The combined bending and axial capacity check covers the interaction of axial load and bending to Clause 6.2.9 appropriate to the type (for example - doubly symmetric) and classification of the section, and provided there is no high shear present.

If high shear is present only on the major axis (i.e. parallel to the web) of a doubly symmetric rolled or plated I section, in combination with uniaxial major bending and axial compression or tension, then the combined bending and axial capacity check will be carried out to the EC3 design rules described in a research paper by Goczek and Supel.¹

All other high shear conditions, including the presence of shear web buckling or class 4 sections, are given a Beyond Scope status.

Class 1 and 2 cross sections (with low shear)

Equation 6.41 is applied. Note that in these calculations the combined effects of axial load and bending are assessed - clause 6.2.9 (4) is not considered.

Also note that the current "reduced plastic moduli" approach that is used in the published tables is adopted and not the approximate method given in clause 6.2.9.1(5). The latter is less conservative than the current approach at low levels of 'n'.

Class 3 cross sections (with low shear)

Equation 6.42 is applied.

¹ ‘Resistance of steel cross-sections subjected to bending, shear and axial forces’ by Jerzy Goczek and Lukasz Supel, Engineering Structures 70 (2014) 271-277, Elsevier.