BOND BEHAVIOR AND DESIGN RECOMMENDATIONS FOR FIBERGLASS REINFORCING BARS

The results of bond tests on 66 straight and 36 hooked Glass- Fiber-Reinforced-Plastic (GFRP) rebars are presented. The tensile load was applied to the rebars in a gradual increment of load level until splitting of concrete, rebar pull-out failure, or rebar fracture occurred. The slip between the rebars and concrete was measured at the loaded and free ends at each load level. Variables included in the study were concrete compressive strength, embedment length, clear concrete cover, rebar diameter, concrete cast depth, radius of bend, and rail length. New criteria for acceptable bond performance of GFRP rebars to concrete were developed and were used to evaluate the experimental results. Design guidelines for calculating the development lengths for straight and hooked GFRP rebars to concrete were derived which parallel those of the ACI Code for steel rebars. In addition, confinement factors were calculated to reflect the influence of concrete cover and casting position.