• 한국강구조학회 논문집
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• 제13권5호
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• pp.443-455
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• 2001

전단 층을 갖는 2개 매개변수 탄성지반 위에 놓인 복합재료 적층판에서 휨 진동 및 좌굴해석을 위해 에너지 방법을 사용해 탄성해를 구하였다. 복합재료 적층판의 점탄성 해석은 유사-탄성방법을 사용해 탄성해를 구하였다. 전단에 의한 효과는 3창 전단변형이론을 적용하여 고려하였다. 유도된 식들을 검증하기 위해 LUSAS 프로그램에 의한 탄성지반위에 놓인 이방성 판의 처짐과 비교하였다. 점탄성 휨 진동 및 좌굴해석에 관한 수치해석결과들은 적층순서, 적층 수 재료 비등방성과 전단지반계수 등에 따른 효과를 보여 준다.

• Advances in nano research
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• 제10권3호
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• pp.281-293
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• 2021

This paper presents a new nonlocal Hyperbolic Shear Deformation Beam Theory (HSDBT) for the free vibration of porous Functionally Graded (FG) nanobeams. A new displacement field containing integrals is proposed which involves only three variables. The present model incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect and its account for shear deformation by a hyperbolic variation of all displacements through the thickness without using the shear correction factor. It has been observed that during the manufacture of Functionally Graded Materials (FGMs), micro-voids and porosities can occur inside the material. Thus, in this work, the investigation of the free vibration analysis of FG beams taking into account the influence of these imperfections is established. Four different porosity types are considered for FG nanobeam. Material characteristics of the FG beam are supposed to vary continuously within thickness direction according to a power-law scheme which is modified to approximate material characteristics for considering the influence of porosities. Based on the nonlocal differential constitutive relations of Eringen, the equations of motion of the nanobeam are derived using Hamilton's principle. The effects of nonlocal parameter, aspect ratio, and the porosity types on the dynamic responses of the nanobeam are discussed.

• Geomechanics and Engineering
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• 제24권5호
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• pp.419-430
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• 2021

Investigation on the compressibility and shear strength of compacted loess is of great importance for the design and operation of engineering infrastructures in filling area. In this study, the mechanical behaviors of Yan'an compacted loess are investigated at various dry densities and water contents by conducting one dimensional compression and direct shear tests. And the elastic compressibility, plastic compressibility, yield stress and strength are obtained from the experiments. Results show that when water content increases, plastic compressibility parameter increases, but yield stress decreases. However, the increase of dry density leads to a decrease in plastic compressibility parameter but an increase in yield stress. In addition, elastic compressibility parameter is found to be a constant which is irrelevant to water content and dry density. As for strength, cohesion and internal friction angle is directly proportional to dry density, but inversely proportional to water content. Moreover, the mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM) tests were also performed to observe the pore size distribution and microstructure of the specimens. Finally, by using results of MIP and SEM tests, the compressibility and strength behaviours of Yan'an compacted loess are explained from the perspective of pore-size distribution and microstructure.

• 터널과지하공간
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• 제21권6호
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• pp.494-507
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• 2011

암석의 절리면 거칠기 평가에 있어서 최적의 거칠기 파라미터를 선택하는 것은 중요한 문제이다. 선행연구에서 절리면 거칠기의 평가는 여러 가지 통계적 방법에 의해 2차원적으로 이루어져왔다. 본 연구에서는 Barton과 Choubey(1977)가 제안한 표준 프로파일(JRC)을 3차원 표면으로 확장하고, 표면평균기울기를 적용하여 절리면 거칠기를 정량화 하였다. 그리고 $Z_2$, Ai파라미터와 비교하여 표면평균기울기를 이용한 거칠기 정량화의 타당성을 검증하였으며, 복제시료를 이용한 절리면 전단시험을 통하여 전단강도와 표면평균기울기의 관계를 분석하였다.

