• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.857-860
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• 2000

An experimental study on the behavior of Steel Fiber Reinforced Concrete Columns under eccentric compression are presented. Forth-one columns were tested; the variables were column type, eccentricity of load, fiber contents, and longitudinal reinforcement ratio. The column size was $250\times160$ mm in cross section with an effective length of 1150 mm. Eccentricity of load was varied in the range from 1/6 to 1/2 times the column depth. This paper is to provides a framework for basic understanding of the steel fiber concrete columns.

• 콘크리트학회논문집
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• 제15권5호
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• pp.715-725
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• 2003

본 연구는 철근콘크리트 교각에 대한 새로운 내진설계법을 개발하기 위한 연구의 일환으로서, 지진하중을 받는 철근콘크리트 교각의 연성도와 심부구속철근량의 상관관계를 분석하고 설계식을 제시함을 목적으로 한다. 이를 위하여, 반복하중을 받는 철근콘크리트 기둥의 횡하중-변위 포락곡선 실험결과를 비교적 정확하게 예측하며, 특히 변형능력 및 연성도에 대하여는 실험결과에 비하여 안전측의 결과를 제공하는 비선형해석 프로그램 [NARCE]를 이용하였다. 해석의 대상 교각으로는, 단면지름, 형상비, 콘크리트 강도, 축방향철근 항복강도, 심부구속철근 항복강도, 축방향철근비, 축력비, 심부구속철근비 등을 주요변수로 하여 총 7,200개의 철근콘크리트 나선철근 기둥 모델을 채택하였다. 해석결과 자료를 대상으로 상관관계를 분석하여 소요연성도에 따른 심부구속철근량의 새로운 설계식을 제안하였으며, 이 식은 연성도에 기초한 철근콘크리트 교각의 새로운 내진설계법에 적용될 수 있을 것이다.

• 한국강구조학회 논문집
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• 제28권4호
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• pp.243-251
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• 2016

두께가 얇아짐에 따라 강바닥판은 윤하중의 작용으로 국부적으로 매우 큰 변형이 발생하고, 이것은 교면포장에 종방향으로 구조적인 균열을 야기 시킬 수 있다. 이 연구에서는 강바닥판의 윤하중 국부해석을 위하여 가로보의 휨 및 비틀림강성을 엄밀히 고려할 수 있는 평면쉘 스트립요소, 프리즘요소, 그리고 이 두요소를 연결하는 링크요소로 구성된 개선된 유한대판법을 제시하고자 한다. 이 방법의 효용성을 검증하기 위하여, 강판 플레이트 거더교의 일부를 해석예제로 선택하여 연직처짐 및 교축직각방향 변형율 결과를 쉘요소, 솔리드요소, 그리고 코히시브요소를 이용한 ABAQUS 해석결과와 비교, 검토하였다.

• KCI Concrete Journal
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• 제14권3호
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• pp.130-137
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• 2002

It is known that lap splice in the longitudinal reinforcement of reinforced concrete(RC) bridge columns is not desirable for seismic performance, but it is sometimes unavoidable. Lap splices were practically located in the potential plastic hinge region of most bridge columns that were constructed before the adoption of the seismic design provision of Korea Bridge Design Specification on 1992. The objective of this research is to evaluate the seismic performance of reinforced concrete(RC) bridge piers with lap splicing of longitudinal reinforcement in the plastic hinge region, to develop the enhancement scheme of their seismic capacity by retrofitting with glassfiber sheets, and to develop appropriate limited ductility design concept in low or moderate seismicity region. Nine test specimens in the aspect ratio of 4 were made with three confinement ratios and three types of lap splice. Quasi-static test was conducted in a displacement-controlled way under three different axial load levels. A significant reduction of displacement ductility ratios was observed for test columns with lap splices of longitudinal steels.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.537-543
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• 1997

A new procedure for the advanced one-side measurement of longitudinal wave and surface wave velocities in concrete is presented in this paper. Stress waves are generated in a consistent fashion with a DC solenoid. Two piezoelectric accelerometers are mounted on the surface of a specimen as receivers. Stress waves propagate along the surface of the specimen and are detected by the receivers. In order to reduce the large incoherent noise levels of the signals, signals are collected and manipulated by a computer program for each velocity measurement. For a known distance between the two receivers and using the measured flight times, the velocities of the longitudinal wave and the surface wave are measured. The velocities of the longitudinal wave determined by this method are compared with those measured by conventional methods on concrete, PMMA and steel.

• 한국안전학회지
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• 제24권6호
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• pp.93-102
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• 2009

Because steel girder bridge has big slenderness ratio, buckling is very important in design. Local buckling of plate girders having two longitudinal stiffeners in different positions under various load conditions is investigated. Various parametric study according to the change of web height, transverse stiffeners and load conditions are examined. These parametric studies are performed by numerical simulation utilizing finite element method. The objective of this study is to present the rational reinforcement location of two longitudinal stiffeners. The results of analysis are compared to that recommended by korean specifications for road bridges(2003).

