LOADING AND DEFORMATIONS OF REINFORCED CONCRETE BEAMS STRENGTHENED WITH FLEXIBLE EXTERNAL BARS

Abstract

Strengthening of reinforce-concrete structures is one of the most promising directions in the practice of reconstruction and building which allows getting a considerable technical and economic effect. A new system of strengthening of reinforced concrete beams has been developed. The system of strengthening includes a tie and external transversal bars. Transversal bars have a broken contour. Such a contour reduces stress in transversal bars and increases the efficiency of the system of strengthening.

Two series of twin beams have been experimentally studied. These beams had an identical reinforcement framework and were made from one and the same batch of concrete. The beams of the reinforced series are strengthened with external bars. Laboratory research on the loading – deformations dependence in beams was also conducted. The loading pattern envisaged load application at the third-points of beam span. Fibre deformations and beam deflection were determined. Crack initiation and crack width were registered in the concrete of beams.

Loading was increased until beam failure. As a result of measurements there were built load – deflection - fibre deformations plots. The effect of strengthening system was evaluated. The application of the proposed system of strengthening allowed increasing the bearing capacity of beams up to four times. Beam deflection was significantly reduced. Crack resistance of beams has been enhanced.

The proposed system of strengthening reinforced concrete beams can be effectively used in the process of reconstruction and building.