Torsional Behaviour of High-Strength Concrete Beams Strengthened Using CFRP Sheets; an Experimental and Analytical Study

An experimental investigation of the strengthening of the torsional resistance of High- Strength Concrete (HSC) beams using Carbon-Fiber-Reinforced-Polymers (CFRP) is conducted. A total of seven beams are tested. Three beams are designated as reference specimens and four beams are strengthened using CFRP wrapping of di erent con guration and then tested. The variables considered in the experimental study include di erent wrap con gurations such as: U-wrapping, full and strip wrapping, the e ect of the number of CFRP plies and the in uence of anchors in U-wrapped test beams. The reference and the strengthened beams are subjected to pure torsional moment. The load, the twist angle of the beams and the strains at longitudinal, transverse re-bars and CFRP are recorded to failure. In the current study, the ductility ratios and their increased percentage are investigated using two rather di erent methods. In further study, increasing the cracking, yield and ultimate torsional capacity of the strengthened beams is evaluated. Finally, experimental results are compared to several analytical results. The ultimate torsional strengths that are obtained by one of the analytical methods are in good agreement with the experimental results.