Distortional buckling of perforated cold-formed steel beams subject to uniformly distributed transverse loads.

Thin-walled channel beams are easily punched with circular holes on the web to allow the access for services such as plumbing pipes and electric wires. The presence of the holes can alter the stress distribution in the member and reduce the cross-sectional property. Consequently, it changes its buckling mode. Since perforated cold-formed steel beams are usually placed between main structural frame and corrugated roof, the most common loading case is the uniformly distributed transverse load. Recent work by Chen and Li has given the solution for distortional buckling of channel-, zed- and sigma-sections subject to the uniformly distributed transverse load. This paper is an extension of Chen and Li's research to explore the distortional buckling behaviour of perforated cold-formed steel beams with holes. The effect of perforations on the critical stress is evaluated. A new model is deduced to predict the critical stress of distortional buckling by reducing the stiffness of the vertical spring. The Rayleigh-Ritz method is used to solve eigenvalue problems. In order to validate the analytical model, finite element analyses have been performed by using ANSYS. When the beam is longer than 3500 mm, the critical stress computed from the analytical model matches well with the critical stress acquired from the finite element analyses. • The distortional buckling of perforated beams under uniformly distributed transverse loads is studied. • The analytical solution is presented for calculating the critical stress. • The finite element model is used to simulate the elastic buckling of beams. • The stress gradient has a significant effect on the critical load of distortional buckling. • The analytical approach is compared against the results of finite element analyses. [ABSTRACT FROM AUTHOR]