Experimental investigation of FRP strengthened reinforced concrete T-beams in torsion

In general, reinforced concrete (RC) members are most commonly influenced by flexural moments, axial and shear forces. However, they may also be subject to torsional moments. Torsion in reinforced concrete (RC) beams is an important phenomenon that affects the structural behaviour of buildings. Both the concrete and steel reinforcement contribute to the torsional resistance of a RC member. However, the contribution of concrete is usually neglected by the modern design codes, due to cracking. Moreover, the subject of maintenance and repair or strengthening of existing RC structures is a significant problem. The last years, fibre reinforced polymer (FRP) is widely used as external reinforcement in flexural and shear strengthening. Nevertheless, its use in torsional strengthening is not so widely investigated. Ιn this paper, the torsional behaviour of RC T-beams reinforced in shear with FRPs is experimentally investigated. Five groups of T-beams subject to pure torsion, two of which are control beams and other three beams are strengthened in shear with U-jacketed FRP fabrics. Experimental results reveal that FRPs can increase the ultimate torsional capacity of the member.