Study On Prediction Of High Speed Vehicle-bridge Coupling Vibration And Viaduct Bridge Structure Noise Radiation

Due to the rapid development of high speed railway and the high proportion of viaduct bridge in high speed railway in China, the vibration and noise radiation of viaduct bridge structure caused by the high-speed train moving on the bridge become one of the focuses which more and more scholars pay attention to. The studies on vibration and noise radiation of the bridge structure have important theoretical values and engineering application values for ensuring the safety and durability of viaduct railway bridge, improving the ride comfort and reducing influences of vibration and noise of high speed railway on the residents and buildings along the line. In this paper, a simply supported high speed railway box bridge is taken as the research object, and a vehicle-track-bridge vertical coupling dynamics model which takes the influences of vibration of track structure on the dynamic responses of bridge structure into consideration and an acoustic analysis model of the bridge structure are developed to study the vibration and noise radiation of the bridge structure.Firstly, a vehicle-track-bridge vertical coupling dynamics model is established. The vehicle subsystem is considered as a multi-rigid-body system with 10 DOFs. The fasteners and the CA(cement and asphalt) mortar layer are modeled by linear spring-damper elements. Two kinds of the dynamic track-bridge interaction subsystems are developed. One of the dynamic track-bridge interaction subsystems is simplified as a multi-beam model in which the rail, track slab and bridge are respectively simplified as the infinite Timoshenko beam, freedom-freedom Euler beam and simply supported Euler beam, and then the dynamic flexibility functions of the vehicle subsystem and the dynamic track-bridge interaction subsystem are deduced. In another dynamic track-bridge interaction subsystem, the track slab is considered as the thin Kirchhoff plate and the bridge structure is modeled by finite element method. Then, the wheel/rail interaction is used to couple the vehicle subsystem and the dynamic track-bridge interaction subsystem, and the vehicle-track-bridge coupling dynamics model is thereby developed.Then, the developed vehicle-track-bridge coupling dynamics model is used to calculate the vertical wheel/rail forces and the dynamic responses of the rail, track slab and bridge structure excited by the wheel/rail geometric irregularity. additionally, based on the vehicle-track-bridge coupling dynamics model, the vertical wheel/rail force amplitude spectrums and the random vibrations of the rail, track slab and bridge structure excited by track spectrum are solved by using pseudo excitation method.Finally, the vertical wheel/rail forces excited by the wheel/rail geometric irregularity are applied on the finite element model of track-bridge coupling dynamic subsystem which is established by ABAQUS finite element software to calculate the dynamic responses of the finite element model of bridge structure. And then, taking the dynamic responses of the finite element model of the bridge structure as the boundary conditions, the noise radiation characteristics of the bridge structure are obtained by the boundary element acoustic analysis model of the bridge structure which is established in Virtual.Lab acoustics software.Depending on all above studies, we can get the conclusions as fellows.The entire structure vibration shape modals of the bridge are mainly in low frequency range. In relative high frequency range, the vibration shape modals of the bridge are mainly the local vibration shape modals of which are mainly the local vibration shape modals of the wing plates. The plate and shell element can well reflect the local structure vibration shape modals of the top plate, web plates and bottom plate, therefore it is suitable for the vibration and noise radiation analysis of the bridge structure.With the frequency increasing, the vertical dynamic flexibility amplitudes of the rail, track slab and bridge minish in order. In whole frequency range, the dynamic flexibility phases of the rail are always negative, however, the dynamic flexibility phases of the track slab and bridge are more complex, which have the trend of more obvious oscillation with the frequency increasing above 1000 Hz. The vibration attenuations in longitudinal direction of the rail are small in the frequency range of less than 1000 Hz but are relatively large in the frequency range of more than 1000 Hz. The vibration attenuations in longitudinal direction of the track slab and bridge are relatively complex.When the vehicle speed is 250 km/h, excited by the wheel/rail geometric irregularity or the German high speed low disturbance spectrum and Sato track spectrum, the vertical vibration accelerations of the vehicle body are mainly concentrated in the frequency range of less than 10 Hz. The vertical vibration accelerations of the rail are mainly in 500~3500Hz, especially around 1000 Hz, and are very small in low frequency range. The vertical vibration accelerations of the track slab are mainly in 300~1500Hz. The vertical vibration accelerations of the bridge are mainly in the low frequency range of less than 300 Hz, and they are almost zero above 300 Hz.The rail vibration absorbers have obvious influences on the dynamic track-bridge interaction system in the frequency ranges of around the first two order resonance frequencies of the rail vibration absorbers. In other frequency ranges, the rail vibration absorbers have hardly any influences. Overall, the influences of the rail vibration absorbers on the vibrations of the rail, track slab and bridge minish in order.The sound field distribution of the bridge struture are more regular and the sound pressures are also larger in the area above the top plate of the bridge structure, compared with that in the area below the bottom plate of the bridge structure. With the distance from the bridge structure increasing, the sound pressures decrease, and the sound field distribution is becoming more and more complex. In low frequency range, the sound field distribution is relatively simple, and becomes more and more complex with the frequency increasing, and there are even layered distribution. Overall, the sound pressure decreases as the distance of the sound field point from the bridge structure increases, especially in the frequency range of less than 70 Hz this decreasing trend is almost linear. The sound pressures of all sound field points reach maximums at about 50 Hz. As the frequency increases, the sound pressure change with frequency of each sound field point fluctuates, and the sound pressure differences between different sound field points not longer simply decrease but more complex as the distance of the sound field points to the bridge structure.