An interface model for characterizing the interaction between fiber-reinforced plastic (FRP) bars and concrete is examined. When the bars have a significant surface structure, the interaction (commonly called bond) can be dominated by a mechanical interlocking. The model provides a macroscopic characterization of the bond behavior within the mathematical framework of elastoplasticity theory. While the bond model has been applied to both steel and FRP bars, the failure mechanisms can be quite different, thus application of the model to the bond of FRP bars merits critical evaluation. Among the important differences is the potential failure of the surface structure of the bar. Calibration and validation results are presented to highlight the potential strengths and weaknesses of the model. The model gives surprisingly accurate predictions of bond strength for four independent experimental studies. Additional experimental data for evaluation of the model are needed, but the initial results indicate the model could potentially be used to evaluate the behavior of structural components reinforced with FRP bars.
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