• Title, Summary, Keyword: Vehicle-track interaction

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Analysis of high-speed vehicle-bridge interactions by a simplified 3-D model

  • Song, Myung-Kwan;Choi, Chang-Koon
    • Structural Engineering and Mechanics
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    • v.13 no.5
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    • pp.505-532
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    • 2002
  • In this study, the analysis of high-speed vehicle-bridge interactions by a simplified 3-dimensional finite element model is performed. Since railroads are constructed mostly as double tracks, there exists eccentricity between the vehicle axle and the neutral axis of cross section of a railway bridge. Therefore, for the more efficient and accurate vehicle-bridge interaction analysis, the analysis model should include the eccentricity of axle loads and the effect of torsional forces acting on the bridge. The investigation into the influences of eccentricity of the vehicle axle loads and vehicle speed on vehicle-bridge interactions are carried out for two cases. In the first case, only one train moves on its track and in the other case, two trains move respectively on their tracks in the opposite direction. From the analysis results of an existing bridge, the efficiency and capability of the simplified 3-dimensional model for practical application can be also verified.

Evaluation of Train Running Safety for Direct Fixation Concrete Track on Light Rapid Transit (경전철 직결식 콘크리트 궤도구조의 열차주행안전성 평가)

  • Choi, Jung-Youl;Kim, Jun-Hyung;Chung, Jee-Seung;Lee, Sun-Gil
    • Journal of the Korean Society of Safety
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    • v.32 no.5
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    • pp.41-46
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    • 2017
  • The coefficient of derailment and the rate of wheel load reduction were used as the index of train running safety that was directly affected the train derailment safety. In aspects of track, the train running safety depends on the complex interaction between wheel and rail, and the track-vehicle conditions (i.e., the curvature, cant, track system, vehicle speed and the operation conditions, etc). In this study, the relationship between the train running safety and the track curvature and vehicle speed for direct fixation concrete tracks currently employed in Korean light rapid transit was assessed by performing field tests using actual vehicles running along the service lines. The measured dynamic wheel load, lateral wheel load and lateral displacement of rail head were measured for same train running on four tested tracks under real conditions, which included curved and tangent tracks placed on the tunnel and bridge, thus increasing the train speed by approximately maximum design speed of each test site. Therefore, the measured dynamic track response was applied to the running safety analysis in order to evaluate the coefficient of derailment, the rate of wheel load reduction and the track gauge widening at each test site, and compare with the corresponding Korean train running safety standard. As the results, the lateral track response of direct fixation concrete track appeared to increase with the decreased track curvature; therefore, it was inferred that the track curvature directly affected the train running safety.

Dynamic Analysis for a Flexible Track Modeling of Turnout (분기기 궤도 유연체 모델링 및 동역학 해석)

  • Kim, Man-Cheol;Hwang, Sung-Ho;Hwang, Kwang-Ha;Hyun, Sang-Hak
    • Proceedings of the KSR Conference
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    • pp.2830-2837
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    • 2011
  • In this paper, a flexible track modeling of turnout was developed and dynamic characteristics of turnout rails were analyzed when a vehicle passed through the turnout. The flexible track modeling is effective to the stiffness and durability design of turnout, because it can capture the deformation and dynamic stress due to the collision of between wheels and rails when the vehicle move to the tongue rail. Also, a more accurate running safety can be obtained by considering the interaction between wheel and rail deformation. Solid finite elements were used for variable cross-sections of rails and the variation of rubber stiffness was modeled. The proposed flexible track modeling in this paper was verified to be valid by comparison with the experiment of the turnout system.

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Dynamic analysis of metro vehicle traveling on a high-pier viaduct under crosswind in Chongqing

  • Zhang, Yunfei;Li, Jun;Chen, Zhaowei;Xu, Xiangyang
    • Wind and Structures
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    • v.29 no.5
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    • pp.299-312
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    • 2019
  • Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train under crosswind. Compared with the conditions of no-wind, crosswind triggers severer vibration of the dynamic system; compared with the short-pier viaduct, the high-pier viaduct has worse stability under crosswind. For these reasons, the running safety of the metro vehicle traveling on a high-pier viaduct under crosswind is analyzed to ensure the safe operation in metro lines in mountain cities. In this paper, a dynamic model of the metro vehicle-track-bridge system under crosswind is established, in which crosswind loads model considering the condition of wind zone are built. After that, the evaluation indices and the calculation parameters have been selected, moreover, the basic characteristics of the dynamic system with high-pier under crosswind are analyzed. On this basis, the response varies with vehicle speed and wind speed are calculated, then the corresponding safety zone is determined. The results indicate that, crosswind triggers drastic vibration to the metro vehicle and high-pier viaduct, which in turn causes running instability of the vehicle. The corresponding safety zone for metro vehicle traveling on the high-pier is proposed, and the metro traffic on the high-pier bridge under crosswind should not exceed the corresponding limited vehicle speed to ensure the running safety.

A recursive multibody model of a tracked vehicle and its interaction with flexible ground

  • Han, Ray P.S.;Sander, Brian S.;Mao, S.G.
    • Structural Engineering and Mechanics
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    • v.11 no.2
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    • pp.133-149
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    • 2001
  • A high-fidelity model of a tracked vehicle traversing a flexible ground terrain with a varying profile is presented here. In this work, we employed a recursive formulation to model the track subsystem. This method yields a minimal set of coordinates and hence, computationally more efficient than conventional approaches. Also, in the vehicle subsystem, the undercarriage frame is assumed to be connected to the chassis by a revolute joint and a spring-damper unit. This increase in system mobility makes the model more realistic. To capture the vehicle-ground interaction, a Winkler-type foundation with springs-dampers is used. Simulation runs of the integrated tracked vehicle system for vibrations for four varying ground profiles are provided.

