• Title/Summary/Keyword: 走行荷重

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Characteristics Method Analysis of Wind Pressure of Train Running in Tunnel (터널을 주행하는 열차의 풍압에 대한 특성해법 해석)

  • Nam, Seong-Won;Kwon, Hyeok-Bin;Yun, Su-Hwan
    • Journal of the Korean Society for Railway
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    • v.15 no.5
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    • pp.436-441
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    • 2012
  • Pressure waves are generated and propagate in tunnel when train enters a tunnel with high speed. Compression wave due to the entry of train head propagates along the tunnel and is reflected at tunnel exit as expansion wave. While expansion wave due to the entry of train tail propagates along the tunnel and is reflected at tunnel exit as compression wave. These pressure waves are repeatedly propagated and reflected at tunnel entrance and exit. Severe pressure change per second causes ear-discomfort for passengers in cabin and micro pressure wave around tunnel exit. It is necessary to analyze the transient pressure phenomena in tunnel qualitatively and quantitatively, because pressure change rate is considered as one of major design parameters for an optimal tunnel cross sectional area and the repeated fatigue force on car body. In this study, we developed the characteristics method analysis based on fixed mesh system and compared with the results of real train test. The results of simulation agreed with that of experiment.

Field Tests and Resonance Behavior Corresponding to the Damping Ratio of a High Speed Railroad Bridge (고속철도 교량의 현장실험 및 감쇠비 개선에 따른 공진 시 동적응답의 분석)

  • Kim, Sungil;Kim, Hyunmin;Park, Donguk
    • Journal of the Korean Society for Railway
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    • v.16 no.4
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    • pp.305-310
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    • 2013
  • In general, it is difficult to measure dynamic responses of a bridge with stepwise increasing speed of a train during commercial service on a high speed railroad. However, before opening the 2nd stage of the Gyeongbu high speed railroad, there was an opportunity for field tests and measurements of the bridge with stepwise increasing speed(from 170km/ h to 315km/h). The measured responses were compared with the results of a developed bridge/train interaction analysis. Although good agreement was found throughout almost the entire range of speeds, relatively large differences were found in the vicinity of the critical speed at which resonance behavior of the bridge occurs. To investigate the cause of this, reanalyses are performed with re-estimated damping ratios from field tests.

Dynamic Stability of a Railroad Bridge Using Bi-prestressing Technology (바이프리스트레싱 기법을 이용한 철도교량의 동적안정성)

  • Choi, Sanghyun;Lee, Changsoo;Lim, Jaehoon;Lee, Seungjoon;Yang, Sungdon
    • Journal of the Society of Disaster Information
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    • v.9 no.2
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    • pp.188-194
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    • 2013
  • As the high speed railroad line increases, researches on developing a more economic high speed railroad bridge system have been actively conducted. In this paper, a new type of prestressed concrete girder based on the bi-prestressing technique, which can introduce additional prestress, is presented. The additional prestress can be introduced using a wedge-shaped pin bar into the upper part of the girder section. The applicability of the new girder technique to the high speed railroad bridge is verified via the dynamic stability analysis. Dynamic moving load analyses using the KTX train load are conducted on bridge systems with the span lengths of 30m, 35m, and 40m, respectively. The results of the analysis show that all bridge systems satisfy the limits prescribed in the design specifications to ensure structural stability, driving safety, and ride quality.

A Convergence Study through Analysis of Strength and Durability on Automotive A-Pillar (자동차의 A필러에 대한 강도 및 내구성 해석을 통한 융합 연구)

  • Oh, Bum-Suk;Cho, Jae-Ung
    • Journal of the Korea Convergence Society
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    • v.10 no.11
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    • pp.297-302
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    • 2019
  • A-pillar is closely related to safety for the purpose of protecting the bodies of passengers by mitigating the impact that may be caused by the vehicle being overturned while driving. Therefore, the A-pillar should protect these parts from a variety of dynamic loads. This study result is thought to contribute for the strength and durability of A-pillar by designing two types of parts before making this product and analyzing the product which thickness is adjusted for the light weight of vehicle. If this study result is practically applied to the parts of A-pillar in a car, it is considered that the damage can be protected by the durability verification of design. By utilizing the data of analysis and design on the strength and durability of automotive A-pillar in this study, the esthetic sense can be given by being grafted onto the real automotive part.

Rail Corrugation Effects on the Dynamic Behavior of Clips of Rail Fastening System in Operation Environment of Urban Railway (도시철도 운영환경에서 파상마모에 의한 레일체결장치 클립의 진동 특성)

  • Kim, Man-Cheol;You, Won-Hee;Sim, Hyoung-Bo
    • Journal of the Korean Society for Railway
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    • v.19 no.4
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    • pp.489-497
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    • 2016
  • The rail fastening system, which provides a structural connection between the rail and the sleepers, is a main track component that plays an important role in retaining the rail gauge within acceptable tolerances, as well as in passing the train load to the roadbed through the sleepers. In this paper, a modal test was first performed to evaluate the dynamic characteristics (e.g., natural frequency) of the clips of the railway fastening system under the condition of rail corrugation in urban railway operation. The corrugation-induced passing frequency was then compared with the natural frequency of the clips to investigate any resonance effect during train passage. Furthermore, a field test under train passage was conducted to measure the accelerations on the rail and the rail fastening clips as well as the strains on the rail fastening clips in the rail corrugation condition. The field measurements indicated that the accelerations on the rail and the rail fastening clips have a close relationship with the rail corrugation, but they had a minimal effect on the strains of the rail fastening clips.

