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High-pier railway bridges are mostly applied in mountainous areas. Due to the large spatial flexibility of the high piers under train dynamic loads, especially under braking conditions, the wheel-rail (WR) dynamic interaction may become more intense in the longitudinal direction, which could induce larger deformation and impact on the train-track-bridge (TTB) coupled system. To investigate the dynamic characteristics of such complex and large system during train braking condition, a 3D train-slab track-high pier bridge (TTHPB) coupled dynamics model is established and verified by considering the system longitudinal vibrations and the spatial flexibility of high piers. In this work, the influence of concerned bridge height from 60 to 160 m on the dynamic performances of the TTHPB system under train braking condition is studied. Results indicate that the operation speed has a significant effect on carbody acceleration and WR force. The longitudinal carbody acceleration due to its high-frequency vibration, as well as its noticeable amplitude induced by the long-time frequent braking, should be carefully considered in the evaluation of riding comfort index. The longitudinal dynamic behaviour of the high pier bridge is considerable and should be paid full attention to in bridge design compared with the other two directions. [ABSTRACT FROM AUTHOR]

The combined centre of gravity (CCOG) height of a suspended monorail train may have a certain influence on the centrifugal forces acting on the train under crosswinds, and changes in centrifugal forces will further affect the dynamic interactions among the crosswind, the vehicle and the bridge subsystem. To investigate the effect of CCOG height on the dynamic behaviour of the train, this paper proposes an improved wind-vehicle-bridge coupling dynamics model considering the CCOG height for the suspended monorail system, in which the uneven passenger weight distribution is simulated with various vehicle parameters, and the aerodynamic wind forces acting on the running vehicles and bridge are simulated considering the effect of resultant wind yaw angle. The influences of passenger number, wind velocity, and vehicle speed on the dynamic behaviours of suspended monorail trains are also explored. The results indicate that the suspended monorail train has a certain self-balancing ability due to its unique structure type, which causes the lateral responses of the car body to attenuate with the increasing car weight. In addition, it is conservative to not consider the effect of CCOG height in the lateral ride comfort evaluation of the suspended monorail train subject to crosswinds. [ABSTRACT FROM AUTHOR]

In order to study the rail corrugation phenomenon with the wavelength of 160-250mm in the steel spring floating slab track of a certain subway straight section, a rigid-flexible coupling dynamics model of the vehicle-steel spring floating slab track is established based on the finite element theory and the vehicle-track coupling dynamics theory. From the point of view of the vibration characteristics of track system and the contact characteristics of wheel and rail, the causes and mitigation measures of rail wave wear are studied by taking the rail wear power as the evaluation index. The generation of rail corrugation may be related to the transverse co-direction/reverse bending vibration modes of the rails on the left and right sides of the 8-15 order, the vertical bending mode of the track plate of the 8-9 order, and the torsional vibration mode of the track plate of the 6-8 order. Under the premise of not affecting driving safety, wear power at the rail wave wear frequency can be reduced by taking the vertical stiffness of the fastener 10~30 MN/ m, the vertical damping of the fastener more than 20 kN·s/m or the lateral damping of the fastener 30 kN·s/m, so as to slow down the development of rail wave wear. [ABSTRACT FROM AUTHOR]

This work elaborately conducts the coupled vibration analysis of suspended monorail train and curved bridge (SMTCB) considering a nonlinear wheel-track contact relation. First, a high-efficiency coupled dynamic model of the SMTCB is developed based on a co-simulation method where the train subsystem is established using the multi-body dynamics software UM and the curved bridge subsystem is built adopting the finite element software ANSYS, whose modal information is extracted to put into the UM software; Two subsystems of the train and bridge are coupled by an improved wheel-track contact model (IWTCM) that considers the real nonlinear radial stiffness of a suspended monorail rubber tire. Then, the effects of the extracted modal orders of the bridge on vehicle-bridge vibrational responses are analyzed and discussed in detail, and the minimum modal orders extracted of the bridge that guarantee the convergence and accuracy of the proposed model are also obtained. Subsequently, the vibrational responses obtained by numerical simulation and field test are compared when the vehicle runs on a curved bridge, validating the reliability of the developed model. On this basis, by comparing the vehicle-bridge vibration responses between the traditional FIALA tire model and the IWTCM, some remarkable differences are distinguished, revealing the significances and advantages of adopting the IWTCM. Finally, employing the developed model, the vehicle-curved bridge coupled vibration features are investigated comprehensively and several key parameters are also chosen reasonably. The research results may provide some useful guidance for the design of the SMTCB. [ABSTRACT FROM AUTHOR]

