The shear mechanism and the debonding-restriction of RC beams strengthened with externally bonded (EB) FRP in consideration of the single effect of the dominate factor of shear span ratio and the coupling effects of shear span ratio and the other critical factors such as size effect, shear steel reinforcement ratio and a FRP strip anchor, will be investigated in this project. Based on a series of experimental and analytical studies, following anticipated achievements are made: (1) the effect of the shear span ratio on the shear performance of FRP strengthened RC beams is clarified and thus a theoretical model for shear contribution of FRP reinforcement under different shear span ratio is developed; (2) the size effect of RC beams and the influence of the shear steel reinforcement ratio on the shear performance under different shear span ratio is explored respectively; (3) a new hybrid bonded system using FRP strips as anchors for restricting the debonding of FRP is developed; the bond-slip relation model of FRP-to-concrete interface of concrete structures strengthened with hybrid bonded FRP is derived and hence the mechanism of the FRP strip anchor in controlling the debonding of FRP and the distribution of the FRP strip anchors in the hybrid bonded system is clearly understanding; (4) and finally, based on the above achievements, the FRP efficient strain model is derived upon which a shear design method of FRP strengthened RC beams in considering all the critical factors is developed. The aforementioned achievements of this project can have a great contribution in the promotion and development of design and construction of concrete structures shear-strengthened with EB-FRP and thus provides a stable academic foundation for the application of FRP material in the rehabilitation of civil engineering structures.