Dynamic Characteristic Analysis of 3-Piece Freight Vehicle with Wedge Friction Damper Using ADAMS (ADAMS를 이용한 3-Piece 마찰 웨지 댐퍼가 장착된 화차의 동특성 해석)

  • Lee, Chul-Hyung;Han, Myung-Jae;Park, Tae-Won
    • Journal of the Korean Society for Railway
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    • v.20 no.3
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    • pp.299-310
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    • 2017
  • In this work, an independent-load friction wedge model was developed using the ADAMS/View program to predict the performance of a freight vehicle with a bogie employing a 3-piece friction wedge. The friction wedge model can generate friction according to lateral and vertical directions of the bolster. The developed friction wedge model was applied to the ADAMS/Rail vehicle model, and results of the dynamic analysis showed a critical speed of 210km/h. In the linear safety analysis, it was confirmed that the lateral and vertical limit of acceleration of the vehicle were satisfied based on UIC518. In the 300R curve line, the application speed was 70km/h, which was satisfied with the limit acceleration of the car-body and bogie based on UIC518. Also, the developed model satisfied the wheel loading, lateral force and derailment coefficient of "The Regulations on Safety Standards for Railway Vehicles"

Seam Tensile Strength of Geotextile Mat and Stress Increment Analysis (지오텍스타일 봉합 인장강도와 지반의 응력증가분 해석)

  • Chae, Yu-Mi;Kim, Jae-Hong
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.4
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    • pp.73-79
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    • 2018
  • In the west coast, south coast, and river basin, the use of geotextile mats has been increasing to improve the soft ground for making industrial facilities space and farmland. As an initial step to improve the vast and soft ground, the geotextile mats are laid and bonded to increase the bearing capacity of the wide ground for supporting construction equipment. Seam strength of geotextile mats exert a force only about 50% of the tensile strength of the fabric, which causes problems such as uplift and sinking in the soft ground. In this study, various types of geosynthetic matting techniques were investigated and the tensile strength of each method was compared and analyzed. Numerical analysis shows that stress increment in the ground due to the overburden load decreases when the seam strength of the geosynthetics mats is increased. When the seam strength was increased to 60, 70 and 80%, the bearing capacity of ground by geotextile mat was increased.

The Effects of Geometrical Imperfections on the Dynamic Characteristics of a Tapered Roller Bearing Cage (테이퍼 롤러 베어링 케이지의 불완전성이 통특성에 미치는 영향)

  • Ahn, Tae-Kil;Park, Jang-Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.4
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    • pp.464-469
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    • 2019
  • Tapered roller bearings are used widely in vans, trucks, and trains because they can support the vehicle in a stable manner even under a heavy load. The cage of a tapered roller bearing maintains the gap between the rollers, which prevents friction wear and suppresses heating. If the cage is severely deformed due to resonance, the roller may not be able to roll smoothly and even leave the cage. Consequently, it is very important to analyze the dynamic characteristics of the cage for reliable performance of a bearing. The cage essentially has geometrical tolerance in the manufacturing process. In this paper, the effects of those geometrical imperfections on the dynamic characteristics of the cage were investigated. As a result, natural frequency separation occurred near the natural frequency of the ideal cage due to geometrical imperfections. In addition, the interval was proportional to the magnitude of the geometric error, and the interval increased with increasing mode number.

Dynamic Behavior on Transition Zone of the Railway Bridge-earthwork by Shape of Transition Zone (구조물 접속부 형상에 따른 철도 교량-토공 접속부의 동적거동)

  • Jung, Kwangsu;Ahn, Kwangkuk;Kang, Hongsig
    • Journal of the Korean GEO-environmental Society
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    • v.22 no.4
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    • pp.5-13
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    • 2021
  • The transition is the zone where support stiffness suddenly increases in the railway industry. If the support stiffness increases, differential settlement will occur at the transition due to difference of stiffness, and the differential settlement causes problems for the train running safety and the roadbed that supports the track. In particular, a study on differential settlement at bridge-earthwork transition was only conducted to considering railway load in most cases. However, these studies have not taken account of earthquake despite earthquake has been occurred frequently in the recent, and it is necessary to consider earthquake. Therefore, in this study numerical analysis has been performed by changing the inclination of approach block, which determines the shape of the transition, and earthwork in order to verify the effect of the shape of the transition on the dynamic behavior at the bridge-earthwork transition. The result shows that the dynamic behavior at the bridge-earthwork transition was affected by the shape of transition.

Bearing Capacity Evaluation of Marine Clay Dredged Deposit Including Desiccated Crust Layer (건조 고결층이 형성된 준설 매립 지반의 지지력 산정에 대한 연구)

  • Park, Hyun-Ku;Byeon, Wi-Yong;Jee, Sung-Hyun;Lee, Seung-Rae
    • Journal of the Korean Geotechnical Society
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    • v.23 no.5
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    • pp.89-100
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    • 2007
  • In this study, various field and laboratory tests were performed to investigate the characteristics of shear strength and bearing behavior to be considered in the estimation of stability and trafficability in early stage of stabilization process in marine clay dredged deposit. Site characterization was carried out to grasp the basic properties of the deposit. Field vane test, unconfined compression test and direct shear test were conducted to evaluate the shear strength distribution for varied depths, and the characteristics of shear strength and stress-strain behavior of the crust layer. Plate load tests were also performed to estimate the bearing capacity and to assess load-settlement behavior and failure pattern of the deposit. The bearing capacity was also estimated using previously proposed methods for double-layered clay deposit. The estimated bearing capacity was compared with the results of the plate load tests and then, the applicability of the estimation method was discussed.