• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.198-199
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• 2011

플로팅 함체는 육상과 달리 지진하중의 영향을 받지 않으며 파랑하중의 영향을 크게 받는다. 파랑하중에 대한 안전성을 확보하기 위하여 범용구조해석 프로그램을 이용하여 해석하였다. 상부구조물의 영향을 확인하기 위하여 함체의 밀도를 변화시켜 상부하중에 대한 함체의 변위 응답을 확인을 한 결과, 밀도에 따른 함체 거동의 변화는 미미하였다. 해석을 통해 얻은 각 주기별 변위를 하중에 적용한 상부구조물의 모멘트 증가비는 파랑하중의 주기가 단주기에서 장주기로 갈수록 감소하는 양상을 보였으며, 축력은 파랑주기의 영향을 적게 받는 것으로 나타났다.

• International Journal of Highway Engineering
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• v.3 no.3 s.9
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• pp.147-158
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• 2001

One of the most important factors accounting for the structural capacity of concrete pavement is load transfer efficiency. Load transfer efficiency is affected by slab temperature gradient, construction of dowel bars, degree of aging, and crack width. The purpose of this study is to determine the patterns of load transfer efficiency of concrete pavement; to determine the factors that affect the load transfer efficiency; and to present the proper measuring method of load transfer efficiency. As a result from this study, load transfer efficiency was affected primarily by the average temperature in concrete slab. Load transfer efficiency decreased with decreasing temperature and increasing crack width. For the sections with dowel bars, there were little differences in load transfer efficiency regardless of temperature changes. For the sections without dowel bars, however, there on great losses of load transfer efficiency at low temperatures. For the old pavement, even in the sections with dowel bars, the load transfer efficiency reduced as the temperature dropped For the sections in this study, 1.4% reduction of the load transfer efficiency was observed for each $1^{\circ}C$ drop in the slab temperature.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.2
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• pp.181-192
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• 2001

이 논문은 샌드위치식 강-콘크리트 복합구조체에서 상하 강판과 격벽으로 구성되는 셀의 형상비가 거동과 성능에 미치는 영향을 다루었다. 이 구조체에서 셀 형상비는 하중전달 메카니즘과 하중분배능력을 변화시킨다. 따라서 셀 형상비에 따라 부재의 응력수준과 하중저항능력이 변화한다. 이 연구에서는 셀 형상비가 이 구조체의 거동과 성능에 미치는 영향을 규명하기 위해, 두 종류의 샌드위치식 복합구조체에 대해 다양한 셀 형상비를 설정하여 비선형 구조해석을 수행하였다. 해석결과로부터 셀 형상비에 따른 하중전달 메카니즘과 부채 응력에서의 차이점을 도출하였으며, 이들 차이점을 바탕으로 셀 형상비가 전단성능, 휨성능, 하중저항성능에 미치는 영향을 분석하였고, 파괴모드와 연성에 미치는 영향에 대해서도 간략히 언급하였다. 연구결과, 셀 형상비가 증가함에 따라 하부 강판과 콘크리트의 응력수준이 낮아지는 결과를 나타내었다. 이것은 각 부재의 유효휨강성과 유효전단강성 증가를 나타내며, 따라서 구조체의 하중저항성능도 향상되는 것으로 판단된다. 특히 셀 형상비의 증가에 따른 성능향상에서 전단성능이 휨성능에 비해 더 큰 효과를 나타내며, 이러한 차이는 파괴모드와 연성에도 영향을 미칠 것으로 판단된다. 즉, 셀 형상비가 증가함에 따라 구조물의 거동 및 파괴모드는 점차적으로 전단에서 휨으로 변화하고, 이에 따라 구조물의 연성도 점차적으로 향상될 것으로 판단된다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.438-441
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• 2009

휨강성이 작은 바닥시스템인 플랫 플레이트 구조는 응력조건 뿐만 아니라 사용성조건에 의하여 구조적 성능이 결정될 수 있으며, 특히 과도한 시공 하중의 작용은 시공 중 안전성에 대한 단기적인 손상 뿐만 아니라 사용성에 관련된 장기적인 손상을 발생시킬 수 있다. 이러한 플랫 플레이트의 시공하중은 동바리지지 층 수, 시공주기, 슬래브 콘크리트의 재료적인 강성 뿐만 아니라, 동바리의 강성과 슬래브에 발생하는 균열에 의한 영향에 의하여 결정된다. 본 논문에서는 다양한 설계조건에 대한 해석연구를 통하여, 동바리-슬래브의 강성비 변화 및 콘크리트 균열에 의한 단면강성저하가 슬래브들 간의 하중 분포에 미치는 영향을 분석하고, 이러한 동바리 강성 및 슬래브 균열의 영향을 고려한 시공하중 산정법을 제안한다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.4
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• pp.731-742
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• 2018

Recently, the construction of the urban area has been rapidly increasing, and the excavation work of the ground has been frequently performed at the upper part of the existing underground structure. Especially, when the structure is constructed after the excavation of the ground, the loading and unloading process is repeated in the lower ground of the excavation so that it can affect existing underground structures. Therefore, in order to maintain the stability of the existing underground structure due to the excavation of the ground, it is necessary to accurately grasp the influence of the excavation and the structure load in the adjoining part. In this study, the effects of the ground excavation and the new structure load on the existing tunnel were investigated by large - scale experiment and numerical analysis. For this purpose, a large model tester with a size reduced to 1/5 of the actual size was constructed, and model tests and numerical analyzes were carried out to investigate the effects of the excavation of the body ground by maintaining the distance between the excavation floor and the tunnel ceiling constant, The impacts were identified. As a result of the study, it was confirmed that the deeper the excavation depth, the larger the influence on the existing tunnel. At the same distance, it was confirmed that the tunnel displacement increased with the increase of the building load, and the ground stress increased up to 2.4 times. From this result, it was confirmed that the effect of the increase of the underground stress on the existing tunnel is affected by the increase of the building load, and the influence of the underground stress is decreased from the new load width above 3.0D.

