• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.63-64
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• 2010

본 연구에서는 전단 보강보에 대한 전단강도 실험값을 EC2와 MCFT(Modified Compression Field Theory)에 의한 전단강도와 비교해보고자 하였다. 해석결과, MCFT는 EC2에 비해 실험값에 더 근사한 값을 얻을 수 있었으며, EC2의 설계 경사각은 MCFT보다 더 작은 값을 가짐을 알 수 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.872-877
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• 2003

The fixed-angle based modified compression field theory (MCFT) was developed to include the slip deformation across the crack, thereby allowing for the non-coincident directions of the principal strain and stress. To investigate the significance of crack modelling on the analysis, a series of tests on beams without transverse reinforcement was predicted by both rotating- and fixed-angle crack models within the frame of the MCFT. The results predicted by the fixed-angle MCFT were comparable to those by the rotating-angle MCFT when the initial crack angle of 45deg. and the related friction law are used.

• KCI Concrete Journal
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• 제11권3호
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• pp.5-17
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• 1999

In recent years. the concept of the modified compression field theory (MCFT) was develped and applied to the analysis of reinforced concrete beams subjected to shear, moment, and axial load. Although too complex for regular use in the shear design or beams. the procedure has value in its ability to provide a rational method of anlysis and design for reinforced concrete members. The objective of this paper is to review the MCFT and apply it for the prediction of the response and shear strength of reinforced concrete beams A Parametric analysis was Performed on a reinforced T-section concrete beam to evaluate and compare the effects of concrete strength. longitudinal reinforcement ratio shear reinforcement ratio, and shear span to depth ratio in two different approaches the MCFT and the ACI code. The analytical study showed that the concrete contribution to shear strength by the MCFT was higher than the one by the ACI code in beams without stirrups, while it was lower with stirrups. On the other hand. shear reinforcement contribution predicted by the MCFT was much higher than the one by the ACI code. This is because the inclination angle of shear crack is much smaller than 45$^{\circ}$assumed in the ACI code.

• 콘크리트학회지
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• 제11권1호
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• pp.173-181
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• 1999

전단보강근이 없는 보의 거동을 이해하기 위하여 서로 다른 트러스 개념으로부터 출발한 두 종류의 해석방법 및 배경이론[압축응력장(MCFT) 및 균열마찰 (CFTM)이론]을 수단으로 콘크리트 기여강도($V_c$)를 구성하는 i)압축지역의 전단응력, ii)균열면의 마찰작용, iii)주근의 장부작용, iv)아치작용 및 최근에 추가된 v)비균열 부위 잔류 인장강도의 상대적인 중요도를 물리적으로 설명하였다. 또한, 두 해석모델의 평가를 위하여, 최근 국내에서 파괴역학 개념의 크기 효과식 개발에 보다 초점을 맞추어 수행된 일련의 고강도 콘크리트보의 실험결과(20개, $f'_c$=53.7Mpa)를 예측하였다. 예측결과에 의하면, 두 해석모델은 a/d비, 주근량 및 보의 춤이 변화함에 따라 관측된 물리적 현상을 정확하게 포착하고 있었으며, 특히 MCFT로부터 얻어낸 보다 자세한 응력 및 변형도 분포 등에 관한 정보는 일련의 추가적인 설명을 가능하게 하였다. 하지만, 보다 완전한 이론적 배경을 지니고 있는 MCFT는 P4.6 및 D915의 파괴하중을 각각 다소 과소 및 과대 평가하는 경향을 나타내고 있어, 주근량 및 크기효과에 대한 보다 완전한 결론을 유도하기 위해서는 추가적인 실험적 연구가 필요한 것으로 판단되었다.

• Advances in concrete construction
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• 제8권4호
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• pp.285-294
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• 2019

In the present paper, the fiber theory has been employed to model the reinforced concrete (RC) deep beams (DBs) considering the reinforcing steel bar-concrete interaction. To simulate numerically the behavior of materials, the uniaxial materials' constitutive laws have been employed for reinforcements and concrete and the bond stress-slip between the reinforcing steel bars and surrounding concrete are taken into account. Because of the high sensitivity of DBs to shear deformations, the Timoshenko beam theory has been applied. The shear stress-strain (S-SS) relationship has been defined by the modified compression field theory (MCFT) model. By modeling about 300 RC panels and employing a produced numerical database, a study has been carried out to show the sensitivity of the MCFT model. This is performed based on the multiple linear regression (MLR) models. The results of this research also illustrate how different parameters such as characteristic compressive strength of concrete, yield strength of reinforcements and the percentages of reinforcements in different directions get involved in the shear behavior of RC panels without applying complex theories. Based on the results obtained from the analysis of the MCFT S-SS model, a relatively simplified numerical S-SS model has been proposed. Application of the proposed S-SS model in modeling and analyzing the considered samples indicates that there is a good agreement between the simulated and the experimental test results. The comparison between the proposed S-SS model and the MCFT model indicates that in addition to the advantage of better accuracy, the main advantage of the proposed method is simplicity in application.

