Study on the performance of cast in situ concrete wet joints in PCSBs under cyclic loading

The wet joint is usually adopted in the closure section of precast concrete segmental bridges (PCSBs); the regular longitudinal reinforcement is discontinuous, which makes this section the most vulnerable part. To study the performance of the wet joint in the closure section under cyclic loading, six specimens are tested, considering loading mode, interface treatment method, setting of regular reinforcement and prestressing. Results show that the damage of the wet joint accumulates and plasticity develops under cyclic loading; the specimens undergo residual deformation, strength attenuation and stiffness degradation. Increase in prestressing level can delay cracking; the cracking load of specimens with a prestressing level of 8 MPa and 10 MPa is 21.9% and 32.8% higher, respectively, than that of the specimen with a stress level of 6 MPa; the results also confirm that an excessive prestressing level cannot significantly improve the shear strength of specimens. When the controlled displacement is small, the residual deformation of the specimen is small and the strength attenuates slowly; with the increase in controlled displacement, the residual deformation of the specimen increases and speeds up, the strength decreases continuously and the development of the crack tends to be stable, leading to a levelling off in the degradation of stiffness.