• Title/Summary/Keyword: 하중 및 변위 증분법

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Large Deflection and Elastoplastic Analysis of the Plane Framed Structure Using Isoparametric Curved Beam Element (Isoparametric 곡선(曲線) 보요소(要素)를 이용한 평면(平面)뼈대 구조물(構造物)의 대변형(大變形) 및 탄소성(彈塑性) 유한요소해석(有限要素解析))

  • Kim, Moon Young;Shin, Hyun Mock;Lee, Chang Yong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.2
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    • pp.41-49
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    • 1993
  • This paper presents a geometrically non-linear and elastoplastic F.E. formulation using a total Lagrangian approach for the two dimensional isoparametric curved beam elements. The beam element is derived by using plane stress elements. The basic element geometry is constructed using the coordinates of the nodes on the element center line and the nodal point normals. The element displacement field is described using two translations of the node on the center line and a rotation about the axes normal to the plane containing the center line of the element. The layered approach is used for the elastoplastic analysis of the plane framed structure with the arbitrary cross section. The iterative load or displacement incremental method for non-linear finite element analysis of the frame structure is used. Numerical examples are presented to demonstrate the behavior and the accuracy of the proposed beam element for geometric and elastoplastic non-linear applications. Comparisons made with present theory and other published data show that tilt' beam element products accurate results with good convergence characteristics.

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Ultimate Strength Analysis of Space Steel Frames Considering Spread of Plasticity (점진적 소성화를 고려한 공간 강뼈대구조의 극한강도해석)

  • Kim, Sung Bo;Han, Jae Young;Park, Soon Cheol;Kim, Moon Young
    • Journal of Korean Society of Steel Construction
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    • v.15 no.3
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    • pp.299-311
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    • 2003
  • This paper presents a finite element procedure to estimate the ultimate strength of space frames considering spread of plasticity. The improved displacement field is introduced based on the inclusion of second-order terms of finite rotations. All the non-linear terms due to bending moment, torsional moment, and axial force are precisely considered. The concept of plastic hinges is introduced and the incremental load/displacement method is applied for elasto-plastic analyses. The initial yield surface is defined based on the residual stress, and the full plastification surface is considered under the combined action of axial forces, bending and torsional moments. The elasto-plastic stiffness matrices are derived using the flow rule and the normality condition of the limit function. Finite element solutions for the ultimate strength of space frames are compared with available solutions and experimental results.

Verification of NASCOM : Nonlinear Finite Element Analysis for Structural Concrete (NASCOM에 의한 실험결과 예측)

  • 조순호
    • Magazine of the Korea Concrete Institute
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    • v.8 no.3
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    • pp.187-195
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    • 1996
  • A finite element formulation based on the CFT(Compression Field Theory), considering the effect of compression softening in cracked concrete, and macro-scopic and rotating crack models etc., was presented for the nonlinear behaviour of structural concrete. Considering the computational efficency and the ability of modelling the post-ultimate behaviour as major concerns, the Incremental displacement solution algorithm involving initial material stiffnesses and the relaxation procedure for fast convergence was adopted and formulated in a type of 8-noded quadrilateral isoparametric elements. The analysis program NASCOM(Non1inear Analysis of Structural Concrete by FEM : Monotonic Loading) developed in this way enables the predictions of strength and deformation capacities in a full range, crack patterns and their corresponding widths, and yield extents of reinforcement. As the verification purpose of NASCOM, the predictions were made for Bhide's Panel(PB21) and Leonhardt's deep beam tests. The predicted results shows somewhat stiff behaviour for the panel test, and vice versa for deep beam tests. More refining process would be necessary hereafter in terms of more accurately simulating the effects of tension-stiffening and compression softening in concrete.

The Analysis of the Bearing Capacity of Layered Clay by Numerical Methods (수치해석적 방법에 의한 층상 점토지반의 극한지지력 해석)

  • 김영민
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.121-129
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    • 2003
  • Numerical studies on bearing capacity problems of layered clay are performed for smooth and rough strip footings. The finite element method and finite difference method (FLAC) are used for computations of the bearing capacity, entire load-displacement curve and the failure mechanism. The presented results show that it is possible to analyze the bearing capacity of layered clay and to give a progressive failure mechanism clearly. To obtain high quality solutions, it is necessary to review the results on control parameters(e.g., yield function, number of calculation) and compare the results by two numerical methods.

A Numerical Approach to Spherical Indentation Techniques for Creep Property Evaluation (크리프 물성평가를 위한 구형압입 수치접근법)

  • Lim, Dongkyu;Lee, Jin Haeng;Choi, Youngsick;Lee, Hyungyil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.10
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    • pp.1229-1237
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    • 2013
  • In this study, the theory of spherical indentation based on incremental plasticity is extended to an indentation method for evaluating creep properties. Through finite element analysis (FEA), the point where the elastic strain effect is negligible and the creep strain gradient constant is taken as the optimum point for obtaining the equivalent strain rate and stress. Based on FE results for spherical indentation with various values of creep exponent and creep coefficient, we derive by regression an equation to calculate creep properties using two normalized variables. Finally a program is generated to calculate creep exponent and creep coefficient. With this method, we obtain from the load-depth curve creep exponents with an average error of less than 1.5 % and creep coefficients with an average error of less than 1.0 %.

Grain-Based Distinct Element Modeling of Thermoshearing of Rock Fracture: DECOVALEX-2023 Task G (입자기반 개별요소모델을 이용한 암석 균열의 Thermoshearing 거동 해석: 국제공동연구 DECOVALEX-2023 Task G)

  • Jung-Wook, Park;Li, Zhuang;Jeong Seok, Yoon;Chan-Hee, Park;Changlun, Sun;Changsoo, Lee
    • Tunnel and Underground Space
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    • v.32 no.6
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    • pp.568-585
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    • 2022
  • In the present study, we proposed a numerical method for simulating thermally induced fracture slip using a grain-based distinct element model (GBDEM). As a part of DECOVALEX-2023, the thermo-mechanical loading test on a saw-cut rock fracture conducted at the Korea Institute of Civil Engineering and Building Technology was simulated. In the numerical model, the rock sample including a saw-cut fracture was represented as a group of random Voronoi polyhedra. Then, the coupled thermo-mechanical behavior of grains and their interfaces was calculated using 3DEC. The key concerns focused on the temperature evolution, thermally induced principal stress increment, and fracture normal and shear displacements under thermo-mechanical loading. The comparisons between laboratory experimental results and the numerical results revealed that the numerical model reasonably captured the heat transfer and heat loss characteristics of the rock specimen, the horizontal stress increment due to constrained displacement, and the progressive shear failure of the fracture. However, the onset of the fracture slip and the magnitudes of stress increment and fracture displacement showed discrepancies between the numerical and experimental results. We expect the numerical model to be enhanced by continuing collaboration and interaction with other research teams of DECOVALEX-2023 Task G and validated in further study.