On the effect of web stiffening of cold-formed steel thin-walled lipped sigma sections in compression members

摘要

Cold-formed steel cross sections are high strength thin-walled profiles which are highly prone to local and distortional instabilities. Stiffening techniques are utilized in the industry as a solution to enhance local and distortional buckling strengths. The sigma section is that channel section which its web pushed inward for the stiffening reason. In this research, the effect of side sway of the web (d_x) on the buckling behavior of lipped sigma sections is investigated. The results demonstrate that stiffening inclined components of the web in lipped sigma sections for d_x up to 0.5512"(14 mm) act as a stiffener and change the dominant mode of the cross section from the local buckling for the non-stiffened web to the distortional buckling for the stiffened web, and as this value rises, more reduction in the formation of local buckling in the web can be observed, but for the amount more than 0.5512"(14 mm), these components of the web act as an independent element and constrain the vertical parts of the web and local buckling of sub-elements of the web is the dominant mode. Also under a parametric study, the effect of d_x on the Euler-local and distortional buckling strengths and influential parameters on them is investigated and the d_x value for an optimum design is computed. Outcomes demonstrate that the more rise in the amount of d_x augments the Euler-local and distortional buckling strengths and the optimum value of d_x is 0.3937"(10 mm) for the target lipped sigma section.