Smart self-sensing fiber-reinforced polymer sheet with woven carbon fiber line sensor for structural health monitoring

With the development of technology to upgrade existing concrete structures using externally bonded fiber-reinforced polymer composites, the properties that are inherent in fiber-reinforced polymer sheets, such as low bonding ductility between fiber-reinforced polymer and concrete, have been highlighted as presenting a challenge. This article presents a novel, smart, self-sensing fiber-reinforced polymer sheet, by hybridizing the fiber-reinforced polymer sheet with woven long-gauge carbon fiber line sensors, in order to monitor the macrostrain changes of the fiber-reinforced polymer sheet. To examine the behavior of the smart fiber-reinforced polymer sheet, a direct tensile test was carried out. The results clarified that the carbon fiber line sensor has a linear relationship with applied stress, and the woven carbon fiber line sensor can work homogeneously with the fiber-reinforced polymer sheet as one unit. A simply supported prestressed concrete beam, strengthened with the smart fiber-reinforced polymer sheet, was tested by means of a four points bending test. This test showed that the carbon fiber line sensor can distinctly detect the cracking load and the initial debonding between the fiber-reinforced polymer sheet and the concrete surface. This article demonstrated that the fabrication of smart fiber-reinforced polymer sheet-sensing structures for structural health monitoring would be beneficial.