• Title/Summary/Keyword: 평면응력

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A Computer Model for the Planar Effects of Concrete Pavements with Skewed Joints. (콘크리트 포장구조의 평면응력 해석을 위한 컴퓨터모델)

  • 조병완
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1989.10a
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    • pp.15-18
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    • 1989
  • The planar effects on the concrete pavements Is mainly due to the concrete shrinkage, subgrade friction, and thermal expansion or contraction. A complete understanding of analytical behavior of concrete pavement requires the development of computer model, stiffness matrix and equivalent nodal load matrices due to the effects mentioned above. A computer program, INPLANE II, has been written to evaluate the planar effects on concrete pavements. The planar effects determine to what degree the joint open and also help In determining factors which affect the joint stiffnesses and structural behavior of concrete Pavements.

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Finite Element Simulation of High-Speed Impact in Plane Structure (고속충격하중을 받는 평면구조의 유한요소해석)

  • 황갑운
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.2
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    • pp.119-128
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    • 1999
  • 본 연구는 등방탄성체에 고속충격하중이 작용하는 경우에 대한 유한요소해석에 관한 것으로 대상구조는 여러 가지 모양의 2차원 평면구조를 택하였다. Galerkin 방법을 이용하여 유한요소 정식화하였으며 직접시간적분법에 의해 수치해를 구하였다. 본 해석에서는 균열이 없는 평판으로 수치해와 이론해를 비교하여 수치해의 신뢰성을 확인하였으며, 0°, 30°, 45°경사 균열이 없는 평판에 적용한 3가지 예를 분석하였다. 수치해석 결과는 이론해의 결과와 상호 잘 일치하였다.

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Optimum Design of Plane Frames Subject to Displacement and Stress Constraints (처짐과 응력제약(應力制約)을 받는 평면(平面) 뼈대의 최적설계(最適設計))

  • Chung, Young Shik;Lee, Jae Whane
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.1
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    • pp.23-31
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    • 1987
  • This work presents an optimality criteria method which gives accurate solution to the structural optimization problem of plane frames subject to displacement and stress constraints. The method is made efficient, as well as rigorous, by including only the lateral displacement of the top floor in the set of behavioral constraints. The bending stresses of members are treated as side constraints based on the concept of fully-stressed-design, but the optimality of the final design is tested by treating them as behavioral constraints and examining if the design satisfies this new optimality criteria. Worked examples show the superiority of the rigorous opimality criteria in spite of its being simple and efficient.

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Crack Extension in Anisotropic Solids Subjected to Uniaxial Load (단축하중을 받는 이방성체내 균열의 진전)

  • 임원균;최승룡;안현수
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.2
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    • pp.161-169
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    • 1999
  • 이방성체의 평면내 직선균열에 대한 균열선단부근의 응력과 변위의 분포는 어떠한 균열체의 형상 및 하중조건에 대해서도 응력확대계수라는 하나의 매개변수로서 나타낼 수 있다고 하는 것이 파괴역학에서 보편화되어 있다. 그러나 많은 경우에 있어서 급수전개식의 이어지는 항은 정량적으로 중요하다. 따라서 본 연구에서는 이러한 항을 유도하고 이것이 균열진전방향에 미치는 영향에 대하여 검초하였다. 이를 위하여 단축하중을 받는 직방성균열체의 해석을 수행하며 재료는 균질이방성체라고 가정하였다. 급수전개식에서 2차항의 영향을 고려하기 위하여 균열선단에서의 응력의 분포를 재해석하였으며, 2차항의 사용은 정확한 균열진전방향의 결정을 위해서 매우 중요함을 보였다. 초기균열진전각도의 결정을 위해서 수직응력비이론을 적용하였다.

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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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Anisotropy in Strength and Deformation Properties of a Variety of Sands by Plane Strain Compression Tests(Part II) -Deformation Characteristics at Extremely Small Strain Level (평면변형률압축시험에 의한 각종 모래의 강도.변형특성의 이방성(II)-미소변형률에서의 변형특성 이방성)

  • 박춘식;장정욱
    • Geotechnical Engineering
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    • v.14 no.4
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    • pp.33-46
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    • 1998
  • Anisotropy of stiffness, from extremely small strains to post-failure strains, of isotropically consolidated air-pluviated 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 at the specimen boundaries. It was found that the maximum Young's modulus $E_{max}$ was irrespective of the angle $\delta$ of the $\delta_1$ direction relative to the bedding plane. However, the normalized$ E_{max}$ was varied with the types of sand. Furthermore, the dependency of the strain and stress level on the stiffness was increased as $\delta$ decreased.

