• Title, Summary, Keyword: Effective buckling length

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Critical Load and Effective Buckling Length Factor of Dome-typed Space Frame Accordance with Variation of Member Rigidity (돔형 스페이스 프레임의 부재강성변화에 따른 임계좌굴하중과 유효좌굴길이계수)

  • Shon, Su-Deok;Lee, Seung-Jae
    • Journal of the Korean Association for Spatial Structures
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    • v.13 no.1
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    • pp.87-96
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    • 2013
  • This study investigated characteristics of buckling load and effective buckling length by member rigidity of dome-typed space frame which was sensitive to initial conditions. A critical point and a buckling load were computed by analyzing the eigenvalues and determinants of the tangential stiffness matrix. The hexagonal pyramid model and star dome were selected for the case study in order to examine the nodal buckling and member buckling in accordance with member rigidity. From the numerical results, an effective buckling length factor of adopted models was bigger than that of Euler buckling for the case of fixed boundary. These numerical models indicated that the influence of nodal buckling was greater than that of member buckling as member rigidity was higher. Besides, there was a tendency that the bifurcation appeared on the equilibrium path before limit point in the member buckling model.

Evaluation of Effective Length Factor by Using an Amplification Factor (확장계수를 적응한 기둥의 유효좌굴길이 계수 산정)

  • Choi, Dong-Ho;Yoo, Hoon;Shin, Jay-In;Kim, Sung-Yeon
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.369-374
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    • 2007
  • For a stability design of steel frames, AISC-LRFD specification recommend to use Alignment Chart and story-based methods in order to determine an effective budding length. Recently, elastic buckling analysis, which is the method that calculate the effective length of members using eigenvalue of the overall structure, has been widely used in practical design of steel frames because this method can be performed effectively and automatically by computers. However, it can in some cases lead to unexpectedly large effective length in column having small axial forces. Therefore, this paper propose a method using elastic buckling analysis, which estimate a proper effective buckling length for all members having a small axial force. For verification of proposed method, it is compared with system based approach and stiffness distribution factor method. As a result, proposed method can rationally solve a problem in some case of column having small axial force. Also, adoption range for proposed method is established.

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Buckling Design of Temporary Bridges Subjected to Both Bending and Compression (압축과 휨을 동시에 받는 가교량 주요부재의 좌굴설계)

  • So Byoung-Hoon;Kyung Yong-Soo;Bang Jin-Hwan;Kim Moon-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.977-984
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    • 2006
  • Generally main girders and steel piers of temporary bridges form the steel rahmen structure. In this study, the rational stability design procedure for main members of temporary bridges is presented using 3D system buckling analysis and second-order elastic analysis. 2 types of temporary bridges, which are possible to be designed and fabricated in reality, are chosen and the buckling design for them is performed considering load combinations of dead and live loads, thermal load, and wind load. Effective buckling length of steel piers, effects of live loads on effective length of main members, transition of ~id buckling modes, and effects of second-order analysis are investigated through case study of 2 temporary bridges.

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Out-of-Plane Elastic Buckling of X-Bracing System with Fixed Ends (고정 지점을 갖는 X-브레이싱의 탄성 면외 좌굴)

  • Moon, Ji-Ho;Yoon, Ky-Yong;Lee, Hak-Eun
    • 한국방재학회:학술대회논문집
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    • pp.293-296
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    • 2007
  • This study investigated the out-of-plane elastic buckling load and effective length factor of X-bracing system. The members of X-bracing system which are studied in this paper are rigidly attached to the structure at their end connections, and are pinned or rigidly connected at their point of intersection. The effective length factors are derived for the general case where the tension and compression brace have different material and geometrical properties.

