• Title/Summary/Keyword: Railroad Bridge

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Study on the improvement of prediction model for the railway environmental noise using ISO 9613-2 (ISO 9613-2를 이용한 철도 환경소음 예측 모델 개선에 관한 연구)

  • Jang, Seungho;Koh, Hyo-In;Hong, Jiyoung
    • Journal of Environmental Impact Assessment
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    • v.26 no.1
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    • pp.11-26
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    • 2017
  • Approximate empirical equations obtained by measuring overall noise levels at different distances have been used to evaluate environmental influence of the railway noise though the accurate prediction of noise levels is important. In this paper, a noise prediction model considering the frequency characteristics of noise sources and propagation was suggested to improve the accuracy of noise prediction. The railway noise source was assorted into track, wheel, traction and aerodynamic components and they were characterized with the source strength and speed coefficient at each octave-band frequency. Correction terms for the acoustic roughness and the track/bridge condition were introduced. The sound attenuation from a source to a receiver was calculated taking account of the geometrical divergence, atmospheric absorption, ground effect, diffraction at obstacles and directivity of source by applying ISO 9613-2. For obtaining the source strength and speed coefficients, the results of rolling noise model, numerical analysis and measurements of pass-by noise were analyzed. We compared the predicted and measured noise levels in various vehicles and tracks, and verified the accuracy of the present model. It is found that the present model gives less error than the conventional one, so that it can be applied to make the accurate prediction of railway noise effect and establish its countermeasures efficiently.

Fatigue performance of a new type PSC girder (신형식 PSC거더의 피로 성능)

  • Choi, Sang-Hyun;Lee, Chang-Soo;Kim, Tae-Kyun;Eui, Chul-Soo
    • Proceedings of the KSR Conference
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    • 2011.05a
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    • pp.965-972
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    • 2011
  • Unlike metallic materials, the importance of fatigue performance of concrete has been ignored. However, it is reported that environmental effects, if it cause deterioration, may increase the risk of fatigue failure under repeated loadings. In case of railroad bridges, the risk may increase due to highly periodic, repetitive, heavier nature of train load, which runs through the fixed passage called the track. Especially, when new material or structure is implemented for a main bridge member, experimental validation should be performed to avoid damage or failure due to unexpected behavior. In this paper, the fatigue performance of an IT girder is examined via a repeated loading test. The IT girder is a new type of a prestressed concrete (PSC) girder with two prestressed H-beams in the top of the girder, which provide additional sectional capacity, and it can be applied to the span longer than 30m which is a typical limit for a usual PSC girder. To obtain the fatigue performance, a 10m IT girder specimen is designed, and a repeated load test is performed by applying the cyclic load two million times. The fatigue performance of the girder is examined according to the Japanese and the CEB-FIB design codes. The fatigue test result shows that the IT girder satisfies both design codes.

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An Experimental Study on Steel Bar Corrosion of Reinforced Concrete Structure (철근콘크리트 구조물의 철근부식에 관한 실험 연구)

  • Chae, Young-Suk;Choi, Il-Yoon;Min, In-Ki
    • Journal of the Korean Society of Safety
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    • v.28 no.6
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    • pp.29-35
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    • 2013
  • The purpose of this study is to investigate the steel bar corrosion and degree of reinforced concrete bridge, and analyze the cause of corrosion occurrence. Therefore they could ensure the durability and stability as to suggest the corrosion prevention of reinforced concrete structure. To study the corrosion state reinforced concrete structure, We investigate the cover of concrete, the compressive strength by schmidt hammer, the neutralization test of site, the compressive strength of core and the measurement of neutralized depth. As the results of test, the corrosion-grade of reinforced concrete structure which the degree of corrosion is 3, 4 degree get to 18% in the used time of 40 years and the time elapsed of 25 years. Therefore the corrosion of steel bar give rise to public discussion. The degree of corrosion is serious, and the neutralization come to the cover of concrete.

