• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.21-33
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• 2006

The purpose of this study is to assess the seismic performance of reinforced concrete bridge columns using nonlinear finite element analysis. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Damage index aims to provide a means of quantifying numerically the damage in reinforced concrete bridge columns sustained under earthquake loading. The proposed numerical method for the seismic performance assessment of reinforced concrete bridge columns is verified by comparison with reliable experimental results.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.233-238
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• 2006

In lifetime estimation, the FEM analysis method is proposed for predicting corrosion failure time of concrete structures exposed to sea-water. This study shows that the corrosion rate of rebar in artificial pore solution can be transferred to the corrosion rate of rebar in concrete using the relationship between pore volume and concrete volume by Jennings' model. And this study considered the pitting corrosion effects of reinforcement bar on corrosion failure analysis, rebar size to cover depth and nonlinear crack analysis. These analysis results have good accordance with the experimental results of Williamson's work. This methodology can be applied to lifetime prediction procedure of reinforced concrete structures and also gives more reasonable results of concrete cover failure time estimation of reinforced concrete structures exposed to sea-water.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.1 s.20
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• pp.17-27
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• 2006

To estimate the retained strength of reinforced concrete structure after fire is very difficult because the complex behavior of structure is hard to understand during course of a fire. However, the damages which is caused by fire of the traffic facility infrastructure are enormous. Therefore the security against fire is important element that must not be overlooked. For this reason, an exact estimate method of the fire endurance is highly demanded. In this study, the validity of the nonlinear finite element method approach for the fire endurance of reinforced concrete structure is verified. The results of fire endurance estimate of underground road way by nonlinear finite element method approach are compared with those by ACI 216R-89.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.409-415
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• 2010

A finite element model for punching shear of flat plate structures is presented. A parametric study also has been conducted to verification of influence of several parameters in terms of the flexural reinforcement ratio, slab thickness. Reisnner-Mindlin assumptions are adopted to consider of shear deformation. Layered shell element is considered for the material non-linearities. The finite element model of this study was verified comparing with existing experimental results. The model is able to predict the capacity of the flat plate structures. The punching shear of flat plate structures varied depending on the flexural reinforcement ratio, slab thickness.

• Journal of the Korean Geophysical Society
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• v.9 no.4
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• pp.301-310
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• 2006

In this short paper, an elasto-plastic repair and retrofit element is developed for the investigation of the seismic performance of damaged reinforced concrete members. The developed element is capable of reflecting the increased characteristics due to both repair and retrofitting for degraded strength and stiffness of the members. The element having both birth and death time can freely be activated within the user-defined time intervals during static and dynamic time-history analysis. Comparative studies are conducted for reinforced concrete members being repaired and retrofitted. Analytical predictions including the developed element display reasonable correlation with experimental results. In short, it is concluded that the developed element is capable of providing salient features for the healthy assessment of seismic performance of RC members being repaired and retrofitted.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.293-308
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• 1999

이 논문에서는 패널, 깊은 보 그리고 전단벽과 같이 평면응력상태하에 있는 철근콘크리트 구조물의 비선형 유한요소해석에 있어서의 직교이방성 콘크리트 구성 모델의 적용성을 보여준다. 등가의 일축 변형을 개념을 토대로 콘크리트의 구성 관계가 주변형률 축과 일치하고 하중이력에 따라 회전하는 직교하는 축에 대해 제시된다. 제안된 모델은 이축 압축응력상태와 인장-압축 응력상태에서 각각 압축강도의 증가와 인장 저항력의 감소효과를 보여주는 이축 파괴영역의 정의를 포함한다. 인장균열이 발생한 후, 콘크리트의 압축강도의 감소효과가 제시되고, 인장강화효과로 알려진 철근에 의해 지지되는 콘크리트의 인장응력이 고려된다. 평균응력과 평균변형률 개념을 사용하여 힘의 평형, 적합조건 그리고 철근과 철근을 둘러싼 콘크리트 사이의 부착응력-슬림 관계를 토대로 인장강화효과를 모사하기 위한 모델이 제안된다. 유한요소 모델에 의한 예측은 유용한 실험자료와의 비교에 의해 입증된다. 이 논문에서는 해석결과와 이상화한 전단 패널실험으로부터 얻어진 실험값의 비교연구가 수행되고, 제안된 모델의 타당성을 보여주기 위해 서로 다른 응력상태하의 전단 패널 보와 벽체의 힘-변위 관계를 평가하였다.

• Computational Structural Engineering
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• v.9 no.4
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• pp.30-34
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• 1996

본문에서는 유한요소법에 의한 철근콘크리트 구조해석에 관한 지난 20여년간의 연구현황에 대해 일리노이대학의 Schnobrich 교수가 쓴 글 (Behavior of Reinforced Concrete Members by Finite Element, APCOM, Sep. 16, 1996, Korea)의 일부를 번역하여 소개한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.69-78
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• 1991

This paper concentrates on the analysis of deflection of the reinforced concrete flexural members under monotonic loading. Concrete is treated as an orthotropic nonlinear material. The concept of equivalent strain and crack strain are used to establish independent stress-strain relationships in the directions of orthotropy. Steel is modeled as an elstoplastic material, and von Mises failure criterion is applied. The finite element computer program for the nonlinear analysis of the deflection of RC flexural members under monotonic loading is developed. The accuracy and reliability of the numerical procedure is demonstrated by the FEM analysis and experiments of the under reinforced concrete beams over the entire loading range up to failure.

• Magazine of the Korea Concrete Institute
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• v.3 no.3
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• pp.149-157
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• 1991

This paper concentrates on the nonlinear analysis of the reinforced concrete flexural members under cyclic loading. To develop a nonlinear material model, concrete is treated as an orthotropic nonlinear material and steel is modeled as an elasto-plastic material. The models for hysteresis behavior with stiffness degradation in compression and for crack opening and closing in tension are included. The finite element computer program for the nonlinear analysis of RC flexural members under cyclic loading is developed. The accuracy and reliabihty of the numerical procedure IS demonstrated by the FEM analysis and test results of underreinforced concrete beams.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.345-352
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• 1999

철근콘크리트 보의 전단강도에 대한 크리효과는 다른 각종 강도에 대한 크기효과에 비해 현저히 나타난다는 것이 많은 실험적 연구로부터 입증되었으며, 이를 배경으로 세계 여러 나라의 전단강도에 대한 설계 기준식들이 전단강도의 크리효과를 반영하고 있는 실정이다. 그러나, 철근콘크리트 구조물이 점점 대형화됨으로써 이와 같은 설계 기준식의 실험적 검토는 사실상 불가능하게 될 것이다. 본 연구에서는 파괴역학에 근거한 비선형 유한요소프로그램을 이용하여 전단보강철근이 없는 대형 철근콘크리트 보의 전단강도에 대한 크기 효과를 재현해 보았다. 또한, 해석 및 실험결과를 이용하여 크기효과가 고려된 몇 가지 대표적인 전단강도식과 비교하였다.