Comparison of the structural behavior of reinforced concrete and steel fiber reinforced concrete tunnel segmental joints

Abstract Segmental joints act as a weak link in the tunnel lining both in terms of structural responses (due to the lower stiffness and strength compared to the main segments) and the serviceability considerations (high risk of water/gas leakage). Despite the wide applications of steel fiber as an alternative material due to the corrosion resistance and the labor reduction in shield tunnel engineering, very limited studies focus on the structural performance of segmental joints with steel fiber reinforced concrete (SFRC). In this paper, full-scale tests were conducted to study the ultimate bearing capacity of the conventional reinforced concrete (RC) and the SFRC joints under different loading conditions with a special attention on the corresponding cracking process. The experimental results demonstrated that the peak load bearing capacity of the SFRC joints was slightly higher than that of the RC joints. Furthermore, SFRC joints provided higher initial cracking load, sufficient ductility in the compressive-flexural actions, equivalent energy absorption capacity at initial cracking, and significant reduction in crack width compared to that of the RC joints. The performance-based engineering (PBE) concept was introduced to assess the robustness of the tested joints. According to these results, it is suggested that the SFRC can substitute the traditional reinforcement in terms of maintained bearing capacity and improved cracking control. Finally, it was verified that the classical joint design method was able to capture the flexural capacity of the tested RC and SFRC joints.