• 한국자동차공학회논문집
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• 제2권1호
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• pp.65-72
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• 1994

Collapse characteristics of thin-walled hatted section tubes are investigated. The square section members with flanges are substituted by the equivalent rectangular tube. The stiffening effects of flanges are transformed to the restraining plate with the equivalency of buckling strength. The square tubes of single-hatted and double-hatted sections are investigated. The double-hatted section members show symmetric and antisymmetric crushing modes depending on the stiffness of flanges. The single-hatted section members show only symmetric modes. The bifurcation point of the compact crushing modes are investigated by experiments and shown almost same thickness-width ratio of the rectangular tubes. A large maximum crippling strength can be obtained by double-hatted section members with proper flange dimensions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.267-274
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• 2001

In this paper, a analytical model which can simulate the post-cracking behavior and tension stiffening effect in a reinforced concrete(RC) tension member is proposed. Unlike the classical approaches using the bond stress-slip relationship or the assumed bond stress distribution, the tension stiffening effect at post-cracking stage is quantified on the basis of polynomial strain distribution functions of steel and concrete, and its contribution is implemented into the reinforcing steel. The introduced model can be effectively used in constructing the stress-strain curve of concrete at post-cracking stage, and the loads carried by concrete and by reinforcing steel along the member axis can be directly evaluated on the basis of the introduced model. In advance, the prediction of cracking loads and elongations of reinforced steel using the introduced model shows good agreements with results from previous analytical studies and experimental data.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.441-444
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• 2004

This paper presnets the tensile behavior of 8 high performance fiber-reinforced cementitious composites (HPFRCCs) members, each reinforced with one deformed bar 16mm in diameter. The variables included HPFRCC(Ductal, steel cord and polyethylene hybrid fiber, PE fiber) versus normal concrete. Fibers used in HPFRCC significantly increased tensile strength, ductility, and tension stiffening of cementitious materials. For HPFRCC, after first cracking, tensile load continue to rise without fracture localization. Sequentially developed parallel cracks contributed to the inelastic strain at increasing stress level. After yielding of the reinforcing bars, HPFRCC showed increases in loads with increasing strains.

• 콘크리트학회논문집
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• 제17권6호
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• pp.1033-1042
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• 2005

최근에 이르기까지 철근콘크리트 휨부재에 있어 콘크리트의 인장응력은 극한강도에 현저한 영향을 미치지 못하기 때문에 그 역할이 고려되어지지 않았다. 그러나 하중-처짐 관계의 구명을 위해서는, 인장증강효과라고 불리는 콘크리트와 보강철근 사이의 인장응력에 의한 강정증가 효과가 반드시 고려되어져야 한다. 이러한 인장증강효과에 영향을 주는 주요 구조변수는 콘크리트의 강도 및 콘크리트와 철근의 부착 등으로 알려져 있다. 이 연구에서는 휨을 받는 보를 대상으론 각기 다른 콘크리트 강도, 피복두께 및 주근의 비부착 길이를 갖도록 모두 20개의 시험체를 제작하여 실험하였다. 이를 통해 각 구조변수들이 시험체의 휨강성, 균열발생 및 진전 등에 미치는 영향 등을 주의 깊게 관찰하고 분석하였다.

• 콘크리트학회논문집
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• 제20권4호
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• pp.459-467
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• 2008

이 논문은 철근콘크리트 휨부재의 균열폭과 처짐 계산에 대한 해석적 모델을 제안한 것이다. 균열 안정화단계에서 철근과 콘크리트 경계면에서 발생하는 실제와 유사한 형태의 부착응력-미끌림 관계와 인장증강효과를 수치적으로 유도한 후, 균열과 균열 사이에서 철근의 매입길이 방향으로 발생하는 철근과 콘크리트의 변형률 차이가 균열면으로 누적되는 양을 계산할 수 있는 평형방정식을 이용하였다. 이로부터 두 재료의 변형량 차이로부터 평균 균열폭을 계산할 수 있는 모델과 인장증강효과를 반영한 철근의 평균변형률과 모멘트-곡률 관계를 도입하여 처짐을 계산하는 모델을 제안하였다. 이렇게 정식화된 새로운 균열폭 및 처짐 모델을 기존 문헌에 발표된 여러 연구자들의 실험자료에 적용하여 그 정확성을 검증한 결과, 제안식에 의한 예측값은 현재 사용되고 있는 여러 설계기준의 사용성 규정으로 계산한 결과와 비교할 때 실험값을 비교적 정확하게 예측하는 것으로 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.304-307
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• 2004

