Contribution to the study of the shear reinforcement of concrete beams with the help of advanced composite materials

This paper presents results of an investigation on the shear strengthening of reinforced concrete ( RC) beams with externally applied fibre reinforced polymer (FRP) composites. The first part of the study reviews and synthesizes the state of the art in the subject. Also, the requirements and recommendations specified in the Canadian CSA S806-02 standards, the American ACI-440 guidelines, as well as the European fib TG9.3 recommendations are compared with the test results reported in the literature so far. This part of the study indicates that the major parameters involved in the behaviour of RC beams strengthened in shear with FRP were not fully investigated. This can explain the observed discrepancies between the resistance values predicted by the codes and guidelines, and those obtained by tests. This has been the main impetus to carry out an experimental investigation, which is the subject of the second part of this paper. The objective of this experimental investigation was to study the influence of the following parameters on the performance of RC beams strengthened in shear with FRP composites: (i) the FRP ratio, (ii) the transverse steel reinforcement ratio, and (iii) the type of beam (deep versus slender). Results clearly showed the interaction between the FRP composite and the internal transverse steel reinforcement in the shear resistance mechanism. Results also showed the influence of the type of beam on the gain due to FRP on the carrying capacity of the beam.