| The research work reported here investigates the behaviour of reinforced concrete beams strengthened in shear with Fibre Reinforced Polymer (FRP) sheets. A full-scale testing program was undertaken to expand the database on beams rehabilitated with FRP. This experimental data was used to develop a rational shear design method that includes and integrates all shear carrying components.;A series of four type G-girders removed from existing bridges were first strengthened with two types of FRP and two repair schemes. The shear capacity of the girders was increased significantly by the FRP sheets. However, due to the geometry of the girder and the loading set-up, the failure occurred in the end diaphragm of the hat-shaped beams. Three commonly used shear strength evaluation methods: (a) Strut-and-Tie, (b) Modified Compression Field Theory, and (c) grid analysis were also investigated and the prediction results were compared to the experimental results. The shear capacity of each beam was accurately predicted but was limited to the ultimate shear load and to the elastic range of the load deflection curves.;The second part of the experimental study involved eight full-scale T-beams cast in laboratory conditions and extensively instrumented. Four parameters were studied: concrete strength, stirrup spacing, height of the beam web, and type of FRP. The contribution of the external FRP sheets was found dependant on the amount of internal reinforcement. The tri-axial glass fibre reinforcement exhibited a more ductile failure than the other beams reinforced by the other types of fibre.;The current shear design methods and the recently proposed models, which include the FRP contribution, were reviewed and were evaluated using the experimental data. From this analysis, new design equations based on the strip model and the shear friction approach were developed. The interaction of concrete, stirrups and FRP sheets is accounted for in these equations. The proposed design equations were validated with 35 available test results found in the literature and good predictions of the beam behaviour were observed. |
