• Title, Summary, Keyword: 좌굴

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Buckling Analysis using Fictitious Axial Forces and Its Application to Cable-Stayed Bridges with HSB800 Steel (가상축력을 이용한 좌굴해석 및 HSB800 강재를 적용한 사장교에 대한 적용성 분석)

  • Choi, Dong Ho;Yoo, Hoon;Gwon, Sun Gil;Lim, Ji Hoon
    • Journal of Korean Society of Steel Construction
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    • v.29 no.1
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    • pp.13-24
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    • 2017
  • System buckling analysis is usually used to determine the critical buckling load in the buckling design of cable-stayed bridges. However, system buckling analysis may yield unexpectedly large effective lengths of the members subjected to a relatively small axial force. This paper proposes a new method to determine reasonable effective lengths of girder and tower members in steel cable-stayed bridges using fictitious axial forces. An improved inelastic buckling analysis with modified tangent modulus is also presented. The effective lengths of members in example bridges calculated using the proposed method are compared with those obtained using the conventional buckling analysis method. The proposed method provides much more resonable effective lengths of the members. When girder and tower members are built with HSB800 steel instead of conventional steel, the effective lengths of the members under a small axial force slightly decreases in the inelastic buckling analysis without fictitious axial forces, while the proposed method that considers fictitious axial forces provides almost no changes in such lengths.

A study on the Thermal Buckling and Postbuckling of a Laminated Composite Beam with Embedded SMA Actuators (형상기억합금 선을 삽입한 복합적층 보의 열좌굴 및 좌굴후 거동에 관한 연구)

  • Choi, S.;Lee, J.J.;Lee, D.C.
    • Composites Research
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    • v.12 no.3
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    • pp.55-65
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    • 1999
  • In this paper, the thermal buckling and postbuckling behaviour of composite beam with embedded shape memory alloy (SMA) wires are investigated experimentally and analytically. The results of thermal buckling tests on uniformly heated, clamped, composite beam embedded with SMA wire actuators are presented and discussed in consideration of geometric imperfections, slenderness ratio of beam and embedding position of SMA wire actuators. The shape recovery force can reduce the thermal expansion of composite laminated beam, which result in increment of the critical buckling temperature and reduction of the lateral deflection of postbuckling behaviours. It is presented quantitatively on the temperature-load-deflection behaviour records how the shape recovery force affects the thermal buckling. The cross tangential method is suggested to calculate the critical buckling temperature on the temperature-deflection plot. Based on the experimental analysis, the new formula is also proposed to describe the critical buckling temperature of a laminated composite beam with embedded SMA wire actuators.

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Development of Buckling Restrained Brace Laterally Supported by Semicircular Springs (반원형 스프링으로 횡지지된 건식형 좌굴방지가새의 개발)

  • Park, Keum Sung;Lee, Sang Sup;Hong, Sung Yub;Bae, Kyu Woong
    • Journal of Korean Society of Steel Construction
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    • v.26 no.6
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    • pp.549-558
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    • 2014
  • Buckling restrained braces(BRBs) developed as a seismic protection element, hysteretic damper, have been investigated in America and Japan mainly. BRBs are composed of a steel core and concrete-filled steel casing. It is one of the major causes of drop in productivity to fill the steel casing with concrete. To improve this problem, the BRB is introduced in which the steel core is restrained with a pair of semicircular springs. In this paper, the numerical and analytical investigation about the desirable configuration for a semicircular spring is presented. Firstly, the stiffness and strength of semicircular spring is determined theoretically to buckle into a very high-order modes. Then, the required stiffness and strength are calculated under the practical design conditions and considered as reference values to find a proper configuration. The material strength and thickness of semicircular spring are chose from the finite element analysis for 5 semicircular springs with varying height. Finally, the nonlinear buckling analysis of BRB with proper semicircular springs shows that the bucking strength of the whole BRB is very similar to the strength of steel core with length between semicircular springs.

