Evaluation of bond strength of glass fiber-reinforced polymer in concrete beams

The performance of concrete structures is affected by the transfer of force between rebar and concrete, which depends on factors such as concrete strength, yield stress, rebar geometry, rebar diameter, concrete cover and splice length. Also, the use of reinforced polymer materials has become popular due to their successful application in structure. In this study, the effect of various factors on the bond strength of glass fiber-reinforced polymer bars, used in concrete beams, is evaluated and the accuracy of the equations proposed by different regulations and researchers is investigated. To investigate the effect of different factors on bond strength of glass fiber-reinforced polymer, the results of 43 tests conducted by different researchers have been used. Factors studied on the bond strength include the effect of the surface shape of the reinforcement, concrete strength, the amount of concrete cover on the bar, the splice length and transverse reinforcement. After examining the effect of various factors, the accuracy of the equations provided by regulations and researchers in determining the bond resistance for these laboratory results, the accuracy and standard deviation of each equation is evaluated. The results showed that increasing the compressive strength of concrete in samples without stirrup increases the bond strength, and in samples with stirrup, it has no effect on the bond strength. Also, the majority of existing equations estimate the amount of bond strength more than the values obtained from experiment results.