A Study on the Limitations in the Field Application of Seismic Mini-tomography (소규모 탐사단면에 대한 탄성파 토모그래피의 현장 적용 한계성 연구)

  • 김중열;김유성;현혜자;김기석
    • The Journal of Engineering Geology
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    • v.6 no.1
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    • pp.15-22
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    • 1996
  • Frequency content of seismic waves observed in field seismic survey in Korea has almost not exceeded 4kHz(wave length 1m). The limited frequency content not only restricts the minimum size of objects which can be surveyed in seismic tomogrpahic application, but also makes a fundamental limit in the resolution of tomogram. This paper shows the resonable result obtained by confirmimg and resolving the problems which can be occured m measuring procedure for the small - sized section through field application. Seismic tomographic field survey was performed for a concrete construction for railroad bridge in Korea, and to this the tomographic measurements for the stone-build foundation construction for a bell house of church in Germany were compared.

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A Case Study on Chloride Corrosion for the End Zone of Concrete Deck Subjected to De-icing Salts Added Calcium Chloride (염화칼슘이 함유된 제설제로 인한 콘크리트 바닥판 단부의 염해에 관한 사례 연구)

  • Chung, Jee-Seung;Kim, Bo-Heon;Kim, Il-Sun
    • Journal of the Korean Society of Safety
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    • v.29 no.6
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    • pp.87-93
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    • 2014
  • In this study, the reinforced concrete rahmen bridge damaged by the chloride attack was investigated. According to the investigation, the degraded concretes on cantilever kerb and end part were intensively observed. Thus, the chloride content test and half-cell method were performed to evaluate the degraded parts. As a result, the contents of chloride on degraded parts were C and D grade. On the other hand, the half-cell potential values of rebar in degraded concrete were measured with the minor corrosion. This rebar corrosion is expected to progressing. Chloride content D grade is due to expansion pressure by corrosion of rebar and freeze-thaw by permeate water, could see progresses rapidly degradation. In order to prevent chloride attack to concrete deck caused by deicing salts, corresponding to the chloride critical concentration must maintain grade b or at least grade c. Chloride condition evaluation standard apply to evaluation of marine structure chloride attack with chloride attack by deicing salts.

Experimental Study on the the Maglev Train Guideway Girder : Composite System with PSC-U Type Girder and Precast Deck (자기부상열차 가이드웨이 거더의 실험적 연구: PSC-U 형 거더와 프리캐스트 바닥판의 합성 시스템)

  • Jin, Byeong-Moo;Kim, In-Gyu;Kim, Young-Jin;Yeo, In-Ho;Chung, Won-Seok
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.46-55
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    • 2008
  • Maglev is a system that a train runs levitated above a rail. Therefore it is very important to maintain a constant levitation gap for achieving serviceability and ride comfort. This study is a cooperation research subject of the 3-1 subject, performance improvement of maglev track structures, of the Center for Urban Maglev Program in Korea, started in 2006. The aim of this study is development of rapid constructions of bridge superstructure for maglev. At present, precast deck is widely used because of its superiority to cast-in-place concrete on quality and the term of works. The research group suggested basic systems of maglev guideway with PSC-U type and trapezoidal open steel box type girder, and precast deck, cooperating with Korea Railroad Research Institute, the managing institute of the 3-1 subject. In this study, longitudinally full-scale guideway girder system was fabricated and static/dynamic test of the girder was performed for the purpose of the performance evaluation.

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Analysis of PSC Box Girder Anchorage Zone using FEM and 2D SUB-3D STM Approach (유한요소법 및 유사 3 차원 스트릿-타이 모델 방법을 이용한 PSC 박스거더 정착부의 해석)

  • Yun, Young-Mook;Kim, Seung-Eock;Oh, Jin-Woo;Park, Jung-Woong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.4 no.2
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    • pp.113-129
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    • 2000
  • This study evaluates the behavior and strength of an anchorage zone of the prestressed concrete box girder bridge on the Kyungboo highway railroad using the 2D SUB-3D STM approach and a linear elastic finite element analysis. The 2D SUB-3D STM approach utilizes several two-dimensional sub strut-tie models that represent the compressive and tensile stress flows of each projected plane of the three-dimensional structural concrete in the selection of a three dimensional strut-tie model, evaluation of the effective strengths of the concrete struts, and verification of the geometric compatibility condition and bearing capacity of the critical nodal zones in the selected three-dimensional strut-tie model. The finite element analysis uses an 8-node brick element and the longitudinal prestressing force is considered as the equivalent nodal force. Analysis results show that the 2D SUB-3D STM approach and linear elastic finite element method can be effectively applied to the analysis and design of three-dimensional structural concrete including a prestressed concrete box girder anchorage zone.

