The Overall Interaction Concept for the design of hot-rolled and welded I-sections under combined loading

This paper investigates the resistance capacity of hot-rolled and welded I-sections subjected to combined loading as influenced by plasticity and local buckling effects. Extensive numerical parametric studies through validated finite element models are carried out to consider different steel grades, section shapes and various load cases including bi-axial bending without axial compression (M-y+M-z), mono-axial bending with axial compression (N+M-y or N+M-z) and bi-axial bending with axial compression (N+M-y+M-z). Based on the Overall Interaction Concept (O.I.C.), a three-dimensional resistance space is built to capture the cross-section behaviour under different load cases and interaction design equations are proposed, based on the numerical results. Overall, it is evidenced that the proposed O.I.C approach provides more continuous and significantly more accurate resistance predictions than existing design standards.