Abstract
The bond between fiber-reinforced polymer (FRP) bars and concrete is the weakest link in the chain of parameters affecting the behavior of FRP-reinforced structures. In this study, eight glass fiber-reinforced polymer (GFRP)-reinforced concrete beams were tested in flexure. There were two control beams and six beams with lap splices. The first control had continuous rebars, whereas the second control had lap splices. A lap length of 40 times rebar diameter was used in tension in the constant moment region. The test variables included the spacing of confining stirrups (no stirrups, 100, and 50 mm) and a gap between rebars in the lap splice zone (0 and 18 mm). The test results revealed that the bond strength of GFRP rebars increases with the enhancement in the gap between rebars and the decrease in the spacing of confining stirrups. The available development length and bond-strength equations were modified to incorporate the effect of the GFRP rebar gap and spacing of confining stirrups in the lap zone. Besides the experimental program, nonlinear finite-element models were prepared to model the behavior of test beams and validate the proposed bond strength equations.