• Journal of the Korean Society for Railway
• /
• v.19 no.3
• /
• pp.341-350
• /
• 2016

Concrete track on railway bridges should be designed to effectively respond to the movement of the superstructure of the bridge. In the design procedure, shear keys are generally placed on the protection concrete layer (PCL) before casting the concrete track so the shear force due to slip between the concrete track and the bridge super-structure can be transferred. In this paper, a nonlinear structural analysis procedure that considers the construction joint has been developed to predict the shear behavior of a shear key. With the developed analysis procedure, it was possible to predict the shear force-shear slip response at the construction joint in a shear key by considering the friction of concrete surface and the dowel action of the rebars. The analysis results showed good agreement with the test results for 4 specimens.

• Journal of Korea Water Resources Association
• /
• v.30 no.6
• /
• pp.721-729
• /
• 1997

Total scour depth at a bridge is comprised of three components: long-term changes, contraction scour and local scour. Therefore, the analysis of long-term bed elevation changes is very important in the estimation of total scour depth at bridge sites. In this research, long-term bed elevation changes at the Namhan River Bridge are analysed using CHARIMA and HEC-6 models. The results show that, for 5-year steady normal stream flow, the bed elevation is aggreded by 45cm for CHARIMA model but degraded by 5cm for HEC-6 model. For 5-year unsteady flow, the bed elevation is changed greatly and it has a great influence on the estimation of total scour depth. Therefore, to make a proper estimation of total scour depth, not only contraction scour and local scour, but also long-term bed elevation changes should be estimated precisely.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.18 no.1
• /
• pp.49-54
• /
• 2012

The purpose of this study is to define emergency response procedures by BDMS [Building Disaster Management System] when earthquake occurs on long-span bridge structures. The study is about developing a computer-based algorithm for various earthquake intensities that works with the System. Presently, long-span bridge disaster prevention relies on closed-system centered on human intervention alone. However, this study combines IT technology and internet-based open system creating a more practical system. Additionally, assigned duties and tasks are clearly defined to all personnel involved in various disaster situations using the Active Action Diagram(AAD) techniques. Also, the design of 3-dimensional view assists to determine the appropriate initial response in times of earthquake and other disasters. The combination of the existing manual emergency response procedures and the scenario-based (IT) response system being developed will create an efficiency and fast response actions in times of emergencies.

• Journal of the Korea Concrete Institute
• /
• v.13 no.5
• /
• pp.430-437
• /
• 2001

Recently, there have been increased much concerns about repair and rehabilitation works for aged concrete structures. It is in particular known that due to repeated overburden vehicles, there are significantly increasing number of aged concrete bridge slabs, which are strongly needed to construct and rehabilitate by innovative construction method. The objective of this research is to develop the new construction method of concrete slab in bridge superstructure, which can contribute to minimize a traffic congestion during repair and rehabilitation works of aged concrete slab, and can sufficiently assure the quality through the minimization of in-situ works at the site. I-beams with punch holes, which are substituted instead of main reinforcing steels in concrete slabs, can be manufactured in accordance with the specification in the factory, and be preassembled into the panel. After erecting the preassembled panels in the site, concrete will be poured into the slab panel. This research is to investigate mechanical properties of I-beam with punch holes itself, and then to investigate structural properties of assembled I-beam panels through static test, of which result can be utilized for the development of the new constructional method for concrete slab in bridge superstructure.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.4
• /
• pp.2391-2400
• /
• 2015

Weather proof steels are used for steel bridges due to its high corrosion resistance under atmospheric conditions. However, instead of forming stabilized rust layers, general rust occurs on weather proof steels under high humidity condition close to seawater or shady places. In Japan, therefore, they perform rust stabilization treatment instead of unpainted treatment due to severe atmospheric conditions. However, most of domestic weather proof steels were constructed unpainted in the form of closed box-girder, which makes the periodical repetition of dry and wet hard to occur. For the steel bridges constructed on the Han river, the evaporation of water, dew condensation due to temperature change, and stagnant water due to rain affect harmfully on the formation of passive film on weather proof steels. Thus, in this research, in order to analyze corrosion properties inside the closed box-girder for the unpainted weather proof steel bridge in the waterworks safety zone, multiple ways of analysis such as observation with eyes, cellophane-tape test, steel thickness measurement, surface corrosion potential measurement, electron microscope analysis, and X-ray diffraction analysis of the rust were performed. As a result, unstable rust layer was observed inside the closed box-girder, and severe corrosion was observed on the top and bottom of the flanges due to the effects of stagnant water caused by rain, dew condensation, and de-icing materials.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.04a
• /
• pp.218-225
• /
• 2000

