• Title/Summary/Keyword: stress-strain relationships

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Mix Design and Properties of Recycled Aggregate Concretes: Applicability of Eurocode 2

  • Wardeh, George;Ghorbel, Elhem;Gomart, Hector
    • International Journal of Concrete Structures and Materials
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    • v.9 no.1
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    • pp.1-20
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    • 2015
  • This work is devoted to the study of fresh and hardened properties of concrete containing recycled gravel. Four formulations were studied, the concrete of reference and three concretes containing recycled gravel with 30, 65 and 100 % replacement ratios. All materials were formulated on the basis of S4 class of flowability and a target C35 class of compressive strength according to the standard EN 206-1. The paper first presents the mix design method which was based on the optimization of cementitious paste and granular skeleton, then discusses experimental results. The results show that the elastic modulus and the tensile strength decrease while the peak strain in compression increases. Correlation with the water porosity is also established. The validity of analytical expressions proposed by Eurocode 2 is also discussed. The obtained results, together with results from the literature, show that these relationships do not predict adequately the mechanical properties as well as the stress-strain curve of tested materials. New expressions were established to predict the elastic modulus and the peak strain from the compressive strength of natural concrete. It was found that the proposed relationship E-$f_c$ is applicable for any type of concrete while the effect of substitution has to be introduced into the stress-strain (${\varepsilon}_{c1}-f_c$) relationship for recycled aggregate concrete. For the full stress-strain curve, the model of Carreira and Chu seems more adequate.

Engineering Properties of Some Sedimentary Rocks from the Gyeongsang Supergroup (경상계(慶尙系) 퇴적암(堆積岩)의 공학적(工學的) 성질(性質)에 관(關)한 연구(硏究))

  • So, Chil-Sup;Choi, Byoung-Ryol
    • Economic and Environmental Geology
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    • v.8 no.4
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    • pp.203-210
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    • 1975
  • The engineering properties of some Gyeongsang sedimentary rocks with respect to the grain size and the orientation of bedding planes were studied. The suitability of the rocks for civil and architectural construction was also investigated. The porosity of the rocks increases in proportion to the grain size. The ratio of the strain due to stress perpendicular to the bedding planes to the strain resulting from stress parallel to the bedding planes increases as the grain size decreases. The study indicates however, that the ratio of Young's modulus due to stress perpendicular to the bedding planes to Young's modulus resulting from stress parallel to the bedding planes increases in proportion to the grain size. The compressive strength of the sandstones studied is much greater than the strength of the conglomerate or shale. Only the coarse grained sandstone can be used for civil and architectural construction, regardless of the orientation of bedding planes. The relationships between compressive strength and density, elasticity and porosity, and compressive strength and mineral content were also studied.

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Strain Rate Sensitive Behavior of Mild Steel Subjected to Dynamic Load (동 하중에 대한 연강 재질의 변형율 속도 민감도 특성 연구)

  • Park, Jong-Chan
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.377-382
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    • 2004
  • The dynamic material characteristics on some mild steel sheets were observed. The dynamic tests were conducted on the ESH servo-hydraulic test machine. It was observed that the mechanical properties of mild steel are highly sensitive to the value of strain rate. The well known Cowper-Symonds constitutive equation was used to generalize the strain rate sensitivity effect. Modified constitutive equations were suggested to couple the strain hardening to the strain rate sensitivity. The dynamic stress-strain relationships for the mild steel sheets used in the present study were reasonably predicted using these modified constitutive equations.

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The Stress-Strain Behavior of Weathered Granite Soil after Cyclic Loading (화강암 풍화토가 반복하중을 받은 후의 변형거동에 관한 소고)

  • 이종규;김주한
    • Geotechnical Engineering
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    • v.7 no.3
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    • pp.33-42
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    • 1991
  • Increasing demand of rational analysis of dynamic soil behavior subjected to repetitive loading has evolved soil dynamics which is essential for proper design and/or analysis of dynamically loaded soil structure. In this paper, the stress-strain behavior of weathered granite soil under cyclic loading is stud- ied by measuring the strength and the strain before and after application of at least 11, 000 cycles of repetitive load. Relationships are suggested for predicting results of soil dynamics from those of soil statics.

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Meso-Scale Approach for Prediction of Mechanical Property and Degradation of Concrete

  • Ueda, Tamon
    • Corrosion Science and Technology
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    • v.3 no.3
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    • pp.87-97
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    • 2004
  • This paper presents a new approach with meso scale structure models to express mechanical property, such as stress - strain relationships, of concrete. This approach is successful to represent both uniaxial tension and uniaxial compression stress - strain relationship, which is in macro scale. The meso scale approach is also applied to predict degraded mechanical properties of frost-damaged concrete. The degradation of mechanical properties with frost-damaged concrete was carefully observed. Strength and stiffness in both tension and compression decrease with freezing and thawing cycles (FTC), while stress-free crack opening in tension softening increases. First attempt shows that the numerical simulation can express the experimentally observed degradation by introducing changes in the meso scale structure in concrete, which are assumed based on observed damages in the concrete subjected to FTC. At the end applicability of the meso scale approach to prediction of the degradation by combined effects of salt attack and FTC is discussed. It is shown that clarification of effects of frost damage in concrete on corrosion progress and on crack development in the damaged cover concrete due to corrosion is one of the issues for which the meso scale approach is useful.

