Experimental study on bond behavior between concrete and GFRP pultruded i-section using push-out test

This paper presents the experimental results of a push-out test on the bond behavior between glass fiber reinforced polymer (GFRP) I-section and concrete. The specimen is in the form of a concrete rectangular column with the GFRP I-section (I-section) encased in the middle. Four specimens with different configurations were cast and tested. The main parameters involved bond length and the transverse stirrups. The specimens were divided into two groups in accordance to the bond length. The two specimens in Group A had the same bond length of 300 mm, and the transverse steel stirrups were used at one of the specimens. The bond length of the two specimens in Group B was 450 mm, and one of the specimens was also reinforced with stirrups. Push-out was used to conduct this test and all the I-sections were pushed out. The experimental results show that I-sections with longer bond length have high ultimate bond strength. The development of cracks on the concrete is reduced by the stirrups. Nevertheless, the ultimate bond strength of the specimen is not improved when stirrups were used. In addition, a preliminary bond stress-slip model is proposed, and the theoretical results are in close agreement with the experimental results