Flexural behaviour of hollow reinforced concrete-filled fibreglass tubular beams

An experimental and numerical study of hollow reinforced concrete-filled glass-fibre-reinforced polymer tubular beams was carried out. Based on bending tests, the working mechanism and failure modes were studied. A finite-element model was established and the validity was assessed by comparing the experimental and numerical results. The main parameters included the wall thickness of the fibreglass tube, reinforcement ratio, hollow ratio, concrete strength and fibre winding angle. The results indicated that the composite beams failed gradually with considerable ductility. The bending capacity increased by about 12% with every 1 mm increment of the fibreglass tube thickness, increased by about 40% as the reinforcement ratio increased from 2.28% to 4.56%, and increased by about 6% with every 5 MPa increment of the concrete strength. The bending capacity decreased and then increased as the fibre winding angles ranged from 10 degrees to 90 degrees, and a small fibre winding angle was preferable for the flexural member. A hollow ratio of 0.375 is proved to be applicable to obtain lighter member self-weight with minimal decrease in strength.