Novel method for the prediction of load bearing capacity of compressed C channels considering interaction of buckling modes

The proposed method focuses on the interaction of global and local buckling. A modified Ayrton‐Perry type buckling curve is proposed to calculate the ultimate compression force resistance of centrically compressed cold‐formed C channel. The new buckling curve incorporates both the effects of global imperfections and shift of the center of gravity caused by local buckling of slender web plate of the considered sections. Distortional buckling usually does not play any role for this configuration.

The effective cross‐section properties for the use of the new buckling curve are determined using critical stresses obtained both by finite‐elements analysis and finite strip analysis. The shift of center of effective cross‐section will produce an additional second order bending moment amplified with the corresponding global buckling multiplier.

The results are compared with the curve proposed by AISI Direct Strength Method for global‐local interaction and with simulation results, in agreement with the recommendations of the new prEN 1993‐1‐14.