Analysis of alternative ductile fiber-reinforced polymer reinforcing bar concepts

Steel-reinforced concrete structural components are often associated with significant maintenance costs as a result of reinforcement corrosion. To mitigate this problem, fiber-reinforced polymer bars have been used in place of traditional steel-reinforcement for some applications. The non-ductile response of typical fiber-reinforced polymer bars is a concern, however. To overcome this problem, hybrid ductile fiber-reinforced polymer bars have been developed for use in concrete flexural members with resulting ductility indices similar to sections reinforced with steel. In this study, five different hybrid ductile fiber-reinforced polymer bar concepts are analyzed and compared in terms of ductility, stiffness, and relative cost. Of primary interest is the effect that the number of materials used in bar construction has on performance. Reinforced concrete beam and bridge deck applications are considered for analysis. It was found that all hybrid ductile fiber-reinforced polymer-reinforced flexural members czonsidered could meet code-specified strength and ductility requirements for steel-reinforced sections, although service load deflections were approximately twice that of steel-reinforced sections of the same depth. In general, ductility increased, and overall material cost decreased, as the bar material layers increased from 2 to 4. The four-material continuous fiber bar approach was found to be most promising, with high ductility as well as relatively low cost.