• Title, Summary, Keyword: 좌굴

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A Study on the Buckling and Postbuckling Behaviors of Laminated Composite Plates and Stiffened Laminated Composite Panels by Finite Element Method (유한요소법을 이용한 복합적층판과 보강된 복합적층 패널의 좌굴 및 좌굴후 거동에 관한 연구)

  • 허성필;양원호;성기득;조명래
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.4
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    • pp.599-606
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    • 1999
  • 복합 적층 판과 보강 재를 설치한 보강된 복합 적층 패널의 좌굴을 고려한 설계에서, 좌굴이 항상 구조물의 최종 파손을 의미하는 것은 아니므로 이들의 좌굴 및 좌굴 후 거동에 대한 정확한 이해와 연구가 필요하다. 본 연구에서는 유한요소 법을 이용하여 적층 메커니즘과 섬유 배향각, 적층 순서 등이 복합 적층 판과 보강된 복합 적층 패널의 좌굴 및 좌굴 후 거동에 미치는 영향을 체계적으로 해석하였고, 각 변수에 따른 좌굴 및 좌굴 후 거동 특성을 분석하였다.

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The Compressive Strength of Longitudinally Stiffened Plates Undergoing Local and Distortional Buckling (국부좌굴과 뒤틀림좌굴이 발생하는 종방향 보강재로 보강된 강판의 압축강도)

  • Park, Ho-Sang;Seo, Sang-Jung;Kwon, Young-Bong
    • Journal of Korean Society of Steel Construction
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    • v.22 no.3
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    • pp.219-228
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    • 2010
  • This paper describes an experimental research on the structural behavior and the ultimate strength of longitudinally stiffened plates subjected to local, distortional, or mixed-mode buckling under compression. The stiffened plate undergoes local, distortional, or interactive local-distortional buckling according to the flexural rigidity of the plate's longitudinal stiffeners and the width-thickness ratios of the sub-panels of the stiffened plate. A significant post-buckling strength in the local and distortional modes affects the ultimate strength of the longitudinally stiffened plate. Compression tests were conducted on stiffened plates that were fabricated from 4mm-thick SM400 steel plates with a nominal yield stress of 235MPa. A simple strength formula for the Direct Strength Method based on the test results was proposed. This paper proves that the Direct Strength Method can properly predict the ultimate strength of stiffened plates when the local buckling and distortional buckling occur simultaneously or nearly simultaneously.

Analysis on the Elastic Shear Buckling Characteristics of Corrugated Steel Plate in Accordance with Corrugation Shape (형상에 따른 주름강판의 탄성전단좌굴 특성 및 경향성 분석 연구)

  • Shon, Su-Deok;Yoo, Mi-Na;Lee, Seung-Jae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.6
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    • pp.11-20
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    • 2014
  • This paper aims at comparing and analyzing shear buckling characteristics between sinusoidal corrugation shape and trapezoidal one. For this, I adopted the equal-length trapezoidal corrugation and sinusoidal one for the analytical models, and analyzed their shear buckling characteristics through linear buckling analysis and on its theory. Generally, the shear buckling shapes of corrugated steel plates are classified into local buckling, global buckling, and interactive buckling from the two buckling modes. Sinusoidal corrugation shape, unlike trapezoidal corrugation, does not have flat sides, which causes another tendency in shear buckling mode. Especially, the changes and different aspects of shear buckling on the boundary between local buckling and global buckling appear in different corrugation shapes. According to the analysis results, interactive buckling mode appeared on the boundary of local buckling and global bucking in trapezoidal corrugation. However, in the case of corrugated steel plates with sinusoidal configuration, interactive buckling mode appeared in the part where global bucking takes place. Besides, trapezoidal shapes are of advantages on shear buckling resistance in the local buckling section, and so are sinusoidal shapes in the global buckling section.