The Development on the Buckling Strength Estimation Formula of Plate Members in Consideration of Inplane Tension(I) (면내인장력을 고려한 판부재의 좌굴강도 평가식 개발 (I))

  • Ham, Juh H.;Kim, Ul N.;Chung, Yun S.
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.2
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    • pp.111-118
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    • 1996
  • Ship structure basically consists of plate members and it's overall strength depends an the stiffness and strength of each plate member. The buckling strength of plate is one of the most important design criteria when we investigate the structural intergraty. Therefore, it is necessary to surly reasonable buckling formula in order to carry out a more efficient and reliable design. In the present study, the buckling design formula of plate panels under combined loads(inplane compression, tension and shear) is obtained on the theoretical solution or reference paper. This formula is compared with the existing theoretical solution, other author's formula[1], design codes of LR and results which are obtained by numerical analysis. It has a good correlation with numerical analysis results or theoretical ones. When we evaluate buckling strength of plate panels, this formula can be presented with reasonable accuracy.

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Buckling Analysis of Inelastic Steel Members (비탄성 강재 부재의 좌굴 해석)

  • Gil, Heung-Bae
    • Journal of Korean Society of Steel Construction
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    • v.12 no.1
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    • pp.29-43
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    • 2000
  • In this study, the computationally efficient inelastic buckling analysis program is developed to be used as the research tool in finding buckling strength of inelastic members. The program can determine buckling loads and buckled shapes of elastic and inelastic members which failed by flexural, lateral-torsional and/or local buckling. It can analyze singly and doubly symmetric I-shape members. In the program, the web of the member is modeled using the plate element and the flanges are modeled by beam elements. Multilinear isotropic hardening rule and the incremental theory of plasticity are used to simulate the inelastic stress-strain relationship from material tests. The program is verified using theoretical solutions and experimental results. The results from the program show good agreement with those from experiments and theory.

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Buckling Strength of Orthogonally Stiffened Steel Plates under Uniaxial Compression (일축압축을 받는 직교로 보강된 판의 좌굴강도)

  • Choi, Dong Ho;Chang, Dong Il;Choi, Hang Yong
    • Journal of Korean Society of Steel Construction
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    • v.10 no.4
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    • pp.731-740
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    • 1998
  • Orthogonally stiffened steel plates are used for orthotropic steel decks of long-span bridges because of high degree of flexural and torsional resistances and good load-distribution behavior. An analytic study is presented for evaluating the buckling strength of orthogonally stiffened plates subjected to uniaxial compression. By using the plate theory, the buckling stress under overall and partial buckling modes, is derived. Parametric studies are performed to show the effects of the stiffness and the number of transverse and longitudinal ribs on the buckling strength. The results show quantitatively strong influence of stiffness and spacing of longitudinal and transverse ribs.

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Buckling Sensitivity of Laminated Composite Pipes Under External Uniform Pressure Considering Ply Angle (등분포하중을 받는 복합재료 관로의 적층각 변화에 따른 좌굴 민감도 분석)

  • Han, Taek Hee;Na, Tae Soo;Han, Sang Yun;Kang, Young Jong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.3
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    • pp.123-131
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    • 2007
  • The buckling behavior of a fiber reinforced plastic pipe was researched. When a cylindrical structure is made of isotropic material, it shows two dimensional buckled shape which has same deformed section along the longitudinal direction. But an anisotropic cylindrical structure shows three dimensional buckled shape which has different deformed section along the longitudinal direction. Because the modulus of elasticity is varied in a certain direction when ply angles are changed, the strength of a pipe are changed as ply angles are changed. In this study, the limitation of two dimensional and three dimensional buckling mode was investigated and the buckling strength of a laminated composite pipe was evaluated.

