• 한국철도학회논문집
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• 제3권2호
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• pp.84-91
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• 2000

The general concept of reinforced roadbed in the high-speed railway is to cope with the soft ground for the bearing capacity and settlement of foundation soil. The cyclic plate load tests were performed to determine the behavior of reinforced ground with multiple layers of geogrid underlying by soft soil. With the test results, the bearing capacity ratio, elastic rebound ratio, subgrade modulus and the strain of geogrids under loading were investigated. Based on these plate load tests, laboratory model tests under cyclic loading were conducted to estimate the effect of geogrid reinforcement in particular for the high-speed rail roadbed. The permanent settlement and the behavior of earth pressure in reinforced roadbed subjected to a combination of static and dynamic loading are presented.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.614-619
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• 2002

Since 1980's in U.S.A and Japan, the studies on increasing the bearing capacity of railway roadbed using geocell have been conducted for repair and reinforcement of railways constructed on soft soils. In this study, the railway roadbed system reinforced with geocells has been analyzed and investigated results of the previous studies were conducted in Korea and other nations, And the method for estimating the railway roadbed thickness was developed based on the equivalent method using the multi-layer theory and the deformation modulus Ev.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.423-429
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• 1999

The design method of Geosynthetics reinforced Railway Roadbed that was developed in Germany in 1997 is presently putting into practice. This method insists that Railway Roadbed Thickness has to be measured by Frost and Bearing Capacity The Maximum Value from the above two measurements is the necessary Railway Roadbed Thickness. This design method has many kinds of advantage in economic, constructive aspect, and environmentalism. Recently a few Korean experts actively have researched on this area, but their results are not enough for proper design method. Ⅰ hope more complete study on this area will be progressed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.979-984
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• 2005

2005, National railway was converted from government enterprise form to public corporation form. Korail is facing in necessity to equip new manpower operating system to achieve public enterprise's part and two purposes called profit creation according to conversion to construction system. Accordingly, railway construction work began services for formation diagnostic and job analysis to construct management formation of new paradigm, personnel management course manpower operation system of the job value priority. This dissertation is research for direction establishment of human resource management(HRM) of railway construction work. Examined problem of current personnel management system with trend of HRM paradigm for this. And presented various strategy to construct greeting executive system of job putting first in person putting first and strengthens formation capacity.

• Structural Engineering and Mechanics
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• 제75권2호
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• pp.271-282
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• 2020

The preservation of historic masonry-arch railway bridges is of paramount importance due to their economic benefits. These bridges which belong to past centuries may nowadays be expected to carry loads higher than those for which they were designed. Such an increase in loads may be because of increase in transportation speed or in the capacity of freight-wagons. Anyway, adequate increase in their load-carrying-capacity through structural-strengthening is required. Moreover, the increasing costs of material/construction urge engineers to optimize their designs to obtain the minimum-cost one. This paper proposes a novel numerical optimization method to minimize the costs associated with strengthening of masonry-arch railway bridges. To do so, the stress/displacement responses of Sahand-Goltappeh bridge are assessed under ordinary train pass as a case study. For this aim, 3D-Finite-Element-Model is created and calibrated using experimental test results. Then, it is strengthened such that following goals are achieved simultaneously: (1) the load-carrying-capacity of the bridge is increased; (2) the structural response of the bridge is reduced to a certain limit; and, (3) the costs needed for such strengthening are minimized as far as possible. The results of the case study demonstrate the applicability/superiority of the proposed approach. Some economic measures are also recommended to further reduce the total strengthening cost.

• Steel and Composite Structures
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• 제18권5호
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• pp.1279-1290
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• 2015

The main role of studs, which act as connectors of the steel-concrete composite structures, is to ensure that the steel and the concrete work together as a whole. The studs in steel-concrete composite structures bear the shearing force in the majority of cases, but in certain locations, such as the mid-span of a simply supported composite beam, the studs bear axial uplift force. The previous studies mainly focused on the shearing performance of the stud by some experimental and theoretical effort. However, rare studies involved the uplift performance of studs. In this paper, the single stud uplift test on 10 composite specimens was performed. Meanwhile, based on the test, numerical analysis was introduced to simulate the concrete damage process due to the stud uplifted from concrete. The static ultimate bearing capacity, under which the stud connector was pulled out from the damaged reinforced concrete, is much larger than the cyclic ultimate bearing capacity, under which the weld joint between stud and steel plate fractured. According to the fatigue test results of 7 specimens, the fatigue S-N curve of the construction detail after minus 2 times standard deviation is $logN=24.011-9.171\;log{\Delta}{\sigma}$, the fatigue strength corresponding to $2{\times}10^6$ cycles is 85.33 MPa.

