• 한국지반환경공학회 논문집
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• 제12권1호
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• pp.41-50
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• 2011

본 연구에서는 단독말뚝의 측면에서 시공되는 터널에 의한 말뚝의 거동에 대하여 3차원 수치해석을 통하여 분석하였다. 수치해석을 통하여 터널-말뚝-지반의 상호거동에 대한 심도 있는 분석을 실시하였다. 수치해석을 통해 말뚝의 침하, 말뚝과 주변지반 사이의 상대변위, 전단응력 및 말뚝의 축력변화를 고찰하였다. 특히 터널굴착에 의한 전단응력의 전이과정에 대한 심도 있는 분석을 실시하였다. 터널굴착에 의한 말뚝과 인근지반에서의 상대변위 변화로 인하여 말뚝에 작용하는 전단응력 및 축력의 분포가 변하게 되는 것으로 나타났다. 터널 중심부의 상부에서는 하향의 전단응력이 발생하는 반면(Z/L=0.0-0.7~0.8), 그 하부에서는 (Z/L=0.7~0.8-1.0) 상향의 전단응력이 발생하여 말뚝에 압축력이 발생된다, 이때 Z는 임의의 심도, L은 말뚝의 길이다. 터널굴착이 종료된 후 말뚝에는 최대 $0.475P_a$의 압축력이 발생하였다, 이때 $P_a$는 말뚝의 설계지지력이다. 수치해석을 통해서 도출된 터널굴착이 말뚝 거동에 미치는 영향에 대해 상세히 고찰하였다.

• 한국지반공학회논문집
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• 제16권3호
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• pp.89-89
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• 2000

The shear behavior of any interface is a function of the fundamental properties of both materials at the interface. This study aimed at investigating the effect of planar surface roughness on the stress-horizontal displacement curve at theinterfaces composed of various geomembrane textures and granular materials. In addition, the extent of surfacialscarring on smooth geomembranes against granular materials during shearing induced by plowing effect was studied. It wasobserved that the displacements required to achieve peak and residual interface resistance, and the stress-displacementcurve at the interface vary greatly with the surface roughness of geomembrane. Quantification of surface roughnessvariations on smooth geomembrane due to plowing effect showed that the surfacial scarring during shearing by the soilparticles is directly related to both the normal stress and the angularity of the soil particles at the interface. The findingsof this study can be used to provide the useful information for the design and selection of counterface materials.

• Steel and Composite Structures
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• 제41권6호
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• pp.805-820
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• 2021

In this research, the buckling and free vibration of three-phase carbon nanotubes/ fiber/ polymer piezoelectric nanocomposite face sheet sandwich microbeam with microsensor and micro-actuator surrounded in elastic foundation based on modified couple stress theory (MCST) is investigated. Three types of porous materials are considered for sandwich core. Higher order (Reddy) and sinusoidal shear deformation beam theories are employed for the displacement fields. Sinusoidal surface stress effects are extracted for sinusoidal shear deformation beam theory. The equations of motion are derived by Hamilton's principle and then the natural frequency and critical buckling load are obtained by Navier's type solution. The determined results are in good agreement with other literatures. The detailed numerical investigation for various parameters is performed for this microsensor-microactuator. The results reveal that the microsensor-microactuator enhanced by increasing of Skempton coefficient, carbon nanotubes diameter length to thickness ratio, small scale factor, elastic foundation, surface stress constants and reduction in porous coefficient, micro-actuator voltage and CNT weight fraction. The valuable results can be expedient for micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) systems.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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• pp.101-104
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• 2000

The general solution of the anti-plane shear problem for the curved interfacial crack between viscoelastic foam and composites was investigated with the complex variable displacement function and Kelvin-Maxwell model. The Laplace transform was applied to treat the viscoelastic characteristics of foam in the analysis. The stress intensity factor near the interfacial crack tip was predicted by considering both anisotropic and viscoelastic properties of two different materials. The results showed that the stress intensity factor increased with increasing the curvature of the curved interfacial crack and it also increased and eventually converged to a specific value with increasing time.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.811-819
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• 2005

In this study, we present a new efficient hybrid-mixed composite laminated curved beam element. The present element, which is based on the Hellinger-Reissner variational principle and the first-order shear deformation lamination theory, employs consistent stress parameters corresponding to cubic displacement polynomials with additional nodeless degrees in order to resolve the numerical difficulties due to the spurious constraints. The stress parameters are eliminated and the nodeless degrees are condensed out to obtain the ($6{\times}6$) element stiffness matrix. The present study also incorporates the straightforward prediction of interlaminar stresses from equilibrium equations. Several numerical examples confirm the superior behavior of the present composite laminated curved beam element.