Stability and Post-buckling Analysis of Stiffened Plate and Shell Structures (보강된 판 및 쉘구조의 좌굴 및 후좌굴해석)

  • 김문영;최명수;민병철
    • Computational Structural Engineering
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    • v.11 no.4
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    • pp.155-168
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    • 1998
  • 보강된 판 및 쉘구조의 안정성 및 후좌굴을 포함하는 기하학적 비선형 해석을 수행하기 위하여, total Lagrangian formulation에 근거한 연속체의 증분평형방정식으로부터 변형된 쉘요소인 유한요소이론을 제시하였다. 쉘구조의 곡률이 불연속적으로 변하거나 쉘부재들이 유한한 각도로 만나는 보강된 판 및 쉘구조의 비선형 해석이 가능하도록 주부재와 보강재 간의 연결점에 대한 일반적인 변환관계를 제시하였으며 좌굴해석 및 기하학적 비선형해석의 경우에 해의 정확성 및 수렴성을 개선시키기 위하여 접선강도행렬 산정시 회전각의 2차항을 포함시켰다. 또한, shear locking 현상을 극복하기 위하여 감차적분을 적용하였고 쉘구조의 좌굴해석에서는 power method를 적용하여 해석의 효율을 높였으며, 후좌굴해석에서는 변위 및 하중증분법을 적절히 결합시켜 보강된 쉘구조의 후좌굴 거동추적이 용이하였다. 또한, 입력자료를 손쉽게 준비하고 좌굴모드 및 후좌굴거동을 효율적으로 분석하기 위하여 전, 후 처리 프로그램을 개발하였고 다양한 해석예제를 통하여 다른 문헌의 해석결과를 비교함으로써 본 연구에서 개발된 유한요소 해석프로그램의 타당성 및 정확성을 입증하였다.

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Out-of-Plane Effective Length Factor of X-Bracing System (X-브레이싱의 면외 유효 좌굴길이 계수)

  • Moon, Ji Ho;Yoon, Ki Yong;Lee, Hak Eun
    • Journal of Korean Society of Steel Construction
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    • v.19 no.1
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    • pp.129-137
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    • 2007
  • In this study, the elastic out-of-plane buckling load and the effective length factor of X-bracing systems were studied. Points of the intersection of diagonals were modeled as a rigid connection or a pinned connection depending on the connection method of diagonals. The boundary condition of the intersection influences the buckling load of X-bracing systems. For each boundary condition of the intersection, effective out-of-plane length factors of X-bracing systems were derived as a function of the length ratio of tension and compression diagonals $L_P$/$L_T$, the applied force ratio of tension and compression diagonals T/P, and the Euler buckling load ratio of tension and compression diagonals $P_{ET}$/$P_{EP}$. The proposed effective out-of-plane length factors of X-bracing systems were compared with the results of previous researchers and those of the finite element analysis and their properties were verified. Finally, the effects of the boundary condition of the intersection on the out-of-plane buckling load of X-bracing systems were investigated.

Shear Design of Trapezoidally Corrugated Steel Webs (제형 파형강판 복부판의 전단 설계)

  • Moon, Jiho;Yi, Jongwon;Choi, Byung-Ho;Lee, Hak-Eun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.4A
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    • pp.497-505
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    • 2008
  • Corrugated steel webs resist only shear force because of the accordion effects. The shear force in the web can cause three different buckling mode: local, global, and interactive shear buckling modes. The shear behavior of the corrugated steel webs have been investigated by several researchers. However, shear buckling behavior of the corrugated webs are not clearly explained yet. And, it lead the conservative design. This paper presents shear strength of trapezoidally corrugated steel webs. A series of the tests were also conducted to verified proposed shear strength. Firstly, local, global, and interactive shear buckling equations provided by previous researchers were rearranged as a simple form considering the profiles of the existing bridges with corrugated steel webs. And, global and interactive shear buckling coefficient, and shear buckling parameter for corrugated webs were suggested in this study. Inelastic buckling strength can be determined from buckling curves based on the proposed shear buckling parameter. From the test results of this study and those of previous researchers, it can be found that suggested shear strength provides good estimation of those of trapezoidally corrugated steel webs.

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