• Computers and Concrete
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• 제11권6호
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• pp.515-529
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• 2013

The moment-curvature relation for simple bending is a well-studied subject and the classical moment-curvature diagram is commonly found in literature. The influence of axial forces has generally been considered as compression onto symmetrically reinforced cross-sections, thus strain at the reference fiber never has been an issue. However, when dealing with integral structures, which are usually statically indeterminate in different degrees, these concepts are not sufficient. Their horizontal elements are often completely restrained, which, under imposed deformations, leads to moderate compressive or tensile axial forces. The authors propose to analyze conventional beam cross-sections with moment-curvature diagrams considering asymmetrically reinforced cross-sections under combined influence of bending and moderate axial force. In addition a new diagram is introduced that expands the common moment-curvature relation onto the strain variation at the reference fiber. A parametric study presented in this article reveals the significant influence of selected cross-section parameters.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.190-197
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• 2000

A moment-curvature relationship to simulate the behavior of reinforced concrete beam under cyclic loading is introduced. Unlike previous moment-curvature models and the layered section approach, the proposed model takes into consideration the bond-slip effect by using monotonic moment-curvature relationship constructed on the basis of the bond-slip relation and corresponding equilibrium equation at each nodal point. In addition, the use of curved unloading and reloading branches inferred from the stress-strain relation of steel gives more exact numerical result. The advantages of the proposed model, comparing to layered section approach, may be on the reduction in calculation time and memory space in case of its application to large structures. The modification of the moment-curvature relation to reflect the fixed-end rotation and pinching effect is also introduced. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed model.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.17-20
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• 2005

Moment-curvature relation of RC pier is influenced greatly in occurrence form of crack and difference is happened according to consideration existence and nonexistence of tension stiffening effect. However, studies considering these is very insufficient misgovernment. Also, it is sometimes unavoidable lap splice of axial reinforcement in plastic hinge region of RC piers. However, specific design standard about lap splice of axial reinforcement is unprepared real condition and study about effect that lap splice of axial reinforcement get in occurrence form of crack is insufficient misgovernment. Therefore, in this paper, experiments are performed with hollow RC piers that do lap splice of axial reinforcement by main variable. And this study present analytical method about moment-curvature relation of hollow RC pier that consider tension stiffening effect and analyze effect that lap splice of axial reinforcement gets in occurrence form of crack. Analytic method of moment-curvature relation of RC pier that present in this study shows very similar motion with experiment result and crack interval of RC pier is suffering dominate impact in the augmented reinforcement amount by lap splice and average crack interval decreases as lap splice ratio increases.

• Computers and Concrete
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• 제4권6호
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• pp.457-475
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• 2007

A simple analytical procedure to analyze reinforced concrete (RC) beams with cracked section is proposed on the basis of the simplified moment-curvature relations of RC sections. Unlike previous analytical models which result in overestimation of stiffness and underestimation of structural deformations induced from assuming perfect-bond condition between steel and concrete, the proposed analytical procedure considers fixed-end rotation caused by anchorage. Furthermore, the proposed analytical procedure, compared with previous numerical models, promotes effectiveness of analysis by reflecting several factors which can influence nonlinearity of RC structure into the simplified moment-curvature relation. Finally, correlation studies between analytical and experimental results are conducted to establish the applicability of the proposed analytical procedure to the nonlinear analysis of RC structures.

• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.357-378
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• 2004

Nonlinear dynamic analysis of a reinforced concrete (RC) frame under earthquake loading is performed in this paper on the basis of a hysteretic moment-curvature relation. Unlike previous analytical moment-curvature relations which take into account the flexural deformation only with the perfect-bond assumption, by introducing an equivalent flexural stiffness, the proposed relation considers the rigid-body-motion due to anchorage slip at the fixed end, which accounts for more than 50% of the total deformation. The advantage of the proposed relation, compared with both the layered section approach and the multi-component model, may be the ease of its application to a complex structure composed of many elements and on the reduction in calculation time and memory space. Describing the structural response more exactly becomes possible through the use of curved unloading and reloading branches inferred from the stress-strain relation of steel and consideration of the pinching effect caused by axial force. Finally, the applicability of the proposed model to the nonlinear dynamic analysis of RC structures is established through correlation studies between analytical and experimental results.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.3-11
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• 2002

A moment-curvature relationship to simulate the behavior of reinforced concrete (RC) columns under cyclic loading is introduced. Unlike previous moment-curvature models and the layered section approach, the unposed model takes into account the bond-slip effect by using a monotonic moment-curvature relationship constructed on the basis of the bond-slip relation and corresponding equilibrium equation at each nodal point. In addition, the use of curved unloading and reloading branches inferred from the stress-strain relation of steel gives more exact numerical result. The pinching enact caused by axial force is considered with an assumption that the absorbing energy corresponding to any deformation level maintains constant regardless of the magnitude of applied axial force. The advantages of the proposed model, comparing tn layered section approach, may be on the reduction in calculation time and memory space in case of its application to large structures.. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed mood.

