An experimental study on the flexural behaviour of RC beams strengthened with high-strength bars

External unbonded strengthening offers advantages in speed and simplicity of installation over other strengthening techniques. Unlike externally bonded steel plate or carbon fibre sheet, surface preparation of the concrete for installation of a high-tension bar is not required and installation is not affected by environmental conditions. An anchoring pin or anchoring plate is installed at the end of the beam to connect the high-tension bar to the concrete beam. The deviators are used so that supplementary external bars follow the curvature of the tested beam. The main test parameters are the section area of strengthening bar, the depth of deviator and the number of deviators. The current paper provides a general description of the structural behaviour of beams strengthened using the technique. The test results of a strengthened beam are compared with those from a reference specimen. It is shown that the reinforcing technique can provide greater strength enhancements to an unstrengthened beam and that the provision of deviator enhances efficiency. The ultimate moment of the specimen with two deviators was higher than that of specimens with one deviator.