• Title, Summary, Keyword: Buckling

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Studies on the Cylindrical Shell Buckling of Weft Knit (편성물의 원통형 좌굴에 관한 연구)

  • 박근순;노정익
    • Textile Science and Engineering
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    • v.28 no.1
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    • pp.25-35
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    • 1991
  • This is a study on the application of cylindrical shell buckling to weft plain stitch-knit fabrics made of cotton ems, which are related to bending deformations affecting textile products, especially hands and wrinkles of shell type apparel. Following conclusions were derived from the studies of cylindrical shell buckling under axial compressions and from the considerations of applicability of buckling theories to typical orthotropic knit fabric supposing as thin homogenous isotropic shell. 1. An apparatus for preparing and clamping specimens, and experimental methods were designed to be possible to measure cylindrical shell buckling properties under the action of uniform axial compression with a general strength tester. 2. Comparing the tendencies of critical buckling stresses to the various yarn numbers and cover factors of weft knit fabrics with the theoretical critical buckling stresses, the absolute values were found to be about 60℃ of theoretical values. 3. Bending stiffnesses calculated with the young's modulus obtained from buckling experiments were found to be fitted approximately with the results form pure bending tester.

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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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Parametric Study of Thermal Stability on Continuous Welded Rail

  • Choi, Dong-Ho;Na, Ho-Sung
    • International Journal of Railway
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    • v.3 no.4
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    • pp.126-133
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    • 2010
  • The thermal buckling analysis of curved continuous welded rail (CWR) is studied for the lateral buckling prevention. This study includes a thermal buckling theory which accounts for both thermal and vehicle loading effects in the evaluation of track stability. The parameters include rail size, track lateral resistance, track longitudinal and torsional stiffnesses, initial misalignment amplitude and wavelength, track curvature, tie-ballast friction coefficient and truck center spacing. Parametric studies are performed to evaluate the effects of the individual parameters on the upper and lower critical buckling temperatures. The results show that the upper critical buckling temperature is highly affected by the uplift due to vehicle loads. This study provides a guideline for the improvement of stability for dynamic buckling in curved CWR track.

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Inelastic lateral-torsional buckling strengths of stepped I-beams subjected to general loading condition

  • Park, Jong Sup;Park, Yi Seul
    • Structural Engineering and Mechanics
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    • v.48 no.2
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    • pp.275-289
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    • 2013
  • The cross sections of multi-span beams are sometimes suddenly increased at the interior support of continuous beams to resist high negative moment. An earlier study on elastic lateral torsional buckling of stepped beams was conducted to propose new design equations. This research aims to continue the earlier study by considering the effect of inelastic buckling of stepped beams subjected to pure bending and general loading condition. A three-dimensional finite element-program ABAQUS and a statistical program MINITAB were used in the development of new design equations. The inelastic lateral torsional buckling strengths of 36 and 27 models for singly and doubly stepped beams, respectively, were investigated. The general loading condition consists of 15 loading cases based on the number of inflection point within the unbraced length of the stepped beams. The combined effects of residual stresses and geometrical imperfection were also considered to evaluate the inelastic buckling strengths. The proposed equations in this study will definitely improve current design methods for the inelastic lateral-torsional buckling of stepped beams and will increase efficiency in building and bridge design.

A Study on Buckling Characteristics of Arch-type Vinyl House Structures according to Analytical Precision (아치형 비닐하우스 구조의 해석정밀도에 따른 좌굴특성 연구)

  • Yoon, Seok-Ho
    • Journal of the Korean Association for Spatial Structures
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    • v.15 no.4
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    • pp.57-64
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    • 2015
  • The construction of vinyl greenhouses are increasing because of economic feasibility, construction period, and construction regulations. However, the vinyl greenhouses are apt to collapse by snow load since they have a small member as a temporary structure. The 3 types of buckling such as global, member and nodal buckling could be occurred to arched structures according to characteristics of cross section. To examine the member buckling, the precision of analysis need to be enhanced. In that case, we can examine the characteristics of the those buckling. The purposes of this study are to verify buckling characteristics of structures using the method of high precision analysis with a center node of member. The results of high precision analysis bring member buckling, and in the analysis method having the center node of member, the value of strength is getting lower than a previous study.

