Bimoment Influence on the Design of Steel Elements According to the European Standards

In addition to axial forces and bending moments, the bimoment can significantlyinfluence both the resistance and stability of steel members, independently of thegeometry of their cross-section. The complex interaction between the bimomentand other internal forces, and its implications for overall frame stability, remains anarea of ongoing research. Despite numerous proposals by various Authors forinteraction equations that account for these effects, the problem is not yet fullyresolved, and current European standards often fail to adequately address thisissue. Specifically, the old version of Eurocode 3 (EN1993-1-1:2005) did notcomprehensively cover the influence of the bimoment on member stability. To coverthis gap, the next generation of Eurocode 3 (EN1993-1-1:2022) introduces two newstability equations that account for the combined effects of all internal forces,including the bimoment.In the paper, after a recall on the Vlasov theorem, the ultimate load carryingcapacity of selected isolated beam elements, experimentally and numericallyevaluated has been compared with those derived from the application of the newEC3-1-1:2022 interaction equations. The selected cases demonstrated theimportance of the new design rules for structural safety.