Axial-moment interaction for 2D welded steel joints using FEA: An initial investigation

A systematic finite element based approach is presented to characterize the interaction between the bending moments and axial forces coming from the connected beams in 2D welded steel joints. The modelling technique is described in the paper, as well as the description of the interaction diagrams between axial forces and bending moments for a series of commercial steel sections. An initial imperfection is included in the finite element model to capture the possible buckling failure modes in the column web and the beam flanges. The approach predicts moment capacities that are very similar to those predicted by Eurocode 3 in the absence of axial forces. Interaction diagrams and moment rotation curves are shown for different levels of axial forces, as well as axial force versus displacements for different levels of bending moments. An investigation is also carried out that shows that the approach leads to axial-bending interaction curves that are path independent. Finally, a nonlinear exponential curve fitting is proposed for the axial-moment interaction diagram.