Compression tests of cold-formed steel built-up T-shaped columns

Abstract

This paper proposes cold-formed steel (CFS) built-up T-shaped columns connected by high-strength bolts and filler plates, and presents a series of axial compression tests conducted on such built-up columns. The built-up T-shaped columns had different cross-sectional dimensions, thicknesses of plates, longitudinal spacing of bolts and length of members, including a total of 16 specimens. The peak load and load versus axial displacement curves have been measured and reported in this paper. In addition, the failure modes, deformed shapes and the effects of different parameters on axial compressive behaviour of the CFS built-up T-shaped column have been observed in the tests and discussed in this paper. For the specimens with a length of 900 mm, the increasing thickness of the plate has the strongest increase in the peak load, and the changes in the web, flange and lip also have different degrees of effect. For the specimens of length 1700 mm, the increasing web height showed the most significant effect on the peak load, while the variation in bolt spacing and section type had less effect on the peak load. These tests provide valuable experimental data for the exploration of the buckling behaviour of such built-up columns, which can compensate for the lack of relevant information. Finally, the test results were in comparison with the design strength determined by the direct strength method. The method in AISI S100-16 was revealed to be unconservative for the determination of the axial compression strengths of such built-up T-shaped columns.