• Structural Engineering and Mechanics
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• 제16권5호
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• pp.533-556
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• 2003

The flutter and buckling analysis of a beam structure subjected to a static follower force is completely studied in the paper. The beam is fixed in the transverse direction and constrained by a rotational spring at one end, and by a translational spring and a rotational spring at the other end. The co-existence of flutter and buckling in this beam due to the presence of the follower force is an interesting and important phenomenon. The results from this theoretical analysis will be useful for the stability design of structures in engineering applications, such as the potential of flutter control of aircrafts by smart materials. The transition-curve surface for differentiating the two distinct instability regions of the beam is first obtained with respect to the variations of the stiffness of the springs at the two ends. Second, the capacity of the follower force is derived for flutter and buckling of the beam as a function of the stiffness of the springs by observing the variation of the first two frequencies obtained from dynamic analysis of the beam. The research in the paper may be used as a benchmark for the flutter and buckling analysis of beams.

• Structural Engineering and Mechanics
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• 제37권5호
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• pp.489-507
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• 2011

The dynamic response of a Timoshenko beam on a tensionless Pasternak foundation is investigated by assuming that the beam is subjected to a concentrated harmonic load at its middle. This action results in the creation of lift-off regions between the beam and the foundation that effect the character of the response. Although small displacements for the beam and the foundation are assumed, the problem becomes nonlinear since the contact/lift-off regions are not known at the outset. The governing equations of the beam, which are coupled in deflection and rotation, are obtained in both the contact and lift-off regions. After removing the coupling, the essentials of the problem (the contact regions) are determined by using an analytical-numerical method. The results are presented in figures to demonstrate the effects of some parameters on the extent of the contact lengths and displacements. The results are also compared with those of Bernoulli-Euler, shear, and Rayleigh beams. It is observed that the solution is not unique; for a fixed value of the frequency parameter, more than one solution (contact length) exists. The contact length of the beam increases with the increase of the frequency and rotary-inertia parameters, whereas it decreases with increasing shear foundation parameter.

• 한국지반공학회논문집
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• 제16권1호
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• pp.19-30
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• 2000

앵커식 고정지지 널말뚝의 설계요소는 널말뚝의 최소 근입깊이, 앵커가 부담하여야 할 장력 및 널말뚝이 받는 최대 휨모멘트이다. 널말뚝 설계는 Rankine의 토압이론을 근거로 가정한 토압분포를 적용하여 변곡점을 중심으로 위쪽과 아래쪽을 나누어 단순보로 보는 Blum의 등가보법이 흔히 쓰이고 있다. 설계용도표가 개발되어 있으나 기하학적 조건과 지반조건의 제약으로 실무적으로 이용하기에 불편함이 있다. 본 논문에서는 이러한 불편함을 해소하기 위해 설계용 도표를 개발하였다. 또한 다양한 설계조건에 대하여 컴퓨터 프로그램으로 생성된 출력자료를 회귀분석하여 설계용 간편식을 제시하였다. 간편식은 설계과정을 단순화하고 오류를 줄이며 필산의 결과에 대한 검산으로도 활용할 수 있다.

• 대한기계학회논문집A
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• 제34권6호
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• pp.771-780
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• 2010

본 논문에서는 제작이 용이한 십자형 구조를 기본구조로 사용하여 판스프링 고정단을 가진 유연한 6축 로드셀을 설계하였다. 이를 위하여 유한요소법해석을 이용하여 강체 고정단과 판스프링 고정단에 대한 변형 분석을 하였으며 이로부터 특성이 우수한 6축 힘/토크 센서를 설계하였다. 변형률 분포를 이용하여 각 축의 하중에 대한 출력변형률이 비슷한 수준이 되도록 스트레인 게이지 위치를 정하고 상호간섭 변형률이 최소화 되도록 이들로 연결된 브리지회로를 구성하였다. 강체 고정단 대신에 스프링판 고정단을 이용하면 고정 경계부의 조건을 변화시킬 수 있어서 십자형 로드셀의 특성을 획기적으로 개선시킬 수 있었다. 치수 변경을 통하여 설계된 6축 로드셀에 대한 상호 간섭오차는 모든 축에서 0으로 계산되었으며 각 축에서 발생하는 출력변형률 값도 $400\;{\mu}m/m$의 비슷한 수준으로 결정되었다.

