Long-term performance of 15-year-old full-scale RC beams strengthened with EB FRP composites

Abstract

Despite the well-known advantages of fiber-reinforced polymer (FRP) composites, concerns of the long-term performance of reinforced concrete (RC) structures strengthened with FRP composites have been an obstacle to the growing applications of FRP composites due to the lack of knowledge and scarce test data about long-term performances. Thus, the long-term performance of three 15-year-old full-scale (6.8 m long) RC beams was investigated in this study. A non-strengthened beam was served as a control specimen and two were strengthened with externally bonded (EB) glass FRP (GFRP) laminates. The three beams that had been left outside for exposure to harsh environmental conditions for over 15 years were tested under the typical three-point bending condition. It was found that the EB GFRP-strengthened RC beams were superior to the non-strengthened RC one from the standpoint of load-carrying capacity, initial stiffness, ductility, and toughness (energy absorption capacity), which indicates that the EB GFRP strengthening was still effective even over 15 years. Furthermore, the long-term effective tensile strength reduction of the GFRP composites due to the over 15-year exposure to the harsh environment was calculated to be 26.5 % in comparison with the design tensile strength, which is crucial information for the EB FRP strengthening technique.