Experimental and analytical investigation of precast fiber-reinforced concrete (FRC) tunnel lining segments reinforced with glass-FRP bars

Abstract

A hybrid use of glass fiber-reinforced polymer (GFRP) reinforcement and fiber-reinforced concrete (FRC) could be a viable option for producing durable precast concrete tunnel lining (PCTL) segments. There is, however, a gap in the literature regarding the behavior of GFRP-reinforced FRC PCTL segments with typical amounts of reinforcement. This paper presents results obtained from both experimental and analytical studies on the behavior of GFRP-reinforced FRC PCTL segments under bending load (flexure). Four full-scale tunnel segment specimens were constructed and tested monotonically under three-point bending load. The influence of concrete type, reinforcement ratio, and tie configurations on the cracking behavior, deflection behavior, failure mechanism, load-carrying capacity, strain behavior, and deformability was evaluated. There is a limited analytical procedure available to predict the shear and flexural capacities of GFRP-reinforced FRC PCTL segments. Therefore, an analytical investigation was carried out in order to propose and evaluate different methods for predicting the flexural and shear capacities of such elements. The results indicate that the use of FRC significantly improved the cracking behavior and failure mechanism while also increasing the load-carrying capacity and deformability by 12% and 71%, respectively. Increasing the reinforcement ratio by 86% enhanced the post-cracking stiffness and peak load by 92% and 31%, respectively, while reducing the service-load crack width by 57%. According to the analytical investigation, the introduced direct method based on the stress–strain behavior of the FRC and the proposed simplified method based on ACI 440.1R-15 could predict the flexural capacity of GFRP-reinforced FRC PCTL segments with high accuracy. Furthermore, the method proposed to modify CAN/CSA S806-12, R2017 to consider the contribution of fibers in shear transferring mechanism yielded rational conservative values for the shear capacity of GFRP-reinforced FRC PCTL segments.