Influence of synthetic fibres on the bond performance of glass fibres reinforced polymers concrete: an experimental investigation and regression-based analysis

Fibre-reinforced polymer bars are considered a suitable alternative to conventional steel bars in harsh and corrosive conditions. However, poor bond performance, in comparison to conventional steel-reinforced concrete, remains a concern in the structural elements reinforced with glass fibre-reinforced polymer (GFRP) bars. The experimental investigation presented in this research comprised pull-out tests conducted on 36 concrete cubes reinforced with GFRP bars by varying the parameters like fibre content, concrete cover, type of reinforcement, and bar diameter. The influence of these parameters on the bond behaviour was evaluated in terms of the bond strength, bond stress-slip response, and the modes of failure. Experimentally, the results showed that by incorporating the synthetic fibres, concrete specimens exhibited considerable improvement in ductile behaviour and bond stress. Moreover, the utilisation of synthetic fibres can allow for reduction in the bond-based concrete cover. Based on the experimentally obtained results, ANOVA and multiple linear regression analysis were also conducted using Minitab. Equations for bond strength were developed by determining the significance level of the investigated parameters through statistical analysis and further utilised to develop the contour plots. The investigation revealed that the influence of the bar diameter and concrete cover on the bond strength is more pronounced than that of the fibre content.