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Tapered Joint Design for Power Transmission of MW-grade Wind Turbine (MW급 풍력발전기 동력전달용 테이퍼 연결장치 설계에 관한 연구)

  • Kang, JongHun;Bae, JunWoo;On, Hanyong;Kwon, Yongchul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.11
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    • pp.1183-1189
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    • 2015
  • This study focuses on the design of the tapered joints of a wind power turbine. The main variables of the tapered joint are the transmitted torque, shaft diameter, contact area of the tapered ring, and tightening torque of the bolts, which applies a compressive pressure from the hub to the shaft. The stress distribution of the taper fit was calculated under axisymmetric plane strain conditions because of the small taper angle. The axial displacement of the clamp can be calculated from the radial elastic deformation and the taper angle. The stress field of each ring is obtained from the cylinder stress equation. To verify the accuracy of the calculation, finite element (FE) analysis was performed, and the results of the calculation and FE analysis were compared. The hoop stress of the tapered surface showed a discrepancy of approximately 10, but the trends of the stress distributions of each component and the relative movement obtained by FE analysis were in good agreement with the analytical calculation results.

An Optimality Criteria applied to the Design of Plane Frames (평면 뼈대 구조물의 설계에 적용된 최적규준)

  • 정영식;김봉익;김창규
    • Computational Structural Engineering
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    • v.9 no.2
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    • pp.121-131
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    • 1996
  • This work proposes an optimality criteria applicable to the optimum design of plane frames subject to multiple behavioral constraints on member stresses and lateral displacements of nodes and also to side constraints on design variables. The method makes use of a first order approximation for both deflection and stress constraints instead of the zero order approximation based on the concept of FSD (fully stressed design). A redesign algorithm is derived from a mathematically rigorous method which uses the Newton-Raphson method to solve the system of nonlinear constraint equations and reduces the design space whenever minimum size restrictions become active. When applied to worked examples it proved more accurate and efficient, and it is often found that optimum designs are not fully stressed designs. This fact suggests that this rigorous method is worth what it claims for complicated computing and thus had better replace the crude stress ratio algorithm adopted by the majority of optimality criteria approaches. This is particularly true as long as we enjoy ever-increasing computing power at negligible costs.

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Analysis on Creep of Concrete under Multiaxial Stresses Using Microplane Model (미세평면 모델을 적용한 다축응력 상태의 콘크리트 크리프 분석)

  • Kwon Seung-Hee;Kim Yun-Yong;Kim Jin-Keun
    • Journal of the Korea Concrete Institute
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    • v.16 no.2 s.80
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    • pp.195-204
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    • 2004
  • Poisson's ratio due to multiaxial creep of concrete reported by existing experimental works was controversial. Poisson's ratio calculated from measured strain is very sensitive to small experimental error. This sensitivity make it difficult to find out whether the Poisson's ratio varies with time or remain constant, and whether the Poisson's ratio has different value with stress states or not. A new approach method is needed to resolve the discrepancy and obtain reliable results. This paper presents analytical study on multiaxial creep test results. Microplane model as a new approach method is applied to optimally fitting the test data extracted from experimental studies on multiaxial creep of concrete. Double-power law is used as a model to present volumetric and deviatoric creep evolutions on a microplane. Six parameters representing the volumetric and deviatoric compliance functions are determined from regression analysis and the optimum fits accurately describe the test data. Poisson's ratio is calculated from the optimum fits and its value varies with time. Regression analysis is also performed assuming that Poisson's ratio remains constant with time. Four parameters are determined for this condition, and the error between the optimum fits and the test data is slightly larger than that for six parameter regression results. The constant Poisson's ratio with time is obtained from four parameter analysis results and the constant value can be used in practice without serious error.

Calculation of Stres Intensity Factor in Arbitrarily Shaped Plane Crack by Mobius Transformation (뫼비우스 사상을 이용한 임의의 3차원 평면균열에서의 응력확대계수 계산)

  • An, Deuk-Man
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.4
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    • pp.734-740
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    • 2001
  • In this paper the stress intensity factor under uniform pressure in the arbitrarily-shaped plane crack configuration transformed elliptic crack by Mobius mapping are determined. Using Dysons formula Boussinesq-Papkovich potentials for mode I deformation are constructed. In the example the stress intensity factors are approximately calculated by least square method.