Flexural performance of RC beams strengthened with CFF and SCCFL sheets under cyclic loading

Carbon fibre reinforced polymer (CFRP) sheets have a high strength to weight ratio and corrosion resistance, and consequently they have attracted much attention for flexurally strengthening deteriorated reinforced concrete (RC) beams. The study experimentally evaluated the flexural performance of RC beams strengthened with two types of CFRP materials carbon fibre fabric (CFF) and silicone coated carbon fibre laminates (SCCFL), under static cyclic loading (load-controlled). Three series of beam specimens were static cyclically loaded until significant damage including unstrengthened control beams and beams strengthened with single and double layers of CFF and SCCFL. As key parameters ultimate load capacity, the load deflection behaviour, the energy dissipation, crack propagation and stiffness degradation were evaluated. Results indicated that strengthening of the beam with CFRP increased the nominal flexural strength, and its fatigue resistance. The two materials used for strengthening exhibited different performance behaviour, among which the SCCFL strengthened beams exhibited higher load capacity and energy dissipation, less crack width and retained stiffness under static cyclic loading (load-controlled). SCCFL is proved to be more effective in retrofitting RC structure to dynamic or fatigue loadings.