• Steel and Composite Structures
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• 제25권6호
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• pp.671-684
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• 2017

Elastic-plastic shear buckling behaviors of the web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear force were investigated further using Finite Element Model (FEM) based on a sub-model, which took the upper part of the web-post under horizontal shear force to represent the whole web-post under vertical shear force. A simplified design method for the web-post elastic-plastic shear buckling strength was proposed based on simulation results of the sub-model. Proper boundary conditions were applied to the sub-model to assure that its behaviors were identical to those of the whole web-post. The equation to calculate the thin plate elastic shear buckling strength was adopted as the basic form to build the design equation for elastic-plastic buckling strength of the sub-model. Parameters that might affect the elastic-plastic shear buckling strength of the whole web-post were studied. After obtaining the vertical shear buckling strength of a sub-model through FEM, the shear buckling coefficient k can be obtained through the back analysis. A practical calculation method for k was proposed through curving fitting the parameter study results. The elastic-plastic shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the FEM and test results. And it was more precise than those obtained from EC3 based on the strut model.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.111-118
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• 2006

The elastic buckling strength of a corrugated culvert made of orthotropic material such as FRP was evaluated. The height and length of a corrugated wave and the thickness of the culvert were considered as factors affecting the buckling strength of the culvert. And also, the ratio of the longitudinal stiffness and transverse stiffness was considered as the parameter affecting on the buckling strength of the used orthotropic material. Buckling strengths of various corrugated culvert models with different shapes and stiffness ratio were evaluated by FE analyses and a formula to estimate the elastic buckling strength was suggested from the regression with FE analysis results. Analysis results show that a corrugated culvert has superior buckling strength to a general flat pipe and the suggested formula estimates accurate buckling strength of the corrugated culverts made of orthotropic material.

• 한국강구조학회 논문집
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• 제17권2호통권75호
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• pp.161-171
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• 2005

대칭 하중을 받는 아치 리브의 경우 면내 강성이 가해지는 하중에 비하여 작은 경우 예기치 않게 면내 방향으로 좌굴이 발생하게 된다. 아치 리브의 종국 면내 좌굴 강도는 재료의 비탄성이 고려되어야 한다. 하지만 탄성 면내 좌굴 강도는 세장비가 큰 경우에는 재료의 탄성 범위에서 좌굴이 발생하기도 하며, 세장비가 작은 경우에도 아치의 지간이나 라이즈, 단면의 개략적인 형태를 결정하는 초기 설계에 유용하게 사용된다. 본 논문에서는 아치 교량의 설계에 자주 이용되는 대칭 하중을 받는 포물선 아치 리브의 형상에 관하여 비선형 유한 요소 해석을 사용하여 탄성 면내 좌굴 강도에 대하여 연구를 수행 하였다. 연구 결과 기존의 탄성 좌굴 이론에서는 휨강성과 탄성 좌굴 강도는 비례하지만, 비선형 해석 결과 아치 단면의 세장비가 작을 경우 휨강성과 아치의 탄성 좌굴 강도가 비선형적인 관계를 보이는 것을 밝혔다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.119-126
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• 2006

The elastic budding strength of a GFRP pipe reinforced with ribs was evaluated. The height and thickness of a rib and the spacing between two adjacent ribs were considered as factors affecting tlje budding strength of the pipe. And also, the ratio of the longitudinal stiffness and transverse stiffness was considered as the parameter affecting on the budding strength because GFRP is orthotropic material. Buckling strengths of various GFRP pipe models with different shapes and stiffness ratio were evaluated by FE analyses and a formula to estimate the elastic buckling strength of a rib-reinforced pipe made of orthotropic material was suggested from the regression with FE analysis results. Analysis results show that a rib-reinforced pipe has superior buckling strength to a general flat pipe and the suggested formula estimates accurate buckling strength of the rib-reinforced pipe.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2003년도 춘계학술발표회
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• pp.167-172
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• 2003

Place that have cutout inner bottom and girder and floor etc. in hull construction absence is used much, and this is strength in case must be situated, but establish in region that high stress interacts sometimes fatally in region that there is no big problem usually by purpose of weight reduction, a person and change of freight piping etc.. Because cutout's existence gnaws in this place, and, elastic buckling strength by load causes large effect in ultimate strength. Therefore, perforated plate elastic buckling strength and ultimate strength is one of important design criteria which must examine when decide structural elements size at early structure design step of ship. Therefore, and, reasonable elastic buckling strength about perforated plate need design ultimate strength. Calculated ultimate strength change several aspect ratioes and cutout's dimension. and thickness in this investigation. Used program applied ANSYS F.E.M code transformation finite element law that is mediocrity finite element analysis code.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.237-244
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• 2004

Plate that have cutout inner bottom and girder and floor etc. in hull construction absence is used much, and this is strength in case must be situated, but establish in region that high stress interacts sometimes fatally in region that there is no big problem usually by purpose of weight reduction, a person and change of freight, piping etc.. Because cutout's existence gnaws in this place, and, elastic buckling strength by load causes large effect in ultimate strength. Therefore, perforated plate elastic buckling strength and ultimate strength is one of important design criteria which must examine when decide structural elements size at early structure design step of ship. Therefore, and, reasonable elastic buckling strength about perforated plate need design ultimate strength. Calculated ultimate strength change several aspect ratioes and cutout's dimension, and thickness in this investigation. Used program applied ANSYS F.E.M code based on finite element method.

