• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.133-144
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• 2003

Generally, diaphragms are installed in the box girder to prevent or decrease the distortion of tile cross section. In engineering practice, diaphragms are spaced in 5m intervals without reasonable basis. ANd the usual diaphragm type is solid-plate type. It is considered to be noneconomical design to the almost design engineers. In this paper, the parametric study was performed to present the design proposal about the diaphragm stiffness and spacing only in tire single cell box girder. For that, the distortional warping normal stress, bending normal stress and transverse bending normal stress were analyzed using finite element program 'SMB' for the accurate structural analysis.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.130-140
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• 2018

U형 강재보를 근간으로 콘크리트 슬래브와 합성을 위하여 A형의 덮개형 강재앵커를 검토하여 AU합성보를 연구하였다. 이는 노출형의 H형강 강재보에 비해 내부 평면의 자율성을 높일 수 있고 공기 단축과 더불어 층고 절감이 가능하며 튜브구조로서 내부에 콘크리틀 충전하여 휨 강도과 휨 강성를 높였다. 본 연구에서는 AU합성보의 휨실험을 통해 성능을 평가하였다. 실험 결과, 하중 초기에 선형적으로 하중이 증가하면서 콘크리트 슬래브의 파괴에 의해 최대 강도에 도달하고 최대 내력의 85% 이상을 발휘하며 연성적 거동을 하였다. 또한, 덮개형 강재앵커를 통해 합성효과를 발휘하였으며 모든 실험체가 최대 내력에 도달할 때까지 완전 합성거동으로 안정적이었다. 그리고 U형 단면의 강판 두께를 증가시켰을 경우에도 휨 강도와 휨 강성이 증가하였고, U형 단면의 하부에 고강도 강판을 용접 부착하였을 경우에도 성능이 개선되었다. AU합성보의 휨강도는 건축구조기준에 따라 제안된 휨 강도식을 적용할 수 있을 것으로 판단되었다.

• 한국안전학회지
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• 제19권4호
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• pp.155-160
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• 2004

판의 두께에 선형적으로 변화하는 온도분포의 열하중을 받는 단순지지의 사각형 박판을 해석하였다. 열에 의한 판의 처짐이 판두께에 비해 상대적으로 과대하여 막응력이 부수적으로 발생하여 문제는 비선형 해석이 된다. 큰 처짐을 가지는 기하학적 비선형 문제를 지배하는 기본방정식은 von Karman 방정식이 사용되며 차분법으로 수치해석 한다. 차분화 하여 얻어지는 유사선형 대수방정식은 반복법을 도입하여 해석하고 결과치를 해석적으로 얻은 해와 비교 검토한다.

• 한국산학기술학회논문지
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• 제13권7호
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• pp.3207-3215
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• 2012

본 논문에서는 3차 전단변형이론이 고려된 비국소 탄성 이론을 이용한 나노 판의 휨 및 진동에 대하여 연구하였다. 비국소 탄성 이론은 미소 규모 효과를 고려할 수 있고 3차원 전단변형이론은 나노 판의 두께방향으로의 전단 변형률과 전단응력의 곡선변화 효과를 고려할 수 있다. 이러한 두 가지 이론을 이용하여 나노 판의 처짐과 고유진동수에 미치는 비국소 이론의 효과를 제시하였다. 국소 탄성이론과의 관계를 수치해석 결과를 통하여 고찰하였다. 또한 (i) 비국소 계수, (ii) 나노 판의 적층형태, (iii) 나노 판의 보강 방향 그리고 (iv) 나노 판의 적층 수 등이 나노 판의 무차원 처짐에 미치는 효과에 대하여 관찰하였다. 본 연구의 결과를 검증하기 위해 참고문헌의 결과들과 비교 분석하였으며 해석결과는 참고문헌의 결과들과 잘 일치함을 알 수 있었다. 비국소 이론에 의한 나노 판의 처짐에 관한 연구는 향후 관련연구에 비교자료로 활용될 수 있을 것이다.

• 대한기계학회논문집
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• 제11권5호
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• pp.800-809
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• 1987

본 연구에서는 원통에 대하여는 Donnel 식과 Flugge식을 사용하여 원통의 유 한길이에 대한 일반적인 해를 구하였고, 평판에 대하여는 막이론과 굽힘이론을 사용하 여 일반해를 구한 후 중첩하였다. 평판과 원통에 발생하는 미정력계를 구하기 위하 여 가장 합리적이라고 생각되는 접합부에 모든 미정력계가 집중하여 작용한다고 가정 하고, 이 부분에서 평판과 원통의 각각에 대한 하중, 모우멘트, 기울기, 변위 등이 연 속하도록 접한조건식을 세웠다.그리고 이론해석의 타당성을 알아보기 위하여 S 45C 강재로 플러시타잎의 모델을 제작하여 실험을 행하였다.

