The possibility of replacing the traditional steel reinforcement with glass fiber reinforced polymer (GFRP) cages in precast concrete tunnel segmental lining has been shown by the authors in previous papers. The use of GFRP rebars as structural reinforcement in precast tunnel segments, allows several advantages in terms of structural durability or in cases of temporary lining that will have to be demolished later. Furthermore, this reinforcement type can be a suitable solution to create dielectric joints, ensuring the interruption of possible stray currents, which often lead to corrosion problems. Nevertheless, this peculiar application requires curvilinear shape of the reinforcement, and then different production process and rebar geometries. In the present work, a suggestion for the optimization of the GFRP reinforcement for tunnel segment is given. Four different GFRP cage typologies are analysed and applied as a reinforcement in full-scale tunnel segments. Both bending and point load tests are developed and the structural performances of the specimens are compared and discussed. Finally, the best solution, in terms of cost-benefit analysis is proposed

The possibility of substituting traditional steel reinforcement with glass fiber–reinforced polymer (GFRP) bars in precast concrete tunnel segmental linings is investigated. The use of GFRP reinforcement in concrete tunnel segments results in several advantages mainly related to durability enhancement or when a temporary lining is required. Full-scale bending tests were performed on concrete segments reinforced with GFRP and steel bars in order to compare their structural performance. The results show the effectiveness of the proposed GFRP solution for this type of application. Additionally, a case study is developed presenting provisions for safety checks on GFRP-reinforced tunnel segments.