AN EXPERIMENTAL STUDY ON STRAIN DISTRIBUTIONS IN FRP IN SHEAR-STRENGTHENED RC BEAMS AT DEBONDING

Abstract

Substantial research has been carried out on the shear strengthening of reinforced concrete (RC) beams with fibre reinforced polymer (FRP) composites. The beams may be strengthened with various methods including the wrapping of FRP around the entire cross-section, and the bonding of U jackets and side strips. For most beams strengthened with FRP wrapped around the entire section, the shear failure process starts with FRP debonding from the sides of the beam, leading to eventual failure by FRP rupture. Most previous research has been concerned with the ultimate failure of FRP wrapped beams when FRP ruptures, but debonding of FRP from the sides of the beam may also constitute a limit state in design, either as a serviceability limit state or a lower bound to the ultimate limit state. This paper presents an experimental study on this debonding failure in which beams with completely wrapped FRP strips were tested. Particular attention is paid to the development and distribution of strains in the FRP strips intersected by the critical shear crack and the contribution of FRP to the shear strength of the beam at the complete debonding of the critical FRP strip.