• 한국철도학회논문집
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• 제8권6호
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• pp.507-512
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• 2005

Railroad transportation system has experienced major changes due to KTX introduction. Kyungbu corridor especially Seoul to Cheonan has line capacity problem and its solution has been a primary concern to researchers and policy decision makers. This study explored pattern of train operation between Seoul and Cheonan after the introduction of KTX in 2004. Both the number of trains and available seat capacity per day have increased but maximum number of trains per specific hour has not been changed much. Demand for train shows that if concentrated in a specific time, so number of trains during the peak hour should be increased. But, it is difficult ? 새 line capacity, so increasing seat capacity per train might be an option. An increase in an avaliable sear should be considered the characteristics of each train lines.

• Earthquakes and Structures
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• 제15권3호
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• pp.275-283
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• 2018

Seismic strengthening is essential for existing bridge piers which are deficient to resist the earthquake. The concrete and CFRP jackets with a bottom-anchoring method are used to strengthen railway bridge piers with low reinforcement ratio. Quasi-static tests of scaled down model piers are performed to evaluate the seismic performance of the original and strengthened bridge pier. The fracture characteristics indicate that the vulnerable position of the railway bridge pier with low reinforcement ratio during earthquake is the pier-footing region and shows flexural failure mode. The force-displacement relationships show that the two strengthening techniques using CFRP and concrete jackets can both provide a significant improvement in load-carrying capacity for railway bridge piers with low reinforcement ratio. It is clear that the bottom-anchoring method by using planted steel bars can guarantee the CFRP and concrete jackets to work jointly with original concrete piers Furthermore, it can be found that the use of CFRP jacket offers advantages over concrete jacket in improving the energy dissipation capacity under lateral cyclic loading. Therefore, the seismic strengthening techniques by the use of CFRP and concrete jackets provide alternative choices for the large numbers of existing railway bridge piers with low reinforcement ratio in China.

• 한국철도학회논문집
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• 제12권4호
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• pp.481-487
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• 2009

포장궤도에서는 프리팩 콘크리트방식으로 도상자갈을 충전층의 골재로 활용한다. 골재의 조건은 강도가 확보되어야 하고, 주입성 확보를 위한 입도가 확보되어야 하며, 모르터의 부착강도를 높이기 위하여 골재 표면의 불순물이 제거되어야 한다. 골재의 원활한 공급 측면에서 기존 도상자갈을 재활용하는 것이 유리하며 재활용성을 높이기 위하여 기존의 철도도상규격을 크게 벗어나지 않는 기준을 적용하는 것이 필요하다. 따라서 본 연구에서는 포장궤도에서의 도상자갈 재활용성을 확보 할 수 있는 판단 기준을 마련하기 위하여 재활용 도상자갈의 재료 및 물리적 특성, 입도별 지지력 특성, 충전성, 강도특성 등을 검토하였으며, 그 결과를 바탕으로 골재 사용기준을 제안하고자 하였다.

• 대한토목학회논문집
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• 제30권3A호
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• pp.211-219
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• 2010

고속철도교량의 설계개념은 정적하중에 따른 충격계수를 고려하여 기존 교량 구조물의 강성을 증가시키기 위한 방안을 적용하고 있으며, 전반적인 구조설계 과정은 선진 외국기술에 의존하고 있는 실정이다. 그러나 고속철도(Korea Train eXpress: KTX)의 긴 연장(380 m)과 고속(300 km/h) 주행은 공진현상에 상당한 영향을 미치기 때문에 고속철도교량의 동적증폭계수(DAF) 및 동적성능 평가는 상세한 검토가 필수적으로 수행되어야 할 것이다. 따라서 이 연구에서는 전형적인 PSC 박스 거더 고속철도교량을 대상으로 동적성능을 효율적으로 검토하고자 하며, 합리적인 구조설계를 위한 기초자료를 제시하고자 한다. 이를 위해, 기존문헌을 토대로 KTX의 하중선도를 고려하여 정적해석을 수행하였다. 또한 다양한 해석변수를 고려하여 KTX의 이동하중을 시계열하중으로 변환하였으며, 변환된 시계열하중을 이용하여 시간이력해석을 합리적으로 평가하였다. 이때, 시계열하중을 산정하기 위한 변수는 KTX의 하중재하 절점간격, 시간증분 및 속도변화를 고려하였다. FE해석 결과를 바탕으로 PSC 박스 거더 고속철도교량의 동적성능을 체계적으로 검토하였으며, 국내외 관련규정에 따라 구조안전성을 정량적으로 평가하였다.