## 3 Simulation and Analysis Model of Train-Track-Station Coupled Vibration
### Dynamic Response Results and Analysis of the Station Under Various Working Conditions  
Based on the previous discussions, a coupled vibration analysis of the vehicle-track-station system was conducted. A CRH3 train formation consisting of 16 cars in a 4\" (powered + trailer + trailer + powered) configuration was selected, and the German Low Interference Spectrum was used to simulate additional track irregularities during train operation. To investigate the dynamic response of the \"building-bridge integrated\" railway bridge station structure with and without the mainline separation joint, as well as the safety and comfort of the train, various track occupancy scenarios were considered: single line (3#), double lines (3#, 4#), triple lines (2#, 3#, 4#), quadruple lines (2#, 3#, 4#, 5#), quintuple lines (1#, 2#, 3#, 4#, 5#), and sextuple lines (1#, 2#, 3#, 4#, 5#, 6#). The dynamic responses of the structure induced by fully loaded trains running on the mainline at speeds of 200-350 km/h and on the arrival-departure lines at 80 km/h were calculated. The maximum dynamic responses of the rail bearing floor slab, platform slab, and train are presented in Tables 7-9. All vibration responses of the structures described below are measured relative to the initial equilibrium position. Table 7 summarizes the maximum dynamic responses of the rail bearing floor slab, for the two types of \"building-bridge integrated\" station structures under various operating conditions, including trains running on the mainline at speeds of 200-350 km/h and on the arrival/departure lines at 80 km/h. It can be observed that when a separation joint is introduced in the mainline, the direct connection between the mainline and the arrival/departure lines is severed. Since the interaction with the soil is not considered in this study, the maximum dynamic responses of the rail bearing floor slab, for the Station Type A, are identical for the double-line condition and the multi-line conditions (triple to sextuple lines). From Table 8, the maximum lateral accelerations for the rail bearing floor slabs of the Station Type A and Station Type B are 0.372 m/s\({}^{2}\) and 0.312 m/s\({}^{2}\), respectively. The maximum vertical accelerations are 1.593 m/s\({}^{2}\) and 1.516 m/s\({}^{2}\), respectively. These values meet the requirements of the Design Code for Railway Bridges and Culverts [26], which stipulates that the lateral and vertical vibration accelerations for ballastless track bridge decks should be less than 1.5 m/s\({}^{2}\) and 5 m/s\({}^{2}\), respectively. Table 8 provides the maximum dynamic response values of the platform slab for the two types of station structures under various operating conditions. For the Station Type A, the dynamic response values for the single-line and double-line conditions are zero. This is because the separation joint in the mainline cuts off the direct connection between the mainline rail bearing floor slab and the platform slab. Therefore, the dynamic response of the platform slab in this station is only caused by the arrival/departure lines (1#, 2#, 5#, 6#). Figure 6: First-Order Vertical Bending Mode Shape Diagram of the Station (Front View). (**a**) Station Type A; (**b**) Station Type B.  
Figure 7: First-Order Longitudinal Drift Mode Shape Diagram of the Station (Front View). (**a**) Station Type A; (**b**) Station Type B.