• Steel and Composite Structures
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• 제45권5호
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• pp.665-682
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• 2022

In the current study, punching behavior of Reinforced concrete (RC) isolated footings was experimentally and numerically investigated. The experimental program consisted of four half-scale RC isolated footing specimens. The test matrix was proposed to show effect of footing area, reinforcement mesh ratio, adding internal longitudinal reinforcement bars and stirrups on the punching response of RC isolated footings. Footings area varied from 1200×1200 mm2 to 1500×1500 mm2 while the mesh reinforcement ratio was in the range from 0.36 to 0.45%. On the other hand, a 3D non-linear finite element model was constructed using ABAQUS/standard program and verified against the experimental program. The numerical results agreed well with the experimental records. The validated numerical model was used to study effect of concrete compressive strength; longitudinal reinforcement bars ratio and stirrups concentration along one or two directions on the ultimate load, deflection, stiffness and failure patterns of RC isolated footings. Results concluded that adding longitudinal reinforcement bars did not significantly affect the punching response of RC isolated footings even high steel ratios were used. On the contrary, as the stirrups ratio increased, the ultimate load of RC isolated footings increased. Footing with stirrups ratio of 1.5% had ultimate load equal to 1331 kN, 19.6% higher than the bare footing. Moreover, adding stirrups along two directions with lower ratio (0.5 and 0.7%) significantly enhanced the ultimate load of RC isolated footings compared to their counterparts with higher stirrups ratio (1.0 and 1.5%).

• Wind and Structures
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• 제35권2호
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• pp.93-108
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• 2022

Steel tubular towers are commonly used in UHV and long crossing transmission lines. By considering effects of the model scale, the solidity ratio and the ratio of the mean width to the mean height, wind tunnel tests under different wind speeds on twenty tubular steel tower body models and twenty-six tubular steel cross-arm models were completed. Drag coefficients and shielding factors of the experimental tower body models and cross-arm models in wind directional axis for typical skewed angles were obtained. The influence of the lift forces on the skewed wind load factors of tubular steel tower bodies was evaluated. The skewed wind load factors, the wind load distribution factors in transversal and longitudinal direction were calculated for the tubular tower body models and cross-arm models, respectively. Fitting expressions for the skewed wind load factors of tubular steel bodies and cross-arms were determined through nonlinear fitting analysis. Parameters for skewed wind loads determined by wind tunnel tests were compared with the regulations in applicable standards. Suggestions on the drag coefficients, the skewed wind load factors and the wind load distribution factors were proposed for tubular steel transmission towers.

• 대한토목학회논문집
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• 제30권6A호
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• pp.503-512
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• 2010

하중-저항계수 설계법에서 조밀단면은 휨모멘트에 의하여 특정단면이 소성모멘트에 도달하기 전에 복부판과 플랜지에 국부좌굴 및 거더의 횡비틈좌굴이 발생하지 않는 단면으로 정의하고 있다. AASHTO LRFD(2007)에서는 수평보강재를 갖지 않는 단면에 관해서만 조밀단면을 만족하는 복부판의 세장비 규정을 제시하고 있다. 복부판에 설치하는 수평보강재의 역할은 휨 좌굴강도를 증가시키는 것이다. 비록 비보강된 복부판이 조밀단면의 기준을 만족하지 못한다고 할지라도, 적당한 수평보강재를 설치한다면 복부판의 좌굴을 방지할 수 있을 것이다. 그러므로 복부판은 소성모멘트에 도달할 수 있을 것이다. 그러나 AASHTO LRFD(2007)에서는 수평보강재를 설치한 복부판이 조밀단면을 만족하지 못하는 이유에 관하여 분명하게 설명하고 있지 않다. 본 연구에서는 수평보강재를 설치한 복부판에서의 휨에 의한 좌굴과 극한강도거동을 선형과 비선형 유한요소법을 통하여 검토하였다. 비록 조밀단면의 세장비를 만족하지 못하는 복부판이라고 할지라도, 충분한 강성과 적절한 위치에 수평보강재로 보강하면 소성모멘트에 도달할 수 있다는 것을 알아냈다. 비선형해석의 분석을 통해 수평보강재를 갖는 복부판의 조밀단면을 만족하는 새로운 세장비 조건식을 제안하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.745-750
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• 2000

The rigidity of pier is important in the analysis of rail on high speed railway bridges. This study is being performed because of followings. 1) Actual longitudinal stiffness of the structure including substructure should be considered in the calculation of longitudinal stresses in rails. 2) There are many uncertainties in piers and foundations for design. 3) Actual guideline for the design of piers is necessary. 4) Measurement on the rigidity of pier according to the types of pier, foundation and soil-condition is needed. Curve for rigidity will be obtained through this study and applied for actual design as the guideline. Stresses in rails can be estimates accurately. A pair of piers, which consists of pot-bearing for fixed support and pad-bearing for movable support, is loaded by steel frame through steel wire ropes. The responses which are intended to measure in the field test are displacements, forces and tilts on the top of piers.