Contribution to strengthened reinforced concrete structures by externally bonded carbon fibres fabrics

The present paper reports results from an experimental investigation of the mechanical behavior of reinforced concrete structures externally strengthened by bonded carbon fibers fabrics (Carbon Fiber Reinforced Polymer or CFRP). The focus is on the local and global strain distribution, the load-carrying capacity and the mode of failure. The effect of fibers fabrics configuration and some geometrical parameters are presented. The CFRP reinforced concrete beams are subjected to four points bending. The extensometer technique based on electrical strain gauge is used to study the local behavior of the structure. This technique allows measuring the strain of steel, carbon fabrics and concrete. The effect of the same parameters on the strengthening structure local behavior is examined. The tests show better results in case of unidirectional fibers and wrapped strengthening use. The ultimate load and strain of the specimens are compared to the reference specimen. The structures cracking and the different failure modes are studied. The cracking mechanisms and the mode of failure under static loading are presented and analyzed. The results show not only an increase of more than 82 % of the load carrying capacity of the corbels and 210 % of that of the reinforced concrete beam but also improvement of their rigidity. The theoretical analysis based on the classical theory of beams and deformation compatibility relationship enables meaningful comparisons between the theoretical and the experimental results.