This paper presents the test results of an experimental study to investigate the effect of elevated temperatures on the bond properties of glass fiber-reinforced polymer bars in concrete. For this purpose, a total of 39 pullout specimens with glass fiber-reinforced polymer bars were cast for bond strength tests. In addition to the laboratory temperature, specimens were exposed to heating regimes of 100, 200, 300 and 350° for a period of 1, 2 or 3 h. The test results are presented in terms of bond strength, bond-slip relationship, and mode of failure. All specimens failed by shearing of the concrete corbels surrounding the bars and almost no damage was seen in the glass fiber-reinforced polymer bars. The results showed that the bond strength decreased as the temperature or exposure period increased. Reductions of about 20% of the original bond strength were recorded after exposure to 100 and 200° for 3 h. Significant reductions of about 50% in the bond strength were recorded after exposure to 350° for periods of 2 and 3 h. A modification to the ACI (American Concrete Institute) and CEB-FIP (Comité Euro-International du Béton-Fédération Internationale de la Précontrainte) equations was developed to consider the effect of elevated temperatures and it showed good agreement with test results.
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