Research On Vehicle-bridge Coupling Limits Of Straddle-type Monorail Traffic Under Cross Wind Disturbance

Rail transit in mountainous cities is developing rapidly,but due to its special geographical environment,the track lines are staggered.On the one hand,compared with the track lines of plain cities,mountain cities adopt the establishment of straddle-type monorail transportation,and viaducts are more susceptible to environmental gusts,causing strong vibration of the vehicle-bridge system: on the other hand,compared with linear track beams,Curved track beams have worse dynamic response and greater vibration under cross-wind disturbances,which in turn will cause a sudden decline in the safety of monorail trains,which may cause derailment or overturning,resulting in traffic interruption.Therefore,from the perspective of dynamics,the operating safety limits of straddle-type monorail vehicles under cross-wind disturbances and their improvement measures are given in order to provide some theoretical basis for the early design and later operation and maintenance of straddle-type monorail vehicles and lines.In the first step,based on the vehicle-bridge interaction theory,a straddle-type monorail vehicle-track beam dynamic model is considered under the consideration of wind load.Among them,the monorail vehicle and the rail beam bridge are considered as two subsystems respectively.The interaction relationship connects the car,tire and track beam into a coupling system.Geometric constraints are imposed on the established finite element model of the track beam,and the first 6 order elastic main modes are calculated to obtain the parameters such as the deflection and the angle of rotation of the simply supported beam.The dynamic model of the straddle-type monorail vehicle-rail beam coupling system is verified by the model,which proves the reliability and accuracy of the model.At the same time,two types of wind load models were established.One was a reference to the European standard EN14067-6 to establish a Chinese cap pulsating gust load model.The dynamic gust wind speed in the wind load model was superposed by the steady wind speed and the fluctuating gust wind speed.The wind speed power spectrum is simulated,and the random pulsating wind speed field at space points is obtained by using the harmonic synthesis method,so as to establish an unsteady random wind load model.At the same time,the aerodynamic load acting on the vehicle can be simplified into side force,lift force,overturning moment,nodding moment and shaking moment.The aerodynamic load acting on the track beam system is simplified by the resistance,lift and moment coefficients,and the aerodynamic and aerodynamic forces are determined.Moment coefficient.In the second step,this thesis chooses the Newmark-β integral method in the calculation method,establishes the wind-vehicle-bridge solution process,establishes the evaluation system of the wind-span monorail vehicle-track beam system,and selects the calculation parameters.In the third step,the influence characteristics of the wind-saddle monorail vehicletrack beam system are analyzed.The wind load,vehicle,track beam radius,and track irregularities are considered.The appropriate working conditions are selected for research.The results show that: the unsteady random wind load is larger than the transient China as a whole and more generally representative to simulate natural wind load.The fluctuation of wind load will directly affect the dynamic response of the monorail train.The larger the peak value of the fluctuation,the greater the dynamic response of the monorail train,and the more obvious the effect.Compared with the light load,the heavy rail is to a certain extent the monorail train runs more smoothly.When two kinds of excitations of track irregularity and wind load act on a monorail vehicle together,the vehicle vibration response effect is obvious.In the last step,based on the above studies,the safety and stability of vehicle operation are evaluated according to the selected monorail vehicle-rail beam evaluation indicators to establish a vehicle operation safety zone.The results show that with the increase of vehicle operating speed,the vehicle’s allowable critical safety Wind speed decreases.When the average wind speed at the standard altitude reaches 12.65 m / s,the critical speed of the vehicle is about 73.4 km / h;and if the vehicle is to be driven at 80 km / h and the speed on the track beam,the standard height wind speed detection should be limited to 11.5 m / s.