Bond between glass fibre reinforced polymer bars and high - strength concrete

YesIn this study, bond properties of glass fibre reinforced polymer (GFRP) bars embedded in high-strength concrete (HSC) were experimentally investigated using a pull-out test. The experimental program consisted of testing 84 pull-out specimens prepared according to ACI 440.3R-12 standard. The testing of the specimens was carried out considering bar diameter (9.5, 12.7 and 15.9 mm), embedment length (2.5, 5, 7.5 and 10 times bar diameter) and surface configuration (helical wrapping with slight sand coating (HW-SC) and sand coating (SC)) as the main parameters. Twelve pull-out specimens reinforced with 16 mm steel bar were also tested for comparison purposes. Most of the specimens failed by a pull-out mode. Visual inspection of the tested specimens reinforced with GFRP (HW-SC) bars showed that the pull-out failure was due to the damage of outer bar surface, whilst the detachment of the sand coating was responsible for the bond failure of GFRP (SC) reinforced specimens. The bond stress – slip behaviour of GFRP (HW-SC) bars is different from that of GFRP (SC) bars and it was also found that GFRP (SC) bars gave a better bond performance than GFRP (HW-SC) bars. It was observed that the reduction rate of bond strength of both GFRP types with increasing the bar diameter and the embedment length was reduced in the case of high-strength concrete. Bond strength predictions obtained from ACI-440.1R, CSAeS806, CSA-S6 and JSCE design codes were compared with the experimental results. Overall, all design guidelines were conservative in predicting bond strength of both GFRP bars in HSC and ACI predictions were closer to the tested results than other codes

Behavior of Slender GFRP Reinforced Concrete Columns

This paper presents an experimental and analytical study on slender concrete columns reinforced with glass fiber-reinforced polymer (GFRP) bars. The experimental program included ten concrete columns with rectangular cross-section (203 × 305 mm) where nine of them were reinforced with #6 GFRP bars and one of them was reinforced with steel rebars. Three different reinforcement ratios of 4.70, 2.82, and 2.04 as well as four slenderness ratios of 17, 22, 40, and 60 were considered under two load eccentricities of 0.1 and 0.25 of width of the cross-section. The analytical model considered the material nonlinearity as well as the geometric nonlinearity. The model was verified against an independent experimental program. The model showed that as the load eccentricity and slenderness ratio increase, the load capacity decreases and as the reinforcement ratios increases, the load capacity slightly increases which shows effectiveness of GFRP bars in compression