Tests on shear failure and size effect of CFRP-wrapped RC beams without stirrups: Influence of CFRP ratio

In practical engineering, the size of the component which need shear strengthening is often much larger than that of the test specimen. Therefore, the analytical models and design equations established from these studies may not predict the actual behavior of large-scale beams strengthened with CFRP. A series of geometrically similar CFRP U-wrapped strengthening concrete beams were designed and tested, with the maximum beam height reaching 1200 mm. In addition, the effect of CFRP ratio on the size effect of shear performance of CFRP-strengthened beams is studied. All beams were subjected to a complete process to measure CFRP strain. In the test, shear failure occurred in all beams, accompanied by CFRP debonding. External CFRP could significantly improve the shear capacity of beams. While the reinforced beam still exists obvious size effect. Even when the CFRP ratio is 0.2505%, the strength of the strengthened beam still decreases by 35%. Moreover, based on the test results, the accuracy and safety of the calculation formula of shear capacity in relevant design codes are discussed. Furthermore, a comparison between experimental data and theoretical data by the size effect law (SEL) was made. The good consistency indicates the rationality.