A suspended monorail transit system is a category of urban rail transit, which is effective in alleviating traffic pressure and injury prevention. Meanwhile, with the advantages of low cost and short construction time, suspended monorail transit systems show vast potential for future development. However, the suspended monorail has not been systematically studied in China, and there is a lack of relevant knowledge and analytical methods. To ensure the health and reliability of a suspended monorail transit system, the driving safety of vehicles and structure dynamic behaviors when vehicles are running on the bridge should be analyzed and evaluated. Based on the method of vehicle-bridge coupling vibration theory, the finite element method (FEM) software ANSYS and multi-body dynamics software SIMPACK are adopted respectively to establish the finite element model for bridge and the multi-body vehicle. A co-simulation method is employed to investigate the vehicle-bridge coupling vibration for the transit system. The traffic operation factors, including train formation, track irregularity and tire stiffness, are incorporated into the models separately to analyze the bridge and vehicle responses. The results show that the coupling of dynamic effects of the suspended monorail system between vehicle and bridge are significant in the case studied, and it is strongly suggested to take necessary measures for vibration suppression. The simulation of track irregularity is a critical factor for its vibration safety, and the track irregularity of A-level road roughness negatively influences the system vibration safety.
Compared with medium and small span bridges, very limited attention has been paid on the research of the impact coefficient of long-span railway bridges. To estimate the impact effects of long-span railway bridges subjected to moving vehicles, a real long-span railway cable-stayed bridge is regarded as the research object in this study, and a coupled model of vehicle-bridge system is established. The track irregularities are taken as the system excitation and the dynamic responses of the vehicle-bridge system are calculated. The impact effects on main girder, stayed cable, bearings, and bridge tower are discussed at various vehicle speeds. The results show that different components of the long-span railway cable-stayed bridge have different impact coefficients. Even for each part, the impact coefficient is also different at different local positions. It reveals that the impact coefficients in the actual situation may have significant differences with the related code clauses in the present design codes.
Based on the theories of aerodynamics, bridge dynamics, and vehicle dynamics, the aerodynamic performances and the vibration characteristics of the wind–vehicle–bridge coupling system of two suspended monorail trains passing each other are analyzed. First, a wind model is presented with spectral representation method, the aerodynamic coefficients of bridge and vehicles before and after meeting are obtained through computational fluid dynamic method, and wind tunnel tests are conducted to verify the aerodynamic coefficients. Then, a vehicle dynamic model and a bridge dynamic model are established with the multi-body dynamic method and finite element method. Finally, a three-dimensional wind–vehicle–bridge coupled vibration model is established in this article using the multi-body dynamic software SIMPACK. The effects of average wind and fluctuating wind on the wind–vehicle–bridge system are studied. It is shown that the aerodynamic coefficients vary greatly under different combinations of vehicle–bridge system. The responses of the leeward vehicle change abruptly at the beginning and the end of the meeting of the two trains. And the mean wind speed has a great negative contribution to the acceleration of leeward vehicle. The lateral responses of suspended monorail vehicle are sensitive to the fluctuating wind. The roll angle of vehicle is presented for describing the running safety of the suspended monorail vehicles.
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