• 제목/요약/키워드: Crack moment

검색결과 239건 처리시간 0.026초

Service load response prediction of reinforced concrete flexural members

  • Ning, Feng;Mickleborough, Neil C.;Chan, Chun-Man
    • Structural Engineering and Mechanics
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    • 제12권1호
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    • pp.1-16
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    • 2001
  • A reliable and accurate method has been developed to predict the flexural deformation response of structural concrete members subject to service load. The method that has been developed relates the extent of concrete cracking, measured as a function of the magnitude of applied moment in a member, to the reduction in the effective moment of inertia of cracked reinforced concrete members under service load conditions. The ratio of the area of the moment diagram where the moment exceeds the cracking moment, to the total area of the moment diagram for any loading, provides the basis for the calculation of the effective moment of inertia. This ratio also represents mathematically a probability of crack occurrence. Verification of this method for the determination of the effective moment of inertia has been achieved from an experimental test program, and has included beam tests with different loading configurations, and shear wall tests subjected to a range of vertical and lateral load levels. Further verification of this method has been made with reference to the experimental investigation of other recently published work.

부분 프리스트레스트 콘크리트 슬래브의 휨 균열 거동에 관한 실험적 연구 (An Experimental Study on the Flexural Cracking Behavior of Partially Prestressed Concrete Slabs)

  • 박홍용;연준희;최익창
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1990년도 봄 학술발표회 논문집
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    • pp.108-115
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    • 1990
  • This paper contains experimental studies on the flexural cracking behabior of PPC one-way slabs. Three post tensioned bonded PPC slabs with the same prestressing ratio and ultimate moment strength were tested. Based upon test results, this paper also presents the crack width prediction formula PPC slab. According to the crack theory developed mainly in Europe, crack width formula is given as the product of crack spacing and mean steel strain after decompression. Aaaaverage crack spacing formula is composed of many factors mainly such as concrete cover, concrete effective area in tension, sum of reinforcing bars perimeters and mixed reinforcements. In particular, it is very important to specify the bond characteristics of mixed reinforcements, since bond characteristics of PC bars are different from those of non-tensioned deformed bars. For this reason, a reduced bond coefficients for PS bars is employed in this study.

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차체구조물에서 면내 굽힘모우멘트 및 과하중이 피로특성과 균열전파 거동에 미치는 영향에 관한 연구 (A Study on the Fatigue Characteristics and the Behavior of Crack Propagation by Overload and Bending Moment in Car Body Structure)

  • 성기찬;장경복;정진우;강성수
    • Journal of Welding and Joining
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    • 제19권6호
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    • pp.652-657
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    • 2001
  • To analyze and predict crack initiation position and propagation directions on the spot welded area are very important for strength design of the automobile body structure. It is necessary to test by method considering random loads with variable amplitude for strength design of vehicle body structure, because driving cars are actually subjected to random loads with variable amplitude in the road. Although this condition, nearly all tests haute been performed under constant load conditions in the laboratory because it is impossible to replay like an actual conditions. In this study, using in-plane bending type specimens, the overload factor affecting on the fatigue strength, crack initiation and propagation directions of spot-welded specimens have been studied.

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크랙을 고려한 휨을 받는 콘크리트보의 해석 (A Rational Approach to the Flexural Concrete Beam Analysis with Crack Growth using Fracture Mechanic Concepts)

  • 허광희;최만용
    • 한국구조물진단유지관리공학회 논문집
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    • 제2권4호
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    • pp.159-171
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    • 1998
  • This study attempts to develop a rational approach to flexural concrete beam analysis with crack growth. In order to develope analytical solutions, several simplification and assumption are made and the Hillerborg fictitious crack model is adapted for new rational approach to the flexural concrete beam. To provide desired results, the concrete beams with various conditions(more than 126 beam conditions) are analyzed. Before producing the results, these assumptions are founded to be justified by comparison with a FE analysis. The results for each condition of the beams are presented in terms of crack lengths, the strength and cracking stability of concrete beams. And also size effects in a flexural concrete beam is studied using a new flexural cracking model.

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순환골재 치환률에 따른 철근콘크리트 보의 휨거동에 관한 실험적 연구 (Experimental Study of Flexural Behavior of Reinforced Concrete Beams with Different Types of Coarse Aggregates)

  • 이영오;전에스더;윤현도;유영찬;김긍환;최기선
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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    • pp.45-48
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    • 2006
  • This study is to evaluate flexural behavior of RC beam with different types of coarse aggregates, so called natural or recycled aggregate. Two reinforced concrete beams were manufactured with different replacement level of recycled coarse aggregates : Concrete made with 0% of coarse aggregates, concrete made with 100% of recycled coarse aggregates. From the test, the general flexural performances of RC beams with different types of coarse aggregates such as cracking moment, crack patterns, maximum moment/crack width are discussed.

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Intermediate crack-induced debonding analysis for RC beams strengthened with FRP plates

  • Wantanasiri, Peelak;Lenwari, Akhrawat
    • Structural Engineering and Mechanics
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    • 제56권3호
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    • pp.473-490
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    • 2015
  • This paper presents the analysis of intermediate crack-induced (IC) debonding failure loads for reinforced concrete (RC) beams strengthened with adhesively-bonded fiber-reinforced polymer (FRP) plates or sheets. The analysis consists of the energy release and simple ACI methods. In the energy release method, a fracture criterion is employed to predict the debonding loads. The interfacial fracture energy that indicates the resistance to debonding is related to the bond-slip relationships obtained from the shear test of FRP-to-concrete bonded joints. The section analysis that considers the effect of concrete's tension stiffening is employed to develop the moment-curvature relationships of the FRP-strengthened sections. In the ACI method, the onset of debonding is assumed when the FRP strain reaches the debonding strain limit. The tension stiffening effect is neglected in developing a moment-curvature relationship. For a comparison purpose, both methods are used to numerically investigate the effects of relevant parameters on the IC debonding failure loads. The results show that the debonding failure load generally increases as the concrete compressive strength, FRP reinforcement ratio, FRP elastic modulus and steel reinforcement ratio increase.