• Journal of Welding and Joining
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• 제12권3호
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• pp.90-100
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• 1994

In this study the fatigue crack growth behavior was investigated for the surface cracks in aluminum alloy A5083-O plate and its weldment. Several kinds of specimens were tested at room temperature. The Eccentric specimens(E1.0, E2.5) subjected to combined stresses(tension+bending) were tested and the welded specimens with weld toes(TOE1, TOE2) were tested in order to verify the method to consider the stress concentration such as weld toe. It was ascertained that the surface crack growth property in the weld toe could be predicted by the corrected Pang's equation proposed in this study.

• Steel and Composite Structures
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• 제27권3호
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• pp.311-325
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• 2018

This article presents the bending analysis of FGM rectangular plates resting on non-uniform elastic foundations in thermal environment. Theoretical formulations are based on a recently developed refined shear deformation theory. The displacement field of the present theory is chosen based on nonlinear variations in the in-plane displacements through the thickness of the plate. The present theory satisfies the free transverse shear stress conditions on the top and bottom surfaces of the plate without using shear correction factor. Unlike the conventional trigonometric shear deformation theory, the present refined shear deformation theory contains only four unknowns as against five in case of other shear deformation theories. The material properties of the functionally graded plates are assumed to vary continuously through the thickness, according to a simple power law distribution of the volume fraction of the constituents. The elastic foundation is modeled as non-uniform foundation. The results of the shear deformation theories are compared together. Numerical examples cover the effects of the gradient index, plate aspect ratio, side-to-thickness ratio and elastic foundation parameters on the thermo-mechanical behavior of functionally graded plates. Numerical results show that the present theory can archive accuracy comparable to the existing higher order shear deformation theories that contain more number of unknowns.

• Structural Engineering and Mechanics
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• 제69권4호
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• pp.383-397
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• 2019

More than one longitudinal web stiffener may be economical in the design of plate girders that have considerably high width-to-thickness ratio of webs. In this study, the bend-buckling strength of relatively deep webs with two horizontal lines of flat plate-shaped single-sided stiffeners was numerically investigated. Linear eigenvalue buckling analyses were conducted for specially selected hypothetical models of stiffened web panels, in which top and bottom junctions of a web with flanges were assumed to have simply supported boundary conditions. Major parameters in the analyses were the locations of two longitudinal stiffeners, stress ratios in the web, slenderness ratios and aspect ratios of web panels. Based on the application of assumptions on the combined locations of the two longitudinal web stiffeners, simplified equations were proposed for the bend-buckling coefficients and compared to the case of one longitudinal stiffener. It was found that bend-buckling coefficients can be doubled by adopting two longitudinal stiffeners instead of one longitudinal stiffener. For practical design purposes, additional equations were proposed for the required bending rigidity of the longitudinal stiffeners arranged in two horizontal lines on a web.

• Steel and Composite Structures
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• 제33권2호
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• pp.307-318
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• 2019

This is the first attempt to consider the nonlinear bending analysis of porous functionally graded (FG) thick annular and circular nanoplates resting on Kerr foundation. The size effects are captured based on modified couple stress theory (MCST). The material properties of the porous FG nanostructure are assumed to vary smoothly through the thickness according to a power law distribution of the volume fraction of the constituent materials. The elastic medium is modeled by Kerr elastic foundation which consists of two spring layers and one shear layer. The governing equations are extracted based on Hamilton's principle and two variables refined plate theory. Utilizing generalized differential quadrature method (GDQM), the nonlinear static behavior of the nanostructure is obtained under different boundary conditions. The effects of various parameters such as material length scale parameter, boundary conditions, and geometrical parameters of the nanoplate, elastic medium constants, porosity and FG index are shown on the nonlinear deflection of the annular and circular nanoplates. The results indicate that with increasing the material length scale parameter, the nonlinear deflection is decreased. In addition, the dimensionless nonlinear deflection of the porous annular nanoplate is diminished with the increase of porosity parameter. It is hoped that the present work may provide a benchmark in the study of nonlinear static behavior of porous nanoplates.

• Structural Engineering and Mechanics
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• 제72권1호
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• pp.61-70
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• 2019

The functionally graded materials (FGM) used in plates contain probably a porosity volume fraction which needs taking into account this aspect of imperfection in the mechanical bahavior of such structures. The present work aims to study the effect of the distribution forms of porosity on the bending of simply supported FG plate reposed on the Winkler-Pasternak foundation. A refined theory of shear deformation is developed to study the effect of the distribution shape of porosity on static behavior of FG plates. It was found that the distribution form of porosity significantly influence the mechanical behavior of FG plates, in terms of deflection, normal and shear stress. It can be concluded that the proposed theory is simple and precise for the resolution of the behavior of flexural FGM plates resting on elastic foundations while taking into account the shape of distribution of the porosity.