• Title, Summary, Keyword: Rail temperature

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The Characteristics of Rail Temperature for Track Maintenance (궤도 관리를 위한 레일 온도의 특성)

  • 구봉근;서사범
    • Journal of the Korean Society for Railway
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    • v.3 no.1
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    • pp.19-26
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    • 2000
  • The rail temperature is important to preserve the joint gap for standard length of rail and to determine the installation temperature which has direct influence on the rail buckling and failure in welded part for continuous welded rail(CWR), Therefore, we have measured and investigated various characteristics of rail temperature for each kind of rail. As the results of this, the correlation between the atmosphere temperature and the rail temperature which is commonly used by Korean Railway should be reconsidered. Also, the daily highest '||'&'||' lowest rail temperature was occurred when each temperature is higher and when it's lower. For the light rail, the rail temperature by the sun-light increases quickly and decreases late. But the time where the highest temperature is attained is same. There are some differences between the shade and sunny place about 3.0∼4.0$\^{C}$. The temperature of rail web is almost close to the conversion rail temperature for rail expansion. The wind of 1 m/s has an influence on the rail temperature around 5$\^{C}$.

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Case of Application of Rail Temperature Detector for Track Management (궤도 관리를 위한 레일온도검지장치 설치 사례)

  • Chung, Sung-Hyun;Shin, Gil-Cheol;Kim, Gil-Soo
    • Proceedings of the KSR Conference
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    • pp.1362-1369
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    • 2007
  • Seoul Metro continuously converted the standard rail into continuous welded rail since the later part of 1990's, and currently, most of the sectors of the Seoul Metro are continuous welded rails. As the continuous welded rail is inhibited by the contraction and expansion force of the rail as well as rail-bed, this force is stored as the internal stress of the rail with the exception of portion of the both ends of the continuous welded rail. If the contraction and expansion of the rail is restricted, the internal stress, that is, the force in the direction of the axis, is proportional to the cross-sectional area of the rail. Therefore, with regards to the temperature changes, the internal stress changes in accordance with the type of rail, bolting apparatus, railroad tie and rail-bed. As such, the rail temperature becomes important data in securing the gap at the adjoining section of the rail in the standard rail section, and to determine the setting temperature for the continuous welded rail. In addition, it becomes basic data for maintenance of the track. Accordingly, this thesis introduces cases of installation of rail temperature detector in order to prevent and manage track defectiveness due to increase in rail temperature, and to utilize as basic data at the time of various construction and maintenance. Furthermore, this thesis aims to assist maintenance of track through systematic temperature management in the future by looking into means of its utilization.

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Rail Temperature under the Domestic Climate Condition (국내 기후환경에서의 레일온도)

  • Lee, Woo-Chul;Lee, Chin-Ok;Choi, Jin-Yu;Lim, Nam-Hyoung
    • Proceedings of the KSR Conference
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    • pp.546-547
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    • 2009
  • To ensure stability of continuous welded rail in extremely hot weather is important to the railway industry's goal of operational safety and maintenance. Rail temperature has direct influence on track buckling. According to climate condition, distribution of rail temperature is different. In this study, the fluctuation of rail temperature were investigated under the domestic climate condition (air temperature, humidity, insolation, etc)

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Field Test to Investigate the Thermal Stress of Continuous Welded Rail on High Speed Railway Bridges in Summer Period (고속철도 교량상 장대레일의 하절기 온도응력 계측)

  • Kwark, Jong-Won;Choi, Eun-Suk;Chin, Won-Jong;Lee, Jung-Woo;Kim, Byung-Suk;Kang, Jae-Yoon
    • Journal of the Korean Society for Railway
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    • v.9 no.2
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    • pp.131-136
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    • 2006
  • Most modern railways, especially the high speed railway tracks, use continuous welded rail(CWR) for the less maintenance. For the CWR track has very few expansion joints, track buckling has always been an unpredictable event and it happens mainly by high compressive stress in rail in summer period. Therefore, it is important to understand the variation of rail stress induced by thermal loads which has direct influence on the rail buckling and stability of railway track. This paper describes the experimental investigation of the variation of rail temperature and stress in a high speed railway track on bridge structure. Field measurement was performed to examine the correlation between the rail temperature and rail stress on the Korean High Speed Railway line. Regression functions were derived from measured data to determine the rail stress f3r an arbitrary rail temperature varies from 20 to 50 degree Celsius.

Effect of temperature gradient on track-bridge interaction

  • Kumar, Rakesh;Upadhyay, Akhil
    • Interaction and multiscale mechanics
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    • v.5 no.1
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    • pp.1-12
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    • 2012
  • Considerable longitudinal rail forces and displacements may develop in continuous welded rail (CWR) track on long-span bridges due to temperature variations. The track stability may be disturbed due to excessive relative displacements between the sleepers and ballast bed and the accompanied reduction in frictional resistance. For high-speed tracks, however, solving these problems by installing rail expansion devices in the track is not an attractive solution as these devices may cause a local disturbance of the vertical track stiffness and track geometry which will require intensive maintenance. With reference to temperature, two actions are considered by the bridge loading standards, the uniform variation in the rail and deck temperature and the temperature gradient in deck. Generally, the effect of temperature gradient has been disregarded in the interaction analysis. This paper mainly deals with the effect of temperature gradient on the track-bridge interaction with respect to the support reaction, rail stresses and stability. The study presented in this paper was not mentioned in the related codes so far.

