Research on axial compression behavior of cold-formed steel built-up T-shaped columns

Abstract

A series of axial compression tests were conducted on cold-formed steel (CFS) built-up T-shaped columns consisting of three identical single-limb sections connected by longitudinally arranged high-strength bolts and filler plates at the webs. At first, the buckling behavior, failure mode, ultimate bearing capacity, and load response curves of columns are analyzed. Subsequently, finite element models of tested columns were then developed and validated to provide a base for conducting parametric studies of built-up T-shaped columns with different slenderness ratio, web height to plate thickness ratio and bolt spacing. Finally, the design methods in the Chinese code GB50018–2002 and AISI S100–16 specifications for predicting the resistance of the built-up T-shaped columns were evaluated by using both the test and numerical results. The study shows that the current design procedure in AISI S100–16 are unstable in predicting the resistance of the built-up T-shaped columns within a certain range of overall slenderness ratio, while the provisions in the Chinese code GB50018–2002 are overly conservative. Hence, a reliable design procedure is proposed based on the the Effective Width Method (EWM) in the Chinese code GB50018–2002 equations obtained from the paper. The strength predictions of the proposed design procedure match well with those of experimental studies in the literature and the experimental and numerical studies of this paper.