Etude de l'interface beton-composite pour un composite lamine directement sur le beton

The main goal of this research is a better understanding of the debonding mode of failure with an emphasis on the effect of the composite material properties on the overall structural behaviour and the composite-concrete bond behaviour. The goal is to get a better understanding of the effect of composite materials properties in order to design RC beams to prevent the debonding mode of failure through proper selection of composite reinforcement.; In the chapter 3, we study the behaviour of composite strengthened RC beams under four point bending.; In chapter 4 we investigate the effect of composite material stiffness on the structural response of strengthened beam. Experimental results show that the strength and mode of failure of hybrid beam depend on composite material properties and its reinforcement ratio.; In chapter 3 the effect of the level of damage is investigated by loading RC beams to two level of damage before composite strengthening. The beams were strengthened by two types of composite. The study shows that the final mode of failure is not affected by the level of damage, however, pre-loaded RC beams when strengthened by composite showed higher strain and higher strain energy absorption capacity compared to undamaged strengthened beams.; In chapter 5 the debond crack was traced to originate at the location of concrete tensile crack opening at the interface. Bond failure most probably starts at the location of a flexural crack, because the crack tip at the interface is the place where the local stress concentration is superimposed on the shear stress produced by loading. An interface crack originated at the composite-concrete interface can be conducted in the direction of already existing shear crack or to be arrested at the position of an aggregate, enter into the concrete, following the aggregate paste interface and separate a thin layer of concrete while delaminating the composite.; In chapter 6, the effect of composite material mechanical properties on the composite-concrete interface properties is investigated using the developed sandwich specimens. In general it was observed that the fracture toughness of the interface is dependent on the phase angle of loading and composite material mechanical properties.; Development of bond crack at the composite-concrete interface plays a significant role in debonding mode of failure. The final failure occurs through the formation of continuous crack bridging the already existing cracks. (Abstract shortened by UMI.)...