• Title/Summary/Keyword: Tension stiffening 모델

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Material Nonlinear Analysis of the RC Shells Considering Tension Stiffening Effects (인장강성 효과를 고려한 RC 쉘의 재료비선형 해석)

  • Jin, Chi Sub;Eom, Jang Sub
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.5
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    • pp.99-107
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    • 1993
  • In this study, material nonlinear finite element program is developed to analyze reinforced concrete shell of arbitrary geometry considering tension stiffening effects. This study is capable of tracing the load-deformation response and crack propagation, as well as determining the internal concrete and steel stresses through the elastic, inelastic and ultimate ranges in one continuous computer analysis. The cracked shear retention factor is introduced to estimate the effective shear modulus including aggregate interlock and dowel action. The concrete is assumed to be brittle in tension and elasto-plastic in compression. The Drucker-Prager yield criterion and the associated flow rule are adopted to govern the plastic behavior of the concrete. The reinforcing bars are considered as a steel layer of equivalent thickness. A layered isoparametric flat finite element considering the coupling effect between the in-plane and the bending action was developed. Mindlin plate theory taking account of transverse shear deformation was used. An incremental tangential stiffness method is used to obtain a numerical solution. Numerical examples about reinforced concrete shell are presented. Validity of this method is studied by comparing with the experimential results of Hedgren and the numerical analysis of Lin.

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Nonlinear Finite Element Analysis of Reinforced and Prestressed Concrete Structures (철근 및 프리스트레스트 콘크리트 구조물의 비선형 유한요소 해석)

  • Kwak, Hyo Gyoung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.2
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    • pp.269-279
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    • 1994
  • This paper concentrates on the finite element analysis of concrete structures considering the material nonlinearity and time-dependent structural behavior. Using the rotating crack model among the smeared cracking model, the structural behavior up to ultimate load is simulated, and concrete is assumed to be an orthotropic material. Especially to include the tension stiffening effect in bending behavior, a criterion based on the fracture mechanics concept is introduced and the numerical error according to the finite element mesh size can be minimized through the application of the proposed criterion. Besides, the governing equation for steel is systematized by embeded model to cope with the difficulty in modeling of complex geometry. Finally, to trace the structural behavior with time under cracked and/or uncracked section, an algorithm for the purpose of time-dependent analysis is formulated in plane stress-strain condition by the age-adjusted effective modulus method.

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Shell Finite Element of Reinforced Concrete for Internal Pressure Analysis of Nuclear Containment Building (격납건물 내압해석을 위한 철근콘크리트 쉘 유한요소)

  • Lee, Hong-Pyo;Choun, Young-Sun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.6A
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    • pp.577-585
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    • 2009
  • A 9-node degenerated shell finite element(FE), which has been developed for assessment of ultimate pressure capacity and nonlinear analysis for nuclear containment building is described in this paper. Reissner-Midnlin(RM) assumptions are adopted to develop the shell FE so that transverse shear deformation effects is considered. Material model for concrete prior to cracking is constructed based on the equivalent stress-equivalent strain relationship. Tension stiffening model, shear transfer mechanism and compressive strength reduction model are used to model the material behavior of concrete after cracking. Niwa and Aoyagi-Yamada failure criteria have been adapted to find initial cracking point in compression-tension and tension-tension region, respectively. Finally, the performance of the developed program is tested and demonstrated with several examples. From the numerical tests, the present results show a good agreement with experimental data or other numerical results.

Unified Method for Nonlinear Finite Element Analysis of RC Planar Members (통합방법을 이용한 철근콘크리트부재의 비선형 유한요소해석)

  • 박홍근
    • Magazine of the Korea Concrete Institute
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    • v.9 no.2
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    • pp.133-144
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    • 1997
  • Concrete plasticity models fol the analysis of reinforced concrete members in plane stress are studied. The proposed plasticity model for reinforced concrete provides a unified approach combining plasticity theory and damage models. It addresses strength mhancement under rnultiaxial compression. and tensile cracking damage. The model uses multiple failure criteria for compressive crushing and tensile cracking. For tensile cracking behavior. rotating-crack and fixed-crack plasticity models are compared. As crushing failure criterion, the Drucker-Prager and the von Mises models are used for comparison. The model uses now and existing damnge models fbr tension softening, tension stiffening. and compression softening dup to tensilt. cracking. Finite element analyses using the unified method are compatxd with existing rxpcrimcntal r.esults. To vei.ify the proposcd crushing and cracking plasticity models, the experiments have load capacities govc11.nc.d either by compressive crushing of'concrete or by yi~lding of' reinforcing steel.

Modeling Technologies for Unbonded Post-Tension Systems (비부착형 포스트텐션 구조의 모델링기법)

  • Kang, Thomas H.K.;Rha, Chang-Soon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.1
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    • pp.33-41
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    • 2011
  • This study presents modeling technologies applicable to an unbonded post-tension system using a finite element software package. In this study, both direct modeling method and multiple spring method were used. The direct modeling method adopts tube-to-tube contact elements to represent the physical feature of a post-tension system. The multiple spring method uses virtual tendons attached to the real tendons using a number of rigid axial springs that freely rotate at the ends. Both modeling technologies provide accurate predictions. However, only the multiple spring method provides numerically stable and reliable responses with a consideration of concrete tension stiffening effects. Therefore, the multiple spring method turned out to be a generally applicable modeling technology for the unbonded post-tension system. Comparisons were made for the analytical and experimental results for the verification of the selected method, and parameter studies were carried out to confirm the appropriateness of the modeling assumptions and parameters adopted in the analysis.

