An interaction formula method for buckling design of steel angles bolted through one leg at their ends

Abstract
Steel angles used as bracings in lattice towers or other types of structures are typically connected through one of their legs at their ends. These semi‐rigid connections are eccentric to the central axis of the member inducing bending moments under axial loading. Nevertheless, the relevant European design standards treat angle bracings as simply supported, centrally loaded members accounting for end joint effects empirically through an effective slenderness. Previous studies have shown that this method cannot provide accurate resistance predictions. The present study proposes an alternative design approach based on the interaction formula method, explicitly accounting for the end restraints and the bending moments due to eccentricities. A numerical parametric study considering angles with bolted end joints is also presented. The accuracy of both the proposed method and the existing design rules is assessed against the numerical results. The comparisons demonstrate that the proposed method achieves high accuracy with significantly lower variability, thus providing more reliable resistance predictions, compared to the normative design rules.