Behaviour of Distressed RC Beams Retrofitted By External Prestressing Using Trapezoidal Tendons

Abstract

Rectangular RC beams were tested before and after retrofitting by external Prestressing. RC beams of 150 mm x 275 mm section and 4 m length were subjected to monotonically increasing static two-point load and the cracks were induced to a limit such that the strain in reinforcing steel was around 85 % of the yield strain. Retrofitting by external Prestressing using trapezoidal tendons was done while the member was subjected to superimposed dead weight of a bridge girder, equivalent to 25 % of the ultimate load of the beam. Retrofitted beams were tested by monotonically increasing two-point load. It was observed that ultimate flexural capacity of the beam is increased by 59 %. Around 10 % of loss was observed due to the friction between tendon and deviators. An analytical model is developed and compared with experimental results.