Experimental and numerical investigations on shear behavior of large keyed tooth joints

Keyed tooth joint(KTJ) is recognized as the key connection component of precast concrete segmental bridges(PCSB). In this study, the shear behavior of eight scenarios of “Z” type KTJ specimens, including different bonding types, geometries and size of the keys, and reinforcement configurations in the key, is investigated through both direct shear tests and numerical simulation, and the test results are compared with formulas in previous studies. The focus of this study is on the large KTJ (joint with a single large key), which owns the advantages of easy fabrication and configuration of internal reinforcements. Based on the load-slip curve and failure modes of the KTJ specimens under the shear, regardless of key type, the shear capacity of the epoxied KTJ is significantly larger than the dry KTJ without epoxy. With the same contact areas, the shear capacity of the large KTJ is larger than that of the KTJ with multi-small keys. The “direct shear” dominates the failure mode of the plain KTJ specimens. Adding internal reinforcements contribute to strengthening the connection at the joint and converting the dominant failure mode to the “crushing” mode. Further, finite element models(FEM) are established to analyze the shear behavior of keyed joints with different reinforcement and stirrup ratios. Compared to stirrups, adding longitudinal reinforcement is more effective in enhancing the load-bearing capacity and ductility of the reinforced large KTJ specimen under shear. Bakhoum's formula is most accurate in predicting the experimental results. From this study, it is suggested to utilize epoxied joint with the reinforced large shear key in precast concrete segmental bridges.