• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1464-1469
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• 2010

In this paper, the dynamic stability evaluation of special bridge for high speed railway under ground excitation is performed. The mass, damping, stiffness matrices of bridge are derived from the modal frequencies and mode shape vectors which can be obtained by commercial program. And the high speed train is modeled as multi-single d.o.f models for the sake of vehicle-bridge interaction analysis. In the vehicle-bridge interaction analysis, the vertical directional interaction is only considered. As a numerical example, the 3 span Extradosed bridge which is expected to be installed in Ho-Nam high speed railroad is considered. The analysis results show that the example bridge satisfies the criteria of dynamic stability.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1392-1394
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• 2007

By the examination of data collected by long-term measuring system on high-speed railway bridges, it has been known that the atmospheric temperature may affect the responses of maximum deflection and acceleration of bridge deck. Collected data show a tendency by seasonal factor to that, by the decrease of temperature, the response of acceleration of bridge deck increases, and the response of deflection decreases. To trace the cause of this tendency, parametric analysis on the stiffness of bridge bearing and track ballast has been performed, and the in-site measurement has been achieved in high-speed railway line to understand seasonal influences.

• 한국강구조학회 논문집
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• 제20권6호
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• pp.761-771
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• 2008

열차운행주파수가 철도교의 고유진동수와 일치하면, 철도교의 공진은 피할 수 없다. 또한, 열차가 교량을 매우 빠르게 통과하면, 계측 가능한 시간응답의 샘플 수는 매우 적다. 본 논문은 그러한 경우에 대하여 철도 교량의 동특성을 매우 효과적으로 추출할 수 있는 TDD기법과 SI기법을 소개한다. 열차통과 직후에 교량의 자유진동 시간응답구간의 상호상관을 이용하여 모드형상은 TDD기법으로 추출하고, 고유진동수 및 감쇠비 등의 시간변수들은 SI기법으로 추출한다. 경부고속철도 시스템에 위치한 2경간 강합성교량의 동특성 추출실험을 통하여 TDD기법과 SI기법의 현장 적용성이 검토되었다. 동특성 추정결과는 기존의 ERADC기법의 결과와 비교 검토되었다. 추정결과는 기존의 방법을 이용하여 획득된 결과와 매우 잘 일치한다.

• 콘크리트학회논문집
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• 제22권6호
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• pp.797-803
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• 2010

경부 고속철의 PSC 박스거더 교량의 동적응답에 대하여 보다 우수한 평가를 얻기 위한 동적거동해석방법을 개발하였다. 특히, 고속철 차량, 교량 그리고 궤도구조물간의 구조적 상호작용을 고려한 3차원 수치해석모델을 개발하여 고속철 속도에 의하여 발생되는 PSC 교량의 동적응답을 정확하게 해석하고 심도깊은 영향평가를 수행하였다. PSC 박스거더 교량은 40 m 경간의 단순교를 뼈대요소를 사용하여 3차원 프레임 모형화 하였다. K-TGV 고속철 차량은 동력차를 포함하여 다련 38자유도 모형으로 개발하고 차체와 대차의 연직변위, 횡변위, 종변위 및 피칭, 롤링, 요잉을 모두 고려하였다. 동적충격계수는 정적해석결과와 Runge-Kutta 기법으로 산출된 동적해석 결과를 비교 산출하였으며, 고속철 차량 속도에 따른 그 차이를 회귀분석을 통하여 추정실험식으로 제안하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2430-2434
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• 2011

Dynamic response is an important consideration because of the possibility of resonance according to KTX running over a railway bridges. When KTX runs over the bridge at critical speed, dynamic response is very depending on damping ratio. Current damping ratio for design of high-speed railway bridges adopted EUROCODE without verification of domestic railway bridges. The purpose of this study is to obtain the coherent damping ratio of high-speed railway bridges. Free vibration signal after KTX runs over a high-speed railway bridge was applied. The representative value from distribution of damping ratio was considered.

• Structural Engineering and Mechanics
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• 제54권5호
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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.

• Structural Engineering and Mechanics
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• 제13권5호
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.82-83
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• 2008

In the cases of high speed railway bridge, dynamic behavior analysis is important because of high passing velocity and moving load at the regular intervals, and the damping ratio is a major element in dynamic behavior analysis. In this paper, damping ratios were estimated by two methods and vibration type sections, and relationship between estimated damping ratio and representative value of bridge vibration. At the results, estimated damping ratio using all time of vibration were more stable then using only free vibration section. And in the case of using extended Kalman filter, estimated damping ratio were trend of growth by growth of representative value of bridge vibration. At last, it was shown that study about reliabilities of estimated damping ratios were need.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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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.

• 한국철도학회논문집
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• 제9권2호
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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.