Axial Load Capacity of Cold-Formed Steel G-Section Columns

Cold-formed thin-walled steel columns can be made into many sections, of which the U-section (also called channel section) and C-section are the most commonly used and studied. However, although the cold-formed thin-walled steel column has the advantages of light weight and short construction period, it is also prone to buckle, which is not conducive to structures. Previous studies have shown that the cold-formed thin-walled steel channel columns with complex edge stiffeners (also called G-section columns) have higher load-bearing capacities and critical distortional buckling stress. In this paper, the axial behavior of pin-ended G-section columns was studied by means of experiments and finite element analysis.
In order to study the influence of cross-sectional dimensions and column lengths on the failure modes and load-bearing capacities of G-section columns, a total of 18 cold-formed thin-walled steel G-section columns with nominal thickness of 2.0 mm were tested, and their failure modes, load-displacement curves, load-strain curves and ultimate capacities were analyzed. There were three kinds of cross-sectional dimensions (nominal web depth was 150 mm, 200 mm and 300 mm, respectively), and the slenderness ratios of specimens varied from 15 to 70. Before the tests, the actual dimensions of cross-section, material properties and initial geometric imperfections of the specimens were measured. In the test, it was observed that the specimens with nominal web depth of 150 mm failed in distortional buckling; for the specimens with nominal web depths of 200 mm and 300 mm, when the length of the specimen was less than or equal to 1000 mm, local buckling failure occurred, and the rest specimens failed in local-global interactive buckling, and the half-wave length of local buckling was approximately equal to the web depth.
Then, the finite element models were established in ABAQUS to simulate the specimens, and the models were validated based on the test results. The calibrated finite element model was subsequently adopted to investigate the influence of the flange width-to-thickness ratio, the web depth-to-thickness ratio and the dimension of complex edge stiffener on the ultimate capacities of the cold-formed thin-walled steel G-section columns. The results showed that the ultimate capacity of the G-section column increased with the increase of flange width-to-thickness ratio and the dimension of complex edge stiffener, and decreased with the increase of web depth-to-thickness ratio.