• 제목/요약/키워드: local buckling

검색결과 529건 처리시간 0.027초

Elastic local buckling of thin-walled elliptical tubes containing elastic infill material

  • Bradford, M.A.;Roufegarinejad, A.
    • Interaction and multiscale mechanics
    • /
    • 제1권1호
    • /
    • pp.143-156
    • /
    • 2008
  • Elliptical tubes may buckle in an elastic local buckling failure mode under uniform compression. Previous analyses of the local buckling of these members have assumed that the cross-section is hollow, but it is well-known that the local buckling capacity of thin-walled closed sections may be increased by filling them with a rigid medium such as concrete. In many applications, the medium many not necessarily be rigid, and the infill can be considered to be an elastic material which interacts with the buckling of the elliptical tube that surrounds it. This paper uses an energy-based technique to model the buckling of a thin-walled elliptical tube containing an elastic infill, which elucidates the physics of the buckling phenomenon from an engineering mechanics basis, in deference to a less generic finite element approach to the buckling problem. It makes use of the observation that the local buckling in an elliptical tube is localised with respect to the contour of the ellipse in its cross-section, with the localisation being at the region of lowest curvature. The formulation in the paper is algebraic and it leads to solutions that can be determined by implementing simple numerical solution techniques. A further extension of this formulation to a stiffness approach with multiple degrees of buckling freedom is described, and it is shown that using the simple one degree of freedom representation is sufficiently accurate for determining the elastic local buckling coefficient.

Local buckling and shift of effective centroid of cold-formed steel columns

  • Young, Ben
    • Steel and Composite Structures
    • /
    • 제5권2_3호
    • /
    • pp.235-246
    • /
    • 2005
  • Local buckling is a major consideration in the design of thin-walled cold-formed steel sections. The main effect of local buckling in plate elements under longitudinal compressive stresses is to cause a redistribution of the stresses in which the greatest portion of the load is carried near the supporting edges of the plate junctions. The redistribution produces increased stresses near the plate junctions and high bending stresses as a result of plate flexure, leading to ultimate loads below the squash load of the section. In singly symmetric cross-sections, the redistribution of longitudinal stress caused by local buckling also produces a shift of the line of action of internal force (shift of effective centroid). The fundamentally different effects of local buckling on the behaviour of pin-ended and fixed-ended singly symmetric columns lead to inconsistencies in traditional design approaches. The paper describes local buckling and shift of effective centroid of thin-walled cold-formed steel channel columns. Tests of channel columns have been described. The experimental local buckling loads were compared with the theoretical local buckling loads obtained using an elastic finite strip buckling analysis. The shift of the effective centroid was also compared with the shift predicted using the Australian/New Zealand and American specifications for cold-formed steel structures.

Elastic local buckling behaviour of corroded cold-formed steel columns

  • Nie Biao;Xu Shanhua;Hu WeiCheng;Chen HuaPeng;Li AnBang;Zhang ZongXing
    • Steel and Composite Structures
    • /
    • 제48권1호
    • /
    • pp.27-41
    • /
    • 2023
  • Under the long-term effect of corrosive environment, many cold-formed steel (CFS) structures have serious corrosion problems. Corrosion leads to the change of surface morphology and the loss of section thickness, which results in the change of instability mode and failure mechanism of CFS structure. This paper mainly investigates the elastic local buckling behavior of corroded CFS columns. The surface morphology scanning test was carried out for eight CFS columns accelerated corrosion by the outdoor periodic spray test. The thin shell finite element (FE) eigen-buckling analysis was also carried out to reveal the influence of corrosion surface characteristics, corrosion depth, corrosion location and corrosion area on the elastic local buckling behaviour of the plates with four simply supported edges. The accuracy of the proposed formulas for calculating the elastic local buckling stress of the corroded plates and columns was assessed through extensive parameter studies. The results indicated that for the plates considering corrosion surface characteristics, the maximum deformation area of local buckling was located at the plates with the minimum average section area. For the plates with localized corrosion, the main buckling shape of the plates changed from one half-wave to two half-wave with the increase in corrosion area length. The elastic local buckling stress decreased gradually with the increase in corrosion area width and length. In addition, the elastic local buckling stress decreased slowly when corrosion area thickness was relatively large, and then tends to accelerate with the reduction in corrosion area thickness. The distance from the corrosion area to the transverse and longitudinal centerline of the plate had little effect on the elastic local buckling stress. Finally, the calculation formula of the elastic local buckling stress of the corroded plates and CFS columns was proposed.

비대칭연단보강재가 설치된 직교이방성 압축재의 탄성 국부좌굴해석 (Analysis of Elastic Local Buckling of an Orthotropic Compression Member with Asymmetric Edge Stiffeners)

  • 최원창;정상균;윤순종
    • 한국복합재료학회:학술대회논문집
    • /
    • 한국복합재료학회 2000년도 추계학술발표대회 논문집
    • /
    • pp.5-8
    • /
    • 2000
  • This paper presents the analytical investigation pertaining to the local buckling behavior of orthotropic open section thin-walled compression members with asymmetric edge stiffeners. In the analysis, 3 different cases of the second moment of inertia are considered to find the asymmetric edge stiffener effect on the local buckling strength. The analytical study results are presented in the graphical form so that the edge stiffener effects on the local buckling strength can be easily found.

