• Structural Engineering and Mechanics
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• 제15권2호
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• pp.249-267
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• 2003

In this study, circular plates subjected to general type of loads and supported on a two-parameter elastic foundation are analysed. The stiffness, elastic bedding and soil shear effect matrices of a fully compatible ring sector plate element, developed by Saygun (1974), are obtained numerically assuming variable thickness of the element. Ring sector soil finite element is also defined to determine the deflection of the soil surface outside the domain of the plate in order to establish the interaction between the plate and the soil. According to Vallabhan and Das (1991) the elastic bedding (C) and shear parameters ($C_T$) of the foundation are expressed depending on the elastic constants ($E_s$, $V_s$) and the thickness of compressible soil layer ($H_s$) and they are calculated with a suitable iterative procedure. Using ring sector elements presented in this paper, permits the generalization of the loading and the boundary conditions of the soil outside the plate.

• Geomechanics and Engineering
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• 제29권6호
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• pp.667-681
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• 2022

This paper presents a thermoelastic analysis of variable thickness plates made of functionally graded materials (FGM) subjected to mechanical and thermal loads. The thermal load is applied to the plate as a temperature difference between the top and bottom surfaces. Temperature distribution in the plate is obtained using the steady-state heat equation. Except for Poisson's ratio, all mechanical properties of the plate are assumed to vary linearly along the thickness direction based on the volume fractions of ceramic and metal. The plate is resting on an elastic foundation modeled based on the Winkler foundation model. The governing equations are derived based on the third-order shear deformation theory (TSDT) and are solved numerically for various boundary conditions using the differential quadrature method (DQM). The effects of various parameters on the stress distribution and deflection of the plate are investigated such as the value of thermal and mechanical loads, volume fractions of ceramic and metal, and the stiffness coefficients of the foundation.

• Coupled systems mechanics
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• 제12권5호
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• pp.461-479
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• 2023

The paper deals with the finite element modelling of the free vibration and structural behavior of a particular four-floor reinforced concrete structure subjected to static equivalent seismic loads and supported by a shallow foundation system called SNSF (Spider Net System Footing). The two FE models are a simple 2D Matlab model and a detailed 3D model based on solid elastic elements using Altairworks (Hypermesh and Optistruct). Both models can simulate the soil structure interaction. We concentrate on the behavior of a representative cell involving two columns on five levels. The influence of the boundary conditions on the external vertical planes of the domain are duly studied. The Matlab model appears relevant for a primary estimation of frequencies and stiffness of the whole structure under vertical and lateral loads.

• 한국농공학회지
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• 제24권3호
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• pp.73-83
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• 1982

study aims to derive a rational method for the analysis of the farm silo supported on an elastic foundation in which it is assumed that the reaction pressure of the soil at a point is proportional to the deflection at that point. In order to investigate the effects of an elastic foundation on the behaviour of the structures on it, the analysis of the farm silo resting on an elastic foundation was compared with the solution that the ground support may be assumed uniform (which was obtained from part I of this paper). To calculate the deformation of an elastic foundation, Boussinesq's solution which allows an interaction of the various parts of ground was adopted. In this case, the foundation was treated as a superparametric element additionally. In the evaluation of an element stiffness matrix, Gauss quadrature' was used. In above numerical integration, 3-point rule for the farm silo wall and the footing was introduced and 2-point rule for the evaluation of a reaction between the footing and the elastic foundation was adopted. The stresses of a farm silo on an elastic foundation were smaller than those which the distribution of contact pressure between the footing and the soil is assumed uniformly. Since the differences of stresses were remarkable in PS structures than RC structures, it is desirable that designers take into account the effect of an elastic foundation for the case of PS structures. It can be noted that while the effect of an elastic foundation was more conspicuously observed in near of the ground, the value of stresses at far from the soil was little affected by an supported soil.

• Geomechanics and Engineering
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• 제19권5호
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• pp.407-420
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• 2019

This paper illustrates the results of a series of seismic geotechnical centrifuge experiments to explore dynamic structure-soil-structure interaction (SSSI) of two structures (named S1 and S2) installed on ground surface. A dense homogeneous ground is prepared in an equivalent shear beam (ESB) container. Two structural models are designed to elicit soil-foundation-structure interaction (SFSI) with different masses, heights, and dynamic characteristics. Five experimental tests are carried out for: (1) two reference responses of the two structures and (2) the response of two structures closely located at three ranges of distance. It is found that differential settlements of both structures increase and the smaller structure (S2) inversely rotates out of the other (S1) when they interact with each other. S2 structure experiences less settlement and uplift when at a close distance to the S1 structure. Furthermore, the S1 structure, which is larger one, shows a larger rocking and a smaller sliding response due to the SSSI effects, while S2 structure tends to slide more than that in the reference test, which is illustrated by an increase in sliding response and rocking stiffness as well as a decrease in moment-to-shear ratio (M/H·L) of the S2 structure.

