Behavior of novel composite beams reinforced with a GFRP rectangular tube and steel angles under bending

Concrete-filled FRP tube beams (CFFBs) with a glass fiber reinforced polymer (GFRP) pultruded tube have become increasing popular in industry and research communities. However, CFFBs with a pultruded FRP tube generally have a lack of ductility due to the slip between the FRP tube and the concrete in the CFFBs under bending. Aiming to address the above issue, this paper develops a novel composite beam reinforced with external thin-walled GFRP rectangular tubes, steel angles and penetrating long bolts. The steel angles are implemented at the tension zone of the beam to ensure a sufficient ductility, and the long bolts are penetrated along the cross-sectional height of the beam to mitigate the relative slip. Four-point flexural test of five beams were conducted in this study. The test results demonstrate the improvement of the ductility due to the use of steel angles, and the relative slip is effectively controlled by the long bolts. In addition, the test results reveal that the strength ratio of steel angle-to-GFRP tube was a significant parameter that affecting the flexural behavior of the novel composite beams.