원주방향 경사관통균열이 존재하는 두꺼운 배관의 탄성 균열열림변위 (Elastic Crack Opening Displacement of Slanted Circumferential Through-Wall Cracks in Thick-Walled Cylinder)

  • 한태송;허남수;심도준;김진수;이진호
    • 한국압력기기공학회 논문집
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    • 제8권3호
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    • pp.13-22
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    • 2012
  • According to recent research on leak-rate estimates to assess rupture probabilities of nuclear piping which contains a circumferential surface/through-wall cracks due to PWSCC, i.e., xLPR (Extremely Low Probability of Rupture) program, it has been revealed that the use of crack shape with an idealized circumferential through-wall crack during actual crack growth can lead to overestimate of the leak-rate. Thus, for accurate estimation of the leak-rate during crack growth, the more realistic crack shape that can simulate the crack shape transition from surface crack to through-wall crack should be used. In this context, in the present study, the elastic crack opening displacement of slanted circumferential through-wall crack in thick-walled cylinder was proposed based on 3-dimensional elastic finite element fracture mechanics analyses. To propose the elastic crack opening displacement of slanted circumferential through-wall crack in thick-walled cylinder, the geometric variables affecting crack opening displacement, i.e., thickness of cylinder, reference inner crack length and slant crack ratio were systematically varied. In terms of loading conditions, axial tension, global bending moment and internal pressure were considered. The present results can be applied to calculate the leak-rate considering more realistic crack shape transition from surface crack to idealized through-wall crack, and can be expected to enhance current leak-rate estimation scheme, for instance, in xLPR program etc.

철근콘크리트 보의 균열 폭과 처짐 관계 (Correlation Between Crack Widths and Deflection in Reinforced Concrete Beams)

  • 강주오;김강수;이득행;이승배
    • 한국구조물진단유지관리공학회 논문집
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    • 제14권2호
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    • pp.184-192
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    • 2010
  • 철근콘크리트 구조물의 사용성을 검토할 때 처짐은 가장 중요한 사항 중 하나이며, 철근콘크리트 휨 부재의 처짐은 일반적으로 유효 단면2차모멘트의 개념을 적용하여 구해진다. 그러나 이미 사용중인 철근콘크리트 보에서 정확한 사용하중을 알기 어려운 경우에는 기존의 방법으로 처짐을 계산하는 것이 쉽지 않다. 따라서, 이 연구에서는 철근콘크리트 보에서 균열과 처짐은 상호 밀접한 관련이 있다는 사실을 바탕으로 작용하는 하중의 크기에 무관하게 철근 콘크리트 보 부재의 균열 상태로부터 처짐을 쉽게 산정할 수 있는 방법을 제안하고자 하였다. 균열폭의 합, 평균변형률 및 곡률 등의 관계를 이용하여 처짐식을 제안하였으며, 수정계수를 적용하여 보다 정확한 처짐식을 제안하고자 하였다. 이 제안식을 사용할 경우, 철근콘크리트 보에 작용하는 하중 크기에 무관하게 균열을 측정함으로써 처짐 추정치를 얻을 수 있으며, 유효 단면 2차 모멘트 값을 산출하여 처짐을 산정하는 기존의 방법에 비해 비교적 간단하게 처짐을 산출 할 수 있다.

해수환경중 부식피로균열 발생수명 평가에 관한 연구 (Research for the Evaluation of Corrosion Fatigue Crack Initiation Life)

  • 김원범;백점기;시도호
    • 대한조선학회논문집
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    • 제44권4호
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    • pp.417-424
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    • 2007
  • With regard to corrosion fatigue crack initiation life (Nc), it has been treated ambiguously for the member which doesn't have stress concentration area. In this research, in order to clarify the corrosion fatigue crack initiation life (Nc), corrosion fatigue tests were carried out. Reasonable and universal corrosion fatigue crack initiation life (Nc) was defined and corrosion fatigue crack initiation/propagation model was suggested also. As the fatigue crack which emanates from the pit is usually small, accordingly it is treated as a small crack. In addition, the observation of the corrosion fatigue fracture surfaces using SEM was conducted. And the fracture mechanics analysis using an intrinsic crack model was conducted for the treatment of the small crack. Finally, the followings were obtained. When there is no clear stress concentration point which seems to fall into a corrosion fatigue crack initiation life, the significance of the definition and suggestion of the moment of the reasonable and universal corrosion fatigue crack initiation life (Nc), at which the fatigue crack propagation rate becomes faster than the corrosion pit growth rate so that the fatigue crack initiates from the pit and propagates in earnest, has been clarified.

An effective stiffness model for RC flexural members

  • Balevicius, Robertas
    • Structural Engineering and Mechanics
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    • 제24권5호
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    • pp.601-620
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    • 2006
  • The paper presents an effective stiffness model for deformational analysis of reinforced concrete cracked members in bending throughout the short-term loading up to the near failure. The method generally involves the analytical derivation of an effective moment of inertia based on the smeared crack technique. The method, in a simplified way, enables us to take into account the non linear properties of concrete, the effects of cracking and tension stiffening. A statistical analysis has shown that proposed technique is of adequate accuracy of calculated and experimental deflections data provided for beams with small, average and normal reinforcement ratios.