Axial capacity assessment and nonlinear behavior of cold formed steel built up columns

Abstract

Cold-Formed Steel (CFS) sections have gained wide popularity due newlineto their numerous favourable features, and through continuous research on the newlinevarious limitations of such members, their utility in the construction sector newlinehas increased manifold. CFS sections are commonly adopted in various forms newlinelike structural as well as non-structural as they offer many advantages like newlinelightweight structures, high strength-to-weight ratio, high stiffness due to newlineimproved sectional profiles, ease of erection and construction and so on. The newlinesingly symmetric open sections have smaller torsional rigidity, and are newlinetherefore more susceptible to undergo complicated buckling modes. However, newlinethe built-up sections provide more resistance to such buckling modes. newlineConsequently, in recent years, the adoption of built-up sections has increased newlineas the single sections do not meet large load demands. The built-up sections newlinecan be formed by connecting different elements using self-driving screws. newlineIn the present research, the nonlinear structural behaviors of CFS newlinebuilt-up battened columns are evaluated through both experimental and newlinenumerical analyses. The built-up battened columns have been formed by newlineplacing two identical lipped channels in the back-to-back arrangement, with newlineadequate transverse spacing, and are connected laterally by using batten newlineplates. The self-driving screws are used as fasteners to connect the batten newlineplates and the flanges of the lipped channels. Additionally, press braking newlineoperation is utilized to form the CFS lipped channels. The dimensions of the newlinechords of the built-up columns are selected based on the geometric limitations newlineprovided in the North American Specification for the design (AISI S100- newline2016) of cold-formed steel structural members. A total of 28 built-up sections newlineare tested under uniform compression in two phases, which consists of two newlinedifferent grades of steel. newline