• Structural Monitoring and Maintenance
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• 제7권4호
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• pp.367-392
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• 2020

The specific characteristics of near-field earthquake records can lead to different dynamic responses of bridges compared to far-field records. However, the effect of near-field strong ground motion has often been neglected in the seismic performance assessment of the bridges. Furthermore, damage to horizontally curved multi-frame RC box-girder bridges in the past earthquakes has intensified the potential of seismic vulnerability of these structures due to their distinctive dynamic behavior. Based on the nonlinear time history analyses in OpenSEES, this article, assesses the effects of near-field versus far-field earthquakes on the seismic performance of horizontally curved multi-frame RC box-girder bridges by accounting the vertical component of the earthquake records. Analytical seismic fragility curves have been derived thru considering uncertainties in the earthquake records, material and geometric properties of bridges. The findings indicate that near-field effects reasonably increase the seismic vulnerability in this bridge sub-class. The results pave the way for future regional risk assessments regarding the importance of either including or excluding near-field effects on the seismic performance of horizontally curved bridges.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.401-408
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• 2001

The main objective of this study is to analyze the distortion of curved steel box girders. For the distortional analysis of steel box girders, two approaches are presented. One is the development of approximate formulas obtained by applying Ritz method. The other is the formulation of stiffness matrix which is derived from the exact solution of the differential equation for distortion. Distortional analysis is carried out by utilizing 3-dimensional elements of a structural analysis computer program (SAP2000). The present analysis focuses on the distortional stress and the effects of the diaphragm. The results of several example cases are compared with those by the Nakai, Sakai, Heins, and Oleinik's theory and get the effect of diaphragm spacing on the distortional warping stress of the curved steel box girder.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.79-80
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• 2010

곡선형 강 박스 거더의 상부 플랜지를 구성하는 콘크리트의 건조수축 및 크리프 현상으로 인해 발생하는 재령종속적 비틀림 거동을 분석하기 위한 실험실 실험을 수행하였다. 재령종속 증분탄성계수(Age-Dependent Incremental Tangent Modulus, ADITM) 에 근거하는 유한요소해석법을 사용하여 실험체의 시간종속적 거동을 예측하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.20-27
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• 2005

Solar radiation causes non-uniform temperature distribution in the structure, depending on the shape of the structure and its shadows. Especially in cases of curved steel box girder bridges, non-uniform temperature distribution due to solar radiation can reduce bridge life and serviceability when combined with another load combination. In this study, the method for predicting the temperature distribution of curved bridges developed by Kim et al., was used to predict the non-uniform temperature distribution which served as a basis for structural analysis of 3-D bridge behavior. In order to seek the most unfavorable conditions of solar radiation, observation data from the Korea Meteorological Administration for solar radiation were analyzed. The region of the most high solar radiation condition was selected and its one year variation of the solar radiation data was considered. From this analysis, the most unfavorable solar radiation condition with lower solar altitude and intense solar radiation was selected. Based on the selected solar radiation condition, structural behavior of curved bridges with diverse bridge direction, span length, radius and support conditions are analyzed.

• Steel and Composite Structures
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• 제37권2호
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• pp.117-136
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• 2020

Curved steel-concrete composite box girder has been widely adopted in urban overpasses and ramp bridges. In order to investigate its mechanical behavior under complicated and combined bending, shear and torsion load, two large-curvature composite box girders with interior angles of 25° and 45° were tested under static hogging moment. Based on the strain and deflection measurement on critical cross-sections during the static loading test, the failure mode, cracking behavior, load-displacement relationship, and strain distribution in the steel plate and rebar were investigated in detail. The test result showed the large-curvature composite box girders exhibited notable shear lag in the concrete slab and steel girder. Also, the constraint torsion and distortion effect caused the stress measured at the inner side of the composite beam to be notably higher than that of the outer side. The strain distribution in the steel web was approximately linear; therefore, the assumption that the plane section remains plane was approximately validated based on strain measurement at steel web. Furthermore, the full-process non-linear elaborate finite element (FE) models of the two specimens were developed based on commercial FE software MSC.MARC. The modeling scheme and constitutive model were illustrated in detail. Based on the comparison between the FE model and test results, the FE model effectively simulated the failure mode, the load-displacement curve, and the strain development of longitudinal rebar and steel girder with sufficient accuracy. The comparison between the FE model and the test result validated the accuracy of the developed FE model.

