• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.179-190
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• 1998

Shear failure of reinforced concrete (RC) beams is serious problem due to sudden brittle failure and many experimental results proved that size effect in shear strength of RC beams is an important feature of reinforced concrete members. As the sizes of RC beams very large, experiments sometimes become very difficult so that empirical design formula or the experimental data on shear strength of RC beams could not be obtained. Then the numerical analyses for size effect on shear strength of RC beams become very important. In this study, finite-element technique of reinforced concrete is employed of shear analysis of RC beams without web reinforcement and the size effects in shear strength are numerically analyzed. The influencing factors to the size effect in the shear strength of RC beams are extensively analyzed and compared with those by major shear strength equations including several standard specifications.

• Magazine of the Korea Concrete Institute
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• v.10 no.4
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• pp.93-100
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• 1998

This paper presents a study on the flexural stiffness, plastic hinge length and plastic hinge rotation capacity of reinforced high performance concrete beams. 15 beams with different strength of concrete, reinforcement ratio and the pattern of loadings were tested. From the test results of reinforced normal strength concrete beams and reinforced high performance concrete beams with the concrete which has cylinder compressive strength of 700kg/${cm}^2$, slump value of 20~25cm and slump-flow value of 60~70cm. It is found that an extreme fiber concrete compressive strain of ${\varepsilon}_{cu}=0.0047$ may be used in ultimate curvature computations of reinforced high performance concrete beams. An empirical equation is proposed to estimate the effective moment of inertia. length and rotation capacity of plastic hinge of simply supported reinforced high performance concrete beams. The estimated deflections using this equation agree well with the experimental values.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1179-1185
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• 2007

The study of girder-to-column joints under experiment and numerical analysis was carried out to evaluate change of the flexural capacity of the joints with the 2-layer upper reinforcement of girder within rectangular section and the single-layered upper reinforcement at the girder flange. According to the analysis results using the flange width, the flange thickness and the location of reinforcements in the upper flange as variables, in the models with a same effective width, the increasing rate of capacity has nothing to do with the flange width with a same effective width. However, the capacity of the models with the upper reinforcements arranged close to the rectangular beam section is larger than that of the models with the upper reinforcements arranged remotely from the rectangular section. If the range of arrangement fur reinforcement exceeds the effective width, despite of increasing the flange thickness, the capacity is not increased.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.261-263
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• 2013

해양환경에서의 아연코팅철근 콘크리트 보의 휨 성능 및 균열 특성 실험을 수행하였다. 또한, 보에서 발생하는 균열 및 파괴양상을 파악하였다. 그 결과, 해양환경에서의 콘크리트 부재의 피복두께를 기존 설계기준보다 작게 적용시켜도 부재에 발생하는 염해에 대한 내구성을 확보할 수 있으며, 아연코팅 철근의 적용은 일반철근 콘크리트 보다 내구성 측면에서 유리하다고 판단된다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.5-8
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• 2008

In this dissertation, experimental research was carried out to study the hysteretic behavior of reinforced high-strength concrete beam-column joints designed by high performance techniques, such as application of high-strength concrete, reducing of joint regions damage, moving of beam plastic hinge, advanced reinforcing detailings and High Ductile Fiber-Reinforced Mortar.(HDFRM) Specimens(HJCI), designed by the development of earthquake-resistant performance, moving of beam plastic hinge, and new design approach, were attained the moving of beam plastic hinge and developed significantly earthquake-resistant performance of such joints. Specimens(HJRP), designed with HDFRM, were indicated more stable hysteresis behavior, high load carrying capacity, and distributed crack pattern of specimens HJRP when compared to the control specimen.

• Magazine of the Korea Concrete Institute
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• v.3 no.2
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• pp.115-121
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• 1991

Slippage of beam longitudinal reinforcement at beam-column connections is an important cause of damage to reinforced concrete frames under static and dynamic loads, This paper summarizes the results of an experimen¬tal study on the effects of confinements and compressive strength of concrete on the local bond stress-slip cha¬racteristics of deformed bars. I t is concluded from experimental results that, as far as the bond splittmg cracks are restrained by the vertical column reinforcement, confinement of concrete by transverse reinforcement has insignigicant direct effect on the local bond behavior. The ultimate bond strength, however, Increases pro¬portionally with the square root of concrete compressive strength. An empirical model was developed for local bond st ressslip relationslip of deformed bars in confined concrete of different compressive strengths.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.537-540
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• 2010