Direct tensile tests were carried out for the tensile members of MMA-modified polymer concrete with different steel kinds and steel diameters and steel ratios to figure out the effect of tensile strength of polymer concrete. In the experiments, MMA-modified polymer concrete with $1000\;kgf/cm^2$ of compressive strength, steel with $5200\;kgf/cm^2$ of tensile strength, and the tensile members with 100 cm of constant length were used. Experimental results showed that, regardless of steel kinds, diameters and steel content, the strain energy exerted by concrete till the initial crack was $14-15\%$ of the total energy till the point of yield: The energy was much larger than the one of high-strength cement concrete. The behaviors of tensile members of MMA-modified polymer concrete were in relatively good agreement with the model suggested by Gupta-Maestrini (1990), which was idealized by the effective tensile stress-strain relationship of concrete and the load-strain relationship of members, while those showed a big difference from CEB-FIP model and ACI-224 equation suggested for the load-displacement relationship that was defined as the cross sectional stiffness of effective axis. Modified ACI-224 model code about the load-displacement relationship for the tensile members of MMA-modified polymer concrete and theoretical equation for the polymer concrete tensile stiffness of polymer concrete suggested through the results of this study are expected to be used in an accurate structural analysis and resign for the polymer concrete structural members.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.387-390
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• 2003

Direct tensile tests were carried out for the tensile members of steel-reinforced polymer concrete with different steel diameters and steel ratios to figure out the effect of tensile strength of polymer concrete. In the experiments, polymer concrete with $1000kgf/cm^2$ of compressive strength, steel with $5200kgf/cm^2$ of tensile strength, and the tensile members with 100 cm of constant length were used. Experimental results showed that, regardless of steel diameters and steel content, the strain energy exerted by concrete till the initial crack was 14-15% of the total energy till the point of yield: The energy was much larger than the one of high-strength cement concrete. The behaviors of tensile members of steel-reinforced polymer concrete were in relatively good agreement with the model suggested by Gupta-Maestrini (1990), which was idealized by the effective tensile stress-strain relationship of concrete and the load-strain relationship of members, while those showed a big difference from CEB-FIP model and ACI-224 equation suggested for the load-displacement relationship that was defined as the cross sectional stiffness of effective axis. Modified ACI-224 model code about the load-displacement relationship for the tensile members of steel-reinforced polymer concrete and theoretical equation for the polymer concrete tensile stiffness of polymer concrete suggested through the results of this study are expected to be used in an accurate structural analysis and design for the polymer concrete structural members.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.193-196
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• 2005

This study deals with the estimation of the crack width by stabilized cracking considering bond-slip relationships in reinforced concrete members. The proposed method utilizes the sameness of tension stiffening and a change of bond-slip relationships because of concrete's splitting. The validity, accuracy and efficiency of the proposed method are established by comparing the analytical results with the experimental date and the major code spcifications. The analytical results of analysis presented in this study indicate that the proposed method can be effectively estimated the crack width of the reinforced concrete members.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.413-416
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• 2004

This paper describes a proposal for crack width and deflection in RC flexural members. Because the serviceability provisions of the current codes are mainly based on only empirical relationships developed from test result and effective moment of inertia, crack width and deflections are contrary to the actual values. Based on nonlinear bond characteristics, tension stiffening effect, arch action and effective concrete tensile area. Then an equation is developed for predicting crack width and deflection in flexural members. The predicted results shows that as proposed model employed, crack width and deflections are different from estimated by the current KCI, MC 90 and EC 2 provisons, and the values predicted are in good agreement with experimentally measured values.

• Structural Engineering and Mechanics
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• 제83권2호
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• pp.179-193
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• 2022

The shear behaviour of reinforced concrete members has been studied over the past decades by various researchers, and it can be simulated by analysing shear panel elements which has been regarded as a basic element of reinforced concrete members subjected to in-plane biaxial stresses. Despite various experimental studies on shear panel element which have been conducted so far, there are still a lot of uncertainties related to what influencing factors govern the shear behaviour and affect failure mechanism in reinforced concrete members. To identify the uncertainties, a finite element analysis can be used, which enables to investigate the impact of specific variables such as the reinforcement ratio, the shear retention factor, and the material characteristics including aggregate interlock, tension stiffening, compressive softening, and shear behaviour at the crack surface. In this study, a non-linear probabilistic analysis was conducted on reinforced concrete panels using a finite element method optimized for reinforced concrete members and advanced sampling techniques so that probabilistic analysis can be performed effectively. Consequently, this study figures out what analysis methodology and input parameters have the most influence on shear behaviour of reinforced concrete panels.