• Structural Engineering and Mechanics
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• 제45권3호
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• pp.277-309
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• 2013

Beam-to-column connections behaviour plays an important role in the analysis and design of steel and precast concrete structures. The paper presents a computer-based method for geometrically nonlinear frames with semi-rigid beam-to-column connections. The analytical procedure employs modified stability functions to model the effect of axial force on the stiffness of members. The member modified stiffness matrix, and the modified fixed end forces for various loads were found. The linear and nonlinear analyses were applied for two planar steel structures. The method is readily implemented on a computer using matrix structural analysis techniques and is applicable for the efficient nonlinear analysis of frameworks.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.335-340
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• 2002

The focus of this experimental study is to verify the effect of openings in reinforced concrete deep beam. Main variables are opening depth, width and vertical locations but the shear span-to-overall depth ratio was fixed by 0.5. The experimental results about 8 deep beams which was tested under two equal symmetrically placed point loads are reported.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.125-128
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• 2003

In machine tool design, fast traversing cannot be achieved without reducing mass of the moving part. Honeycomb sandwich panel is extremely lightweight, and relatively rigid at the same time. We can reduce much weight when we selectively utilize honeycomb sandwich panels as stiffeners on machine tool structures. Feasibility of reducing weight is studied using a beam structure with both ends fixed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.339-342
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• 1999

The equation of output voltage from the PVDF was derived. When impact force applied to the PVDF films of cantilever beam and one-end fixed, other-end supported beam structure, output voltage equation induced. Experimental output voltages by falling ball agreed quite well with induced theoretical data. This PVDF film showers to be in high possibility in a warning system of abnormal pulse rate and breathing, and in detecting impact force and/or mechanical energy.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.100-110
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• 2000

In practical design of girder bridges or reinforced concrete slab bridges with T-type piers, it is usually assumed that vertical movements of superstructures are completely restrained at the locations of bearings(shoes) on a cap beam of the pier, The resulting vertical reactions are applied to the bearing for the calculation of bending moments and shear forces in the cap beam. However, in reality, the overhang parts of the cap beam will deform under the dead load of superstructures and the live load so that it may act as an elastic foundation. Due to the settlement of the elastic foundation, the actual distribution of the reactions at the bearings along the cap beam may be different from that obtained under the assumption that the vertical movements are fixed at the bearings. In the present study, investigated is the effects of elastic deformations of the T-type pier on the distribution of reactions at the bearings along the cap beam through 3-dimensional finite element analysis. Herein, for this purpose the whole structural system including the superstructure and piers as well is analyzed. It appears that the conventional practice which neglects the elastic deformations of the cap beam exhibits considerably different distributions of the reactions as compared with those obtained from the present finite element analysis. It is, therefore, recommended that in order to assess the reactions at bearings correctly the whole structural system be analyzed using 3-dimensional finite element analysis.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1218-1220
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• 2005

We have developed laser absorption spectroscopy system for the measurement of excited Xe atoms in micro-discharged AC-PDP plasma. In this study, we have measured the absorption signals for the $1S_5$ xenon metastable state in the PDP cell with the various gas mixtures of Ne-Xe(1%), Ne-Xe(4%) and Ne-Xe(10%) under fixed gas pressure of 350 Torr and the eletrode gap distance of 50um. It is found that the maximum excited xenon densities are $1.2^{\ast}10^{12}\;cm^{-3}$, $1.8^{\ast}10^{12}\;cm^{-3}$ and $2.7^{\ast}10^{12}cm^{-3}$ for gas mixtures of Ne-Xe(1%), Ne-Xe(4%) and Ne-Xe(10%) respectively, in this experiment.