  • PDF

펄트루젼 구조용 휨부재의 국부좌굴 거동 (Local Buckling Behavior of Pultruded Structural Flexural Members)

  • 정재호;윤순종
    • 한국복합재료학회:학술대회논문집
    • /
    • 한국복합재료학회 2003년도 춘계학술발표대회 논문집
    • /
    • pp.147-151
    • /
    • 2003
  • In this study, we discussed the local buckling behavior of pultruded structural flexural members. Previous works were briefly reviewed and the local buckling behavior of orthotropic box-shape flexural members was discussed. The simplified form of equation for finding the width ratio of plate element of box-shape flexural members in which all plate components buckle simultaneously was proposed and the macro flow-chart for finding local buckling strength of pultruded flexural members was also suggested. To establish the design guide line for the local buckling of pultruded flexural members, further studies need to be performed as follows; the simplified form of solutions for finding the minimum buckling coefficient of orthotropic plate with various loading and boundary conditions including rotationally restrained boundary conditions, the simplified form of equation for calculating the coefficient of restraint provided by the adjacent plate elements.

  • PDF

직교이방성 I-Shape 압축재의 국부-전체 상호좌굴에 관한 해석적 연구 (An Analytical Study on the Local - global Interaction Buckling of Orthotropic I-Shape Compression Members)

  • 김학군;정상균;윤순종
    • 한국복합재료학회:학술대회논문집
    • /
    • 한국복합재료학회 2000년도 추계학술발표대회 논문집
    • /
    • pp.1-4
    • /
    • 2000
  • This paper presents the analytical results of local - global interaction buckling of orthotropic I-shape compression members. Employing the equilibrium approach, the characteristic equation for local and global interaction buckling of I-shape compression member is derived. Using the derived equation, the buckling coefficients with respect to the ratio of length to width for the I-shape column are suggested as a graphical form. In addition, graphical forms of local, global and FEM results are presents, and they are compared with those in published document.

  • PDF

I형강기둥의 국부좌굴 특성 (Local Buckling Characteristics of a column with I section)

  • 임종완;임장근
    • 한국자동차공학회논문집
    • /
    • 제2권4호
    • /
    • pp.18-26
    • /
    • 1994
  • The buckling characteristics of I - shaped columns which are composed of thin web and equal upper/lower flange plates are generally classified into the local and global modes. In this paper, its local buckling problem has been formulated on the basis of the assumed buckling modes using the finite element method for beams and plates. The effects of local bucklings are studied for various size rations and end conditions of I-shaped columns. The calculated results are comparatively well consistent with values obtained from the existing studies. The global buckling characteristics calculated by the present method are in good agreement with the classical rigid web solution

  • PDF

Effect of local web buckling on the cyclic behavior of reduced web beam sections (RWBS)

  • Akrami, Vahid;Erfani, Saeed
    • Steel and Composite Structures
    • /
    • 제18권3호
    • /
    • pp.641-657
    • /
    • 2015
  • Application of reduced web beam section (RWBS) as a sacrificial fuse element has become a popular research field in recent years. Weakening of beam web in these connections may cause local web buckling around the opening area which can affect cyclic behavior of connection including: maximum load carrying capacity, strength degradation rate, dissipated energy, rotation capacity, etc. In this research, effect of local web buckling on the cyclic behavior of RWBS connections is investigated using finite element modeling (FEM). For this purpose, a T-shaped moment connection which has been tested under cyclic loading by another author is used as the reference model. Fracture initiation in models is simulated using Cyclic Void Growth Model (CVGM) which is based on micro-void growth and coalescence. Included in the results are: effect of opening corner radii, opening dimensions, beam web thickness and opening reinforcement. Based on the results, local web buckling around the opening area plays a significant role on the cyclic behavior of connection and hence any parameter affecting the local web buckling will affect entire connection behavior.

모서리 곡률이 존재하는 상자형 단면 기둥의 좌굴 (Buckling Strength of Box-Shape Column with Corner Rounding)

  • 한금호;한택희;김기언;강영종
    • 한국전산구조공학회:학술대회논문집
    • /
    • 한국전산구조공학회 2004년도 봄 학술발표회 논문집
    • /
    • pp.325-331
    • /
    • 2004
  • Generally, the buckling of thin-walled structures has studied for rectangular sections or circular sections. Rectangular sections have small stiffness and circular sections have large stiffness when they are compared with rectangular sections for local buckling. But both of them have similar stiffness to column buckling. Therefore in this paper, we are going to analyze the local buckling for the box section with rounded comer and compare with rectangular section. Also we confirm that the rounded comer section has larger local buckling strength than rectangular section.

  • PDF

편심압축하중을 받는 사각튜브의 분기세장비 (Bifurcation Criterion in Eccentrically Compressed Rectangular Tubes)

  • 김천욱;한병기;정창현;김치균
    • 한국자동차공학회논문집
    • /
    • 제7권6호
    • /
    • pp.270-278
    • /
    • 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.

  • PDF