Strengthening Effect Analysis of Circular Concrete Column Strengthened with Laminated CFS (적층성을 띤 CFS로 보강된 원형 콘크리트 기둥의 보강효과 해석)

  • 이상호;허원석
    • Journal of the Korea Concrete Institute
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    • v.11 no.3
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    • pp.89-100
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    • 1999
  • The purpose of this study is to develop an analytic model of the concrete column strengthened with laminated CFS, and to provide a basic guideline for the strengthening design by CFS considering orthotropic properties of laminate. In this study, an analytical stress-strain model of laminated CFS is presented based on Tsai-Hill failure criterion. This model has been implemented in an algorithm which can evaluate the confinement effect of CFS. Through this algorithm, the stress-strain relationship of confined concrete is obtained and compared with experimental results of other studies. Using the constitutive relationships, section analyses of concrete column strengthened with CFS are done, and load-moment and load-curvature interaction curves are obtained. In addition, the strengthening effects of CFS according to various laminated angles are analyzed. Analytical results show that the strengthening effects of the strengthened concrete columns are significantly different in compression, flexure, and ductility according to the laminated ways. In compressive direction of principal stress shows the superiority, where an in flexural strengthening effects, [0/90]s does. In the aspect of ductility, [90]s shows the best effect.

Study of Al-Alloy Foam Compressive Behavior Based on Instrumented Sharp Indentation Technology

  • Kim Am-Kee;Tunvir Kazi
    • Journal of Mechanical Science and Technology
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    • v.20 no.6
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    • pp.819-827
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    • 2006
  • The stress-strain relation of aluminum (Al) alloy foam cell wall was evaluated by the instrumented sharp indentation method. The indentation in a few micron ranges was performed on the cell wall of Al-alloy foam having a composition or Al-3wt.%Si-2wt.%Cu-2wt.%Mg as well as its precursor (material prior to foaming). To extract the stress-stram relation in terms of yield stress ${\sigma}_y$, strain hardening exponent n and elastic modulus E, the closed-form dimensionless relationships between load-indentation depth curve and elasto-plastic property were used. The tensile properties of precursor material of Al-alloy foam were also measured independently by uni-axial tensile test. In order to verify the validity of the extracted stress-strain relation, it was compared with the results of tensile test and finite element (FE) analysis. A modified cubic-spherical lattice model was proposed to analyze the compressive behavior of the Al-alloy foam. The material parameters extracted by the instrumented nanoindentation method allowed the model to predict the compressive behavior of the Al-alloy foam accurately.

Anisotropy in Strength and Deformation Properties of a Variety of Sands by Plane Strain Compression Tests(Part III) -Shear Deformation Characteristics- (평면변형률압축시험에 의한 각종 모래의 강도.변형특성의 이방성(III) -전단변형 특성-)

  • 박춘식;황성춘;장정욱
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.95-105
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    • 2000
  • Anisotropy of stiffiness, from extremely small strains to post-failure strains, of isotropically consolidated air-pulviated sands in plane strain compression was studied by using the newly developed instrumentation for small strain measurements. Seven types of sand of the world-wide origins were tested, which have been extensively used for research purposes. Stress-strain relationships for a wide range of strain from about 0.0001% to 10% were obtained with measuring axial and lateral strains locally free from the effects of bedding and membrane penetration errors at the specimen boundaries. It was found that the maximum shear modulus Gmax was irrespective of the angle $\delta$of the $\sigma$1 direction relative to the bedding plane. However, the normalized Gmax was varied with the types of sand. Furthermore, the dependency of the strain and stress level on the stiffness increased as decreased.

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Stress Analysis of the Clutch Housing of a Washing Machine (탈수속도 변화에 따른 세탁기 클러치하우징의 강도해석)

  • Kim, Wan-Du;Lee, Hak-Ju;Han, Seung-U
    • 연구논문집
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    • s.26
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    • pp.33-42
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    • 1996
  • The transmission system of a washing machine which is called by the clutch is one of the most important components to preserve the performance. The clutch housing has a role to guard and mount the transmission system on the frame of the machine. The load which is applied on the clutch housing depends on the operating conditions. Nowadays the dehydration speed is higher and higher in order to improve the efficiency. In this study, the strains on the predicted weak positions were measured using the strain gage and its measuring equipment. The relationships between the dehydration speeds and the maximum principal strains were obtained. Finite element analysis is executed to acquire the effect of the dehydration speed on the stress of the clutch housing. The distributions of the equivalent stress and the maximum stresses under the various speeds, the various loading directions and the various thickness of the clutch housing were obtained.

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The Relationships between Excess Pore Water Pressure and Strain in Normally Consolidated Saturated Clays During Undrained Shear (포화된 정친압밀점토의 비배수 전단중에 발생하는 과잉간극 수압과 변형의 관계)

  • 박정용;정인주
    • Geotechnical Engineering
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    • v.2 no.1
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    • pp.15-26
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    • 1986
  • Consolidated undrained standard triaxial tests for two remoulded clays and one undisturbed clay were carried out in order to find out the relationship between excess pore water pressure and axial strain in mortally consolidatated saturated clays during undrained shear. Tests were performed with isotropically-normally consolidated specimens by strain controlled and stress controlled loading. As the result of this stud!'a hyperbolic function expressing the relationship between pore water pressure and strain was found out, and it showed the same form as the Kondner's hyperbolic function for stress·strain behaviour. Two parameters used for the function can be obtained by CU-triaxial test.

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