• Computers and Concrete
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• 제15권5호
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• pp.807-831
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• 2015

In the previous analytical studies on 2D reinforced concrete (RC) beam-column joints, the modified compression field theory (MCFT) and the strut-and-tie method (STM) are usually employed. In this paper, the limitations of these analytical models for RC joint applications are reviewed. Essentially for predictions of RC joint shear behaviour, the MCFT is not applicable, while the STM can only predict the ultimate shear strength. To eliminate these limitations, an improved STM is derived and applied to some commonly encountered 2D joints, viz., interior and exterior joints, subjected to monotonic loading. Compared with the other STMs, the most attracting novelty of the proposed improved STM is that all critical stages of the shear stress-strain relationships for RC joints can be predicted, which cover the stages characterized by concrete cracking, transverse reinforcement yielding and concrete strut crushing. For validation and demonstration of superiority, the shear stress-strain relationships of interior and exterior RC beam-column joints from published experimental studies are employed and compared with the predictions by the proposed improved STM and other widely-used analytical models, such as the MCFT and STM.

• Structural Engineering and Mechanics
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• 제30권2호
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• pp.211-223
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• 2008

A number of studies have suggested that the use of high ductile and high shear materials, such as Engineered Cementitious Composites (ECC) and High Performance Fiber Reinforced Cementitious Composites (HPFRCC), significantly enhances the shear capacity of structural elements, even with/without shear reinforcements. The present study emphasizes the development of a nonlinear model of shear behaviour of a HPFRCC panel for application to the seismic retrofit of reinforced concrete buildings. To model the shear behaviour of HPFRCC panels, the original Modified Compression Field Theory (MCFT) for conventional reinforced concrete panels has been newly revised for reinforced HPFRCC panels, and is referred to here as the HPFRCC-MCFT model. A series of experiments was conducted to assess the shear behaviour of HPFRCC panels subjected to pure shear, and the proposed shear model has been verified through an experiment involving panel elements under pure shear. The proposed shear model of a HPFRCC panel has been applied to the prediction of seismic retrofitted reinforced concrete buildings with in-filled HPFRCC panels. In retrofitted structures, the in-filled HPFRCC element is regarded as a shear spring element of a low-rise shear wall ignoring the flexural response, and reinforced concrete elements for beam or beam-column member are modelled by a finite plastic hinge zone model. An experimental study of reinforced concrete frames with in-filled HPFRCC panels was also carried out and the analysis model was verified with correlation studies of experimental results.

• 콘크리트학회지
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• 제10권1호
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• pp.40-48
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• 1998

• Steel and Composite Structures
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• 제7권4호
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• pp.263-278
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• 2007

A finite element implementation of the modified compression field theory (MCFT) using a tangential formulation is presented in this work. Previous work reported on implementations of MCFT has concentrated mainly on secant formulations. This work describes details of the implementation of a modular algorithmic structure of a reinforced concrete constitutive model in nonlinear finite element schemes that use a Jacobian matrix in the solution of the nonlinear system of algebraic equations. The implementation was verified and validated using experimental and analytical data reported in the literature. The developed algorithm, which converges accurately and quickly, can be easily implemented in any finite element code.

• 한국전산구조공학회논문집
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• 제22권6호
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• pp.597-605
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• 2009

본 연구에서는 철근 보강된 Engineered Cementitious Composite(ECC) 면내요소에 대한 2축응력 상태에서의 면내전단거동에 관한 예측 모델을 제시하였다. 기존의 철근콘크리트와 상이한 특성, 즉 ECC 요소의 복수미세균열 현상에 의한 높은 연성의 인장 거동, 일반 콘크리트에 비하여 연성적인 압축 연화 거동, 그리고 ECC 균열면에서의 전단전달 거동 특성 등을 모델에 반영하였다. 면내 순수전단거동에 대한 실험 및 해석결과를 통하여 개발된 R-ECC-MCFT 모델은 ECC 면내전단거동 예측에 효과적인 것으로 평가되었다. 또한 철근 보강된 ECC 면내요소는 철근콘크리트 면내요소에 비하여 최대전단강도 및 전단변형률이 증가하기 때문에 면내전단변형에서 높은 연성을 확보하는 것으로 평가되었다.