Experimental study on the mechanical and self-sensing behaviors of prestressed carbon fiber–reinforced polymer reinforced concrete composite structures

A type of self-sensing prestressed carbon fiber–reinforced polymer reinforced concrete composite structure was proposed and studied, composed of reinforced concrete beam, prestressed carbon fiber–reinforced polymer plate, and long-gauge fiber Bragg grating sensors. The carbon fiber–reinforced polymer plate was prestressed and bonded to the bottom of the reinforced concrete beam. Two types of anchorage systems were compared and studied. The long-gauge fiber Bragg grating sensors were used as active elements for the self-sensing of mechanical responses, which were installed on the tensile rebars, carbon fiber–reinforced polymer plates, and concrete. A series of static and fatigue 4-point flexural experiments were carried out to study the bending and fatigue performances of the composite structures. After a prescribed number of fatigue loading cycles, monotonic flexural bending was performed to investigate the deterioration of properties. The results showed that the long-gauge fiber Bragg grating sensor is valid for the mechanical response sensing of the proposed structures. The compatibility of the prestressed carbon fiber–reinforced polymer plate and concrete in the pure bending zone is excellent even under fatigue loading. The load-carrying capacities were improved by more than 30% due to the application of prestressed carbon fiber–reinforced polymer plates. The stiffness was also improved remarkably and generally decreased with the accumulation of fatigue cycles linearly.