Flexural Strengthening of RC Beams with CFRP Sheets and UJackets

ABSTRACT

This paper presents results obtained from an experimental program on the flexural strengthening performance of reinforced concrete (RC) beams strengthened with externally epoxy-bonded carbon fibre-reinforced plastic (CFRP) sheets. The parameters of study included level of loading and the type of CFRP sheets strengthening system. The test program consisted of four groups of beams. The first group was unstrengthened control group. The remaining three groups were divided into five series by the first CFRP sheet length and number of U-jackets. The first CFRP sheet layers, which were bonded directly to tension bottom concrete surfaces,had length of 640, 1080 and 1540 mm. CFRP sheets plus 50 mm in width strips of CFRP sheets (we called "U-jacket) wrapping up to 300 mm in full height of specimen to prevent debonding of the sheet layer. And the amount of U-jacket at a spacing 50 mm was made to change 0, 4, 8,12 and 16 strips. These beams were tested in flexure and the experimental data on strength, deflection, strain on the CFRP sheet and rebar, and the modes of failure were investigated. The results show that in the case of RC beams with U-jackets of 16 strips, the maximum load of strengthened RC beams was almost the same regardless of the first CFRP sheet layer length, but the displacement at ultimate load increased with increase in number of U-jackets