Transfer and Development Lengths of Carbon Fiber Reinforced Polymers Prestressing Reinforcement

Recently, the use of fiber-reinforced polymers (FRPs) in reinforcement has been used for several structures and bridges as a solution for the corrosion problem. Fundamental understanding of the behavior and specific characteristics of FRP prestressing tendons such as bond strength, transfer, and development lengths are of prime importance for the development of design guidelines and codes for concrete structures prestressed with FRP reinforcements. This paper is a continuation of the paper published in the May-June 1998 issue of this journal entitled, "Bond Properties of Carbon Fiber Composite Prestressing Strands." In this study, the results of 52 tested specimens are used to determine the transfer and development length of two types of carbon FRPs. The reinforcements used in this study are Leadline bars, carbon fiber composite cables (CFCCs), and steel strands used for control specimens. The new configuration of the concrete prism used in this study is proposed as a standard test to evaluate the transfer and development lengths of FRP prestressing reinforcements. The effect of concrete confinement, simulating the effect of shear reinforcement, on the transfer and flexural bond lengths is included. Effect of shrinkage and creep of concrete on the transfer length is also reported. Based on the experimental results, design models are proposed to predict the transfer and flexural bond lengths of Leadline and CFCCs.