Reinforced HSC beams strengthened with CFRP plates under bending

Poststrengthening and retrofitting is a growing reality, as existing structures are required to meet the demands of modern society. Apart from the need to increase load capacity, upgrading of a structure may be necessary due the deterioration of the structure on account of corrosion or accidental damage, a change in the structural system, or to rectify initial design and construction faults. A commonly observed mode of failure for beams strengthened using carbon-fiber-rein forced polymer composite material plates is due to the plate peeling off prematurely and unpredictably at relatively low magnitudes of applied loading. End plate anchorages and long unanchored plate lengths, which can add significantly to the overall cost of a strengthening solution, overcome this problem. The objective of this investigation is to study the effectiveness of the length of carbon FRP laminate on performance of repaired reinforced high strength concrete (HSC) beams. This objective is achieved by conducting the flexural four-point testing of reinforced HSC beams with a different amount of tensile reinforcement that is strengthened with different plate configuration up to failure and calculating the flexural response. The result of tests show that, in contrast with a control beam, initial cracking loads of strengthened beams increase slightly, while ductility decreases and ultimate loads increase considerably. Examination of the crack distribution indicated that the size and density of the cracks were significantly less in the strengthened beams than in the control specimens, thereby producing a more durable system, which is less susceptible to the ingress of water and other potentially corrosive solutions. After the experimental study, three-dimensional nonlinear finite element models (FEMs) are adopted by ANSYS to examine the structural behavior of the reinforced high strength concrete (HSC) beams strengthened with FRP sheets. Lastly, a comparison between the finite element analysis results and the experimental data available on the specimens is made. The load deflection plots obtained from the numerical study show good agreement with the experimental results.