This paper presents intermediate results of an on-going research for identification of the modal and the stiffness parameters of a bridge based on the ambient vibration data caused by the traffic loadings. The main algorithms consist of the random decrement method incorporating band-pass filters for estimation of the free vibration signals the cross spectral density method for identification of the modal parameters and the neural networks technique for estimation of the element-level stiffness changes. An experimental study is carried out on a scaled bridge model with a composite section subjected to various moving vehicle loadings. Vertical accelerations are measured at several locations on the girder. The estimated frequencies and mode shapes are found to be well-compared with those obtained from the impact tests. The estimated stiffness changes using the neural networks are found to be very good for the case with the simulated data. However the accuracy is found to be not quite satisfactory for the case with the experimental data particularly for the small value of the stiffness changes.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2013.10a
• /
• pp.395-397
• /
• 2013

항로표지는 해상에서 선박의 안전한 항행에 필수적인 요소이며, 현재는 LED를 광원으로 사용하는 등명기를 개발 및 사용하고 있다. LED 멀티롤 랜턴을 개발하여 항로표지의 표체조명, 교량표지, 방파제 표시등 등으로 개발하고하는 연구가 진행되고 있다. 이를 위하여 LED 멀티롤 랜턴의 내부 LED 배치에 따른 배광특성을 분석하였다. 본 논문에서 멀티롤 랜턴은 아크릴 환봉과 설치를 위한 금속재로 구성하였으며, 내부에 LED를 2열로 배치하였다. 최적의 설계를 위하여 아크릴 환봉을 투명한 것과 유백색인 것으로 구분하고 2열의 LED 모듈에 집광렌즈($45^{\circ}$, $60^{\circ}$, 미설치)에 따른 배광특성을 분석하였다. $60^{\circ}$ 집광렌즈를 사용한 경우의 시인효과가 우수하여 이를 바탕으로 LED 멀티롤 랜턴을 최종적으로 설계하였다. 투명 아크릴 환봉에 2열의 LED를 배치하고, $60^{\circ}$ 집광렌즈를 사용한 평판형 및 v형의 2종과 집광렌즈를 사용하지 않은 v형 1종으로 선정하고, 녹색과 홍색으로 제작하여 LED의 배열에 따른 배광특성을 본석하였다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.195-196
• /
• 2010

The objective of this experiments is to investigate chloride diffusivity of high performance concrete based binary cimentitious materials such as ordinary portland cement and ground granulated blast furnace slag. The results from the study will be utilized as the basic data and guideline in making standard mixproportions and the manufacture, construction work and quality control of HPC.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.04a
• /
• pp.427-439
• /
• 2003

A previous study evaluated the seismic response of typical multi-span simply supported (MSSS) and multi-span continuous (MSC) steel-girder bridges in the central and southeastern United States. The results showed that the bridges were vulnerable to damage resulting from impact between decks, and large ductility demands on nonductile columns. Furthermore, fixed and expansion bearings were likely to fail during strong ground motion. In this paper, several retrofit measures to improve the seismic performance of typical multi-span simply supported and multi-span continuous steel girder bridges are evaluated, including the use of elastomeric bearings, lead-rubber bearings, and restrainer cables. It is determined that lead-rubber bearings are the most effective retrofit measure for reducing the seismic vulnerability of typical bridges. While isolation provided by elastomeric bearings limits the forces into the columns, the added flexibility results in pounding between decks in the MSSS steel-girder bridge. Restrainer cables, which are becoming a common retrofit measure, are only moderately effective in reducing the seismic vulnerability of MSSS and MSC steel girder bridges.

• Computational Structural Engineering
• /
• v.9 no.3
• /
• pp.54-59
• /
• 1996

시속 300km로 주행하는 고속철도 열차의 주행안정성 및 승차감을 확보하기 위해서는 열차하중을 고려한 정교한 정적, 동적해석 및 설계가 이루어져야 한다. 따라서 차량과 궤도의 동적상호작용 및 차량과 교량의 동적상호작용, 터널의 미기압 및 공기압, 대단면 터널굴착의 안정성평가, 열차주행에 의한 지반진동의 예측 등에 전산수치해석기법의 활용 및 개발이 현재 활발히 이루어지고 있다. 그러나 고속철도 보유국을 포함한 선진국들에 비하면은 이러한 전산수치해석분야에 있어서 아직도 더 많은 연구 및 개발이 본 공단을 포함하여 학계 및 연구소에서 이루어져야 하겠으며, 본 경부고속철도 건설사업으로 인하여 차량, 전기시설분야의 각종 첨단기술개발 및 발전과 더불어 하부 토목구조물의 건설 및 설계 해석분야에 많은 발전이 기대된다 하겠다.