Bending behaviour of precast concrete segmental girders with steel rebars through epoxy joints

Abstract

Precast concrete segmental bridges (PCSBs) with epoxy or dry joints offer significant construction advantages, but their crack resistance and load-bearing capacity are typically lower than monolithic bridges due to the interruption of reinforcing steels at joints. In this study, the authors propose a solution to address this issue by introducing steel rebars through segmental girders’ joints (SR-TJs), inspired by the structural forms of prefabricated columns. To investigate the efficacy of this solution, five internal-bonded precast concrete I-girders were fabricated, including two segmental girders with steel rebars through the joint (PCSG-SRs), two traditional segmental girders, and one monolithic girder. Four-point flexural tests were conducted on these girders, which revealed the cracking at joints for PCSG-SRs was significantly higher than those observed in the traditional segmental girder and even the monolithic girder, demonstrating an improvement in crack resistance. To gain a more detailed understanding of the joint behaviour, a fibre beam model was developed. The model incorporated reinforcing fibres in the fibre beam element to represent the contribution of SR-TJs. The fibre beam model exhibited excellent agreement with the entire loading process of the girders, providing valuable insights into the behaviour of PCSBs with SR-TJs. Furthermore, the authors derived a simplified sectional method based on the findings to calculate the ultimate load during bond slip. And top plate crushing load was compared with the optimized calculation method in AASHTO. In summary, this study demonstrates that the addition of steel rebars through segmental girders’ joints improves both crack resistance and load-bearing capacity, offering the potential for the advancement of PCSBs.