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Development of a 4kW, High Efficiency, Series-Resonant DAB Converter (4kW급 고효율 직렬 공진형 DAB 컨버터 개발)

  • Sangmin, Lee;Gil-Dong, Kim;Seung-Hwan, Lee
    • The Transactions of the Korean Institute of Power Electronics
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    • v.27 no.6
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    • pp.498-506
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    • 2022
  • This study proposes a design methodology for bidirectional, series-resonant, dual-active bridge (SRDAB) converters. The circuit parameters of the SRDAB converters are designed by considering the output power and efficiency of the converter. The proposed method can be used to design a high-power, high-efficiency SRDAB converter. A voltage controller is employed to manipulate the output voltage of the converter, and the controller gains are selected using the transfer function and frequency response of the controller. Simulation results show that the output power of the designed SRDAB converter is 2 kW per converter module as designed. In addition, the performance of the voltage controller is evaluated using the simulation and experimental results. The output voltage follows the reference voltage within 10 ms under the step change of the reference command. The output voltage also follows the reference voltage under the step load change. The efficiency of the designed SRDAB converter is 95.6%.

Development of Automated 3D Modeling System to Construct BIM for Railway Bridge (철도 교량의 BIM 구축을 위한 3차원 모델 생성 자동화 시스템 개발)

  • Lee, Heon-Min;Kim, Hyun-Seung;Lee, Il-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.31 no.5
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    • pp.267-274
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    • 2018
  • For successful BIM settlement, it is a key technic for engineer to design structures in the 3-dimensional digital space and to work out related design documents directly. Lately many BIM tool has been released and each supports their 3-dimensional object libraries. But it is not easy to apply those libraries to design transportation infra structures that were placed along the route(3-dimensional line). Moreover, in case of design changes, it is so difficult to reflect those changes with the integrated model that was assembled by them. Because of they were developed without consideration for redundancy of parameters between objects that were placed nearby or were related each other. In this paper, a method to develop module for modeling and placing 3-dimensional object for transportation infra structures is presented. The modules are employed by a parametric method and can deal with design changes. Also, for a railroad bridge, through developing user interface of the integrated 3-dimensional model that was assembled by those modules the applicability of them was reviewed.

Static Behavior of Stud Shear Connector for UHPC Deck (초고성능 콘크리트 바닥판을 위한 스터드 전단연결재의 정적 거동)

  • Lee, Kyoung-Chan;Kwark, Jong-Won;Park, Sang-Hyeok;Kim, Jee-Sang
    • Journal of the Korea Concrete Institute
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    • v.26 no.5
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    • pp.573-579
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    • 2014
  • Typical composite girder has been composed with conventional concrete deck and steel girder. Recently, ultrahigh-performance-concrete (UHPC) deck is proposed in order to enhance durability and reduce weight of deck as well as to increase stiffness and strength of the composite girder. This study investigates that a headed stud is still compatible as a shear connector for the UHPC deck and steel girder composite beam. Twelve push-out specimens are prepared to evaluate the static strength of stud shear connectors embedded in the UHPC deck. The test program proves that the static strength of the stud shear connectors embedded in UHPC well meets with design codes described in AASHTO LRFD. Chosen experimental variables are aspect ratio of height to diameter of stud, thickness of deck and thickness of concrete cover over the head of stud. From the test program, aspect ratio and cover thickness are investigated to mitigate the regulations of the existing design codes. The minimum aspect ratio and the minimum cover thickness given in AASHTO LRFD are four and 50mm, respectively. This limitation hinders to lower the thickness of the UHPC deck. The results of the experiment program give that the aspect ratio and the cover thickness can be lower down to three and 25mm, respectively. Eurocode-4 regulates characteristic relative slip at least 6mm. However, test results show that stud shear connectors embedded in UHPC provide the characteristic relative slip only about 4mm. Therefore, another measures to increase ductility of stud should be prepared.