Interactive buckling of thin-walled functionally graded columns
with trapezoidal and square cross-sections were considered. The
three-mode approach that accounted for an influence of the global
buckling mode on the lowest primary local buckling mode and,
additionally, the secondary local mode corresponding to the primary
buckling mode was assumed in the analysis. In the case of
interactive buckling of the structure with one axis of symmetry
of the cross-section, the secondary local buckling mode was a supplementary
mode in the analysis of coupled buckling. Attention
was drawn to the effect of the imperfection sign (sense) and the
nonsymmetrical stable post-buckling equilibrium path on the
load-carrying capacity.