• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1989.04a
• /
• pp.61-65
• /
• 1989

In this study, measured and calculated responses are compared in order to give how the static and dynamic responses occurred in steel railway bridges Sue to train loads could be calculated appropriately. From this, it is known that the static response ratios (measures / calculated) is high comparing to the highway blisses, and the dynamic response should be obtained by the moving mass problem. And it is known that the factors specifies in the present railway bridge code are very safe under the present service speed below 100 km/h, but are not under the rapid transit system above 100 km/h.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2002.11a
• /
• pp.351-358
• /
• 2002

현재 우리나라에서 공용중인 강철도교의 50% 이상이 공용기간 50년 이상 경과된 교량으로 구성되어 있는데, 이와 같이 공용기간이 오래된 강교량의 내구성에 영향을 미치는 주된 열화손상으로 피로와 부식이 보고되고 있다. 이 가운데 부식열화현상에 관한 조사에 의하면 부식손상의 대부분은 국부적인 것으로 분류할 수 있으나 부식면적이 대상부재의 25%를 넘는 경우도 부재의 특성에 따라서는 l∼6%에 이르는 것으로 보고되고 있다. 그러나 부식으로 인한 단면감소에 따른 응력 발생 특성에 대한 연구나 실교량에서의 각 부재별 부식손상 정도에 따른 실측자료의 축적이 미흡한 실정이어서 유지관리에서의 부식에 대한 정량적인 평가가 체계적으로 이루어지고 있지 않다.(중략)

• Proceedings of the KSR Conference
• /
• 2003.10b
• /
• pp.557-562
• /
• 2003

The responses of the floor system of a railway bridge are investigated for fatigue life prediction of damaged members using fracture mechanics approach. Numerical analysis of the structure is performed in order to see the influence of track-structure interaction and continuity of the truss connection on the response of the bridge members. Fatigue crack growth analysis is carried through equivalent stress obtained from time-history analysis. The results of time-history analysis agree with measured responses. The fatigue propagation life increases as the curvature in the coped stringer increases.

• Proceedings of the KSR Conference
• /
• 2003.10b
• /
• pp.544-551
• /
• 2003

Despite the number of steel bridges being under in service more than 50 years reaches about $50\%$ in present, the Quantitative estimation in maintenance on steel railway bridges is not possible because a ton of the field data in the bridges have not been plentifully accumulated. Therefore a series of field tests on the steel plate girder bridge and steel truss bridge, the typical types of steel railway bridges, are executed, and the stress characteristics according to the structural types of the bridges are Quantitatively estimated in this study.

• Proceedings of the KIEE Conference
• /
• 1989.07a
• /
• pp.21-23
• /
• 1989

This paper deals with the design method of Superconduting AC Generator(SCG). The establishment of design principle and design procedure of SCG are included in this study. Electric characteristics of SCG, such as synchronous reactance and subsubtransient reactance, are specified first as constraints and the size of SCG is calculated. A 20 KVA with double-shield single-rotor is chosen for case study.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1062-1067
• /
• 2007

This study presents an experimental technique to monitor the dynamic behavior of the railway bridge system simultaneously using multiplexed fiber Bragg grating (FBG) sensors. The measuring quantities include stains, curvatures, vertical deflections, and vertical accelerations. The strains are directly measured from multiplexed FBG sensors at various locations of the test bridge followed by curvature calculations based on the plane section assumption. Vertical deflections are then estimated using the Bernoulli beam theory and regression analysis. Finally, vertical accelerations are obtained from the numerical differentiation in time domain. In order to verify the proposed method, several conventional electric strain gauges, displacement transducers, and accelerometers are installed at the mid-span of the bridge for comparisons. A test train is passed over the bridge to monitor the dynamic response of the bridge. The monitoring results show that the multiplexed FBG sensing system is able to capture the essential behavior of the test bridge while resolving wiring problem in practice.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1074-1079
• /
• 2007

It is important to evaluate the effect in the maintenance of steel bridge because the fatigue of the bridge is affected by the structural characteristic of bridge such as structure type, span and steel grade, etc. In this study, we analyzed the effect of fatigue strength by the changes of span of the bridge and the steel grade in many factors which have influence on the fatigue life of the bridge. For this analysis, we selected the objective bridges and performed the structural analyses for the various parameters such as span and steel grade. The fatigue evaluations were carried out by FAST which is a program for fatigue estimation and the results were compared.

• Journal of the Korean Society of Safety
• /
• v.15 no.1
• /
• pp.132-139
• /
• 2000

In this study, the fatigue life assessments of steel railway bridge in Japan National Railway were carried out. This railway bridge has been under in service from 1957, and fatigue damages were occurred at bead toe of upper part of vertical stiffeners of stringers, bead toes of scallop in lower part of vertical stiffeners in stringers and crossings of cross beams and stringers. From this study, a series of field tests were carried out by stress history measurement about above mentioned points. And as a results of stress histogram analysis, cummulative fatigue damage rate and fatigue life of these members should be calculate quantitatively. And from this estimation technique, cummulative fatigue damage rate and fatigue life of this railway bridge were strongly affected in passing tonage every year and the histories of live load.

• Journal of Korean Society of Steel Construction
• /
• v.8 no.4 s.29
• /
• pp.19-29
• /
• 1996

In this paper, it is presumed that the stress time history was generated by simulation method and investigated compatibility in regard to the reappearance of stress time history. In this procedure, the identified frequency distribution of stress range of the steel railroad bridge varies with the rational values of cut off point and bar width. Thus, we show variable aspect of the equivalent stress range results from change of cut off point and bar width. In addition, we analyze the variable of RMC and RMS model due to the cut off point and bar width of the measured stress history which influencs the prediction of fatigue life in the steel railroad bridge. The simulated stress time history is carried out by the superposition method incorporating the vertical load with rotation moment obtained from the Hermition interpolation function, and compared with developing stress results from measured maxi mum stress. Through this study, we can estimate the remaining fatigue life from a safety point of view and comparative accuracy.

• Journal of Korean Society of Steel Construction
• /
• v.8 no.4 s.29
• /
• pp.95-103
• /
• 1996

단순 전단연결 구조를 가진 강철도교의 세로보 단부의 절취부위에서 많은 피로균열이 발견되었으며, 이러한 부위의 피로균열은 피로손상의 전형적인 예이다. 피로균열을 가진 세로보 절취부위의 보강방법을 연구하기 위하여 가로보 및 세로보의 상부 플랜지에 인장판을 부착한 경우와 부착하지 않은 경우로 구분하여 피로실험을 수행하였다. 피로실험에 사용된 하중은 현장에서 측정된 실동응력을 기초하여 빈도해석을 통해 산정하였다. 피로실험 결과, 인장판으로 보강한 모멘트 저항 연결구조상세가 철도교에서 균열성장을 효과적으로 정지시킬 수 있는 것으로 판명되었으며, 피로손상을 가진 절취부위의 보강방법으로 제시될 수 있을 것으로 사료된다.