Retrofitting Method for Reinforced Concrete Structures with Externally Prestressed Carbon Fiber Sheets

In this paper, a new method to use Carbon Fiber Sheets (CFS) which is prestressed before they are bonded to the concrete surfaces based on the concept of prestressing technique is developed. A prestressing system is first designed to be suitable for strengthening existing concrete structures. An experimental program is carried out to verify the reinforcement effects of beams such as on the improvements of flexural strength, ductility, stiffness and crack resistance. To avoid the debonding failure near the ends upon releasing the pre-tensioned methods and the effects of anchorage treatments are also discussed. An effort is also made to investigate the determination of appropriate prestressing stress level of CFS and structural optimization of reinforcement.