• 한국강구조학회 논문집
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• 제18권6호
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• pp.737-746
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• 2006

본 연구에서는 리브로 보강된 GFRP(Glass Fiber Reinforced Plastic) 관로의 탄성 좌굴 강도를 산정하였다. 보강된 리브의 두께, 높이, 배치 간격은 관로의 좌굴 강도에 영향을 미치는 주요 인자이다. 또한, GFRP 재료는 이방성 재료이므로, 재료의 방향별 강성 또한 관로의 좌굴강도에 영형을 미치는 인자로서 고려되어야할 부분이다. 이러한 매개변수를 적용하여, 직교 이방성 재료로 구성된 리브 보강 관로의 좌굴 강도를 유한요소 해석을 이용하여 매개변수를 수행하고, 회귀분석을 통하여 좌굴 강도 산정을 위한 간략식을 제시하였다.

• Steel and Composite Structures
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• 제43권3호
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• pp.341-351
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• 2022

This paper presents an inelastic buckling behavior analysis of rectangular hollow steel tubes with geometrical imperfections under elevated temperatures. The main variables are the temperature loads, slenderness ratios, and exposure conditions at high temperatures. The material and structural properties of steels at different temperatures are based on Eurocode (EN 1993-1-2, 2005). In the elastic buckling analysis, the buckling strength decreases linearly with the exposure conditions, whereas the inelastic buckling analysis shows that the buckling strength decreases in clusters based on the exposure conditions of strong and weak axes. The buckling shape of the rectangular steel column in the elastic buckling mode, which depicts geometrical imperfection, shows a shift in the position at which bending buckling occurs when the lower section of the member is exposed to high temperatures. Furthermore, lateral torsional buckling occurs owing to cross-section deformation when the strong axial plane of the model is exposed to high temperatures. The elastic buckling analysis indicates a conservative value when the model is exposed to a relatively low temperature, whereas the inelastic buckling analysis indicates a conservative value at a certain temperature or higher. The comparative results between the inelastic buckling analysis and Eurocode 3 show that a range exists in which the buckling strength in the design equation result is overestimated at elevated temperatures, and the shapes of the buckling curves are different.

• Geomechanics and Engineering
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• 제31권3호
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• pp.329-337
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• 2022

In this paper, the thermal post-buckling characteristics of functionally graded (FG) pipes with initial geometric imperfection are studied. Considering the influence of initial geometric defects, temperature and geometric nonlinearity, Euler-Lagrange principle is used to derive the nonlinear governing equations of the FG pipes. Considering three different boundary conditions, the two-step perturbation method is used to solve the nonlinear governing equations, and the expressions of thermal post-buckling responses are also obtained. Finally, the correctness of this paper is verified by numerical analyses, and the effects of initial geometric defects, functional graded index, elastic foundation, porosity, thickness of pipe and boundary conditions on thermal post-buckling response are analyzed. It is found that, bifurcation buckling exists for the pipes without initial geometric imperfection. In contrast, there is no bifurcation buckling phenomenon for the pipes with initial geometric imperfection. Meanwhile, the elastic stiffness can significantly improve thermal post-buckling load and thermal post-buckling strength. The larger the porosity, the greater the thermal buckling load and the thermal buckling strength.

• 한국산학기술학회논문지
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• 제17권8호
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• pp.456-464
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• 2016

건설 재료가 나날이 발전함에 따라 재료 강도는 과거에 비하여 획기적으로 증대 되었으며, 이는 구조물의 자중을 경감 시켜 경제적인 설계를 가능하게 할 뿐 아니라, 심미적 요건까지 만족 시키고 있다. 특히 고강도 강재의 경우, 항복강도는 약 480MPa로, 일반 구조용 강재 보다 약 50% 더 크다. 그러나 고강도 재료의 사용은 단면을 세장하게 하여 국부 좌굴 안정성에 영향을 미칠 수 있다. 세장 단면은 탄성 좌굴을 일으킬 수 있으며, 탄성 좌굴 강도는 경계조건에 대하여 매우 민감하다. I형 거더의 경우 복부판은 압축 플랜지의 경계조건을 결정하므로, 복부판의 강성은 얇은 압축 플랜지의 탄성 좌굴 강도에 영향을 미칠 수 있다. 따라서 본 연구에서는 유한요소해석을 통해 플랜지 및 복부판의 세장비가 휨 모멘트를 받는 이축대칭 I형 거더의 플랜지 탄성좌굴에 미치는 영향을 분석 하였다. 유한요소해석결과, 탄성좌굴강도와 좌굴모드는 복부판의 지지조건의 영향 뿐 아니라 플랜지와 복부판의 세장비의 비율에 따라 큰 영향을 받는 것으로 판단된다.