Effect of External Ring Stiffener and GFRP Strip Wrapping on the Buckling Behaviour of Cold-Formed Steel Tubular (CFST) Column

Circular Hollow Sections are round tubular steel sections that are used for a variety of purposes in civil engineering. They are usually available in the market as hot-rolled or cold-formed sections. Hot-rolled circular hollow sections are usually employed for structural purposes such as columns, struts, ties, etc. Cold-formed sections are usually used as purlins and as framing for lightweight building construction. The Cold-Formed Steel Tubular column was tested for failure under axial compression. The parameters varied in this study are the slenderness ratio (24, 26, 28 and 30), the diameter of the tubular section (D1 = 76.2 mm and D2 = 3.3 mm) and retrofitting techniques (External Ring Stiffeners and GFRP strip wrapping). All the specimens were tested for failure by loading using Universal Testing Machine. The failure mode and load deflection behaviour was studied in detail. From the study, it was observed that the control specimen without the ring stiffener and GFRP strip wrapping with slenderness ratio 24 are found to be stiffer than other slenderness ratios. The increase in the D/t ratio from 31.7 to 38.1 increases the load-carrying capacity and overall behaviour of the tubular column. The analytical results are close to the experimental, but slightly less than the experimental results because of the rigid body connection.