Study on shear behavior and acoustic emission characteristics of precast concrete segmental cover beams with large key teeth

The mechanical characteristics of segmental joints are pivotal in defining the comprehensive stress behavior of prefabricated assembled cover beams. In this research, direct shear tests were conducted on dry key-tooth joints, and acoustic emission technology was employed for monitoring purposes. The shear failure mechanism was explored under a range of influential parameters. Building upon these observations, the study delved into the mechanical response of joints within segmental cover girders subjected to concurrent bending and shear forces. Specimen K-3-3 exhibited a higher shear carrying capacity compared to other specimens, indicating that the shear resistance of dry joints proportionally increases with the height of the specimen and the strength of the concrete. The carrying capacity of Specimen K-4 was marginally lower than that of Specimens K-3-1 and K-3-2, suggesting that increasing the number of keys does not significantly impact the shear resistance of dry joints. Notably, Specimen K-3 demonstrated exceptional shear carrying capacity, exhibiting minimal relative slip during failure, and streamlined the casting process. Consequently, these dry joints featuring large key teeth are deemed more appropriate for use as shear connectors in precast concrete segmental cover beams. Crack patterns in large key tooth precast concrete segmental cover beams propagate along the joints. A damage evolution model for the specimens, based on spatial b-values and T-values, visually depicts the damage extent in large key tooth precast concrete segmental cover beams. This model demonstrates excellent agreement with experimental results and provides a solid foundation for theoretical research and practical applications of large key tooth precast concrete segmental cover beams.