• 한국강구조학회 논문집
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• 제11권1호통권38호
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• pp.13-22
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• 1999

본 연구에서는 처짐각법을 개선하여 강박스형교의 뒤틀림 거동을 분석할 수 있는 프로그램을 개발하였다. 박스거더의 뒤틀림 거동을 분석하는 대표적인 방법으로 BEF유사법과 EBEF법이 있으나, 전자는 등단면에 국한되고 경계조건에 따른 적분상수를 계산하기 위해 복잡한 삼각함수를 적용해야 하는 번거로움이 있다. 후자는 격벽의 강성을 무한으로 하여 연속보로 해석하는 근시적인 수치해석 방법이다. 따라서 본 연구에서는 변단면과 격벽의 강성을 해석에 반영할 수 있는 방법을 개발하였다. 몇 가지 예제 해석을 통하여 본 연구에서 개발한 프로그램의 타당성을 검증하였고, 격벽의 강성에 따른 매개변수 연구를 수행하였다.

• Steel and Composite Structures
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• 제20권1호
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• pp.57-70
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• 2016

The predominant type of buckling that I-steel concrete composite beams experience in the negative moment area is distortional buckling. The key factors that affect distortional buckling are the torsional and lateral restraints by the bottom flange. This study thoroughly investigates the equivalent lateral and torsional restraint stiffnesses of the bottom flange of an I-steel concrete composite beam under negative moments. The results show a coupling effect between the applied forces and the lateral and torsional restraint stiffnesses of the bottom flange. A formula is proposed to calculate the critical buckling stress of the I-steel concrete composite beams under negative moments by considering the lateral and torsional restraint stiffnesses of the bottom flange. The proposed method is shown to better predict the critical bending moment of the I-steel composite beams. This article introduces an improved method to calculate the elastic foundation beams, which takes into account the lateral and torsional restraint stiffnesses of the bottom flange and considers the coupling effect between them. The results show a close match in results from the calculation method proposed in this paper and the ANSYS finite element method, which validates the proposed calculation method. The proposed calculation method provides a theoretical basis for further research on distortional buckling and the ultimate resistance of I-steel concrete composite beams under a variable axial force.

• 한국지진공학회논문집
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• 제2권1호
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• pp.23-34
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• 1998

연약한 지반위에 기초한 유연한 구형 액체 저장탱크의 Rocking 운동에 대한 3차원 지진응답을 규명하기 위해서 동적 유체-구조 물-지반 계의 상호작용 해석방법을 개발하였다. 수평방향 병진 운동과 Rocking 운동을 받는 3차원의 구형 탱크의 운동 지배방정식을 Rayleigh-Ritz 방법을 적용하여 유도하였고 기반암위 토층의 표면에 놓인 강체 기초의 동적 강성행렬과 유체-구조물 계의 지배방정식을 결합하여 계산하였다.

• Earthquakes and Structures
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• 제26권4호
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• pp.251-259
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• 2024

In this paper, the thermal post-buckling behavior of graphene platelets reinforced metal foams (GPLRMFs) plate with initial geometric imperfections on nonlinear elastic foundations are studied. First, the governing equation is derived based on the first-order shear deformation theory (FSDT) of plate. To obtain a single equation that only contains deflection, the Galerkin principle is employed to solve the governing equation. Subsequently, a comparative analysis was conducted with existing literature, thereby verifying the correctness and reliability of this paper. Finally, considering three GPLs distribution types (GPL-A, GPL-B, and GPL-C) of plates, the effects of initial geometric imperfections, foam distribution types, foam coefficients, GPLs weight fraction, temperature changes, and elastic foundation stiffness on the thermal post-buckling characteristics of the plates were investigated. The results show that the GPL-A distribution pattern exhibits the best buckling resistance. And with the foam coefficient (GPLs weight fraction, elastic foundation stiffness) increases, the deflection change of the plate under thermal load becomes smaller. On the contrary, when the initial geometric imperfection (temperature change) increases, the thermal buckling deflection increases. According to the current research situation, the results of this article can play an important role in the thermal stability analysis of GPLRMFs plates.

• 한국지반공학회논문집
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• 제39권3호
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• pp.29-40
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• 2023

본 연구에서는 파형 마이크로파일의 기초보강 효과를 분석하기 위해서, 매립토-풍화토-풍화암의 지층구조를 보이는 지반에 마이크로파일을 설치한 뒤 현장 재하시험을 수행했다. 단일 마이크로파일 재하시험 결과, 파형 마이크로파일은 토사층에서 발현되는 주면마찰력만으로도 충분한 지지력을 가져 암반층의 심도가 깊은 지반 조건에서 유리한 시공성을 가질 수 있음을 확인하였다. 또한 동일한 설계하중이 적용되었음에도, 단일 마이크로파일 재하시험 시 설계 하중 범위 내에서 평가된 파형 마이크로파일의 연직강성이 일반 마이크로파일의 연직강성에 비해 약 2.2배 큰 것으로 나타났다. 일반 및 파형 마이크로파일로 구성된 무리말뚝 재하시험 결과, 강성이 큰 마이크로파일이 높은 하중을 분담하는 것으로 나타났다. 일반 및 파형 마이크로파일 모두 동일한 설계하중이 적용되어 지지력에는 큰 차이를 보이지 않았음에도, 강성이 큰 파형 마이크로파일이 작게는 1.7배에서 크게는 3.2배 큰 하중 분담율을 보였다. 파형 마이크로파일은 대부분 보강기초로 활용될 것으로 예상되는데, 증축 리모델링 등을 통해 추가적인 하중 작용 시 많은 하중을 분담함으로써 기존 기초의 지지력 파괴 가능성을 낮출 수 있을 것으로 기대된다.