• 콘크리트학회지
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• 제24권4호
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• pp.39-42
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• 2012

• 콘크리트학회지
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• 제28권6호
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• pp.42-46
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• 2016

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.335-342
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• 1999

It is well known that l-girders are weak in torsion and it might be more economical to use a box girder, which has great torsional rigidity. The use of box beams does, however, present a potential problem in that cross-sectional distortions can induce large warping normal stresses and transverse bending stress. Accordingly a sufficient number of diaphragms are provided to make the distortional effects minimal. In engineering practice, diaphragms are spaced in 5m intervals without reasonable basis. It is considered to be noneconomical design to the almost design engineers, and it may produce the unsafe structural systems in special cases such as curved bridges with large initial curvature. These problems have not been solved for the lack of adequate tools of structural analysis. In this study, on the basis of the parametric studies, the design formulas for the distortional warping stress and the reasonable diaphragm spacing of box girder were presented.

• 한국전산구조공학회논문집
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• 제28권2호
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• pp.161-168
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• 2015

평면내 곡선교량은 편심하중뿐만 아니라 자중만으로도 비틀림하중을 받게 되고, 이는 지점부 부반력 발생의 원인이 된다. 본 논문에서는 경간장 48.8m를 가지는 단경간 곡선강박스 거더교량에 대해 내부곡률각도를 0.49~1.35rad으로 조정하면서 곡률효과에 따라 지점에서 발생하는 수직반력을 분석하였다. 부반력 발생가능성을 고려하여 반력 크기 및 방향을 예측하기 위해 곡선교량 상부구조를 각 독립된 요소로 분리하여 반력산정식을 해석적으로 개발하였다. 콘크리트 바닥판 및 강재 하부플랜지는 각각 면의 차원을 가지는 기학학적 환형섹터로, 수평면내에서 폭이 좁게 투영되어 나타나는 상부플랜지 및 복부판은 선의 차원을 가지는 기하학적 호로 가정되었다. 제안된 반력산정식의 형식은 비교적 단순하고 그 예측값은 유한요소해석으로 얻은 값과 비교하였을 때 오차가 1% 수준으로 잘 일치하였다.

• 대한토목학회논문집
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• 제34권6호
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• pp.1731-1741
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• 2014

교통수요의 증가에 따른 교통혼잡을 피하기 위하여 고가도로와 고속도로, 경전철 등이 활발히 건설되고 있으며, 이에 따라 접속부 등과 같은 곡률반경이 작은 곡선교 구간의 발생이 증가하고 있다. 초기에는 직선형의 주형을 연결하여 곡선을 이루는 방법을 사용하였으나, 공사비의 증가와 미관성 측면에서 용이하지 않아 강재를 사용한 곡선주형이 개발되어 적용되고 있다. 강재의 특성상 기하학적인 형상을 구현하는데 상대적으로 손쉽기 때문에 대부분의 곡선교에서는 강재를 이용한 강박스 거더교를 주로 사용하고 있다. 그러나 강박스 거더교는 초기 공사비가 고가이고, 도장과 같은 지속적인 유지관리가 필요한 문제점을 가지고 있다. 최근에는 I형 강재 플레이트 거더를 사용하는 방법이 활발히 연구되고 있으나 곡선 I형상의 특성상 개단면이고 얇은 플레이트를 사용하기 때문에 비틀림 강성이 매우 작아 안전성에 문제가 있는 것으로 지적되고 있다. 이러한 곡선강교의 대안으로 경제성과 안전성이 확보되는 프리캐스트 PSC 곡선거더가 제시되고 있다. 이에 본 연구에서는 프리캐스트 PSC 곡선거더를 효율적으로 제작할 수 있는 스마트 몰드 시스템을 개발하고 이를 적용한 2주형 40m 실물교량의 정적 휨 파괴 실험을 통하여 안전성을 확인하고자 한다. 제작단계에서 단일 거더는 곡률반경에 의해 거더의 전도에 대한 안정성이 문제가 있으나 가로보로 연결된 멀티거더는 하중분배가 적절히 이루어지며 안정성이 확보되는 것으로 나타났다. 정적구조 실험결과에서는 균열하중(1,400 kN)이 설계하중(450 kN)의 약 3배 이상 높은 것으로 나타났으며, 허용처짐량에 해당하는 하중은 설계하중의 4배인 1,800 kN에서 발생하여 사용성과 안전성이 모두 확보되는 것으로 나타났다.