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A Study on the Buckling Strength and Effective Length of Tubular Member with Gusset Plate Considering End Restraints (단부구속효과를 고려한 관통 가셋트 부착 강관부재의 좌굴내력 및 유효세장비 산정에 관한 연구)

  • Kim, Woo Bum
    • Journal of Korean Society of Steel Construction
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    • v.15 no.2
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    • pp.159-165
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    • 2003
  • A tubular member with through-gusset plate is often used to transmit axial compression in an electric transmission towers. In current code, the strength of tubular member is evaluated with an effective length factor k=0.9 without considering the deformation of boundary element. A buckling strength of member with end gusset plate is affected by stiffness ratio($\beta$) and the length ratio(G) between main tubular member and end gusset plate. In this study theoretical mechanism based on the elastic buckling behavior was investigated, and finite element analysis was performed to propose a formula for the buckling strength and effective length factor of tubular member in elsatic and inelastic ranges.

Determination of Effective Buckling Length of Plane Frames using Elastic and Inelastic System Buckling Analysis (탄성 및 비탄성 좌굴 고유치해석을 이용한 강뼈대구조의 유효좌굴길이)

  • Song, Ju-Young;Kyung, Yong-Soo;Kim, Moon-Young
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.18 no.2
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    • pp.169-179
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    • 2005
  • An improved method for evaluating effective buckling lengths of beam-column members in plane frames is newly proposed based on system inelastic buckling analysis. To this end, the tangent stiffness matrix of be am-column elements is first calculated using stability functions and then the inelastic buckling analysis method is presented. The scheme for determining effective length of individual members is also addressed. Design examples and numerical results ?uc presented to show the validity of the proposed method.

Buckling analysis of semi-rigid gabled frames

  • Rezaiee-Pajand, Mohammad;Shahabian, Farzad;Bambaeechee, Mohsen
    • Structural Engineering and Mechanics
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    • v.55 no.3
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    • pp.605-638
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    • 2015
  • It is intended to perform buckling analysis of steel gabled frames with tapered members and flexible connections. The method is based on the exact solutions of the governing differential equations for stability of a gabled frame with I-section elements. Corresponding buckling load and subsequently effective length factor are obtained for practical use. For several popular frames, the influences of the shape factor, taper ratio, span ratio, flexibility of connections and elastic rotational and translational restraints on the critical load, and corresponding equivalent effective length coefficient are studied. Some of the outcomes are compared against available solutions, demonstrating the accuracy, efficiency and capabilities of the presented approach.

A Proposed method of the Strength Calculation of Pipe Support (파이프 서포트의 내력 산정 방안)

  • 이영욱;최순주
    • Journal of the Korean Society of Safety
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    • v.16 no.1
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    • pp.59-64
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    • 2001
  • Even though there is a guideline for the required strength of pipe support in inspection, it does not mean the nominal strength which can be used for the form work design. And, Concrete Specification defines that the pipe support should be designed according to the steel design guidelines but the design details are not provided, such as buckling length and the sectional modulus, etc. For the better prediction of strength of pipe support, the slenderness ratio of support which reflects the boundary condition should be considered. In this paper, the elastic buckling formula based on the slenderness is derived. The formula contains the strength reduction factor that consider the strength deduction caused by initial lateral deformation and is 0.65 consistently regardless of boundary conditions. And the coefficient of effective buckling length is calculated from the experiment.

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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.

An Improved Stability Design of Steel Cable-Stayed Bridges using Second-Order Effect (2차효과를 고려한 강사장교의 개선된 좌굴해석)

  • Kyung Yong-Soo;Kim Nam-Il;Lee Jun-Sok;Kim Moon-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.993-1000
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    • 2006
  • Practical stability design method of main members of cable-stayed bridges is proposed and discussed through a design example. For this purpose, initial tensions of stay cables and axial forces of main members are firstly determined using initial shaping analysis of bridges under dead loads. And then the effective buckling length using system elastic/inelastic buckling analysis and bending moments considering $P-{\delta}-{\Delta}$ effect by second-order elastic analysis are calculated for main girder and pylon members subjected to both axial forces and moments, respectively. Particularly, load combinations of dead and live loads, in which maximum load effects due to live loads are obtained, are taken into account and effects of live loads on effective buckling lengths are investigated.

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