• Computational Structural Engineering
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• v.6 no.3
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• pp.67-80
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• 1993

This paper presents the results of an analytical study to evaluate the inelastic seismic response characteristics of multistory building structures, the effects of gravity load on the seismic responses and its implications on the earthquake resistant design. Static analyses for incremental lateral force and nonlinear dynamic analyses for earthquake motions were performed to evaluate the seismic response of example multistory building structures. Most of considerations are placed on the distribution of inelastic responses over the height of the structure. When an earthquake occurs, bending moment demand is increased considerably from the top to the bottom of multistory structures, so that differences between bending moment demands and supplies are greater in lower floos of multistory structures. As a result, for building structures designed by the current earthquake resistant design procedure, inelastic deformations for earthquake ground motions do not distribute uniformly over the height of structures and those are induced mainly in bottom floors. In addition, gravity load considerded in design procedure tends to cause much larger damages in lower floors. From the point of view of seismic responses, gravity load affects the initial yield time of griders in earlier stage of strong earthquakes and results in different inelastic responses among the plastic hinges that form in the girders of a same floor. However, gravity load moments at beam ends are gradually reduced and finally fully relaxed after a structure experiences some inelastic excursions as a ground motion is getting stronger. Reduction of gravity load moment results in much increased structural damages in lower floors building structures. The implications of the effects of gravity load for seismic design of multistory building structures are to reduce the contributions of gravity load and to increased those of seismic load in determination of flexual strength for girders and columns.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.265-268
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• 2011

하중 속도에 따른 콘크리트 재료의 역학적 특성은 구조물의 동적파괴거동에 영향을 미친다. 본 연구는, rigid-body-spring network를 이용하여 파괴해석을 수행하고, 거시적 시뮬레이션에서 속도효과를 표현하기 위하여 점소성 파괴모델을 적용하였다. 보정을 위해서 Perzyna 구성관계식의 점소성 계수들이 다양한 하중속도에 따른 직접인장실험을 통해서 결정되었다. 동정상승계수를 이용하여 하중 속도가 증가함에 따른 강도 증가를 표현하였고 이를 실험결과와 비교하였다. 다음으로 느린 하중속도와 빠른 하중속도에 따라 단순 콘크리트 보와 철근 콘크리트 보에 대한 휨 실험을 수행하였으며, 하중 속도에 따라서 서로 다른 균열 패턴을 관찰할 수 있었다. 빠른 하중은 보의 파괴가 국부적으로 나타나게 만드는데, 이는 속도 의존적 재료의 특성 때문이다. 구조적인 측면에서, 보강재는 느린 하중속도에서 균열의 크기를 줄이고 연성을 높이는 데 큰 영향을 미친다. 본 논문은 속도 의존적 거동에 대한 이해와 동적하중에 대한 보강효과를 제시한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.853-860
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• 2017

To evaluate the effects of mode II on the crack initiation and propagation stages, the effects in the fatigue threshold region under a mixed-mode I+II loading state was experimentally investigated. In the case of mixed-mode I + II, during the crack initiation stage, as the loading application angle (${\theta}$) increased, cracks occurred in the lower load owing to the effects of mode II, while the crack propagation rate decreased. The effects of mode II were experimentally investigated in the crack propagation stage by means of multilevel loading direction variation. Following mixed-mode I+II ($0^{\circ}{\rightarrow}{\theta}{\rightarrow}60^{\circ}$), as the load application angle increased, the fatigue crack propagation rate decreased, as did the fatigue crack propagation rate, which occurred later. Following mixed-mode I + II in case of(${\theta}{\geq}75^{\circ}$), the fatigue crack propagation rate was found to increase, while the fatigue life decreased.

• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.11-21
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• 2005

To examine adequacy of existing multi-layer elastic analysis of layer interface conditions, this study compared outputs of finite element analysis and multi-layer elastic analysis as vertical load was applied to the surface of asphalt pavements. Structural pavement analysis considering influence of a horizontal load was also carried out in order to simulate passing vehicle loads under various interface conditions using ABAQUS, a three dimensional finite element program. Pavement performance depending on interface conditions was quantitatively evaluated and fundamental study of layer interface effect was performed in this study. As results of the study, if only vertical load is applied, subdivision of either fully bonded or fully unbonded is enough to indicate interface condition. On the other hand, when horizontal load is applied with vertical load, pavement behavior and performance are greatly changed with respect to layer interface condition.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.67-76
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• 1992

A procedure to determine the axle load limits of asphalt concrete pavements are proposed in this study. Axle load limits are determined by calculating maximum tensile strains at the bottom of the asphalt stabilized base layer and maximum vertical strains at the top of the subgrade. In order to investigate the efficiency of axle configuration, calculated influence line of wheel load on domestic expressway pavement system is used. Limiting strains are selected through the analysis of conventional failure criteria. From the analysis of axle load limits about axle composition(single-axle, tandem-axle, tridem-axle), it is found that the axle load limits of tandem-axle and tridem-axle can be calculated by muitipling the axle load limits of single-axle by axle numbers and that axle load limits are closely related to the thickness of each layer of pavement structure. It is also found that the axle load limits by tensile strains are more critical than those by vertical strains on asphalt concrete pavement models of YOUNG-DONG, KYONG-IN and KYONG-BU expressways.