This check is used for channel sections. Such sections can be Class 1, 2 or 3 Plastic, Compact or Semi-compact (Class 4 Slender sections and Effective Class 2 sections are not allowed in this release).

Note that, whilst this check could be used for any section type dealt with in the subsequent sections, the results can never be any better than the alternatives but can be worse.

Two formula are provided in clause 4.8.3.3.1, both are checked; the second is calculated twice – once for the top flange and once for the bottom flange.

See also the Important Note at the end of Member buckling resistance, clause 4.8.3.3.2.

Only one value of F is used, the worst anywhere in the length being checked. If the axial load is tensile, then F is taken as zero.

If this check is invoked as part of an Annex G check, and thus M_b is governed by Annex G, then m_LT is taken as 1.0.