Compressive behavior of FRP-confined elliptical concrete-filled high-strength steel tube columns

• Published in: Composite structures Vol. 266; p. 113808
• Main Authors: Zeng, Jun-Jie, Liang, Sheng-Da, Li, Yong-Long, Guo, Yong-Chang, Shan, Guo-Yi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.06.2021
• Subjects: Axial compression; Concrete-filled steel tube (CFST); Confinement; Elliptical column; Fiber-reinforced polymer (FRP) jackets; Strengthening; Strengthening; Concrete-filled steel tube (CFST); Confinement; Fiber-reinforced polymer (FRP) jackets; Axial compression; Elliptical column
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2021.113808

Elliptical concrete-filled steel tube (ECFST) columns have been widely used, while they suffer deterioration due to various reasons. On the other hand, the concrete in ECFST columns is ineffectively confined due to the non-uniform confinement and the elliptical steel tube in ECFSTs is easy to experience buckling failure. To this end, fiber-reinforced polymer (FRP) jackets are proposed to strengthen the ECFST columns. In this study, axial compression tests on FRP-confined elliptical CFST (FCECFST) columns with a high-strength steel tube are carried out and the effects of the FRP jacket thickness (0, 1, 2, 3 layers) and the cross-sectional aspect ratio (1, 1.5 and 2) are investigated. The experimental results show that the elastic stifness, the ultimate axial load and ultimate axial strain of FCECFST columns increase with the FRP thickness at a given cross-sectional aspect ratio, while decrease with the cross-sectional aspect ratio at a given FRP jacket thickness. Also, FCECFST columns generally exhibit monotonic ascending load-strain behavior, implying that the performance of ECFST columns, which generally have a post peak descending load-strain behavior, is substantially enhanced. Given that the existing strength model is inaccurate and incapable to predict the ultimate condition of confined concrete in FCECFST, a new model of ultimate axial stress and ultimate axial strain is proposed and the verification demonstrates that the proposed model is of good accuracy.