EFFECT OF SHEAR-SPAN RATIO ON SHEAR FAILURE AND SIZE EFFECT OF CONCRETE BEAMS WITHOUT WEB REINFORCEMENT STRENGTHENED BY CFRP

The shear-span ratio has an important influence on the crack development and on the failure mode of reinforced concrete (RC) beams strengthened with carbon fiber reinforced polymer (CFRP). However, there were few studies on the effects of its shear strength and size effect. A mechanical analysis model for shear failure of reinforced concrete beams strengthened with CFRP was established by using three-dimensional numerical meso-scale simulation method, considering the meso-heterogeneity of the concrete and the interaction between the CFRP and concrete. Based on the verification of the rationality of the meso-scale method, the influence mechanism and law of the shear-span ratio on the shear failure and size effect of CFRP-strengthened RC beams were simulated and analyzed. The results show that: the shear-span ratio has a great influence on the shear failure mode of the strengthened beam, and the larger the shear-span ratio, the closer the beam is to the cable-stayed failure with better ductility. The shear-span ratio had better shear capacity for CFRP-strengthened beams and the influence on the size effect of shear strength was small. The shear-span ratio has a greater influence on the CFRP shear contribution in the strengthened beam. The larger the shear-span ratio, the better the shear effect of CFRP on strengthened beams. The beam reinforcement effect of the shear-span ratio (λ = 2.5) is most effective.