• 대한기계학회논문집A
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• 제33권12호
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• pp.1410-1416
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• 2009

In this paper, the purpose is to investigate the stability and variation of natural frequency of a cracked cantilever beams subjected to follower force and tip mass. In addition, an analysis of the flutter instability(flutter critical follower force) of a cracked cantilever beam as slenderness ratio and crack severity is investigated. The governing differential equations of a Timoshenko beam subjected to an end tangential follower force is derived via Hamilton's principle. The two coupled governing differential equations are reduced to one fourth order ordinary differential equation in terms of the flexural displacement. Finally, the influence of the slenderness ratio and crack severity on the critical follower force, stability and the natural frequency of a beam are investigated.

• 대한기계학회논문집A
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• 제21권10호
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• pp.1580-1588
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• 1997

A modeling method for the flapwise bending vibration of a rotating cantilever beam which has small slenderness ratio is presented in this paper. It is shown that as the slenderness ratio decreases the shear and rotary inertia effects increase. Such effects become critical for the accurate estimation of the natural frequencies and modeshapes, especially higher frequencies and modes, as the angular speed increases. It is also shown that the flapwise bending natural frequencies are higher than the chordwise bending natural frequencies. The discrepancy between first natural frequencies are especially significant when the hub radius ratio is small.

• 소음진동
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• 제6권2호
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• pp.179-185
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• 1996

This paper presents a modeling method for the vibration analysis of a rotating beam the slenderness ratio of which is relatively small. The smaller the slenderness ratio becomes, the larger the shear and rotary inertia effects become. Such effects become critical for the accurate estimation of the natural frequencies and modeshapes, especially higher frequencies and modes, as the angular speed increases. It is also shown that the effects are important for the accurate estimation of the critical angular speed of the beam.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.442-445
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• 1997

With increasing use of high strength concrete tied columns in structural engineering, it becomes necessary to examine the applicability of related sections of current design codes. High strength concrete has an advantage of strength capacity and stiffness especially for column elements. This paper presents an experimental study of high strength concrete tied columns subjected to eccentric loading. The main variables included in this test were concrete compressive strength, steel amount, eccentricity, and slenderness ratio. The concrete compressive strength varied from 34.9Mpa(356kg/$\textrm{cm}^2$ ) to 93.2Mpa(951kg/$\textrm{cm}^2$ ) and the longitudinal steel ratios were between 1.1% and 5.5%. The eccentricity was selected for the different failure modes, i.e., compression control, balanced point, and tension control. The slenderness ratio varied from 19 to 61. The column specimens with same slenderness ratio but with different concrete compressive strength were constructed and tested. The purpose of this paper is to show failure modes of high strength reinforced concrete columns.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.514-519
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• 2004

The paper discusses the general behavior of fire-damaged slender reinforced concrete columns on the basis of results obtained from parametric studies. Effects of slenderness ratio, concrete strength, cover thickness, reinforcement ratios, exposed time to fire, and eccentricity on the ultimate capacity of fire-damaged column are theoretically observed. With the increase of slenderness ratio, similar tendency of relative strength reduction was observed between fire-damaged columns and columns at room temperature.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 춘계학술대회 논문집
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• pp.137-141
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• 1993

In the case of a boring bar, the vibration amplitude is generallylarge due to its high slenderness. The boring bat is then modelled as a cantilever with dynamic force acting at the free end and a generalized model of nonlinear continous system is obtained. The Analysis of model is conducted for the specific case with a zero side cutting edge angle. The dynamic behaviour is investigated for machining processes in which the the overlap factor of regenerative effect is considered. The vibration characteristics of boring bar depth of cut rather than feed rate in given slenderness.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.33-37
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• 1995

A side-cut grinding generates a machining error by the decrease of the quill rigidity. In this paper, The effect on the grinding force, machining error and surface roughness due to the change of the quill rigidity is investigated experimentally. The slenderness ratio of the quill is a significant factor to analyse the change of the grinding force and machining error.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.270-278
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• 1999

This paper describes the collapse characteristics of the rectangular tube under eccentric compressive load. Overall buckling stress and bifurcation criterion (slenderness ration)are investigated. modified secant formula(MSF) is proposed to decide overall buckling stress. The bifurcation criterion which can distinguish between the local and overall buckling mode shapes is suggest by equating the local and overall buckling stresses. Additionally the effect of initial imperfection on bifurcation criterion is investigated.

• Steel and Composite Structures
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• 제9권5호
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• pp.419-444
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• 2009

Flange and web local buckling in beam plastic hinge regions of steel moment frames can prevent beam-column connections from achieving adequate plastic rotations under earthquake-induced forces. Reducing the flange-web slenderness ratios (FSR/WSR) of beams is the most effective way in mitigating local member buckling as stipulated in the latest seismic design specifications. However, existing steel moment frame buildings with beams that lack the adequate slenderness ratios set forth for new buildings are vulnerable to local member buckling and thereby system-wise instability prior to reaching the required plastic rotation capacities specified for new buildings. This paper presents results from a research study investigating the cyclic behavior of steel I-beams modified by a welded haunch at the bottom flange and reinforced with glass fiber reinforced polymers at the plastic hinge region. Cantilever I-sections with a triangular haunch at the bottom flange and flange slenderness ratios higher then those stipulated in current design specifications were analyzed under reversed cyclic loading. Beam sections with different depth/width and flange/web slenderness ratios (FSR/WSR) were considered. The effect of GFRP thickness, width, and length on stabilizing plastic local buckling was investigated. The FEA results revealed that the contribution of GFRP strips to mitigation of local buckling increases with increasing depth/width ratio and decreasing FSR and WSR. Provided that the interfacial shear strength of the steel/GFRP bond surface is at least 15 MPa, GFRP reinforcement can enable deep beams with FSR of 8-9 and WSR below 55 to maintain plastic rotations in the order of 0.02 radians without experiencing any local buckling.

• Structural Engineering and Mechanics
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• 제59권6호
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• pp.1139-1153
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• 2016

Elastic constraints are usually simplified as "spring forces" exerted on beam ends without considering the "spring deformation". The partial differential equation governing the free vibrations of a cantilever Bernoulli-Euler beam considering the deformation of elastic constraints is firstly established, and is nondimensionalized to obtain two dimensionless factors, $k_v$ and $k_r$, describing the effects of elastically vertical and rotational end constraints, respectively. Then the frequency equation for the above Bernoulli-Euler beam model is derived using the method of separation of variables. A numerical analysis method is proposed to solve the transcendental frequency equation for the continuous change of the frequency with $k_v$ and $k_r$. Then the mode shape functions are given. Finally, effects of $k_v$ and $k_r$ on free vibration characteristics of the beam with different slenderness ratios are calculated and analyzed. The results indicate that the effects of $k_v$ are larger on higher-order free vibration characteristics than on lower-order ones, and the impact strength decreases with slenderness ratio. Under a relatively larger slenderness ratio, the effects of $k_v$ can be neglected for the fundamental frequency characteristics, while cannot for higher-order ones. However, the effects of $k_r$ are large on both higher- and lower-order free vibration characteristics, and cannot be neglected no matter the slenderness ratio is large or small.