An Experimental Study on the Flexural Bonding Characteristic of a Concrete Beam Reinforced with a GFRP Rebar

Abstract

This study was conducted to examine the bond strength of a beam reinforced with a GFRP (Glass Fiber Reinforced Polymer) rebar through a four-point bending test, adopting the British standard. The variables were made to have a bonding length 5 times (5 d(b)), 10 times (10 d(b)), and 15 times (15 d(b)) that of the nominal diameter of a GFRP rebar. This was done to analyze the relationship between the bonding strength and the slip. The results of the test reveal that pull-out failure was dominant in the 5 d(b) and 10d(b) specimens. Both patterns of the pull-out failure and concrete-splitting failure appeared in the 10 d(b) specimen. On the other hand, the 15d(b) specimen showed only concretesplitting failure at the end of its bonding length. Therefore, it was proven in this study that the available bonding length of GFRP rebar under a bending condition in a static test is over 15 d(b). Further research should be conducted on this subject, though, particularly a fatigue bending test and an FEM (Finite Element Method) parameter study, and a bonding model must be developed.