Local/global coupled instabilities of slender I-sections under compression

Current standards usually deal with local/global interactive buckling behaviour rather roughly through combining the traditional Effective Width Method (E.W.M.) with member buckling curves; this leads to long and tedious design calculation processes, sometimes also providing inaccurate resistance predictions. A more economic and simple design method following the actual local/global interactive behaviour is proposed here, based on the Overall Interaction Concept (O.I.C.), through decomposing interactive buckling through local/global interaction factors. The accuracy of this O.I.C.-based design proposal is evaluated against numerical results from validated shell F.E. models, which evidences that the O.I.C. predicts more accurate member resistance than the current Eurocode 3 and American Standards recommendations, for both hot-rolled and welded slender I-section members under axial compression. The reliability of the proposed O.I.C. approach is also found excellent, following statistical analysis guidelines from EN 1990.