• 한국전산구조공학회논문집
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• 제13권3호
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• pp.361-371
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• 2000

RC 구조물은 서로 다른 재료적 특성을 지닌 콘크리트와 철근의 복합구조이고, 특히 콘크리트는 복잡한 소성거동을 나타내는 재료이다. 따라서 RC 구조물의 소성해석을 위해서는 콘크리트와 철근 각각의 재료특성과 소성거동을 묘사할 수 있는 세밀한 모델링 기법이 필요하지만, 이때 발생하는 모델링의 어려움, 모델링 규모, 계산용량 및 수렴성 등의 문제점으로 인하여 소성해석 수행에 많은 시간과 노력이 소요되거나 해석자체가 불가능하게 된다. 따라서 본 논문에서는 간편한 RC 구조물의 소성해석을 위해 RC 부재와 동일한 소성거동을 나타내는 균질·등방 재료로의 물성치환 방법을 제시하였다. 물성치환 원리는 RC 부재의 소성거동 특성, 즉 항복모멘트, 항복곡률 및 극한모멘트, 극한곡률로 표현되는 bi-linear 형태의 모멘트-곡률 관계를 이용하여, 이와 동일한 모멘트-곡률 관계(bi-linear 형태의 응력 변형률 관계)를 갖는 균질·등방 재료를 생성하였다. 또한 실제 RC 부재 해석모델과 치환된 균질·등방 재료를 이용한 해석모델에 대한 소성해석 결과를 비교·분석하여 본 연구의 타당성을 검증하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.445-450
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• 2003

The moment-curvature envelope describes the changes in the flexural capacity with deformation during a nonlinear analysis. Therefore, the moment-curvature analysis for reinforced concrete columns, indicating the available flexural strength and ductility, can be conducted providing the stress-strain relation for the concrete and steel are known. The moments and curvatures associated with increasing flexural deformations of the column may be computed for various column axial loads by incrementing the curvature and satisfying the requirements of strain compatibility and equilibrium of forces. Clearly it is important to have accurate information concerning the complete stress-strain curve of confined high-strength concrete in order to conduct reliable moment-curvature analysis to assess the ductility available from high-strength columns. However, it is not easy to explicitly characterize the mechanical behavior of confined high-strength concrete because of various parameter values, such as the confinement type of rectilinear ties, the compressive strength of concrete, the volumetric ratio and strength of rectangular ties, etc. So a stress-strain confinement model is developed which can simulate a complete inelastic moment-curvature relations of a high-strength reinforced concrete column

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.475-482
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• 2002

A moment-curvature relationship to simulate the behavior of reinforced concrete (RC) columns under cyclic loading is introduced. Unlike previous moment4curvature models and the layered section approach, the proposed model takes into account the bond-slip effect by using a monotonic moment-curvature relationship constructed on the basis of the bond-slip relation and corresponding equilibrium equation at each nodal point. In addition, the use of curved unloading and reloading branches inferred from the stress-strain relation of steel gives more exact numerical result. The pinching effect caused by axial force is considered with an assumption that the absorbing energy corresponding to any deformation level maintains constant regardless of the magnitude of applied axial lone. The advantages of the proposed model, comparing to layered section approach, may be on the reduction in calculation time and memory space in case of its application to large structures. Finally, correlation studies between analytical result and experimental studies are conducted to establish the validity of the proposed model.

• 콘크리트학회논문집
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• 제15권5호
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• pp.747-758
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• 2003

The moment-curvature envelope describes the changes in the flexural capacity with deformation during a nonlinear analysis. Therefore, the moment-curvature analysis for reinforced concrete columns, indicating the available flexural strength and ductility, can be conducted providing the stress-strain relation for the concrete and steel are known. The moments and curvatures associated with increasing flexural deformations of the column may be computed for various column axial loads by incrementing the curvature and satisfying the requirements of strain compatibility and equilibrium of forces. Clearly it is important to have accurate information concerning the complete stress-strain curve of confined high-strength concrete in order to conduct reliable moment-curvature analysis that assesses the ductility available from high-strength concrete columns. However, it is not easy to explicitly characterize the mechanical behavior of confined high-strength concrete because of various parameter values, such as the confinement type of rectilinear ties, the compressive strength of concrete, the volumetric ratic and strength of rectangular ties. So a stress-strain model is developed which can simulate complete inelastic moment-curvature relations of high-strength concrete columns.