3-D Numerical Simulation of Seismic Response of the Induced Joint of a Subway Station

In recent times, induced joints have been set along the length of subway stations in order to avoid disordered cracking of the main structures occurring due to temperature stress, concrete shrinkage, creep, or uneven foundation settlement. At present, the use of induced joints in subway station structures is mainly based on engineering experience. The seismic response of induced joints has not yet been well explained, much less mastered. In this study, a 3-D numerical model of a subway station incorporating certain sorts of induced joints is established systematically. Then, the seismic response of those induced joints applied in different positions and various forms has been studied under different seismic waves by varying the spectral characteristics and peak acceleration values of the waves. The results show that the horizontal relative sliding displacement of the structures on both sides of an induced joint increases gradually from bottom to top along the structure of the subway station. While the vertical sliding displacements that occur along the section width are larger at both ends of the induced joints than in the middle. What is more, with an increase in seismic intensity, the horizontal relative sliding displacement becomes larger, while the vertical displacement becomes even smaller. In addition, the relative sliding displacement can be reduced by increasing the residual longitudinal reinforcement ratio of the induced joint. Furthermore, it is discovered that the setting of key grooves at the bottom plate of the induced joint section has a certain effect on controlling the horizontal relative sliding displacement, as well as a significant effect on preventing the vertical relative dislocation of the structures on both sides of the induced joint.