• 한국농공학회논문집
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• 제47권4호
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• pp.15-24
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• 2005

This study is focused on modeling to predict the behavior of two-way RC slabs. A new finite element model will be presented to analyze the nonlinear behavior of RC slabs. The numerical approach is based on the p-version degenerate shell element including theory of anisotropic laminated composites, theory of materially and geometrically nonlinear plates. In the nonlinear formulation of this model, the total Lagrangian formulation is adopted with large deflections and moderate rotations being accounted for in the sense of von Karman hypothesis. The material model is based on the Kuper's yield criterion, hardening rule, and crushing condition. The validity of the proposed p-version nonlinear RC finite element model is demonstrated through the load-deflection curves and the ultimate loads. It is shown that the proposed model is able to adequately predict the deflection and ultimate load of two-way slabs with respect to steel arrangements and steel ratios.

• 한국농공학회논문집
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• 제47권5호
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• pp.17-26
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• 2005

The objectives of this study are to determine the behavior of simply supported skew RC slabs subjected to a point load. The p-version nonlinear skew RC FE model has been used. Integrals of Legendre polynomials are used for shape functions with p-level varying from 1 to 10. In the nonlinear formulation of this model, the material model is based on the Kupfer's yield criterion, hardening rule, and crushing condition and layered model is used through the thickness. The cracking behavior is modeled by a smeared crack model and the fixed crack approach is adopted as the crack model. It is shown that the proposed model is able to adequately predict the deflection and ultimate load of nonlinear skew RC slabs with respect to steel arrangements and steel ratios.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.365-372
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• 2004

A new finite element model will be presented to analyze the nonlinear behavior of not only RC beams and slabs, but also RC beams strengthened by a patch repair. The numerical approach is based on the p-version degenerate shell element including theory of anisotropic laminated composites, theory of materially and geometrically nonlinear plates. In the nonlinear formulation of this model, the total Lagrangian formulation is adopted with large deflections and moderate rotations being accounted for in the sense of von Karman hypothesis. The material model is based on hardening rule, crushing condition, plate-end debonding strength model and so on. The Gauss-Lobatto numerical quadrature is applied to calculate the stresses at the nodal points instead of Gauss points. The validity of the proposed p-version finite element model is demonstrated through several numerical examples for the load-deflection curves, the ultimate loads, and the failure modes of reinforced connote slabs and RC beams bonded with steel plates or FRP plates compared with available experimental and numerical results.

• 한국농공학회논문집
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• 제48권1호
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• pp.61-68
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• 2006

The p-version nonlinear finite element model has been developed to analyze the nonlinear behavior of simply supported RC slabs strengthened with carbon fiber reinforced plastic sheets. The shape function is adopted with integral of Legendre polynomials. The compression model of concrete is based on the Kupfer's yield criterion, hardening rule, and crushing condition. The cracking behavior is modeled by a smeared crack model. In this study, the fixed crack approach is adopted as being geometrically fixed in direction once generated. Each steel layer has a uniaxial behavior resisting only the axial force in the bar direction. Identical behavior is assumed fur tension and compression of steel according to the elastic modulus. The carbon fiber reinforced plastic sheets are considered as reinforced layers of equivalent thickness with uniaxial strength and rigidity properties in the present model. It is shown that the proposed model is able to adequately predicte the displacement and ultimate load of nonlinear simply supported RC slabs by a patch with respect to reinforcement ratio, thickness and angles of CFRP sheets.

• 한국전산구조공학회논문집
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• 제17권4호
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• pp.375-387
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• 2004

팻취 보강된 철근콘크리트 구조물 해석을 위한 p-version 비선형 유한요소 모델이 제시되었다. 이방성 적층평판이론에 기초를 둔 제안된 모델은 Total Lagrangian기법에 기초한 von Karman의 대변형-소변형률 이론과 증분소성이론(incremental theory of plasticity)을 적용하였다. 콘크리트의 경화법칙(hardening rule)과 그에 따른 파괴기준을 고려하고, 단부 계면 층분리 모델(plate-end interfacial debonding model) 즉, 보강판 끝 부분에서의 콘크리트 탈락에 대한 기준으로서 Oehlers Model과 Raoof and Zhang Model을 사용하였다. 콘크리트는 두께 방향으로 층상화기법(layered model)이 이용되며, 철근과 보강판은 환산층(smeared reinforcing layer)으로 계산되도록 하였다 적분형 르장드르 다항식이 형상함수로 사용되며, 절점에서의 응력값 산출을 위해 Gauss Lobatto 수치적분법을 사용하였다. 본 연구의 목적은 p-version 유한요소법을 사용하여 RC구조물에 대한 수피해의 정확도 및 모델의 단순성을 높인 수 있도록 하였다. 따라서, 철근과 콘크리트모델에 대한 이론적 근거는 기존의 연구문헌에 근거를 두었으며, 수치해석의 적정성은 팻취 보강된 RC보와 슬래브에 대한 문헌의 실험치 및 해석치와 비교 분석되었다.