ON LTB RESISTANCE ASSESSMENT OF PRISMATIC I-SECTION BEAMS ACCORDING TO EUROCODE 3

The lateral-torsional buckling resistance (LTB resistance) of beams bent about the major axis is dealt in Eurocode 3 twofold: a) directly in clause 6.3.2, referring to the lateral-torsional buckling curves of the so-called General case in 6.3.2.2 and of Special case of rolled sections and equivalent welded sections in 6.3.2.3, and indirectly in 6.3.3 as a special case of beam-columns in bending and compression (provided that the axial force and the bending moment about z-z axis vanish). In the latter, interaction factors are evaluated either from Annex A (alternative method 1) or from Annex B (alternative method 2). This paper discusses the issue of interrelations of mentioned above direct and indirect approaches for the evaluation of the lateral-torsional resistance of beams under moment gradient.

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