Bond-slip behaviour between GFRP I-section and concrete

This paper presents the results of an experimental study on the bond behaviour of glass fibre reinforced polymer (GFRP) I-section embedded in concrete. A total of five specimens with the same cross-section dimension were cast and tested using push-out test. The main parameters investigated in this study were bond length (300 mm and 450 mm), transverse stirrups and sand coating. The experimental results show that the ultimate bond stress can be improved by a longer bond length and sand coating. However, the ultimate bond stress was reduced when stirrups were used, and the reason may be because the application of stirrups affected the vibration of the concrete, causing a weak bond at the interface. The bond stress distribution at the web and the flange is analysed based on the strain of the I-section. Finally, a bond stress-slip model is proposed for the GFRP I-section with a smooth surface. Based on this model, the theoretical results are in good agreement with the experimental results.