Experimental Study on Performance Evaluation of Steel Frame with Buckling Control Brace (좌굴제어 가새를 가진 가새골조의 성능향상에 관한 실험적 연구)

  • Lee, Sang-Ju;Han, Sang-Eul;Noh, Sam-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.5
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    • pp.181-188
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    • 2007
  • This research presents two methods to prevent local buckling from circular tube brace and then verify their performance capacity through a cyclic loading test. As control methods on local buckling, one is to restrict local buckling as attaching cover plate at range of buckling. And the another is to exclude danger of buckling as inserting contraction device with rod and spring at the center of brace. The purpose of this research is to develop structural device for restriction of local buckling or for exclusion of its. And we investigate appliance of suggested methods through an experiment. We also estimate the improvement of performance capacity in a quantitative respect.

Evaluation and Test of Slenderness Ratio Effect on Buckling Characteristics of Thin Cylindrical Structures Subjecting the Shear Loads (전단하중을 받는 얇은 원통구조물의 세장비에 따른 좌굴특성 평가 및 시험)

  • 구경회;김종범;이재한
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.3
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    • pp.535-543
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    • 2002
  • The purpose of this paper is to investigate the slenderness ratio effect on buckling characteristics of thin cylindrical structures subjecting the shear loads in detail. To do this, the buckling strength evaluations were carried out with using the evaluation formulae proposed by J. Okada. From the results of the buckling strength evaluations, the three types of staled cylindrical test specimen, which have L/R=3.1, 1.6, and 1.0, are determined for the numerical analyses and tests. From results, target slenderness ratio over L/R=3 results in dominant bending buckling mode, smaller slenderness ratio under L/R=1 results in dominant shear buckling mode, and near L/R=1.6 region shows the mixed buckling mode which has the bending and shear buckling mode simultaneously. Most results of buckling characteristics obtained by the numerical analyses and the evaluation formulae we in good agreement with those of tests.

Nonlinear Buckling and Imperfection Sensitivity Analyses of Shell Structures (셸 구조물의 비선형좌굴 및 결함민감도 해석)

  • 원종진
    • Journal of the KSME
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    • v.33 no.7
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    • pp.614-627
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    • 1993
  • 좌굴하기 쉬운 구조물을 설계할 때는 반드시 좌굴특성에 대한 어떤 직관을 가져야 한다. 이글의 목적은 셸 구조물이 비선형붕괴(nonlinear collapse), 분기좌굴(bifurcation buckling) 또는 이들 모드의 조합에 의해서 어떻게 좌굴될 것인가에 대한 감각을 전하는데 있다. 이 불안정에 대한 직관적 이해는 보강되고 여러 요소들로 조립되며 분지셸(branched shell)을 갖거나 복잡한 벽구 조를 갖는 실제 셸 구조물 등의 많은 예에 의해서 얻어질 수 있다. 이 글에서는 수식의 개발이 아니라 불안정의 예측에 주안점을 두고 있으며, 큰 처짐과 소성의 조합에 의해 발생되는 비선 형좌굴과 결함민감도가 특히 강조된다. 또한 최적화된 구조물의 국부 및 전체 불안정, 좌굴모드의 상호작용, 그리고 결함민감도(imperfection sensitivity) 등이 예시된다.

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Approximate Solution for In-Plane Elastic Buckling of Shallow Parabolic Arches (낮은 포물선 아치의 탄성 면내좌굴에 관한 근사식)

  • Moon, Ji Ho;Yoon, Ki Yong;Yi, Jong Won;Lee, Hak Eun
    • Journal of Korean Society of Steel Construction
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    • v.18 no.4
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    • pp.427-436
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    • 2006
  • The classical buckling theory assumes that prebuckling behavior is linear and that the effect of prebuckling deformations on buckling can be ignored. However, when the rise to span ratio decreases, prebuckling deformation cannot be ignored and the symetrical buckling strength can be smaler than the asymetrical buckling strength. Finally, arches can fail due to snap-through buckling. This paper investigates the non-linear behavior and strength of pin-ended parabolic shallow arches using the non-linear governing differential equation of shallow arches. These results were compared with the solution for the symmetrical buckling load of pin-ended parabolic shallow arches was suggested.

