North American Design Guidelines for Concrete Reinforcement and Strengthening Using Frp: Principles, Applications, and Unresolved Issues

This paper reports on the North American state-of-the-art in the use of FRP composites in concrete structures. FRP bars have been used as the internal reinforcement in concrete members to replace conventional steel rebars for a host of reasons. The principles for design and construction have been established and proposed to industry by the American Concrete Institute (ACI). The fundamental principles are rooted in the steel-reinforced concrete practice with modifications to account for the physico-mechanical characteristics of FRP. Strengthening of concrete members with externally bonded FRP laminates or near surface mounted (NSM) bars has received remarkable attention. The design and construction principles for use in practice are being finalized by ACI. On the application side, FRP materials have been used in some multi-million dollar projects for strengthening parking garages, multipurpose convention centers, office buildings and silos. The drivers for this technology are several, but perhaps the most relevant one is the ease of installation. In the repair/upgrade arena (as well as new construction), perhaps one of the most important unresolved question remains that of durability (including fire resistance). Resolving these issues will increase the degree of confidence in the technology and allow for its more economical exploitation.