• Title, Summary, Keyword: Running Safety

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A framework for carrying out train safety evaluation and vibration analysis of a trussed-arch bridge subjected to vessel collision

  • Xia, Chaoyi;Zhang, Nan;Xia, He;Ma, Qin;Wu, Xuan
    • Structural Engineering and Mechanics
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    • v.59 no.4
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    • pp.683-701
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    • 2016
  • Safety is the prime concern for a high-speed railway bridge, especially when it is subjected to a collision. In this paper, an analysis framework for the dynamic responses of train-bridge systems under collision load is established. A multi-body dynamics model is employed to represent the moving vehicle, the modal decomposition method is adopted to describe the bridge structure, and the time history of a collision load is used as the external load on the train-bridge system. A (180+216+180) m continuous steel trussed-arch bridge is considered as an illustrative case study. With the vessel collision acting on the pier, the displacements and accelerations at the pier-top and the mid-span of the bridge are calculated when a CRH2 high-speed train running through the bridge, and the influence of bridge vibration on the running safety indices of the train, including derailment factors, offload factors and lateral wheel/rail forces, are analyzed. The results demonstrate that under the vessel collision load, the dynamic responses of the bridge are greatly enlarged, threatening the running safety of high-speed train on the bridge, which is affected by both the collision intensity and the train speed.

Analysis of the Influence of Track Alignment on Ride Comfort and Safety of KTX (방향틀림이 KTX 주행거동에 미치는 영향 분석)

  • Choi, Il-Yoon;Um, Ju-Hwan;Kim, Man-Cheol
    • Journal of the Korean Society for Railway
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    • v.16 no.2
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    • pp.110-116
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    • 2013
  • Track irregularities is one of the key factors influencing the running behavior of trains. In order to ensure safety and ride comfort of train, the criteria for track irregularities should be adequately established regarding vehicle velocity, vehicle characteristics, characteristics of the track recording car, and measurement interval. Also, track maintenance should be carried out thoroughly according to the criteria for managing track irregularities. Numerical analysis was conducted to investigate the influence of track alignment on the running behavior of Korean high speed train(KTX). Various wavelengths and amplitudes of lateral alignment were considered as parameters for this study using the Vampire program, a vehicle dynamics modeling package in railway environment. Derailment, lateral load, bogie acceleration and body acceleration of numerical analysis results due to alignment were investigated. Finally, the influence of the alignment on safety and ride comfort for the KTX was evaluated. This study indicates that alignment irregularities have significant impacts on running safety, and that the criteria used to manage alignment irregularities should be restrictive to ensure the running safety of the KTX.

Evaluation of Curving Performance and Running Safety of New High-Power Electric Locomotive (신형 고출력 전기기관차의 곡선추종성 및 주행안전성 평가)

  • Ham, Young Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.6
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    • pp.827-832
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    • 2013
  • In this study, curve responsiveness was assessed based on the lateral force and running safety was evaluated based on the wheel unloading ratio and derailment coefficient, which is the ratio of the wheel load and the lateral force. The evaluation of the curving performance and running safety of the new high-power electric locomotive showed that the derailment coefficient appeared higher when the wheel-set was set to the front of the train instead of being placed backward, and the maximum value of the derailment coefficient was recorded as 0.572 on the Gyeongbu line. Furthermore, the lateral force increased in curved sections, and it appeared to be proportional to the curve radius. Meanwhile, a maximum axis lateral force of 77.6 kN was recorded on the Taebaek line, and the wheel unloading ratio was 47.6% on the Yeongdong line. Finally, the running safety at the maximum speed as well as the through-curve performance of the curve radius satisfied the required standards.

Dynamics of high-speed train in crosswinds based on an air-train-track interaction model

  • Zhai, Wanming;Yang, Jizhong;Li, Zhen;Han, Haiyan
    • Wind and Structures
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    • v.20 no.2
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    • pp.143-168
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    • 2015
  • A numerical model for analyzing air-train-track interaction is proposed to investigate the dynamic behavior of a high-speed train running on a track in crosswinds. The model is composed of a train-track interaction model and a train-air interaction model. The train-track interaction model is built on the basis of the vehicle-track coupled dynamics theory. The train-air interaction model is developed based on the train aerodynamics, in which the Arbitrary Lagrangian-Eulerian (ALE) method is employed to deal with the dynamic boundary between the train and the air. Based on the air-train-track model, characteristics of flow structure around a high-speed train are described and the dynamic behavior of the high-speed train running on track in crosswinds is investigated. Results show that the dynamic indices of the head car are larger than those of other cars in crosswinds. From the viewpoint of dynamic safety evaluation, the running safety of the train in crosswinds is basically controlled by the head car. Compared with the generally used assessment indices of running safety such as the derailment coefficient and the wheel-load reduction ratio, the overturning coefficient will overestimate the running safety of a train on a track under crosswind condition. It is suggested to use the wheel-load reduction ratio and the lateral wheel-rail force as the dominant safety assessment indices when high-speed trains run in crosswinds.

