Contact buckling effects in built-up cold-formed steel beams.

The aim of this paper is to investigate the effects of contact interactions on local buckling of a built-up cold-formed steel member assembled by mechanical fasteners. To this end a finite element model was developed. The numerical model was validated against the experimental results of four point bending tests carried out on three specimens with different spacing of connections and configuration of web beads. The comparison with experimental results showed a good agreement with test data in terms of both the ultimate bending strength of the beam and the deformed shape at collapse. The calibrated finite element model was used to estimate the effects on buckling resistance of contact forces among the parts of the beam, varying the spacing of connections.