Behavior of concrete-filled GFRP tube short columns under axial compression loading

Abstract

A column is an essential structural component that bears the load of a structure. If a column fails, it can lead to the collapse of the entire structure. Therefore, strengthening and enhancing the ductility of columns is necessary to prevent failure. This research examines the behavior of concrete-filled glass fiber-reinforced polymer (GFRP) tube-confined columns under axial compression. The study investigated transverse reinforcement using tie and spiral made of steel and GFRP. Eight column specimens were tested, each with a diameter of 250 mm and a height of 700 mm. The studied variables included the thickness of the GFRP tube 3 mm, the spacing of stirrups (50 and 150 mm), the type of stirrup (tie or spiral), and the stirrup material (steel or GFRP). The test results revealed that the GFRP tie column with 150 mm spacing had an 8% higher compressive strength than the steel tie column with the same spacing. Additionally, the ductility at the failure point of the GFRP tie column with 150 mm spacing was 21% higher than that of the steel tie column. The steel spiral column with 50 mm spacing exhibited 7 % higher compressive strength than the steel tie column with the same spacing. Furthermore, the ductility at the failure point of the steel spiral column with 50 mm spacing was 17 % higher than that of the steel tie column. It was observed that steel spiral reinforcement with a spacing of 50 millimeters resulted in the highest compressive strength and ductility, indicating its suitability as the most effective option. Furthermore, the equation for predicting the ultimate compressive strength of columns proposed by Gao et al. [11], as well as the equation for calculating the compressive strength of concrete confined by fiber-reinforced polymer tubes ( ) developed by Mander et al. [14], produced predictions closely aligned with the experimental results. Both models exhibited high predictive accuracy, thereby supporting their applicability for design purposes and ensuring structural safety.