Noise and Vibration Mitigation Performance of Damping Pad under CRTS-III Ballastless Track in High Speed Rail Viaduct

Linya Liu,Rui Song,Yun-Lai Zhou,Jialiang Qin 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.8

This study proposes a frequency domain vehicle-track coupling model for the CRTS (China railways track system)-III type damping track system based on the two-dimensional vehicle-track-viaduct coupling model, and utilizes dynamic compliance method to determine the dynamic compliance for the vehicle and track systems. The accelerations for the viaduct are hereinafter obtained and are compared between CRTS-III damping track system and conventional CRTS-III track system, and the structure-borne noises for near field and far field of the viaduct are assessed with finite element method (FEM). The acoustic contribution rates for the substructures of the viaduct to the near-field and far-field noises are analyzed. The results reveal that in comparison with the conventional CRTS-III system, the CRTS-III damping track system can mitigate the viaduct acceleration peak with 69.9%, and mitigate the average acceleration with 60.4%. The near field and far field noise measurement points are captured for the CRTS-III damping track system, the sound pressure levels decline by 8.15 dB and 8.36 dB, respectively. The acoustic contribution rates for the viaduct top plate reach 65.28% and 68.30%, respectively. The viaduct top plate thus becomes the major noise source and the damping track system can effectively mitigate the structure-borne noise of the viaduct.

Structural noise mitigation for viaduct box girder using acoustic modal contribution analysis

Liu Linya,Jialiang Qin,Yun-Lai Zhou,Rui Xi,Siyuan Peng 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.4

In high-speed railway (HSR) system, the structure-borne noise inside viaduct at low frequency has been extensively investigated for its mitigation as a research hotspot owing to its harm to the nearby residents. This study proposed a novel acoustic optimization method for declining the structure-borne noise in viaduct-like structures by separating the acoustic contribution of each structural component in the measured acoustic field. The structural vibration and related acoustic sourcing, propagation, and radiation characteristics for the viaduct box girder under passing vehicle loading are studied by incorporating Finite Element Method (FEM) with Modal Acoustic Vector (MAV) analysis. Based on the Modal Acoustic Transfer Vector (MATV), the structural vibration mode that contributes maximum to the structure-borne noise shall be hereinafter filtered for the acoustic radiation. With vibration mode shapes, the locations of maximum amplitudes for being ribbed to mitigate the structure-borne noise are then obtained, and the structure-borne noise mitigation performance shall be eventually analyzed regarding to the ribbing conduction. The results demonstrate that the structural vibration and structure-borne noise of the viaduct box girder mainly occupy both in the range within 100 Hz, and the dominant frequency bands both are [31.5, 80] Hz. The peak frequency for the structureborne noise of the viaduct box girder is mainly caused by 16th and 62th vibration modes; these two mode shapes mainly reflect the local vibration of the wing plate and top plate. By introducing web plate at the maximum amplitude of main mode shapes that contribute most to the acoustic modal contribution factors, the acoustic pressure peaks at the field-testing points are hereinafter obviously declined, this implies that the structure-borne noise mitigation performance is relatively promising for the viaduct.

Study on vibration energy characteristics of vehicle-track-viaduct coupling system considering partial contact loss beneath track slab

Linya Liu,Zhiyuan Zuo,Qinyue Zhou,Jialiang Qin,Quanmin Liu 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.4

CA mortar layer disengagement will give rise to the overall structural changes of the track and variation in the vibration form of the ballastless track. By establishing a vehicle-track-viaduct coupling analysis and calculation model, it is possible to analyze the CRTS-I type track structure vibration response while the track slab is disengaging with the power flow evaluation method, to compare the two disengaging types, namely partial contact loss at one edge beneath track slab and partial contact loss at midpoint beneath track slab. It can also study how the length of disengaging influences the track structures vibration power. It is showed that when the partial contact loss beneath track slab, and the relative vibration energy level between the rail and the track slab increases significantly within [10, 200]Hz with the same disengaging length, the partial contact loss at one edge beneath track slab has more prominent influence on the vibration power than the partial contact loss at midpoint beneath track slab. With the increase of disengaging length, the relative vibration energy level of the track slab grows sharply, but it will change significantly when it reaches 1.56 m. Little effect will be caused by the relative vibration energy level of the viaduct. The partial contact loss beneath the track slab will cause more power distribution and transmission between the trail and track slab, and will then affect the service life of the rail and track slab.

Prediction of vibration and noise from steel/composite bridges based on receptance and statistical energy analysis

Quanmin Liu,Linya Liu,Huapeng Chen,Yunlai Zhou,Xiaoyan Lei 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.3

The noise from the elevated lines of rail transit has become a growing problem. This paper presents a new method for the rapid prediction of the structure-borne noise from steel or composite bridges, based on the receptance and Statistical Energy Analysis (SEA), which is essential to the study of the generation mechanism and the design of a low-noise bridge. First, the vertical track-bridge coupled vibration equations in the frequency domain are constructed by simplifying the rail and the bridge as an infinite Timoshenko beam and a finite Euler-Bernoulli beam respectively. Second, all wheel/rail forces acting upon the track are computed by taking a moving wheel-rail roughness spectrum as the excitation to the train-track-bridge system. The displacements of rail and bridge are obtained by substituting wheel/rail forces into the track-bridge coupled vibration equations, and all spring forces on the bridge are calculated by multiplying the stiffness by the deformation of each spring. Then, the input power to the bridge in the SEA model is derived from spring forces and the bridge receptance. The vibration response of the bridge is derived from the solution to the power balance equations of the bridge, and then the structure-borne noise from the bridge is obtained. Finally, a tri-span continuous steel-concrete composite bridge is taken as a numerical example, and the theoretical calculations in terms of the vibration and noise induced by a passing train agree well with the field measurements, verifying the method. The influence of various factors on wheel/rail and spring forces is investigated to simplify the train-track-bridge interaction calculation for predicting the vibration and noise from steel or composite bridges.

Acoustic Radiation and Dynamic Study of a Steel Beam Damped with Viscoelastic Material

Quanmin Liu,Xiaozhen Li,Peipei Xu,Linya Liu,Yun-Lai Zhou 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.7

Steel structures subject to dynamic loads are prior to generate excessive vibration and noise. Viscoelastic treatment is an effective measure to mitigate the vibration and noise from thin-walled structures in a broad frequency range. H-shaped steel beams are widely used in civil engineering. So an experiment system is established and a series of impact hammer tests are conducted to assess the modal parameters, dynamic response and acoustic behaviour of an H-shaped steel beam coated with various viscoelastic treatments. Firstly, the spectra of the velocity response and acoustic radiation of the bare beam are analysed based on the tested data. Secondly, the resonance frequencies and modal loss factors of the beam with various viscoelastic treatments derived from the frequency response function are compared. Finally, the effect of the layout and thickness of viscoelastic patches on the mitigation of vibration and noise is discussed experimentally. It is shown that the modal loss factor of the first mode increases from 0.012 to 0.191 when the web is treated with 5 mm thick constrained layer damping (CLD). The viscoelastic patches on the web of the H-shaped beam are more effective to control the vibration and noise of the beam than the patches on the flanges. The viscoelastic treatment has distinct effect on the reduction of structural vibration and noise owing to the different dominant frequencies of vibration and noise as well as the frequency-dependent radiation efficiency. The normal velocity level of the H-shaped beam with an 8 mmthick web can be reduced by more than 10 dB and the sound pressure level around the beam about 8 dB when the web is partially covered with the constrained layer damping composed of 2.0 mm thick damping layer and 3.0 mm thick constraining layer.