• Computers and Concrete
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• 제1권2호
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• pp.151-168
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• 2004

A two-dimensional nonlinear finite element model is developed to simulate time-dependent cracking of reinforced concrete members under service loads. To predict localized cracking, the crack band model is employed to model individual crack opening. In conjunction with the crack band model, a bond-interface element is used to model the slip between concrete and reinforcing steel permitting large slip displacements between the concrete element nodes and the steel truss element nodes at crack openings. The time-dependent effects of concrete creep and shrinkage are incorporated into the smeared crack model as inelastic pre-strains in an iterative solution procedure. Two test examples are shown to verify the finite element model with good agreement between the model and the observed test results.

• 콘크리트학회논문집
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• 제13권4호
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• pp.389-396
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• 2001

이 논문에서는 지진시 철근콘크리트 교각의 피로거동을 해석적으로 예측할 수 있는 기법을 제시하였다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근모델을 조합하여 고려하였다. 이에 대한 콘크리트의 균열모델로서는 분산균열모델을 사용하였다. 두께가 서로 다른 부재간의 접합부에서 단면강성이 급변하기 때문에 생기는 국소적인 불연속 변형을 고려하기 위한 경계면 요소를 도입하였다. 또한, 같은 변위진폭에 있어서의 하중재하 회수에 의한 효과를 고려하였다. 이 연구에서는 지진시 철근콘트리트 교각의 피로거동을 파악하기 위해 제안한 해석기법을 신뢰성 있는 연구자의 실험결과와 비교하여 그 타당성을 검증하였다.

• 콘크리트학회논문집
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• 제12권6호
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• pp.83-90
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• 2000

This paper presents an analytical prediction of the elastic behavior of discontinuous displacement in reinforced concrete column-footing joint under earthquake. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The proposed numerical method for hysteretic behavior of discontinuous displacement in reinforced concrete column-footing joint will be verified by comparison with reliable experimental results.

• Advances in concrete construction
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• 제7권4호
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• pp.203-210
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• 2019

Concrete structures in marine environment are susceptible to chloride attack, where chloride diffusion results in the corrosion of steel bar and further lead to the cracking of concrete cover. This process causes structural deterioration and affects the response of concrete structures to different forms of loading. This paper presents the use of ABAQUS Finite Element Software in simulating the processes involved in concrete's structural degradation from chloride diffusion to steel corrosion and concrete cover cracking. Fick's law was used for the chloride diffusion, while the mass loss from steel corrosion was obtained using Faraday's law. Pressure generated by steel corrosion product at the concrete-steel interface was modeled by applying uniform radial displacements, while concrete smeared cracking alongside the Extended Finite Element Method (XFEM) was used for concrete cover cracking simulation. Results show that, chloride concentration decreases with penetration depth, but increases with exposure time at the concrete-steel interface. Cracks initiate and propagate in the concrete cover as pressure caused by the steel corrosion product increases. Furthermore, the crack width increases with the exposure time on the surface of the concrete.

• 한국지진공학회논문집
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• 제5권4호
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• pp.39-49
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• 2001

이 논문에서는 주철근 단락을 갖는 철근콘크리트 교각의 내진성능평가를 위한 비탄성 해석 기법을 제시하였다. 하중의 단계에 따라 수반하게 되는 콘크리트의 균열 및 철근의 항복, 이로 인한 부착효과와 골재의 맞물림 현상 및 강도의 감소 등과 같은 재료적 비선형성을 고려하였다. 이에 대한 콘크리트의 균열모델로서는 분산균열 모델을 사용하였다. 두께가 서로 다른 부재간의 접합부에서 단면강성이 급변하기 때문에 생기는 국소적인 불연속변형을 고려하기 위한 경계면 요소를 도입하였다. 또한, 횡방향 구속철근으로 인한 강도의 증가 효과를 고려하였다. 이 연구에서는 주철근 단락을 갖는 철근콘크리트 교각의 내진성능평가를 위해 제안한 해석기법을 신뢰성 있는 연구자의 실험결과와 비교하여 그 타당성을 검증하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.296-303
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• 2000

The purpose of this study is to find inelastic behavior and ductility capacity of reinforced concrete bridge columns under earthquake. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, due to the abrupt change in their stiffness local discontinuous deformation can be taken into account by introducing interface element. Also an analytical model is developed to express the confining effects of lateral tie which depend on the existence or nonexistence and the amounts of transverse confinement, etc. The proposed numerical method for inelastic behavior and ductility capacity of reinforced concrete bridge columns will be verified by comparison with reliable experimental results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.99-104
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• 2002

This paper presents an analytical prediction of the fatigue damage of reinforced concrete bridge columns subjected to cyclic load. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, local discontinuity in deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel and concrete. The proposed numerical method for fatigue damage of reinforced concrete bridge columns subjected to cyclic load is verified by comparison with reliable experimental results.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.131-138
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• 2001

The purpose of this study is to investigate size effect on inelastic behavior of reinf bridge piers subjected to cyclic load. A computer program, named RCAHEST(Reinforced Co Analysis in Higher Evaluation System Technologr), for the analysis of reinforced concret was used. Material nonlinearity is taken into account by comprising tensile, compressiv models of cracked concrete and a model of reinforcing steel The smeared crack app incorporated. In boundary plane at which each member with different thickness is conne discontinuous deformation due to the abrupt change in their stiffness can be taken into introducing interface element. The effect of number of load reversals with the same d amplitude has been also taken into account to model the reinforcing steel. To determine th on bridge pier inelastic behavior, a 1/4-scale replicate model was also loaded for compar full-scale bridge pier behavior.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.133-140
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• 2002

The purpose of this study is to investigate the seismic behavior of reinforced concrete bridge piers and to provide the data for developing improved seismic design criteria. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected. local discontinuity in deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel and concrete. The proposed numerical method for the prediction of seismic behavior for reinforced concrete bridge piers is veri fief by comparison with the reliable experimental results.

• 한국지진공학회논문집
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• 제4권4호
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• pp.37-51
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• 2000

이 연구는 지진 시 철근콘크리트 교각의 비탄성 거동 및 연성능력을 해석적으로 파악하는데 그 목적이 있다. 재료적 비선형성에 대해서는 균열 콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근 모델을 조합하여 고려하였다. 이에 대한 콘크리트의 균열 모델로서의 분산균열모델을 사용하였다. 두께가 서로 다른 부재간의 접합부에 단면강성이 급변하기 때문에 생기는 국소적인 불연속변형을 고려하기 위한 경계면 요소를 도입하였다. 또한, 축방향철근의 유무 및 그 양 등에 따른 구속효과를 적절히 표현할 수 있는 해석 모델을 개발하였다. 본 연구에서는 철근콘크리트 교각의 비탄성 거동 및 연성 능력의 파악을 위해 제안한 해석기법을 신뢰성 있는 연구자의 실험결과와 비교하여 그 타당성을 검증하였다.