• KCI Concrete Journal
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• 제13권2호
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• pp.49-57
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• 2001

Flat-plate buildings are commonly modeled as two-dimensional frames to calculate unbalanced moments, lateral drift and shear at slab-column connections. The slab-column frames under lateral loads are analyzed using effective beam width models, which is convenient for computer analysis. In this case, the accuracy of this approach depends on the exact values of effective beam width to account for the actual behavior of slab-column connections. In this parametric study, effective beam width coefficients for wide range of the variations are calculated on the several types of slab-column connections, and the results are compared with those of other researches. Also the formulas for effective beam width coefficients are proposed and verified by finite element analysis. The proposed formulas are founded to be more suitable than others for analyzing flat-plate buildings subjected to lateral loading.

• KCI Concrete Journal
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• 제14권1호
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• pp.1-7
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• 2002

This paper reports the experimental and analytical investigations for evaluating the flexural strength of a RC slab strengthened with carbon fiber sheet (CFS). The evaluation of the ultimate flexural strength of a slab is tried under the assumption that the failure occurs when the shear stress mobilized at the interface between the concrete bottom and the glued CFS reaches its bond strength. The shear stress is evaluated theoretically and the bond strength is obtained by a laboratory test. The ultimate flexural strength is obtained by flexural static test of the slab specimen, which corresponds to the part of a real slab. From the results, the new approach based on the bond strength between concrete and CFS looks feasible to evaluate the flexural strength of the CFS and RC composite slab.

• Steel and Composite Structures
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• 제5권4호
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• pp.259-269
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• 2005

Many slab-on-girder bridges around the world are being assessed because they are approaching the end of their anticipated design lives or codes are permitting higher allowable loads. Current analytical techniques assume that the concrete and steel components act independently, typically requiring full-scale load testing to more accurately predict the remaining strength or endurance of the structure. However, many of the load tests carried out on these types of bridges would be unnecessary if the degree of interaction resulting from friction at the steel-concrete interface could be adequately modeled. Experimental testing confirmed that interface friction has a negligible effect on the flexural capacity of a slab-on-girder beam however, it also showed that interface friction is significant under serviceability loading. This has led to the development of an improved analytical technique which is presented in this paper and referred to as the slab-on-girder mixed analysis service load assessment approach.

• Earthquakes and Structures
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• 제3권3_4호
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• pp.495-506
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• 2012

An elasto-dynamic model for pile-soil-pile interaction together with a simple plate model is used in this study to assess the effect of flexible foundation slabs on the dynamic response of pile groups. To this end, different pile configurations with various slab thicknessesare considered in two soil media with low and high elastic moduli. The analyses include dynamic impedances and seismic responses of pile-group foundations. The presented results indicate that the stiffness and damping of pile foundations increase with thickness of the foundation slab; however, the results approach those for rigid slab as the slab thickness approaches twice the pile diameter for the cases considered in this study. The results also reveal that pile foundations with flexible slabs may amplify the earthquake motions by as much as 10 percent in the low to intermediate frequency ranges.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.279-282
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• 2008

The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of the end rotation of the overhang due to the vertical load. When the up-lifting force exceeds the clamp force of the fastener clip, the rail pad is out of fastener, which makes decrease the serviceability of the railway, such as noise and vibration. Furthermore, it is possible to reduce the safety of the track as the longitudinal resistance. This study is focused on guideline suggestion to decrease up-lifting force in the fastener adjacent to the civil joint of slab track of bridge throughout the parametric analysis between the vertical spring stiffness of the fastener as the material approach, the space of fastener adjacent to bridge transition, the rigidity of the girder as the geometrical approach and up-lifting force under the train load.

• Steel and Composite Structures
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• 제2권6호
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• pp.429-440
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• 2002

A finite strip method is developed for fatigue reliability analysis of steel highway bridges. Flat shell strips are employed to model concrete slab and steel girders, while a connection strip is formed using penalty function method to take into account eccentricity of girder top flange. At each sampling point with given slab thickness and modulus ratio, a finite strip analysis of the bridge under fatigue truck is performed to calculate stress ranges at fatigue-prone detail, and fatigue failure probability is evaluated following the AASHTO approach or the LEFM approach. After the failure probability is integrated over all sampling points, fatigue reliability of the bridge is determined.

