Analysis Of Bridge-Vehicle Coupling Vibration On Curve Bridge Of Straddle Monorail Transit

Straddle-type monorail transit is a new type of urban rail transit. It has better ability of grade climbing and better adaptability to pass complex terrain, and it is particularly well suited to be used for the primary transportation in the mountain cities that are more ups and downs on the ground. The construction of the new traffic system is mainly elevated bridge and the most of route is curve, its track beam is bridge structures that bear loads as well as the guide of the vehicles. The body's structure of monorail vehicles is unique, and bogies with rubber tires wheel are adopted, so the running and guiding mechanism and the wheel-rail contact relationship are obviously different from the tradition steel wheel and steel rail transit system, and all of the feature lead to the bridge-vehicle interaction to straddle monorail system is peculiarity. At present, research on straddle monorail transit is still little, only a few research papers are limited to the analysis of the dynamic interaction of the straddle-type monorail built by straight beam. The theory of bridge-vehicle coupling vibration interaction is imperfect and immature, and that has effect on the further promotion and application of the new technology. On the base of the straddle-type monorail system numbered two in Chongqing, equations of bridge-vehicle coupling vibration are derived and established, the track irregularity and seismic load are introduced to the analysis, the corresponding analysis software of vehicle-bridge coupling vibration is developed and also verified by test, based on the verification software, the author discuss the influence to the result of vehicle-bridge coupling vibration for the difference such as bridge span, vehicle speed, track irregularity, curve radius, earthquake, etc. The main contents and research results are as follows:1) Dynamic analysis model of curved track beamBased on the simple torsion theory, using the methods of structural mechanics, the stiffness matrix of the curved beam element is derived in the flow curve coordinate system, the concentrated load and uniform load on the curved element are equivalent to the node load, and all of the node load is assembled to the node matrix. Further more, the consistent mass matrix of a curved beam is derived and established. Final, the global stiffness matrix, mass matrix and node load matrix are established by "set-in-right-position" rule. The curved beam damping matrix is also created that is based on the Rayleigh proportional damping. 2) Dynamic analysis model of monorail vehicleAccording to the structure and running gear features of straddle-type monorail vehicle, the dynamic model of monorail vehicle with15DOFS is established. Based on point contact model of the inflatable rubber tires, the tire has been simplified. That are deduced included the radial force of the wheel, damping force, side force, self aligning torque(SAT) and moment produced by yaw. According to D'Alembert principle, dynamic equations of straddle-type monorail bridge-train interaction are deduced. When the radius of curve beam tends to infinity, dynamic mode of straddle monorail transit with curve beam is approached to that with straight beam.3) The simulation of track irregularity and preparation for solution algorithm on bridge-vehicle coupling analysis programReferring to the sixth track irregularity power-spectral-density function of U.S.A railways, and power spectrum of road roughness and power spectral density function of surface roughness of rail beam measured in Japanese literatures, based on triangle series method, track irregularity series on time are simulated to be generated. Step by step integration algorithm of Nemark's β method is adopted to solve the vibration equations, and the "prediction-correction" method is used at each time step.4) Development program and test verification on analysis of bridge-vehicle coupling vibration to the curve bridge of straddle monorail transitBased on the theoretical equations on bridge-vehicle coupling vibration and design ideas to solve bridge-vehicle vibration analysis, the program on bridge-vehicle coupling vibration analysis is developed. By verification of test in straight and curve bridge of straddle monorail transit in Chongqing, theory on bridge-vehicle coupling vibration in this paper is proved to be accurate and the program is effective.5) The influence of bridge structure design parameters and operating parameters to dynamic response of bridge-vehicle systemIt is based on the bridge-vehicle coupling vibration program of verification for the dynamic behaviors analysis of straddle monorail bridge and vehicle, the influence is discussed of the bridge span, the radius of curve, train speed, track irregularity, etc. The results are as follows:①The influence of bridge-vehicle coupling vibration performance on the bridge span and train speed is complex and is showed the impact of complex shape.②When the curve radius is greater than600m, the influence of the curve radius can be approximation ignored;③Track irregularity on the surface of bridge significantly affect the bridge-vehicle coupling vibration performance, the accuracy of track irregularity simulated is directly related to the reliability of the analysis result.6) Theory of bridge-vehicle coupling vibration analysis with earthquake and parameter sensitivity analysisThe input pattern of earthquake wave is study, bridge-vehicle coupling vibration equations with earthquake is derived, the program is developed, the bridge-vehicle coupling vibration performance under earthquake is discussed on the influence of the initial conditions, train speed, the curve radius, etc. The research results are as follows:①Seismic influence the coupled vibration of the track beam and vehicle;②The input pattern of seismic excitation can be seismic acceleration wave;③Monorail vehicle is equivalent to the role of the bridge damper, the vibration response of the bridge is slightly weakened, but the vehicle has a significantly increase in the vibration response;④The initial position of the train at the time of earthquake coming has a great impact on the results of bridge-vehicle coupling vibration.⑤When the curve radius is less than600m, the bridge-train vibration significantly increased with the reduction of the radius, and when the curve radius is greater than600m, the influence of the radius can be ignored.⑥The effect of train speed to vibration response under earthquake is not obvious.