Development of Serviceability Model for RC Flexural Members (철근콘크리트 휨부재의 사용성 모델 개발)

  • Lee, Ki-Yeol;Kim, Jang-Hyun;Ha, Tae-Gwan;Kim, Dae-Joong;Kim, Woo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.413-416
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    • 2004
  • This paper describes a proposal for crack width and deflection in RC flexural members. Because the serviceability provisions of the current codes are mainly based on only empirical relationships developed from test result and effective moment of inertia, crack width and deflections are contrary to the actual values. Based on nonlinear bond characteristics, tension stiffening effect, arch action and effective concrete tensile area. Then an equation is developed for predicting crack width and deflection in flexural members. The predicted results shows that as proposed model employed, crack width and deflections are different from estimated by the current KCI, MC 90 and EC 2 provisons, and the values predicted are in good agreement with experimentally measured values.

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Analysis for Nonlinear Behavior of Concrete Panel Considering Steel Bar Buckling (철근 좌굴을 고려한 콘크리트 패널의 비선형 거동에 대한 해석)

  • Lee, Sang-Sup;Park, Keum-Sung;Bae, Kyu-Woong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.6
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    • pp.130-137
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    • 2018
  • Many constitutive models for concrete have been developed to predict the nonlinear behavior of concrete members considerably. The constitutive model for reinforcing bar that include the tension stiffening effect due to the bond characteristics between steel bars and concrete is being studied but the bilinear model is generally used. It was found that the buckling of the longitudinal reinforcing bars is controlled the nonlinear behavior of hybrid precast concrete panel, which is being developed for core wall. In this study, the constitutive models that can consider the embedding and buckling effects of reinforcing bar are investigated and a new model combing these constitutive models is proposed. In order to verify the proposed model, the analysis results are compared with experimental results of the concrete wall and hybrid precast concrete panel. The analysis of embedding-effect-only modeling predicted that the deformation increases continually without the decrease in the load carrying capacity. However, the analysis results of proposed model showed good agreement with some experimental results, thus verifying the proposed computational model.

Evaluation of Ductility Capacity of Reinforced Concrete Bridge Columns Subject to Cyclic Loading Using Flexibility-Based Fiber Element Method (유연도법 섬유요소모델에 의한 반복하중을 받는 철근콘크리트 교각의 연성능력 평가)

  • 고현무;조근희;조호현
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.3
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    • pp.11-21
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    • 2002
  • The evaluation of displacement ductility is performed by direct method through tracking the inelastic hysteretic behavior of RC bridge columns subject to cyclic loading using a flexibility-based fiber element mode. To reasonably track the inelastic behavior until the RC bridge column reaches its ultimate state, the average stress-average strain relations and joint elements, which agree well with experiments, are modified and applied considering the tension stiffening behavior and discontinuous displacement between the column and its base. In addition the evaluation of displacement ductility is performed by a direct method easily applicable to numerical analysis. Locations for the integration points, values for the post-crushing concrete strength and low-cycle fatigue failure of longitudinal reinforcement that affect the calculation of yielding and ultimate displacements are proposed for the application to flexibility-based fiber element model. Since less than 10% of error occurs during the displacement ductility analysis, the yielding and ultimate displacements evaluated by the applied analysis method and model appear to be valid.

A New Refined Truss Modeling for Shear-Critical RC Members (Part I) - lts derivation of Basic Concept - (전단이 지배하는 RC부재의 새로운 트러스 모델링 기법 연구 (전편) - 기본 개념 유도를 중심으로 -)

  • Kim Woo;Jeong Jae-Pyong;Kim Dae-Joong
    • Journal of the Korea Concrete Institute
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    • v.16 no.6 s.84
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    • pp.785-794
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    • 2004
  • This paper describes a new refined truss modeling technique derived based on the well-known relationship of V=dM/dx=zdT/dx+Tdz/dx in a reinforced concrete beam subjected to combined shear and moment loads. The core of the model is that a new perspective on the shear behavior can be gained by considering the variation of the internal arm length along the span, so that the shear resistance mechanism can be expressed by the sum of two base components; arch action and beam action. The sharing ratio of these two actions is determined by accounting for the compatibility of deformation associated to the two actions. Modified Compression Field Theory and the tension-stiffening effect formula in CEB/FIP MC-90 are employed in calculating the deformations. Then the base equation of V=dM/dx has been numerically duplicated to form a new refined truss model.

Realistic Deformation Analysis of Reinforced Concrete Walls (철근(鐵筋)콘크리트 벽부재(壁部材)의 실제적(實際的)인 변형해석(變形解析))

  • Oh, Byung Hwan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.3 no.4
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    • pp.1-10
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    • 1983
  • The deformation and crack width of concrete walls of slabs, plates, panels and shells reinforced by a regular rectangular net of reinforcing bars and subjected to in-plane (membrane) internal forces is analyzed on the basis of a realistic model which takes into account the frictional-dilatant behavior of rough interlocked cracks, the effect of tension stiffening, and the dowel action of bars at crack crossings. Extensive numerical computer studies are carried out, and the reinforcement designs obtained from equilibrium conditions alone on the basis of either the classical frictionless approach or the recent frictional approach are compared in terms of the resulting crack widths. It is found that the use of frictional equilibrium design based on a low friction coefficient leads to a much smaller crack width than the classical frictionless design. The influences of bar diameter and crack spacing on the crack width are also studied. The model allows more realistic deformation analysis of reinforced concrete structures.

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