Buckling and Postbuckling Control of a Composite Beam with Embedded SMA Wire Actuators (형상기억합금 선 작동기를 삽입한 복합적층 보의 좌굴 및 좌굴후 제어)

  • Choi, S.;Lee, J.J.;Seo, D.C.;Choi, S.W.
    • Composites Research
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    • v.12 no.3
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    • pp.45-54
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    • 1999
  • In this paper, an experimental study on the buckling and postbuckling control of a laminated composite beam with eccentrically embedded SMA wire actuators is performed. For the purpose of enhancing the critical buckling load, buckling control is investigated through the use of reactive moment associated with the shape recovery force of SMA wire actuators. To improve the control authority for the buckling and postbuckling control of the SMA-composite beam, closed-loop control is used. The buckling and postbuckling control behaviours are presented and discussed qualitatively and quantitatively on loaddeflection plots considering the stacking sequence of the laminate, slenderness ratio of the beam and activation conditions of the SMA wire actuators. By maintaining the desired deflection shape with the proper reactive moment, buckling control can be extended to the postbuckling of the SMA-composite beam subjected to an external load.

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Buckling oad and Post-buckling Behavior of Tapered Column with Constant Volume and Both Clamped Ends (일정체적 양단고정 변단면 기둥의 좌굴하중 및 후좌굴 거동)

  • 이병구
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.41 no.5
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    • pp.112-122
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    • 1999
  • 이 논문은 일정체적을 갖는 양단고정 변단면 기둥의 좌굴하중 및 후좌굴 거동에 관한 연구이다. 기둥의 변단면으로는 직선형, 포물선형, 정현의 선형을 갖는세 가지 변단면을 채택하였다. Bernoulli-Euler 보 이론을 이용하여 압축하중이 작용하여 좌굴된 기둥이 정확탄성곡선을 지배하는 미분방정식을 유도하였다. 유도된 미분방정식을 Runge-Kutta 법과 REgula-Falsi법을 이용하여 수치해석하였다. 수치해석의 결과로 좌굴하중, 좌굴기둥의 평형경로 및 정확탄성곡선을 산출하였다. 또한 좌굴하중-단면비 곡선으로부터 최강기둥의 좌굴하중과 단면비를 산출하였다.

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A Study on the Moment Capacity of H-Section Flexural Members with Local Buckling (국부좌굴이 발생하는 H-형강 휨부재의 강도에 관한 연구)

  • Seo, Gun-Ho;Seo, Sang-Jung;Kwon, Young-Bong
    • Journal of Korean Society of Steel Construction
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    • v.23 no.6
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    • pp.647-657
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    • 2011
  • This paper describes the moment capacity of flexural members with local buckling based on a series of FE and experiment results. Thin-walled flexural members undergo local, lateral-torsional, or interactive buckling according to the section geometries and lateral boundary conditions. Flexural members with large width-to-thickness ratios in the flanges or the web may undergo local buckling before lateral-torsional buckling. Local buckling has a negative effect on the flexural strength based on the lateral-torsional buckling of flexural members. This phenomenon should be considered in the estimation of the flexural strength of thin-walled sections. Flexural members with various width-to-thickness ratios in their flanges and web were analyzed. Initial imperfections in the local buckling mode, and residual stresses, were included in the FE analyses. Simple bending moment formulae for flexural members were proposed based on the FE and test results to account for local and lateral-torsional buckling. The proposed bending moment formulae for the thin-walled flexural members in the Direct Strength Method use the empirical strength formula and the grosssection modulus. The ultimate flexural strengths predicted by the proposed moment formulae were compared with the AISC (2005), Eurocode3 (2003), and Korean Highway Bridge Design Specifications (2010). The comparison showed that the proposed bending moment formulae can reasonably predict the ultimate moment capacity of thin-walled flexural members.