Uniform and tapered welded I-sections: Lateral buckling of columns and out-of-plane buckling of beam-columns

The out-of-plane buckling resistance of welded I-section columns and beam-columns is investigated using an extensive parametric study. Non-linear analyses of uniform and web-tapered doubly symmetric S275 and S355 welded members subjected to an axial force, or to a combined axial force and bending moment are performed. The ultimate resistances are determined for welded members with hot-rolled or flame-cut flanges. The numerical results point to the exceeding conservatism of the Eurocode 3 rules for welded members with flame-cut flanges. Thus, proposals are made to improve the prediction of the weak-axis buckling resistance of welded columns accounting for the flame-cut flanges. The current European rules prove somewhat conservative also for uniform welded columns with hot-rolled flanges having a medium or high slenderness. Thus, a proposal is made to improve the flexural buckling resistance for welded columns with hot-rolled flanges. The design methods proposed for welded members with flame-cut flanges in bending or in compression are used together for welded beam-columns with flame-cut flanges. The proposals are given in the format used in the framework of the Eurocode 3 interaction formulae and General Method.