Section Moment Capacity of Cold-Formed Steel Sigma Sections

Cold-formed steel (CFS) is a lightweight building material characterized by its robust strength, stiffness, and simplicity in fabrication. The strength of the cold-formed sections relies on a variety of factors: such as the geometric properties and the material property of the cross-section. Even though previous studies in the sigma sections proved to be very efficient in terms of bending, detailed studies are not available regarding the effect of flange width, lip length, and bent angle of sections on the moment carrying capacity of the sigma beams. This paper seeks to thoroughly investigate how the ultimate moment of beams under four-point bending is influenced by factors such as bent angle, section depth, flange width, and thickness. Experimental results available in the literature were validated using ABAQUS software and a parametric study of 192 models was conducted. The depth of the sections was taken as 140 mm, 200 mm, 240 mm, and 300 mm, the flange width was taken as 50 mm & 70 mm, and the lip length was varied between 15 mm and 20 mm. The sections with a bent angle of 10° performed better than the sections with a bent angle of 60°. It was concluded that doubling or tripling the thickness can lead to a drastic increase in the ultimate moment of the sigma sections. It was also found that the sections with 1 mm thickness failed predominantly by local buckling and those with 2 mm thickness and 3 mm thickness failed by distortional buckling. The sections with a 60° angle failed by buckling predominantly than shear while those with 10° failed by shear predominantly.