Selection of Design Parameters of Straddle Monorail System Considering Vehicle–bridge Interaction

Vehicle-bridge interaction (VBI) is an essential focal point in the design of straddle monorail systems. Existing studies on them primarily use multibody dynamics software, however, it is disadvantageous as several important factors such as nonlinear excitations, structural nonlinearity, and bridge alignment defects cannot be analyzed. Therefore, a co-simulation approach is proposed in this paper to investigate the dynamic responses of the straddle monorail VBI system where various factors can be easily considered. The proposed approach couples bridge and vehicle subsystems through global iterations with the exchange of wheel-rail contact forces and bridge responses calculated using MATLAB and ANSYS, respectively. The accuracy of the proposed approach is validated using numerical and experimental data reported in existing literature. Further, the effect of design parameters on the dynamic responses of the straddle monorail VBI system is analyzed using the proposed approach. The analysis results indicate that a single-axle straddle monorail train outperforms the conventional two-axle train with reduced dynamic responses and lighter mass. Recommendations are provided for the stiffness and damping of the guiding, stabilizing, and riding wheelsets, as well as for the vertical and lateral stiffness and damping of the air springs. The radius of a girder curve should be at least 150 m over regular operation sections to ensure riding safety; it can be less at special entrance and exit sections where the train speed is low. The findings of these parametric analyses provide guidelines to select proper design parameters for straddle monorail systems to mitigate dynamic responses.