To study the impact coefficient of track beams due to moving suspended monorail vehicles under the bridge deck, this paper presents a vehicle-bridge dynamic model based on the rigid-flexible coupling method. Finite element method is used to establish the bridge model, and the vehicle is simulated as a multi-body dynamic model The mechanical characteristics of running tire are precisely modelled and the dynamic equations for the suspended monorail vehicle-bridge coupling system are derived. The proposed approach employs a double-line 7-span bridge with 210 m length as a numerical example, the impact performance of two track beams are studied and the results are verified by comparing with the theoretical solutions. The influences of critical system parameters, such as the train formation and double-line trains loads, on the dynamic responses of vehicles and the bridge are explored. The results show that it is feasible to study the impact effect with the proposed method. The separation phenomenon of rubber running tires jumping up on track surface occurs when vehicle speed is high, which may lead to negative impact coefficients. The impact coefficients of the track beam vary much with different locations, which can even be negative values at locations nearing the pier area. [ABSTRACT FROM AUTHOR]

This work presents an integrated and large-scale field measurement of the dynamic responses of a suspended monorail train–bridge system, which is rarely reported. This experimental train uses a high-capacity lithium battery for the operation. The maximum running speed of the train is up to 60 km/h. The experimental line was constructed on a full-scale steel bridge composed of a straight section, curved sections with different horizontal radiuses and a slope section of 60‰. First, the train–bridge dynamic responses under different conditions are extracted based on the field test. Then, the car-body accelerations under different train speeds and bridge sections are analysed in detail, and the running stability of the vehicle is assessed by adopting the Sperling index. By comparing the dynamic responses of the train–straight bridge interaction and the train–curved bridge interaction, some significant discrepancies and interesting phenomena could be found. Subsequently, based on the test data, the vertical rotation angles of the beam end and the dynamic amplification factors of the bridge displacements under different vehicle speeds and bridge sections are obtained, and then the vibration levels of the bridge under different conditions are evaluated. Finally, by analysing the frequency spectra of the dynamic responses, the dominant frequencies of the acceleration signals of this monorail vehicle and bridge subsystems are revealed; in addition, the sensitive wavelengths that influence the running stability of the vehicle are found. These measurement results may provide valuable guidance for the design of the suspended monorail system and numerical model validation. [ABSTRACT FROM AUTHOR]

This study aims to select the proper key parameter values of suspended monorail system (SMS) by analysing the vehicle–bridge dynamical interaction. First, a coupled dynamical model of vehicle–bridge system is established by using ANSYS parameter design language (APDL). Further, the car-body accelerations obtained by the proposed model and field test are systematically analysed in frequency domain. A sensitive parameter influencing the vehicle ride comfort is identified. The key parameter value of the bridge is selected with the objective to improve the vehicle-bridge vibration level. Finally, accounting the out-of-round tyre, the dynamical performance of vehicle and bridge is investigated under periodic harmonic disturbance, and proper values of secondary suspension parameters of vehicle subsystem are selected. Results show that the space between bridge stiffeners is a sensitive parameter that can aggravate the car-body acceleration. This space is finally suggested to be 1.2–1.4 m in order to effectively reduce the vehicle-bridge dynamical interaction. Controlling the vertical stiffness of secondary suspension to be less than 0.2 MN/m, the periodic harmonic disturbance can be effectively isolated. To ensure a reasonable vibration level of vehicle–bridge system suffering from periodic harmonic disturbance, the vertical damping of secondary suspension is suggested to be about 27 kN·s/m. [ABSTRACT FROM AUTHOR]