Enhancing structural robustness of segmental bridge joints via crossing reinforcement: experimental and analytical study

Joints in precast concrete segmental bridges (PCSBs) are prone to brittle failure because of reinforcement discontinuity. To enhance structural robustness and seismic resilience, this study proposes a ductile reinforced joint using continuous longitudinal reinforcement crossing the joint interface. Direct shear tests were conducted to compare the proposed joint with a traditional concrete key, with emphasis on reinforcement ratio and bonding condition. The results showed that the reinforced joint with a 0.7% reinforcement ratio achieved 1.65 times the ultimate shear capacity and a 16.97-fold increase in deformation capacity relative to the conventional key. Increasing the reinforcement ratio enhanced shear strength and restrained joint opening, although the improvement diminished beyond 0.25%. Epoxy bonding increased the ultimate capacity by 37% but changed the failure mode from ductile deformation to brittle fracture. Based on the observed load-transfer mechanisms, a Dual-Phase Analytical Model was developed to describe the sequential activation of interfacial adhesion, friction, and dowel action. The model reproduced the experimental results with a mean absolute error of less than 5%, demonstrating its potential for evaluating the shear capacity and robustness of reinforced segmental bridge joints.