A Theoretical Method for Fracture Resistance of Shear-Strengthened RC Beams with FRP

So far, the conventional, theoretical, and numerical analyses in fracture mechanics have been applied to study concrete flexural beams, which are strengthened using fiber-reinforced polymer (FRP) composite sheets. However, there is still little knowledge about the shear capacity of a side face FRP-strengthened cracked beam. A theoretical analysis is herein presented to obtain the fracture resistance in a four-point reinforced concrete beam, with two inclined initial notch on the supports, which is strengthened with side face FRP strips. The fracture process zone (FPZ) at the head of the crack is used as the base of a fictitious crack to obtain shear stress distribution in the cross section of the beam. Based on equilibrium equation in the beam notch cross section, the change of shear force against the FPZ length and the tensile forces due to FRP are obtained. Then, in double notch four-point beam, Mode II of the stress intensity factor due to the external load is determined. Finally, the relationship between the shear capacity and the FPZ length is used to express the fracture resistance as a function of the FPZ length. It is observed that the FPZ and the FRP sheets have positive effects on the fracture toughness and they play important roles in preventing the propagation of shear cracks.