Buckling resistance of non-uniform steel members based on stress utilization: General formulation

In this paper, a novel general formulation for stability design of steel columns, beams and beam-columns with variable geometry, loads and complex support conditions is presented. The verification is based on the buckling mode as shape of the initial imperfection with an amplitude previously calibrated for the standard prismatic simply-supported columns and beams in Eurocode 3. The verification is performed as an interaction equation where the first and second order contributions to the longitudinal stress utilization are added for each cross-section along the member length. Several aspects regarding the member behaviour in the context of a specific buckling mode are discussed and finally, validation of the approach is carried out to show its consistency and accuracy.