Advancements to the equivalent compression flange method

Abstract The simplified method of the equivalent compression flange represents an illustrative and easy‐to‐use engineering model for lateral torsional buckling. The basic concept of the verification procedure has existed since its introduction in the 1950s. It is still frequently used today for preliminary design and application cases where the solution of the ‘correct lateral torsional buckling problem’ is complex and time‐consuming. To adapt the method to the current state of the art, it was further developed in the framework of the Eurocode 3 evolution. This ‘new’ method is part of the second generation of Eurocode 3, Part 1‐1 and is valid for classes 1 to 3 cross sections in major axis bending. The method must be adapted for use in other contexts and for specific applications. Applying the equivalent compression flange verification method to the structural fire design of building structures must consider the temperature‐dependent material properties of steel and their impact on the stability behaviour. Moreover, typical applications for bridge structures, runway beams, and H‐piles in combined walls require additional consideration of class 4 cross sections and various combined loadings, e. g., N – M interaction behaviour. This article presents theoretical studies on extending the simplified method of the equivalent compression flange to meet these demands. Finally, the application of the verification method is demonstrated in working examples.