The use of slender steel members promotes the competitiveness of steel structures in structural engineering. However, it requires an efficient design, in particular for the structural stability behaviour and lateral torsional buckling. Therefore, the simplified design method with reduction factors is very important. Despite the increased application of computer-based analysis and design as well as the use of numerical methods, this simplified method is still widely used in engineering practice and is also well-known to engineers from other domains than steel structures. Often-used connections in structural engineering, such as typical main and secondary beam connections, often deviate from the idealizations on which the method is based, in particular the simply supported member. Depending on the type of connection, the torsional stiffness varies and a significant difference in the structural behaviour between idealized and real structures is to be expected. For head-plate connections, the fixed effect on warping is known but is generally not considered. And finally, at the system level, there are only a few simple members. Continuous members or frame members are more common.

The project addresses open questions in the engineering community, which often lead to uncertainties in design and their consequences. Engineers from design offices and steel construction companies often express the intention to be able to consider effects of connections and realistic boundary conditions of steel structures and system effects in simplified design methods. Therefore, the research project aims to extend the application range of the simplified design methods and to adapt the well-known simplified stability method to state-of-the-art requirements.