BOND STRENGTH AND LOAD DISTRIBUTION OF COMPOSITE GFRP REINFORCING BARS IN CONCRETE

The objective of this study was to investigate the bond strength of gl ass fiber reinforced plastic (GFRP) reinforcing bars in concrete. Twen ty concrete beams reinforced with four nominal diameters from 12.7 to 25.4 mm of GFRP and steel reinforcing bars were tested to determine th e bond strength of GFRP reinforcing bars in comparison with steel rein forcing bars. Additionally, the distribution of tensile and bond stres ses along the embedment length of GFRP reinforcing bars was investigat ed by five pullout tests using instrumented 19.1-mm-diameter GFRP rein forcing bars compared with steel reinforcing bars in concrete. Only on e type of GFRP reinforcing bar was used in this study. Test results in dicate that the diameter effect on bond observed for steel reinforcing bars is also present for GFRP reinforcing bars. The bond strength of GFRP reinforcing bars is lower (60 to 90 percent) than that of steel r einforcing bars. The bond strength from beam tests is lower (55 to 95 percent) than that from pullout tests. Furthermore, it was found that the distribution of bond stress along the embedment length of GFRP rei nforcing bars is nonlinear.