OPTIMUM DESIGN OF THE THICKNESS OF CARBON FIBRE REINFORCED POLYMER MATERIAL (CFRP) REQUIRED FOR STRENGTHENING OF DEFICIENT REINFORCED CONCRETE BEAM

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Department of Engineering

ABSTRACT
A Carbon fiber-reinforced polymer (CFRP) has emerged as promising material for rehabilitation of existing reinforced concrete structures. However, one of the major concerns of using this material is its high cost. In this research, a classical optimization technique was employed to optimize the thickness of Carbon Fibre Reinforced Polymer material used in strengthening of shear and flexuralydeficient reinforced concrete beam. A simply supported reinforced concrete beam was designed in accordance with Eurocode 2 design criteria;the beam was subjected to shear deficiency and subsequently flexural deficiency at 25% capacity reduction level. Strengthening of the beam was achieved using externally bonded system with CFRP material of 1.2mm design thickness and in accordance with Intelligent sensing for imaging structures(ISIS2004) strengthening guidelines. Results indicate that the application of CFRP material increased the overall shear and flexural resistance of the beam by 95% and 79% respectively.Generalised Reduced Gradient (GRG) method was employed for the optimization. An optimum CFRP thickness of 0.06mm and 0.41mm was obtained from the result of the GRG program implemented for shear and flexural strengthening of the deficient Reinforced Concretebeam. Sensitivity analysis was carried out to determine the influence of parameters such as load ratio, steel reinforcement ratio and different CFRP elastic modulus on the optimum thickness of the material at 10, 20, 30, 40, 50 60, 70, 80, and 90% capacity levels. CFRP modulus of 25GPa, 50GPa, 75GPa 100GPa125GPa and 150GPawas considered in the analysis. The results indicate that the optimum thickness of the FRP material depends largely on the magnitude of load ratio, the elastic modulus of the CFRP material and the steel reinforcement ratio.