抄録
The flexural crack width of a beam reinforced with grid shape fiber reinforced plastics (FRP) is larger than that of a RC beam reinforced with reinforcing steel bars due to a small tensile rigidity of FRP. As expected from the strain increment of tensile reinforcement in a FRP beam, the deflection of a FRP beam is larger than that of a RC beam. In calculating the shear capacity of a FRP beam, the cross sectional area of FRP should be decreased by the ratio of Young's modulus of elasticity of FRP to that of reinforcing steel bar in a RC beam. During the sustained flexural moment for a year, the value of deflection increment of a FRP beam is larger than that of a RC beam. However, the ratio of deflection increment to the deflection immediately after loading of a FRP beam is about half as much as that of a RC beam. In order to improve the mechanical behaviors of a FRP beam, chemical prestress was introduced by use of an expansive concrete. Based on the test results, it was assured that the effects of chemical prestress on the flexural crack width and the shear capacity of a FRP beam were obtained.
