Performance-based optimal design of compression-yielding FRP-reinforced concrete beams

The application of fiber-reinforced polymer (FRP) composite in concrete structures has drawn worldwide interest recently. However, a critical drawback of the resulting structures is their poor ductility performance, due to FRP’s linear-elastic mechanical properties. “Unless ductility requirements are satisfied, FRP materials cannot be used reliably in structural engineering applications” [1]. To resolve this problem, the authors recently developed a new technology to improve the ductility of flexural members through compression yielding (CY). In the experimental and theoretical investigations that have been undertaken so far, the CY concept has proved to be not only theoretically interesting and attractive, but also practically feasible. As CY beams make use of a different avenue to deliver ductility, their design is different from that in conventional reinforced concrete theory. This paper investigates the mechanical behavior of CY structures and proposes a criterion-based optimal design methodology that directly and quantitatively addresses ductility and strength demands.