Development Length of Glass Fiber-Reinforced Polymer Bars in Concrete

Glass fiber-reinforced polymer (GFRP) reinforcing bars have become a viable option for reinforcement in concrete when corrosion is a concern. The objective of this research was to investigate the bond performance of GFRP reinforcing bars in concrete, to evaluate the existing ACI Committee 440 recommendations for development length of FRP bars in concrete, and to develop new design recommendations if needed. An equation for the development length of GFRP reinforcing bars in concrete was formulated by applying a methodology similar to one used to create the development length equation for steel reinforcing bars. Data collected from beambased bond tests in the literature were used to construct two equations for development length: one based on a splitting mode of failure and the other on a pullout mode of failure. The effects of bar diameter, bar tensile strength, concrete compressive strength, cover, and the presence of transverse reinforcement were investigated. The proposed equations appear to be a conservative yet reasonable means to calculate the development length of GFRP reinforcing bars in concrete given the available test data. The proposed equations are compared to those found in ACI 440.1R-03 and the Japanese Design Guidelines. [PUBLICATION ABSTRACT]