Bending analysis of partially restrained channel-section purlins subjected to up-lift loadings

Cold-formed steel section beams are widely used as the secondary structural members in buildings to support roof and side cladding or sheeting. These members are thus commonly treated as the restrained beams either fully or partially in its lateral and rotational directions. In this paper an analytical model is presented to describe the bending and twisting behaviour of partially restrained channel-section purlins when subjected to uplift loading. Formulae used to calculate the bending stresses of the roof purlins are derived by using the classical bending theory of thin-walled beams. Detailed comparisons are made between the present model and the simplified model proposed in Eurocodes (EN1993-1-3). To validate the accuracy of the present model, both available experimental data and finite element analysis results are used, from which the bending stress distributions along the lip, flange and web lines are compared with those obtained from the present and EN1993-1-3 models.

► It presents an analytical model describing bending and twisting behaviour of purlins.
► It derives the formulae to calculate the bending stresses of roof purlins.
► It provides detailed comparisons between different models and calculation methods.
► It provides an illustration of the development of the EN1993-1-3 model.