Investigation on the Temperature Characteristics of CWR for the Climate Change (기후변화에 대비한 장대레일 온도특성 연구)

  • Choi, Jin-Yu;Lee, Gyu-Sei;Bae, Hyun-Ung;Park, Beom-Ho;Lim, Nam-Hyoung
    • Journal of the Korean Society for Railway
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    • v.13 no.2
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    • pp.179-185
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    • 2010
  • In order to secure safety for the buckling and fracture of continuous welded rail and improve the efficiency of maintenance work, it is very important that grasp the characteristics of rail temperature. Recently, the maximum air temperature in summer season rises gradually and the minimum air temperature in winter season is decreasing gradually due to the climate change. Therefore, these phenomenon influences in the change amount of yearly rail temperature and can cause change of laying and maintenance temperature. In this study, actual measurement of rail temperature including climatic factors is carried out by constructing the temperature and climate measurement system as realistic as possible. Through the intensive investigation of actual data, it is founded that the existing prediction formulas for rail temperature may be used only in certain climatic conditions (certain combination of climatic factors). It may be more reasonable that the rail temperature considering actual climatic factors in site is predicted on probabilistic approach.

Investigation of Thermal Stress of Continuous Welded Rail on High Speed Railway Bridge (경부고속철도 교량상 장대레일의 온도응력 계측 실험)

  • Kang, Jae-Yoon;Choi, Eun-Suk;Chin, Won-Jong;Lee, Jung-Woo;Kwark, Jong-Won;Kim, Byung-Suk
    • Proceedings of the KSR Conference
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    • pp.458-461
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    • 2007
  • Recently, the continuous welded rail(CWR) track has been used for less maintenance of the High-speed railway tracks. In case of CWR track, track buckling has always been an unpredictable event under the high compressive stress in rail. The behavior and stress state of CWR track is manily influenced by its thermal variations, and it is important to understand seasonal variations of rail temperature and stress to predict the track stability. This paper describes the in-site measurement for the rail temperature and rail stress, and the correlation between the rail temperature and stress was examined.

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Nonlinear earthquake response analysis of CWR on bridge considering soil-structure interaction. (지반-구조물 상호작용을 고려한 교량상 장대레일의 비선형 지진응답해석)

  • Shin Ran Cheol;Cho Sun Kyu;Yang Shin Chu;Choi Jun Seong
    • Proceedings of the KSR Conference
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    • pp.733-738
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    • 2004
  • Recently continuous welded rail is generally used to ensure running performances and to overcome the problems such as structural vulnerability and fastener damage at the rail expansion joint. Though the use of continuous welded rail on bridge has the advantage of decreasing the vibration and damage of rail, it still the risk of buckling and breaking of rail due to change of temperature, starting and/or breaking force, axial stress concentration and so on. So, VIC code and many methods has been developed by researchers considering rail-bridge interaction. Although there are many research concerning stability of continuous welded rail about temperature change on bridge and starting and/or breaking force, the study of continuous welded mil for earthquake load is still unsufficient. In this study, the nonlinear seismic response analysis of continuous welded rail on bridge considering soil-structure interaction, geotechnical characteristic of foundation and earthquake isolation equipment has been performed to examine the stability of continuous welded rail.

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Fatigue Crack Growth Behavior of Rail Steel at Low temperature (저온하에서 레일강의 피로균열진전거동)

  • Kim Chul-Su;Yo Yoon-Kee;Kim Young-Kyun
    • Proceedings of the KSR Conference
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    • pp.85-90
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    • 2003
  • Among rail defects, the transverse crack, which has been the most dangerous fatigue damage, is developed from shelling near the rail running face and grows perpendicular to the rail surface. Moreover, the crack has occurred frequently fatigue damage during winter. Therefore, to assure the safety of railway vehicles, it is necessary to investigate growth behavior of transverse crack for rail steel. In this study, fatigue crack growth behavior of rail steel and its gas pressure welded part at room and low temperature are performed. The fatigue crack growth rate of the welded part was lower than that of the base part within a lower ${\Delta}K$ region at both room and low temperature, and this difference decreases with increasing the ${\Delta}K$ due to the decrease of the fracture toughness.

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Interaction analysis of Continuous Slab Track (CST) on long-span continuous high-speed rail bridges

  • Dai, Gonglian;Ge, Hao;Liu, Wenshuo;Chen, Y. Frank
    • Structural Engineering and Mechanics
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    • v.63 no.6
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    • pp.713-723
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    • 2017
  • As a new type of ballastless track, longitudinal continuous slab track (CST) has been widely used in China. It can partly isolate the interaction between the ballastless track and the bridge and thus the rail expansion device would be unnecessary. Compared with the traditional track, CST is composed of multi layers of continuous structures and various connecting components. In order to investigate the performance of CST on a long-span bridge, the spatial finite element model considering each layer of the CST structure, connecting components, bridge, and subgrade is established and verified according to the theory of beam-rail interaction. The nonlinear resistance of materials between multilayer track structures is measured by experiments, while the temperature gradients of the bridge and CST are based on the long-term measured data. This study compares the force distribution rules of ballasted track and CST as respectively applied to a long span bridge. The effects of different damage conditions on CST structures are also discussed. The results show that the additional rail stress is small and the CST structure has a high safety factor under the measured temperature load. The rail expansion device can be cancelled when CST is adopted on the long span bridge. Beam end rotation caused by temperature gradient and vertical load will have a significant effect on the rail stress of CST. The additional flexure stress should be considered with the additional expansion stress simultaneously when the rail stress of CST requires to be checked. Both the maximum sliding friction coefficient of sliding layer and cracking condition of concrete plate should be considered to decide the arrangement of connecting components and the ultimate expansion span of the bridge when adopting CST.