• Steel and Composite Structures
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• 제18권6호
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• pp.1353-1368
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• 2015

A finite element model is presented for the analysis of composite steel-concrete beams based on a refined high-order theory. The employed theory satisfies all the kinematic and stress continuity conditions at the layer interfaces and considers effects of the transverse normal stress and transverse flexibility. The global displacement components, described by polynomial or combinations of polynomial and exponential expressions, are superposed on local ones chosen based on the layerwise or discrete-layer concepts. The present finite model does not need the incorporating any shear correction factor. Moreover, in the present $C^1$-continuous finite element model, the number of unknowns is independent of the number of layers. The proposed finite element model is validated by comparing the present results with those obtained from the three-dimensional (3D) finite element analysis. In addition to correctly predicting the distribution of all stress components of the composite steel-concrete beams, the proposed finite element model is computationally economic.

• Structural Engineering and Mechanics
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• 제60권2호
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• pp.175-191
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• 2016

The present article is aimed at an investigation of stresses produced in a microstretch elastic half-space due to a moving load. The expressions of normal stress, shear stress and tangential couple stress produced in this case have been obtained in closed form. To find the displacement fields the perturbation method is applied. Significant effect of moving load on variation of stresses developed at different depths below the surface due to the depth of substrate and frictional coefficient of the rough surface of the medium has been observed. The effects of different shapes of irregularity and depth of irregularity on normal, shear and tangential couple stresses have been discussed. Some particular cases have also been deduced from the present investigation. Finally, the analytical developments have been illustrated numerically for aluminium-epoxy-like material substrate under the action of moving load.

• Geomechanics and Engineering
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• 제2권4호
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• pp.281-302
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• 2010

An extended model for the response of a rigid footing on a reinforced foundation bed on super soft soil is proposed by incorporating the rough membrane element into the granular bed. The super soft soil, the granular bed and the reinforcement are modeled as non-linear Winkler springs, non-linear Pasternak layer and rough membrane respectively. The hyperbolic stress-displacement response of the super soft soil and the hyperbolic shear stress-shear strain response of the granular fill are considered. The finite deformation theory is used since large settlements are expected to develop due to deformation of the super-soft soil. Parametric studies quantify the effect of each parameter on the stress-settlement response of the reinforced foundation bed, the settlement and tension profiles.

• Smart Structures and Systems
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• 제15권6호
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• pp.1569-1582
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• 2015

Two hyperbolic displacement models are used for the bending response of simply-supported orthotropic laminated composite plates resting on two-parameter elastic foundations under mechanical loading. The models contain hyperbolic expressions to account for the parabolic distributions of transverse shear stresses and to satisfy the zero shear-stress conditions at the top and bottom surfaces of the plates. The present theory takes into account not only the transverse shear strains, but also their parabolic variation across the plate thickness and requires no shear correction coefficients in computing the shear stresses. The governing equations are derived and their closed-form solutions are obtained. The accuracy of the models presented is demonstrated by comparing the results obtained with solutions of other theories models given in the literature. It is found that the theories proposed can predict the bending analysis of cross-ply laminated composite plates resting on elastic foundations rather accurately. The effects of Winkler and Pasternak foundation parameters, transverse shear deformations, plate aspect ratio, and side-to-thickness ratio on deflections and stresses are investigated.

• 한국지반공학회논문집
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• 제20권6호
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• pp.119-126
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• 2004

본 논문에서는 현장계측을 통해 관측된 소일네일링 벽체의 거동을 분석하였다. 연구의 주요내용으로는 인발시험을 통해 산정한 네일과 지반의 경계면에서 전단강도의 발생, 지반의 수평변위, 네일에 발생하는 인장력의 분포 및 경계면에서의 전단강도의 발현 등이다. 특히, 경계면에서의 전단응력 발생 과정 및 전단강도 발현에 대한 심도있는 분석을 실시하였다. 본 연구에서 분석된 자료는 국내 소일네일링의 예비설계 단계시 참고 자료로 활용될 수 있을 것으로 기대된다.