###### Abstract
Several studies on the dynamic behavior of monorail traffic were carried out based on the above research results. [PERSON] and [PERSON] [25] proposed a method to study the dynamic responses of straddle-type monorail trains, under the action of transverse winds, and used shock absorbers to control the lateral and rolling motion of the vehicle. [PERSON] [26] proposed a substructure method to study the dynamic responses of monorails during high-speed operation. The vehicles were regarded as a moving substructure comprising rod elements, whereas the bridge was regarded as rigid bodies with viscoelastic links. Hence, the complex equations of motion of the system were replaced by those of two simple substructures. [PERSON] [27] established a monorail-bridge-foundation system model to assess the vibration characteristics of the monorail system. However, the motion equation of the vehicle was complicated, and the motion equation of the elastic monorail-bridge system was difficult to solve due to the particular structure of straddle-type monorails. The vehicle in a straddle-type monorail is a typical multi-rigid body structure. Therefore, a method based on multibody dynamics was developed to study the dynamic behavior of straddle-type monorail-bridge systems. [PERSON] [28; 29; 30] established the motion equation of a straddle-type monorail vehicle through multibody dynamics and studied its curve passing performance, without considering the deformation of the track beam. [PERSON] et al. [31; 32] established a straddle-type monorail vehicle model with the multibody software SIMPACK, analyzed the dynamic response of the vehicle in curve driving, and proposed a reasonable curve driving speed. However, supporting structures or bridges of monorail traffic were ignored. [PERSON] et al. [33] conducted a dynamic test on the typical sections of the Chongqing straddle-type monorail, during which they tested the strain, displacement, and acceleration of the track beam under different speeds and braking conditions, thereby, providing a database for follow-up studies on the dynamic behavior of straddle-type monorails. [PERSON] et al. [34] established a monorail suspension model with SIMPACK and carried out dynamic analysis of the coupled vehicle-bridge system, through which they studied the influence of factors, such as speed and track irregularity, on the dynamic characteristics of the coupled system. [PERSON] [35] carried out dynamic simulations on straddle-type monorail vehicle-bridge coupled systems, and proposed improved design parameters for the track beam. Several scholars made substantial efforts to solve the problem of vehicle-bridge coupling vibrations in straddle-type monorails, based on the multibody dynamic theory. However, although the supporting bridge of a monorail is a typical elastic structure, it is still necessary to explore a suitable method to study vehicle-bridge coupling vibrations, based on the characteristics of straddle-type monorails and bridges. In this study, a combined method based on FE theory and multibody dynamics was proposed, which accounted for the dynamic characteristics of the vehicle and the bridge. In this study, a coupled vehicle-bridge model was proposed, based on FE theory and multibody dynamics. The FE method was used to establish an elastic bridge model, whereas the multibody dynamics theory was used to establish a vehicle model. These were combined by the coordination of wheel-rail contact points. Taking the bridge dynamic response and vehicle dynamic response as the main indices, the influence laws of the vehicle speed, pier height, vehicle load, and track irregularity, on the dynamic performance and riding comfort of straddle-type monorails were studied. Finally, measures to improve the riding comfort of straddle-type monorails were proposed, which could provide some basis for designing similar projects.