The Fatigue Life Evaluation of CWR based on the Rail Grinding (레일연마를 고려한 장대레일의 피로수명 평가)

  • Kong, Sun-Young;Sung, Deok-Yong;Park, Yong-Gul
    • Journal of The Korean Society of Civil Engineers
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    • v.35 no.5
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    • pp.1191-1198
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    • 2015
  • In this study, vehicle/track interaction analysis by the Saemaul powered vehicle was carried out. The prediction equation for the bending stress of rail was estimated using the rail bending stress by the rail surface irregularities at welds. Also, the fatigue analysis using a S-N curve of welds in the conventional railway was carried out. We estimated the fatigue life of CWR by the fracture probability. By the rail grinding, the fatigue life of CWR was evaluated in consideration to reduce the rail bending stress through removing the rail surface irregularities. Therefore, it presented the fatigue life of CWR according to the rail grinding execution plan in the conventional railway.

Prediction and Control of the Propogation of Underground Train Systems-induced Ground Vibration: State of the Art (지하철 차량운행에 의한 진동영향 평가: State of the Art)

  • Lee, In-Mo;Choe, Sang-Sun
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.73-82
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    • 1993
  • Ground-borne vibration is one of the main causes of environmental impact from subway systems. The vibration resulting from track-train interaction is transuutted through the tunnel structure and the surrounding ground to adjacent buildings. This paper provides a summary of proposed noise and vibration criteria, a review of the ground vibration propagation mechanism and the theoretical isolation effectivenesss of each of the following underground transit systems : track, tunnel and vehicle itself.

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A Study on the dynamic behavior of rail due to diped joints (레일이음매에서 발생되는 궤도동적거동에 대한 연구)

  • Kang, Yun-Suk;Yang, Shin-Chu
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.337.2-337
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    • 2002
  • When vehicle travelling along the track which has irregularity such as vortical profile, dynamic forces arise at the Wheel/Rail contact patch by wheel/rail interaction. In particular short wavelength irregularities on dipped joint and small stiffness of connecting rail bring about intense wheel/rail dynamic effects at higher speed. In the paper, a new model for dipped joint rail is developed to study dynamic behavior of track. (omitted)

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Wind loads on a moving vehicle-bridge deck system by wind-tunnel model test

  • Li, Yongle;Hu, Peng;Xu, You-Lin;Zhang, Mingjin;Liao, Haili
    • Wind and Structures
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    • v.19 no.2
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    • pp.145-167
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    • 2014
  • Wind-vehicle-bridge (WVB) interaction can be regarded as a coupled vibration system. Aerodynamic forces and moment on vehicles and bridge decks play an important role in the vibration analysis of the coupled WVB system. High-speed vehicle motion has certain effects on the aerodynamic characteristics of a vehicle-bridge system under crosswinds, but it is not taken into account in most previous studies. In this study, a new testing system with a moving vehicle model was developed to directly measure the aerodynamic forces and moment on the vehicle and bridge deck when the vehicle model moved on the bridge deck under crosswinds in a large wind tunnel. The testing system, with a total length of 18.0 m, consisted of three main parts: vehicle-bridge model system, motion system and signal measuring system. The wind speed, vehicle speed, test objects and relative position of the vehicle to the bridge deck could be easily altered for different test cases. The aerodynamic forces and moment on the moving vehicle and bridge deck were measured utilizing the new testing system. The effects of the vehicle speed, wind yaw angle, rail track position and vehicle type on the aerodynamic characteristics of the vehicle and bridge deck were investigated. In addition, a data processing method was proposed according to the characteristics of the dynamic testing signals to determine the variations of aerodynamic forces and moment on the moving vehicle and bridge deck. Three-car and single-car models were employed as the moving rail vehicle model and road vehicle model, respectively. The results indicate that the drag and lift coefficients of the vehicle tend to increase with the increase of the vehicle speed and the decrease of the resultant wind yaw angle and that the vehicle speed has more significant effect on the aerodynamic coefficients of the single-car model than on those of the three-car model. This study also reveals that the aerodynamic coefficients of the vehicle and bridge deck are strongly influenced by the rail track positions, while the aerodynamic coefficients of the bridge deck are insensitive to the vehicle speed or resultant wind yaw angle.

Random vibration analysis of train-slab track-bridge coupling system under earthquakes

  • Zeng, Zhi-Ping;He, Xian-Feng;Zhao, Yan-Gang;Yu, Zhi-Wu;Chen, Ling-Kun;Xu, Wen-Tao;Lou, Ping
    • Structural Engineering and Mechanics
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    • v.54 no.5
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    • pp.1017-1044
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    • 2015
  • This study aimed to investigate the random vibration characteristic of train-slab track-bridge interaction system subjected to both track irregularities and earthquakes by use of pseudo-excitation method (PEM). Each vehicle subsystem was modeled by multibody dynamics. A three-dimensional rail-slab- girder-pier finite element model was created to simulate slab track and bridge subsystem. The equations of motion for the entire system were established based on the constraint condition of no jump between wheel and rail. The random load vectors of equations of motion were formulated by transforming track irregularities and seismic accelerations into a series of deterministic pseudo-excitations according to their respective power spectral density (PSD) functions by means of PEM. The time-dependent PSDs of random vibration responses of the system were obtained by step-by-step integration method, and the corresponding extreme values were estimated based on the first-passage failure criterion. As a case study, an ICE3 high-speed train passing a fifteen-span simply supported girder bridge simultaneously excited by track irregularities and earthquakes is presented. The evaluated extreme values and the PSD characteristic of the random vibration responses of bridge and train are analyzed, and the influences of train speed and track irregularities (without earthquakes) on the random vibration characteristic of bridge and train are discussed.