The verification of a column made from a lipped cold-formed channel section, subjected
to pure axial compression relative to the gross cross-section, often results in a
combined verification of bending and compression due to the appearance of a shift
of the centroid of its effective cross-section. Following Eurocode 3 rules, this requires
the determination of two distinct effective cross-sections and various interaction
factors. This paper, based on an analytic approach, offers a modification to the actual
buckling curve, based on Ayrton–Perry formulation, to include the second-order effects
raised by the eventual shift of the effective centroid due to local buckling of the
compressed web plate. This eliminates the need to use an interaction formula. The
modified buckling curve is verified based on a GMNIA analysis performed on a numerical
parametric model, which was previously validated by laboratory tests. In addition,
the results are compared with strength results provided by appropriate Eurocode 3
formulas and AISI Direct Strength Method for global-local interaction and with classic
experimental results.
