Strengthening of RC beams with opening in shear zone using external prestressing technique

Abstract

Structures may need to be strengthened because they have reached their life expectancy, they may not be compatible with upgraded design standards, there may be mistakes in their design or construction, or they may have been exposed to unpredicted loads such as a vehicle strike or powerful earthquake. An experimental investigation on five strengthened and two non-strengthened rectangular reinforced concrete (RC) beams with openings in the shear zone was carried out to validate the effect of using external prestressing on the behaviour of the shear zone.A control beam without an opening was tested as a reference specimen. The effects of shape, dimensions and distribution of the opening on the deflection behaviour, crack patterns, mode of failure, failure loads and steel strains were examined. The test results showed that external prestressing is a very effective strengthening method to increase the shear load-carrying capacity of existing concrete beams, especially those with circular openings and rectangular openings with opening length to shear span length ratio less than 0 . 2.