The calculation of deflections for thin-walled cross-sections does not seem correct to me. In my model, the deflection was over 70 mm. According to a manual calculation with the given parameters, it should be around 30 mm.
What could be the cause of this?

Question

The calculation of deflections for thin-walled cross-sections does not seem correct to me. In my model, the deflection was over 70 mm. According to a manual calculation with the given parameters, it should be around 30 mm.
What could be the cause of this?

Accepted Answer

The difference in deflections is caused by the activated Torsional Warping add-on. When you disable this add-on, you will get the deflection you expected.
The reason for is that the shear center of the channel section is not the same as the center of gravity. In a normal calculation with 6 degrees of freedom, the load and support of the member are considered at the shear center, while with 7 degrees of freedom, both are at the center of gravity. This results in a torsional moment and increased deformation. For more information, please refer to this webinar (as of the time 1:00:50).
Webinar | Consideration of Torsional Warping in RFEM 6 and RSTAB 9

Deflection of Thin-Walled Cross-Section

The calculation of deflections for thin-walled cross-sections does not seem correct to me. In my model, the deflection was over 70 mm. According to a manual calculation with the given parameters, it should be around 30 mm.What could be the cause of this?

The calculation of deflections for thin-walled cross-sections does not seem correct to me. In my model, the deflection was over 70 mm. According to a manual calculation with the given parameters, it should be around 30 mm.
What could be the cause of this?