Axial monotonic and cyclic compressive behavior of square GFRP tube–confined steel-reinforced concrete composite columns

Abstract

Fiber-reinforced polymer tube–confined steel fiber–reinforced concrete column is a novel composite column proposed recently, which consists of a traditional steel-reinforced concrete column and an external glass fiber–reinforced plastic tube for lateral confinement. In order to investigate the axial compression behavior of steel fiber–reinforced concrete columns, a total of 16 square specimens were fabricated and tested under axial monotonic and cyclic compressive loading. Three different configurations of inner shaped steels, including cross-shaped, box-shaped with wielding, and box-shaped without wielding were considered. Two thicknesses of glass fiber–reinforced concrete tubes were also considered as the main experimental parameters. On the basis of test results, a thorough analysis of the failure process based on strain analysis was discussed. The test results showed that steel fiber–reinforced concrete columns exhibited higher ductility and load capacity compared with fiber-reinforced plastic–confined plain concrete columns. Two quantitative indexes were proposed to measure the confinement of steel fiber–reinforced concretes. The axial cyclic mechanical behaviors were discussed through comparative analysis with monotonic behaviors. The remnant strains and modulus of the cyclic behaviors were also discussed.