Title: Punching-Shear Behavior of GFRP-Reinforced Precast Concrete Tunnel Segments

Author(s): Ahmed Elbady, Salaheldin Mousa, Hamdy M. Mohamed, and Brahim Benmokrane

Publication: Structural Journal

Volume:

Issue:

Appears on pages(s):

Keywords: deflection and strain; glass fiber-reinforced polymer (GFRP) bars; precast concrete tunnel lining (PCTL) segments; punching shear; reinforcement ratio; segment length; shear stirrups; theoretical predictions

DOI: 10.14359/51740709

Date: 3/20/2024

Abstract:
The behavior of precast concrete tunnel lining segments (PCTLs) reinforced with glass fiber-reinforced polymer (GFRP) bars under punching loads is one area in which no research work has been conducted. This paper reports on an investigation of the punching-shear behavior of GFRP-reinforced PCTL segments induced by soil conditions, such as rock expansion or the geotechnical conditions surrounding a tunnel. Six full-scale rhomboidal PCTL specimens measuring 1500 mm (59 in.) in width and 250 mm (9.8 in.) in thickness were constructed and tested up to failure. The investigated parameters were: (1) reinforcement type (GFRP or steel); (2) reinforcement ratio (0.46% or 0.86%); (3) stirrups as shear reinforcement; and (4) segment length (2100 mm or 3100 mm [82.7 in. or 122 in.]). The experimental results are reported in terms of cracking behavior, punching-shear capacity, deflection, strain in the reinforcement and concrete, and failure modes. The results reveal that the GFRP-reinforced PCTL segment was comparable with its steel counterpart with the same reinforcement ratio and satisfied serviceability limits. Both increasing the reinforcement ratio and decreasing the segment length enhanced the punching-shear strength. The shear stirrups improved the structural performance and increased the punching and deformation capacities of the GFRP-reinforced PCTL segments. In addition, theoretical predictions of the punching-shear capacity using the current design provisions were compared to the experimental results obtained herein. The theoretical outcomes show the suitability of using current FRP design provisions for predicting the punching capacity of PCTL segments reinforced with GFRP bars.