engleski

Bending resistance of cold-formed back-to-back built-up steel sections

Cold-formed back-to-back built-up steel beams are efficient and very attractive structural elements which with the material savings and low self-weight can also offer excellent efficiency in production, especially with the application of CNC technologies. The connection between the cold-formed back-to-back built-up steel components can be easily obtained by screws, but the developments in the welding process also lead to other solutions like continuous (MIG brazing) or discrete spot welding. The paper summarises the results of the numerical analysis of different combinations of connection between back-to- back built-up steel elements and the cross- section resistance of such sections. Based on the validation of the numerical model, the paper presents the influence of several parameters, i.e.: the initial imperfections and type of the lateral support, continuous and discrete connections between channels, the number and the distance between discrete connections along the beam axis and along the beam height, the type of the channel section i.e. lipped and plain channel. From the parametric study, it is concluded that the cross-section capacity of the cold-formed back- to-back built-up steel beams is highly affected by the type of connections. Tied web connection results in the highest capacity and highest ductility, but such type of connection is not always possible. In the case of discrete connections, results are affected by the configuration and the number of discrete connections. In the case of back-to-back built- up elements besides different capacities of the cross-sections influenced by connections arrangements two plastic mechanisms are also possible and more discrete connections will concentrate the plastic mechanisms to only one cross-section.

Cold-formed steel members ; Simple built-up beams ; Parametric numerical studies ; Different types of the connections ; Bending resistance

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