Flexural behaviour of hollow reinforced concrete-filled fibreglass tubular beams

An experimental and numerical study of the hollow reinforced concrete-filled glass-fibre- reinforced-polymer tubular beams was carried out. Based on the 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 fibreglass tube, the reinforcement ratio, the hollow ratio, the concrete strength and the 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 about 40% as the reinforcement ratio increasing from 2.28% to 4.56%; and increased about 6% with every 5 MPa increment of the concrete strength. The bending capacity decreased and then increased as the fibre winding angles ranging from 10° to 90°, and small fibre winding angle was preferable for the flexural member. The hollow ratio of 0.375 is proved to be applicable to obtain lighter member self-weight with minimal strength decrease.