Increasing Superelevation on Freeway Interchange Ramp based on Running Speed (주행속도를 고려한 고속도로 나들목 연결로의 편경사 상향조정에 관한 연구)

  • Roh, Jeonghoon;Kim, Hong-bae;Seo, Mu In;Lee, Gil Jae
    • International Journal of Highway Engineering
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    • v.18 no.6
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    • pp.161-171
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    • 2016
  • OBJECTIVES : Many roadway departure crashes on the freeway interchange are due to the running speed being greater than the design speed. This study aims to ensure a safe and pleasant driving experience for the driver by increasing the superelevation based on the running speed on the highway interchange ramp. METHODS : The mean running speed for each type of ramp is calculated on site survey more than 10 interchanges. Using the mean running speed, we calculated the superelevation and the side friction using the method given in "A Policy on Geometric Design of Highways and Street" (Pages 145-166, 2001). Then, we applied the modified method to the superelevation range. Finally, we ensured safety using the Degree of Safety that is proven by the centrifugal acceleration ratio as suggested by Joseph Craus (1978). RESULTS : The mean running speeds are 50 km/h and 65 km/h when the design speeds are 40 km/h and 50 km/h, respectively. After the application of the new method used in this study, the superelevation will be increased by 9.0% and 10.0% when the mean running speeds are 50 km/h and 65 km/h, respectively. CONCLUSIONS : A higher superelevation can give the driver a more comfortable and safe driving environment. However, the driver needs to be aware of snow and low-temperature conditions.

The Effect of KTX Vehicle Size Adjustment on High-Speed Railway Bridge Vibration : Numerical Study (수치해석을 통한 KTX 객차 길이 조정이 고속철도교량의 동적거동 특성에 미치는 영향 연구)

  • Shin, Jeong-Ryol;Kim, Hyun-Min;Sohn, Hoon;Yun, Chung-Bang
    • Proceedings of the KSR Conference
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    • pp.854-863
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    • 2008
  • A high attention has been paid on the running safety of Korean high-speed train, KTX. In running of KTX on bridge, the running unsafety problem issued from a resonance phenomenon of bridge, which was usually caused by the periodic wheel-loads of train. Therefore, many researches on this running safety of train on bridge have been conducted by domestic or foreign researchers. In this paper, for PSC box-girder bridge which is the representative high-speed railway bridge type, some numerical analyses on the dynamic characteristics of bridge with the non-periodic wheel-loads through vehicle size adjustment were performed. These numerical analyses shows the fact that the resonance phenomenon on bridge was mitigated through vehicle size adjustment. Additional numerical analyses on the vibration reduction of bridge in accordance with the location of size-adjusted vehicle were performed. From these results, it was represented that the adjustment of vehicle size has an effect on the running safety of train as well as the ride comfort.

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Vibrational Characteristics of an End Beam of a Freight Cal- on the Taebaek Line (태백선을 주행하는 화차 엔드빔의 진동특성에 관한 연구)

  • 문경호;홍재성;이동형;서정원;함영삼
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.10
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    • pp.962-967
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    • 2004
  • A bogie is the device that connects a car body and wheel sets of a rail vehicle. It is the critical component that determine:; the running safety, The bogie consists of a frame, suspensions, brakes and wheel sets. Various analyses including a numerical simulation using a finite element method, a static load test, a fatigue test, ai)d r running test should be carried out to design the bogie. However cracks have been found at some end beams of the bogies mounted on the freight cars running with the high speed. The cracks of the end beam results in deterioration of the brake performance an the running safety, A new design has been suggested to solve this problem by ROTEM company and it's performance has been tested in this paper. Numerical simulations and dynamic tests are carried out to figure out the causes of cracks in the conventional bogie, and the vibrational characteristics of the improved bogie are compared with those of the conventional one.

Evaluation of Running Safety and Ride Comfort for High Speed Train in Cases of Superimposition of Vertical and Horizontal Curves (종곡선과 평면곡선의 경합조건별 차량주행안전성 및 승차감 평가)

  • Um, Ju-Hwan;Choi, IL-Yoon;Kim, Man-Cheol
    • Journal of the Korean Society for Railway
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    • v.16 no.4
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    • pp.311-317
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    • 2013
  • In railway construction, superimposition of horizontal and vertical curves has critical effects on the running stability and the ride comfort of vehicles as well as on construction costs. In this study, running safety, ride comfort, and track acting forces were analyzed by a numerical analysis using the VAMPIRE program according to cases of superimposition of vertical and horizontal curves. From the analysis results, it was found that running safety, riding comfort, and track acting forces in the case of superimposition of vertical and horizontal curves as well as vertical and transition curves meet all of the criteria. Also, in the case of the superimposition of vertical curves and curvature change between horizontal transition curves and circular curves meet all of the criteria.