Retrofitting of Concrete Beams Using Carbon-Fibre-Reinforced Polymer

This project is the experimental study to investigate the behaviour of structurally damaged full-scale-reinforced concrete beams retrofitted carbon-fibre-reinforced polymer (CFRP) with CFRP laminates in shear or in flexure. The main variables considered were the internal steel ratio, location of retrofitting and therefore the length of CFRP. The experimental results, generally, indicate that beams retrofitted in shear and flexure by using CFRP laminates are structurally efficient and are restored to stiffness and strength values nearly equal to or larger than those of the control beams. It was found that the strengthening technique by CFRP in flexure varied depending on the length of the CFRP used. The main failure mode in the experimental work was plate debonding in retrofitted beams. Fibre composite can be used in reinforcing concrete structures externally. Fibre composite materials have low density, can be easily installed and are easy to cut to length on site. Therefore, fibre composite as external reinforcement for concrete structures has become very attractive and popular around the world. It is important to understand the behaviour of a strengthened structure well and realise what parameters affect the failure mode and load-bearing capacity. The aim of this project is therefore to investigate and improve the understanding of the behaviour of reinforced-concrete beams strengthened with fibre composite. These structures have a critical problem implying that they may fail in a sudden manner. This failure involves separation between composite and concrete. Special attention is paid to this phenomenon, which is called debonding. The influence of several parameters such as length and width of fibre composite and properties of adhesive were investigated. Large width and length of fibre composite and soft adhesive would yield to reduce tendency of debonding and increase thus of the utilisation of fibre composite and increase load capacity.