Development of new design recommendations for structural steel joints under M‐N

Abstract
In steel structures, most of the joints are typically subjected to shear (V) and/or bending (M) forces only, and their behaviour can be fully characterised using the component method as recommended in EN 1993‐1‐8. However, in some situations, these joints may also be exposed to axial (N) forces. Under such a loading condition, Eurocode 3 currently proposes only a simplified M–N interaction criterion, for which no comprehensive derivation methodology is provided, and whose scientific background is not really founded. Moreover, previous research has already shown that this criterion may also be unsafe or too conservative in certain cases. This paper thus aims to present the main findings of a comprehensive set of analyses, conducted on various joint configurations coming from the literature. These analyses notably include predictions of the joint resistance with an advanced analytical model, a validation of this analytical model using experimental data and comparisons with the prediction from the commercial software COP. Finally, drawn from the outcomes of these analyses, new design recommendations have been formulated to address the identified issues in the European standard.