본 논문에서는 보의 주철근을 대상으로 건물정보모델링(BIM, Building Information Modeling)통합 설계 시스템 상에서 배근 설계 및 철근 형상화 알고리즘을 구축하여 자동배근 시스템(ARPM, Automatic Reinforcement Placing Module)을 개발하는데 목적이 있다. 구조분야에서의 BIM 프로세스는 정보호환체계를 구축하는 과정에 있으며, 철골 구조 프로세스의 경우 표준 호환 포맷을 이용하여 원활한 정보 호환 체계를 유지하고 있다. 하지만, 철근 콘크리트의 BIM 통합 설계 시스템은 철근 배근정보의 생성과 호환이 원활하지 않아 표준 정보 호환 체계가 구축되지 않은 실정이다. 기존 2차원 기반 프로세스에서는 철근 배근 설계에 있어 표준화된 기준에 따른 배근이 아닌 관행이나 일률적인 배근 지침에 따라 배근 상세를 정하고 있고, 2차원 배근 설계 결과만 제시하고 있어 상호 호환 가능한 철근 배근 정보데이터가 생성되지 않는다. 철근 콘크리트 구조에서의 철근 배근 정보를 생성하고 BIM 통합 구조 설계시스템에서의 정보 호환성을 확보하기 위해, 보의 주철근을 대상으로 구조 해석 데이터베이스와 통합 설계 플랫폼 간의 호환 시스템을 생성하고, 콘크리트학회 콘크리트 구조설계기준에 따른 배근 설계 및 철근 형상화 알고리즘을 구축하여 자동배근시스템(ARPM)을 개발하는데 목적이 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.259-267
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• 2008

The ultimate strengths of reinforced concrete deep beams are governed by the capacity of the shear resistance mechanism composed of concrete and shear reinforcing bars, and the structural behaviors of the beams are mainly controlled by the mechanical relationships according to the shear span-to-effective depth ratio, flexural reinforcement ratio, load and support conditions, and material properties. In this study, a simple indeterminate strut-tie model reflecting all characteristics of the ultimate strengths and complicated structural behaviors is presented for the design of simply supported reinforced concrete deep beams. In addition, a load distribution ratio, defined as a magnitude of load transferred by a vertical truss mechanism, is proposed to help structural designers perform the design of simply supported reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of a load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie is introduced to ensure the ductile shear failure of reinforced concrete deep beams, and the prime design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete influencing the ultimate strength and behavior are reflected upon based on various and numerous numerical analysis results. In the companion paper, the validity of presented model and load distribution ratio was examined by employing them to the evaluation of the ultimate strengths of various simply supported reinforced concrete deep beams tested to failure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.483-493
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• 2013

The high strength materials have been more widely used in a large reinforced concrete structures. It is known that the use of high strength material in RC structures give the benefits of the mechanical and durable properties, but the ductility decreases with an increase in the strength of the materials. In the design of a reinforced concrete beam, both the flexural strength and ductility need to be considered. So, it is necessary to assess accurately the ductility of the beam with high strength materials in order to ensure the ductility requirement in design. In this study, the effects of the material strength on the flexural behavior and curvature ductility factor of reinforcement concrete beam sections with various reinforcement conditions have been evaluated and a newly prediction formula for curvature ductility factor of RC beam has been developed considering the stress of compression reinforcement at ultimate state. The proposed predictions for the curvature ductility factor which is applicable to both singly and doubly reinforced concrete beam are verified by comparisons with other prediction formulas and the proposed formula offers fairly accurate within 9% error and consistent predictions for curvature ductility factor of reinforced concrete beam.

• Magazine of the Korea Concrete Institute
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• v.5 no.1
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• pp.103-113
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• 1993

일반적으로 스터럽이 없는 철근콘크리트 보의 전단강도는 콘크리트 압축강도, 주철근비, 전단스팬비 및 보 유효깊이에 좌우된다는 것이 많은 연구를 통하여 밝혀지고 있다. 따라서, 본 연구에서는 고강도 콘크리트를 사용한 철근콘크리트 보의 거동 및 전단강도 특성을 분석하기 위하여 주철근비, 전단스팬비 및 보 유효깊이를 변수로 두고 총 22개의 단철근 보 실험체를 제작하여 실험을 수행하였다. 실험결과는 ACI규준식, Zsutty식 및 Bazant & Kim식의 예측값들과 함께 비교, 분석되었는데, ACI 규준식은 주철근비 및 전단스팬비의 효과를 과소평가할 뿐만 아니라 유효깊이가 915mm인 큰 보의 경우 안전측이 아니어서 이에 대한 고려가 필요할 것으로 판단된다. Zsutty식은 주철근비의 효과를 적절하게 평가하는 것으로 나타났으며, Bazant & Kim 식은 유효깊이 증가에 따른 전단강도 감소 경향을 잘 예측하는 것으로 나타났다. 또한, 다른 연구자들의 실험치와 비교, 분석해본 결과 주철근비 및 전단스팬비의 효과는 콘크리트 압축강도 수준에 따라 큰 변화가 없는 것으로 판단된다.