Behavior of hollow concrete-filled rectangular GFRP tube beams under bending

Concrete-filled fiber reinforced polymer (FRP) tube (CFFT) members have become increasing popular, while the study on CFFT beams especially hollow CFFT beams is rather limited. This paper presents an experimental study on the flexural behaviour of hollow concrete-filled rectangular glass fiber reinforced polymer (GFRP) tubes beams. A total of six beams was fabricated and tested by using four-point bending. The parameters investigated in this study included the size of the hollow cores (0%, 5.7%, 12%, 27%) and the shape of the hollow cores (circle and rectangle). The experimental results show that the hollow CFFT beams exhibit an almost linear load–displacement behaviour and a brittle failure mode. The flexural stiffness of the hollow CFFT beams is slightly affected by the size and shape of the hollow cores. In addition, the proposed theoretical model verifies that the hollow core in the tension region also has a small effect on flexural strength of the hollow CFFT beams, and the flexural behavior is highly depended on the material properties of the GFRP tubes. In comparison with the conventional steel reinforced concrete beams, the hollow CFFTs beams have a lighter dead weight and a higher load-carry capacity