A consistent methodology for the out-of-plane buckling resistance of prismatic steel beam-columns

This paper presents a design proposal for the out-of-plane buckling resistance of prismatic beam-columns subject to axial compression and uniaxial major-axis bending that was developed based on the well-known Ayrton-Perry format. Firstly, the relevant theoretical background is summarized, closely following the theoretical derivation performed by Szalai and Papp (2010). Secondly, the required transformations for the engineering application of the design procedure are detailed and extended to arbitrary bending moment distributions. Appropriate generalized initial imperfection factors for the out-of-plane buckling of beam-columns are defined so as to achieving complete consistency across the stability verifications for columns, beams and beam-columns. The proposed procedure is subsequently validated against a large set of advanced numerical simulations. A good agreement was found between the numerical results and the estimates provided by the proposed design procedure, both in terms of the overall trend and the specific quantitative results. Based on a statistical assessment, the comparison with the interaction expression of Eurocode 3 (2005) (method 2) showed that this proposal slightly outperforms the Eurocode procedure, both in terms of average values and dispersion of results.