Quasi-static cyclic behavior of precast high-strength concrete tunnel segments reinforced with GFRP bars

The cyclic behavior of fiber-reinforced polymers (FRP) reinforced precast concrete tunnel lining (PCTL) segments under quasi-static cyclic flexural loading has not yet been experimentally tested and reported on in the literature. This study investigated the cyclic behavior of glass-FRP (GFPR) reinforced precast high-strength concrete (HSC) tunnel lining segments. Full-scale segments measuring 3100 x 1500 x 250 mm were tested under quasi-static cyclic flexural loading. Two cycles of loading and unloading were applied at 1.25%, 2.5%, 5%, 10%, 25%, 50%, and 75% of the maximum displacement obtained from the static testing results, followed by a single cycle up to failure. The test parameters included concrete compressive strength, longitudinal reinforcement ratio and transverse reinforcement configuration (closed ties versus double U-shaped ties). The experimental findings of this study revealed that the GFRP-reinforced HSC PCTL segments exhibited stable hysteretic response until failure. In addition, the test results show that the GFRP-reinforced HSC PCTL segments were able to achieve adequate ductility indexes as well as deformability limits. A theoretical prediction according to the North American codes and design guidelines, including flexural capacities, cracking moment, and crack width, was made and the results compared to the experimental results. This research illustrates the advantages of using HSC for PCTL segments internally reinforced with GFRP bars under quasi-static cyclic flexural conditions.