Numerical Study of Buckling Behaviour of Cold-formed C-channel Steel Purlin with Perforation

Abstract

Cold-formed C-channel steel purlins are widely used in construction industry. Since the cost of the steel is the main consideration in design, the concept of introducing web opening has been applied in the construction. A numerical study was undertaken to investigate the lateral-torsional buckling behaviour of cold-formed C-channel purlin with web opening. For this purpose a finite element model was developed using LUSAS software. It was then used in a detailed parametric study to simulate the lateral-torsional buckling and capacity of cold-formed steel purlins under varying perforated conditions. Five different shapes of opening were established to investigate the shape that gives the least reduction in buckling moment. Opening in the form of C-hexagon opening shape was used to develop models with different edge distance, different numbers of openings, different opening spacing and also different size of openings. For 3 m span, 0.5D opening size, where D is 175mm, 750mm edge distance with a total number of 13 openings with spacing 125mm is found to reduce buckling moment by 3.56% but at the same time reducing the volume of the section by 5.16%. For the same span, edge distance, number of openings and spacing with 0.75D opening size, buckling moment reduced significantly by 9.16% while volume reduction by 11.61%. For all different size of openings, spacing and edge distance, the deformation pattern are similar. In conclusion, perforation do affects the buckling moment capacity of the C-channel purlin.