In structural and industrial engineering, hall columns are subjected to horizontal loads on the facade, vertical loads from the roof and runway beams, which act eccentrically on the column. This results in scheduled torsion for the columns. In order to describe the structural behaviour of these members more rigorously, numerical simulations were carried out. The load-rotation behaviour, the development of internal forces during load increase and the remaining elastic cross-sections were evaluated and analyzed for members with mono- and double-symmetric cross-sections in compression, biaxial bending and torsion.

In this research work, the load-bearing behavior of these beams is examined in detail using numerical calculations. For this purpose, a FE model using shell elements is developed which realistically depicts the load-bearing behavior of beams exposed to torsion. The FE-model is validated on the basis of several experimental investigations. The FE model then forms the basis for the investigation of various influencing factors, such as varying field lengths, cross-section geometries or load situations on the load-bearing behavior of single-span and two-span girders.

As part of the revision and further development of Eurocode 3, a verification method for simply supported members in compression, biaxial bending and torsion was developed and included in prEN 1993-1-1:2020. The verification method is based on the procedure regulated in EN 1993-1-1:2005 Section 6.6.3 for members with double symmetric cross sections in biaxial bending and compression, and also on the procedure, regulated in EN 1993-6:2007 Appendix A for the verification of lateral torsional buckling of simply supported runway beams in biaxial bending and torsion. The verification method can be used for members with double- and mono-symmetric cross-sections.

The findings from the investigations are then used to derive a simplified design method based on the equivalent imperfection method. In first step, an imperfection approach combined of pre-deformation and pre-torsion is proposed. In order to consider scheduled torsional loads, a modification coefficient is then introduced as second step, which represents the load-bearing behavior simulated in the numerical calculations.

Bours, A.-L., Winkler, R., & Knobloch, M. (2019a). Buckling resistance of mono-symmetric I-/H-section members in biaxial bending, axial compression, and torsion. In F. Wald & M. Jandera (Hrsg.), Stability and ductility of steel structures 2019: proceedings of the International Colloquia on Stability and Ductility of Steel Structures, Prague, Czech Republic, September 11-13, 2019 (S. 189–196).

Bours, A.-L., Winkler, R., & Knobloch, M. (2019b). Ergänzende Untersuchungen zum Tragverhalten einfachsymmetrischer I‐Querschnitte unter Biegung, Druck und Torsion. Stahlbau, 88(9), 836–850. https://doi.org/10.1002/stab.201900060

Winkler, R., Bours, A.-L., Walter, A., & Knobloch, M. (2019). Redistribution of internal torsional moments caused by plastic yielding of structural steel members.   Structures, 17, 21–33. https://doi.org/10.1016/j.istruc.2018.12.008

Knobloch, M., & Winkler, R. (2018). Spatial buckling of steel members - on the influence of torsional loads. In D. Bigoni, F. Ubertini, & A. Corigliano (Hrsg.), ESMC 2018: 10th European Solid Mechanics Conference, 2–6 July 2018, Bologna, Italy.

Winkler, R., Walter, A., Knobloch, M., & Lange, J. (2018). Zum Stabilitätsnachweis von Stahlbauteilen aus einfach- und doppeltsymmetrischen I-Querschnitten unter Biegung, Druck und Torsion: Herrn Prof. Dr.‐Ing. Jörg Lange zur Vollendung seines 60. Lebensjahres gewidmet. Stahlbau, 87(5), 476–490. https://doi.org/10.1002/stab.201810608

Walter, A., Herbersagen, J., Winkler, R., & Knobloch, M. (2017). Structural behaviour of simple steel beams subject to axial compression, biaxial bending moments and torsion. In J. Jönsson (Hrsg.), Eurosteel 2017 Conference: 8th European Conference on Steel and Composite Structures : Copenhagen, 13-15 September 2017 (S. 1076–1085). https://doi.org/10.1002/cepa.148