• Journal of Korean Society of Steel Construction
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• v.11 no.1 s.38
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• pp.55-67
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• 1999

The ratios of elastic to shear modulus of the structures as laminated composite plates and shells, are very large. They are much susceptible to effect of shear deformation. In order to obtain the accurate solutions of laminated composite plate and shells, the effects of shear strain should be considered for the analysis and design of them. Especially, the more exact solution can be obtained in applying to higher-order shear deformation theory. Therefore, in this paper, the third-order shear deformation theory is used to present the distributions of bending, the characteristics of natural frequencies and the buckling load according to the effects of ply orientation, number of layers for the laminated composite plates and shells with simply supported boundary conditions.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.4
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• pp.1-13
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• 2003

For spatial free vibration of non-symmetric thin-walled curved beams with shear deformation, an improved formulation is proposed in the present study. The elastic strain and the kinetic energies are first derived by considering constant curvature and shear deformation effects due to shear forces and restrained warping torsion. Next equilibrium equations and force-deformation relations are obtained using a stationary condition of total potential energy. And the finite element procedures are developed by using isoparametric curved beam element with arbitray thin-walled sections. Particularly not only shear deformation and thickness-curvature effects on vibration behaviors of curved beams but also mode transition and crossover phenomena with change in curvatures of beams are parametrically investigated. In order to illustrate the accuracy and the reliability of this study, various numerical solutions for spatial free vibration are compared with results by available references and ABAQUS's shell element.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.181-187
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• 2011

This paper deals with free vibrations of the Timoshenko beam supported by two elastomeric bearings at two far ends. The ordinary differential equation governing free vibrations of such beam is derived, in which both effects of rotatory inertia and shear deformation are included as the Timoshenko beam theory. Also, boundary conditions of the free end are derived based on the Timoshenko beam theory. The ordinary differential equation is solved by the numerical methods for calculating natural frequencies and mode shapes. Both effects of the rotatory inertia and shear deformation on natural frequencies are extensively discussed. Also, relationships between natural frequencies and slenderness ratio, foundation modulus and bearing length are presented. Typical mode shapes of bending moment and shear force as well as deflection are given in figures which show the positions of maximum amplitudes and nodal points.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1785-1790
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• 2010

To study the vortex induced vibrations the wind tunnel and the two story shear building were designed and built. The wind tunnel was designed to generate the wind speed up to 24 m/s, and the building was designed to have the two lowest natural frequencies within the range of the vortex frequencies generated by the wind tunnel. The resonance behaviors by the locking-on phenomena were observed during the wind tunnel tests of the shear building with the cylinder attached. From the locking-on phenomena observed it is found that the effects of the amplitudes and the frequencies of the cylinders should be considered on the forces generated by the vortex shedding.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.157-164
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• 2005

Urban conditions such as underground facilities and ambient noises due to cultural activity restrict the application of conventional geophysical techniques in general. We used the refraction microtremor (REMI) technique as an alternative way to get the geotechnical information, in particular shear-wave (S-wave) velocity information, at a site along an existing rail road. The REMI method uses ambient noises recorded using standard refraction equipment to derived shear-wave velocity information at a site. It does a wavefield transformation on the recorded wavefield to produce Rayleigh wave dispersion curve, which are then picked and modeled to get the shear-wave velocity structure. At this site the vibrations from the running trains provided strong noise sources that allowed REMI to be very effective. REMI was performed along the planned new underground rail tunnel. In addition, Suspension PS logging (SPS) were carried out at selected boreholes along the profile in order to draw out the quantitative relation between the shear wave velocity from the PS logging and the rock mass rating (RMR) determined from the inspection of the cores recovered from the same boreholes, These correlations were then used to relate the shear-wave velocity derived from REMI to RMR along the entire profile. The correlation between shear wave velocity and RMR was very good and so it was possible to estimate the RMR of the total zone of interest for the design of underground tunnel,

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.2
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• pp.82-88
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• 1977