• 한국전산구조공학회논문집
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• 제14권3호
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• pp.401-411
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• 2001

본 논문은 등분포 면내응력을 받고 비균질 Pasternak지반에 의해 지지된 장방형판의 진동해석을 다룬 것이다. Winkler 지반계수와 전단지반계수가 고려된 2 변수지반을 Pasternak 지반이라 불리운다. 판의 중앙부분과 가장자리부분의 Winkler 지반계수값을 각각 k₁과 k₂로 선택하였고 전단지반계수값은 판의 전지역에 대해 일정한 값을 취하였다. 전체 휨강성행렬, 기하강성행렬, 질량 행렬 및 Pasternak 지반의 강성행렬을 조합하고 이 행렬들로 이루어지는 고유값 문제를 푼다. 그 결과 지반강성을 고려할 때 전단지반계수가 무시되면 안된다는 것으로 나타났다.

• Steel and Composite Structures
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• 제42권4호
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• pp.477-487
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• 2022

The shear stiffness of headed-stud shear connectors has no unified definition due to the nonlinear characteristics of its load-slip relationship. A unified framework was firstly adopted to develop a general expression of shear load-slip equation for headed-stud shear connectors varying in a large parameter range based on both force and energy balance. The pre- and post-yield shear stiffness were then determined through bilinear idealization of proposed shear load-slip equation. An updated and carefully selected push-out test database of 157 stud shear connectors, conducting on studs 13~30mm in diameter and on concretes 30~180 MPa in cubic compressive strength, was used for model regression and sensitivity analysis of shear stiffness. An empirical calculation model was also established for the stud shear stiffness. Compared with the previous models through statistical analysis, the proposed model demonstrates a better performance to predict the shear load-slip response and stiffness of the stud shear connectors.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.711-714
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• 2005

This paper is for the vibration analysis of thick plate with concentrated mass on a inhomogeneous pasternak foundation. the thick rectangular plate resting on a inhomogeneous pasternak foundation is isotropic, homogeneous and composite with linearly elastic material. In order to analyize plat which is supported on inhomogeneous pasternak foundation, the value of winkler foundation parameter(WFP) of centural and border zone of plate are chosen as Kw1 and Kw2 respectively. The value of Kw1 and Kw2 can be changed as 0, 10, $10^2,\;10^3$ and the value of SFP(shear foundation parameter) also be changed 0, 5, 10, 15 respectively. Finally, In this paper, vibration of retangular plate on the inhomogeneous pasternak foundation, natural frequency of this plate with Concentrated Mass are calculated

• Steel and Composite Structures
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• 제20권5호
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• pp.1087-1102
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• 2016

The paper proposes to characterize the free vibration behaviour of non-uniform cylindrical shells using spline approximation under first order shear deformation theory. The system of coupled differential equations in terms of displacement and rotational functions are obtained. These functions are approximated by cubic splines. A generalized eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector which are spline coefficients. Four and two layered cylindrical shells consisting of two different lamination materials and plies comprising of same as well as different materials under two different boundary conditions are analyzed. The effect of length parameter, circumferential node number, material properties, ply orientation, number of lay ups, and coefficients of thickness variations on the frequency parameter is investigated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.805-809
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• 2004

This paper is for the vibration analysis of thick plate with concentrated mass on a inhomogeneous pasternak foundation. The vibration of rectangular plate on the inhomogeneous pasternak foundation, natural frequency of this plate with Concentrated Mass are calculated A thick rectangular plate resting on a inhomogeneous pasternak foundation is isotropic, homogeneous and composite with linearly elastic material. In order to analysis plate which is supported on inhomogeneous pasternak foundation, the value of winkler foundation parameter(WFP) of centural and border zone of plate are chosen as WFP1 and WFP2 respectively. The value of WFP1 and WFP2 can be changed as 10, 10$^3$ and the value of SFP(shear foundation parameter) also be changed 5, 15 respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.852-857
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• 2003

This paper has the object of investigating natural frequencies of thick plates on inhomogeneous Pasternak foundation by means of finite element method and providing kinematic design data lot mat of building structures. This analysis was applied for design of substructure on elastic foundation. Mat of building structure may be consisdered as a thick plate on elastic foundation. Recently, as size of building structure becomes larger, mat area of building structure also tend to become target and building structure is supported on inhomogeneous foundation. In this paper, vibration analysis or rectangular thick plate is done by use or serendipity finite element with 8 nodes by considering shearing strain of plate. The solutions of this paper are compared with existing solutions and finite element solutions with 4${\times}$4 meshes of this analysis are shown the error of maximum 0.083% about the existing solutions. It is shown that natrural frequencies depend on not only Winkler foundation parameter but also shear foundation parameter.