• 콘크리트학회논문집
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• 제17권5호
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• pp.687-694
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• 2005

건설 재료와 기술의 발달로 건축물이 장스팬화 ·경량화 되어 가고 있다. 이로 인해 건축물 바닥의 고유진동수(Frequency)와 감쇠비(damping ratio)가 감소함에 따라 거주자들의 바닥판의 수직진동에 대한 문제가 발생하고 있다 그러나 현행 사용성 기준은 바닥판의 최대 정적 처짐에 의해 결정하고 있다. 하지만 선행연구(Han et al., 2003)에서 현행 기준을 만족하는 바닥이 수직진동에 대한 사용성 기준을 만족하지 못하는 것을 볼 수 있다. 따라서 본 연구에서는 거주자들의 뒤꿈치 충격하중에 대한 수직진동 사용성 기준을 만족하는 바닥 두께를 제안하고자 하였다. 슬래브 재료의 특성과 뒤꿈치 충격하중 및 마감 고정하중의 불확실성을 고려하기 위해 Monte Carlo Simulation을 사용하여 확률적으로 접근하였다. 그 결과 4변 단순지지의 경우 두께가 스팬 길이의 $1/14\~1/17$에서, 4변 고정지지의 경우 스팬 길이의 $1/18\~1/25$인 경우에 초과 확률이$0\%$에 도달하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.265-268
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• 2008

슬래브-기둥 접합부는 많은 구조물의 시공에 사용되고 있다. 그러나 횡하중을 받는 슬래브-기둥 접합부의 파괴거동 및 극한강도를 예측하는 것이 매우 어렵기 때문에 현행 구조물 설계기준은 횡하중을 받는 슬래브-기둥 접합부의 파괴 거동을 명확하게 설명하지 못하고 있다. 본 논문에서는 횡하중을 받는 슬래브-기둥 접합부의 극한해석과 설계를 위하여 응력교란영역을 가지는 3차원 구조의 해석과 설계를 위하여 제안된 3차원 격자 스트럿-타이 모델 방법을 파괴실험이 수행된 43개의 횡하중을 받는 슬래브-기둥 접합부의 극한강도 평가에 적용하고, ACI 318-05 기준과 FIB 1999 기준에 의한 극한강도 평가결과와 비교함으로써 3차원 격자 스트럿-타이 모델 방법의 타당성을 검토하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제16권3호
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• pp.99-108
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• 2012

본 연구에서는 철근콘크리트 슬래브의 내부식성과 경량화를 도모하기 위하여 GFRP bar를 휨보강근으로 사용하는 경량골재콘크리트 슬래브를 고려하고 이 구조물에 대하여 기초적인 거동을 조사하였다. 경량콘크리트의 압축강도 및 인장강도 그리고 콘크리트 파괴에너지 측정, 일련의 슬래브 휨실험, 비선형유한요소해석을 통한 수치해석, 휨실험과 수치해석의 결과비교 등이 행하여졌다. 그 결과, GFRP bar를 휨보강근으로 사용한 경량콘크리트 슬래브는 기준시험체로 사용된 동일 규격의 철근콘크리트 슬래브에 비하여 무게를 28%정도 감소시킬 수 있었지만 파괴하중은 36%정도 감소되었다. 이는 GFRP bar의 낮은 축강성과 경량콘크리트의 낮은 부착강도 때문인 것으로 판단된다. 그리고 경량콘크리트의 부착력 감소 특성을 고려하기 위하여 GFRP bar와 콘크리트 경계면 사이에 계면요소를 사용한 수치해석 결과는 계면요소의 사용이 실험결과에 더 근접해갈 수 있는 방법임을 보여주었다.

• Structural Engineering and Mechanics
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• 제24권5호
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• pp.561-584
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• 2006

The paper presents results of parametric studies, and an overall approach for the design of a modular bridge system which incorporates a steel-reinforcement free concrete slab cast on top of carbon FRP stiffened deck panels which act as both structural formwork and flexural reinforcement, spanning between hollow box type FRP girders. Results of the parametric studies are highlighted to elucidate important relationships between critical configurational parameters and empirical equations based on numerical studies are presented. Results are discussed at the level of the individual deck and girder components, and as a slab-on-girder bridge system. An overall design methodology for the components and bridge system including critical performance checks is also presented.