Bond Performance of GFRP Bars Embedded in Seawater–Sea Sand Concrete: Experimental Study and Analytical Modeling

This paper presents an experimental and theoretical study of the bond behavior between glass fiber–reinforced polymer (GFRP) bars with different surface characteristics and concrete. The effects of several key factors, including surface characteristics of the bars, embedment length, and concrete strength, on the bond performance of specimens were explored, and the bond mechanism between GFRP bars and concrete was analyzed. Test results indicate that bond strength increases with concrete strength, and reducing the embedment length leads to an increment in bond strength up to 191.2%. Note that the effect of the bar surface geometric properties is more pronounced with a variation in bond strength from 5.4% to 305.8%. Due to the mechanical characteristics of ribbed GFRP bars, the residual branch of the bond-slip curve exhibits a certain degree of wavy pattern, which is closely related to the surface geometric properties of the bar and the concrete strength. Finally, based on experimental analysis, a new model for predicting the residual branch of the bond-slip curve for the ribbed bar is proposed. By comparing with the bond-slip curve of the existing test, the predicted deviation of the developed model is generally controlled within 20% with average absolute error (AAE) and standard deviation (SD) equal to 0.14 and 0.21 respectively, which indicates that the proposed model possesses satisfactory accuracy.