1장이 축방향으로 자유로이 움직일 수 있는 단선지시보의 진동에 있어서 그 진폭이 크고, 축방향의 관성력과 전단변형을 고려할때 의 진동을 살폈다. 운동방정식을 처짐을 독립변수로 하는 비선형편미분방정식으로 표시하고, model expansion과 Galerkin 방법에 의해서 비정형연립상미분방정식으로 변형한 다음에 Perturbation method of muthod of multiple scale로 유사해를 구하였다. 또한 보의 진동수-진폭의 관계에 대한 일반적 표현을 구하고, 간단한 구체적 해에 대하여 1차근사해와 진동수-진폭관계를 계산하여 이미 이루어진 연구결과와 비교하였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.125-138
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• 2001

고유진동수와 감쇠비는 지진이나 바람과 같은 동적 횡하중에 대해 구조물의 응답을 결정하는 주요한 특성이다. 본 연구는 지진하중에 대하여 목표응답 수준을 만족하는 구조물의 고유진동수와 감쇠비를 지정하고, 이 값을 실현하는 점탄성 감쇠기 파라미터의 처적분포를 구하는 설계방법을 제안한다. 여기서 지정할 고유진동수와 감쇠비는 목표응답 수준을 만족하는 여러 조합 중 설계조건과 원래 건물의 특성에 따라 결정될 수 있다. 제안한 설계방법은 점탄성 감쇠기의 감성 파라미터를 고유값의 기울기 정보를 바탕으로 분포시키므로 최적 위치와 크기에 대한 정보를 동시에 제공한다. 예제로서 평면 10층 전단 건물을 대상으로 최적설계를 수행하여 지정된 고유값을 실현하는 파라미터의 최적분포를 구하고 이를 통해 제안한 최적 설계의 특성을 확인하였다. 또한 더 나아가 3차원 일방향 비대칭 전단전물에 제안된 최적설계를 수행하여 그에 대한 적용가능성을 확인하였다.

• The Journal of the Acoustical Society of Korea
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• v.36 no.3
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• pp.158-164
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• 2017

Typical hydrophones in line array sensors for early detection of covert underwater targets can measure only sound-pressure-magnitude with the limitation of being unable to identify the direction of an incoming wave. In this study, a thickness shear mode vibrator was proposed as the main component of an inertia type vector hydrophone to measure both magnitude and direction of acoustic signals from targets. The equation to analyze the output voltage of the vibrator to an external force was derived, and the validity of the equation was verified through finite element analysis of a PMN-PT single crystal vibrator. The analysis results from this study will be utilized in the future for the design of inertia type vector hydrophones made of thickness shear vibrators.

• Journal of the Korean GEO-environmental Society
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• v.11 no.11
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• pp.47-54
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• 2010

Nowadays, geosynthetics for reinforcement and protection are widely applied to the waste landfill site. Current research indicates the potential for progressive failure in geosynthetic-soil system depends on the interface shear strength governed by several intrinsic factors such as moisture, normal stress, chemical, etc. In particular, the effect of the acidity and basicity from the leachate is intensively reviewed to assess the chemical reaction mechanism of interface shear strength under the cyclic loading condition. New multi-purpose interface apparatus(M-PIA) has been manufactured and the cyclic direct shear tests using submerged geosynthetics and soils under the different chemical conditions have been performed, consequently, the thickness of interface and shear stress degradation are verified. The basic schematic of the Disturbed State Concept(DSC) is employed to estimate the shear stress degradation in the interface, then, normalized disturbed function is obtained and analyzed to describe the shear stress degradation of geosynthetic-soil interface with chemical influence factors under dynamic condition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.48-54
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• 2022

This research describes a quantitative procedure used to estimate the effect of concrete cracking on stiffness degradation of concrete shear walls and provides analytical references for the seismic design of concrete shear walls. As preliminary research on the seismic response of concrete shear walls, nonlinear transient analysis was performed with commercial FE software. The study presents the nonlinear time history analysis results in terms of concrete damage and cracking behavior induced by seismic input motions. By varying the input motions, concrete strength and shear wall thickness, the seismic responses of a shear wall were examined with nonlinear time history analysis, and the progressive cracking behavior and corresponding hysteresis loop were described. Based on the analysis results, frequency and stiffness degradation of the shear wall from progressive concrete damage and cracking were captured with respect to the seismic levels. The results of this study suggest that stiffness degradation from concrete cracking should be appropriately considered when determining the seismic capacity of RC shear wall structures.