Behavior of concrete-filled FRP tube columns internally reinforced with FRP-steel composite bars under axial compression. (10th January 2022)

• Record Type: Journal Article
• Authors: Guo, Yong-Chang; Xiao, Shu-Hua; Zeng, Jun-Jie; Su, Jia-Ying; Li, Tian-Zi; Xie, Zhi-Hong
• Is Part Of: Construction & building materials. Volume 315(2022)
• Publication Date: 2022-01-10
• Subjects: FRP -- FRP-steel composite bar -- FRP tube -- FRP spiral -- Confinement -- Hybrid column; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.125714
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: CFFT-CB columns have been developed and tested under axial compression. SRCs and CFFT-Fs/CFFT-CBs have a two-segment and three-segment axial stress-axial strain curves respectively. The FSCB spiral is formed by separated a GFRP spiral and a steel spiral, while the GFRP spiral and the steel spiral deform compatibly. The model of Ilki et al. provides the most accurate predictions among four existing models. Abstract: Although concrete-filled fiber-reinforced polymer (FRP) tube (CFFT) columns (CFFTs) have become increasingly popular, CFFTs has a weak bending performance as the orientation of the fibers in the FRP tube is generally close to the transverse direction. To this end, this paper proposes novel Concrete-Filled FRP Tube columns internally reinforced with FRP-steel Composite Bars (referred to as CFFT-CB columns ) which consist of an external FRP tube, some longitudinal reinforcing FRP-steel composite bars (FSCBs), an FSCB spiral and concrete filled in the entire section. In this study, FSCBs are composed of separated FRP bars and steel bars due to fabrication difficulty. The axial compressive behavior CFFT-CB columns is studied experimentally in this paper. The effects of the spiral type, the spiral pitch, and the thickness of the FRP tube are carefully investigated and the test results confirm the effectiveness of the proposed columns. The ultimate condition of concrete in test columns are compared with four existing stress–strain models, with the confining stresses from both the FRP tube and the FSCB spiral being accounted for. The durable CFFT-CB columns are particularly suitable for marine and coastal structures constructed in harsh environment.