ULTIMATE SHEAR CAPACITY OF REINFORCED-CONCRETE BEAMS STRENGTHENED WITH WEB-BONDED FIBER-REINFORCED PLASTIC PLATES

The ultimate shear capacity of reinforced concrete beams can be increa sed by epoxy-bonding fiber-reinforced plastic (FRP) plates to web of t he beam. The shear crack inclination angle is changed as a result of b onding of the plate. In this paper truss analogy and compression field theory are used to determine the effect of the FRP plate an the shear capacity and crack inclination angle of reinforced concrete beams at ultimate stale. Following the calculation of the crack inclination ang le, the equilibrium and compatibility equations are used to obtain the shear force resisted by the plate. A parametric study was carried out to reveal the effect of important parameters such as plate thickness and fiber orientation on the crack inclination angle and shear capacit y The upper bound value of crack inclination angle found in this study is suggested as a conservative value for determining the shear capaci ty of the retrofitted beam. Knowing the inclination angle of cracks, t he shear force in the composite plate and concrete beam can be calcula ted and used for the design of this type of beam. The results of this method have shown close agreement to experimental results.