On the plastic moment of I-sections subjected to moderate shear forces

• The classic slip-line field solutions for rectangular cantilevers are very accurate.
• The configuration of the supports may influence the M–V interaction significantly.
• The effect of moderate biaxial shear is generally negligible.
• A simple and accurate interaction equation for biaxial bending with shear is proposed.

This paper presents an investigation concerning the plastic moment–shear (M–V) interaction of elastic–perfectly plastic compact I-section cantilever beams, focusing specifically on the effect of small-to-moderate shear forces. First, rectangular beams are analysed and the accuracy of the classic solutions for the M–V interaction is assessed through comparisons with numerical results, obtained with 2D solid finite element models. Then, I-section beams under major axis bending are examined, using shell finite element models and also available analytical solutions. Finally, the biaxial bending interaction for I-sections, together with uniaxial/biaxial shear, is investigated using 3D solid finite element models. A simple but accurate model for the biaxial bending interaction is proposed, which is based on the behaviour of rectangular cross-sections.