therefore, a new theory for torsional warping is needed— one in which also shear-deformation are taken into account in warping.

FEM-Design allows arbitrary cross-section shapes in beam FE analysis, and a new theory—the Modified Kollbrunner theory—makes it possible to use 7 DOF for any beam and any cross-section shape. It also enables the creation of 3D warping models, where torsional stability loss modes are formed by the interaction of many 3D beam elements.

When torsional warping no longer has shape or wall-thickness limitations, concrete, timber, and aluminum members can also be analyzed for warping and torsional stability loss modes. This is what we call General 7 DOF.

Because this is General 7 DOF, this new feature will be available to all FEM-Design Steel Design license holders. In practice, this means that almost all clients can apply this new beam theory.

Why should you join this webinar?

• You want to learn when 6 DOF is not enough—the answer might surprise you. Torsional warping is everywhere, and we will show the typical mistakes made when using traditional 6 DOF models.
• You have already used 7 DOF models in the past and want to learn how this General 7 DOF approach differs from them.
• You want to truly understand how the torsional warping mechanism works—don’t worry, we will not go deeply into the mathematics.
• Learn the basics of building 3D models with General 7 DOF beams and how torsional warping is transmitted through beam connections.
• You are a steel designer (or perhaps a timber or concrete designer as well) and want to improve your skill level.
• You want to learn about the latest FE innovations.
• You want to learn the basics of how to use General 7 DOF in FEM-Design.

See you at the webinar.

Date & Time:
Wednesday, 28 January 2026
14:00–15:00 EET (UTC+2)
12:00–13:00 UTC
13:00–14:00 CET

Event registration has ended.

For more information, please contact:

Joni Hytönen
Country Manager – Finland
Phone: +358 505 452 200
Email: joni.hytonen@strusoft.com
Bio: Joni has helped and trained hundreds of engineers in structural analysis in Finland. He works in both civil and mechanical engineering fields with structural analysis. Joni has over 15 year of experience in structural design of many types and sizes of steel, concrete and timber structures. Joni is the Product Owner of our JIGI software and Country Manager for Finland. Please free to contact Joni if you need any help to solve your structural analysis problems.