Distortional and local buckling of steel-concrete composite box-beam

  • Jiang, Lizhong;Qi, Jingjing;Scanlon, Andrew;Sun, Linlin
    • Steel and Composite Structures
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    • v.14 no.3
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    • pp.243-265
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    • 2013
  • Distortional and local buckling are important factors that influences the bearing capacity of steel-concrete composite box-beam. Through theoretical analysis of distortional buckling forms, a stability analysis calculation model of composite box beam considering rotation of steel beam top flange is presented. The critical bending moment calculation formula of distortional buckling is established. In addition, mechanical behaviors of a steel beam web in the negative moment zone subjected separately to bending stress, shear stress and combined stress are investigated. Elastic buckling factors of steel web under different stress conditions are calculated. On the basis of local buckling analysis results, a limiting value for height-to thickness ratio of a steel web in the elastic stage is proposed. Numerical examples are presented to verify the proposed models.

Position optimization of circular/elliptical cutout within an orthotropic rectangular plate for maximum buckling load

  • Choudhary, Prashant K.;Jana, Prasun
    • Steel and Composite Structures
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    • v.29 no.1
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    • pp.39-51
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    • 2018
  • Position of a circular or elliptical cutout within an orthotropic plate has great influence on its buckling behavior. This paper aims at finding the optimal position (both location and orientation) of a single circular/elliptical cutout, within an orthotropic rectangular plate, that maximizes the critical buckling load. We consider linear buckling of simply supported orthotropic plates under uniaxial edge loads. To obtain the optimal positions of the cutouts, we have employed a MATLAB optimization routine coupled with buckling computation in ANSYS. Our results show that the position of the cutout that maximizes the buckling load has great dependence on the material properties, laminate configurations, and the geometrical parameters of the plate. These optimal results, for a number of plate geometries and cutout sizes, are reported in this paper. These results will be useful in the design of perforated orthotropic plates against buckling failure.

Buckling behavior of composite cylindrical shells with cutout considering geometric imperfection

  • Heidari-Rarani, M.;Kharratzadeh, M.
    • Steel and Composite Structures
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    • v.30 no.4
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    • pp.305-313
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    • 2019
  • Creating different cutout shapes in order to make doors and windows, reduce the structural weight or implement various mechanisms increases the likelihood of buckling in thin-walled structures. In this study, the effect of cutout shape and geometric imperfection (GI) is simultaneously investigated on the critical buckling load and knock-down factor (KDF) of composite cylindrical shells. The GI is modeled using single perturbation load approach (SPLA). First, in order to assess the finite element model, the critical buckling load of a composite shell without cutout obtained by SPLA is compared with the experimental results available in the literature. Then, the effect of different shapes of cutout such as circular, elliptic and square, and perturbation load imperfection (PLI) is investigated on the buckling behavior of cylindrical shells. Results show that the critical buckling load of a shell without cutout decreases by increasing the PLI, whereas increasing the PLI does not have a great impact on the critical buckling load in the presence of cutout imperfection. Increasing the cutout area reduces the effect of the PLI, which results in an increase in the KDF.

A method for analyzing the buckling strength of truss structures

  • Pan, Yi;Gu, Renqi;Zhang, Ming;Parke, Gerry;Behnejad, Alireza
    • Earthquakes and Structures
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    • v.16 no.2
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    • pp.129-139
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    • 2019
  • This paper develops a new method for estimating the elastic-plastic buckling strength of the truss structures under the static and seismic loads. Firstly, a new method for estimating the buckling strength of the truss structures was derived based on the buckling strength of the representative member considering the parameters, such as the structure configurations, boundary conditions, etc. Secondly, the new method was verified through the buckling strength estimation and the finite element method (FEM) analysis of the single member models, portal frame models and simple truss models. Finally, the method was applied to evaluate the buckling strength of a simple truss structure under seismic load, and the failure loads between the proposed method and the FEM were analyzed reasonably. The results show that the new method is feasible and reliable for structure engineers to estimate the buckling strengths of the truss structures under the static loads and seismic loads.

Nonlinear buckling and post-buckling of functionally graded CNTs reinforced composite truncated conical shells subjected to axial load

  • Do, Quang Chan;Pham, Dinh Nguyen;Vu, Dinh Quang;Vu, Thi Thuy Anh;Nguyen, Dinh Duc
    • Steel and Composite Structures
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    • v.31 no.3
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    • pp.243-259
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    • 2019
  • This study deals with the nonlinear static analysis of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) truncated conical shells subjected to axial load based on the classical shell theory. Detailed studies for both nonlinear buckling and post-buckling behavior of truncated conical shells. The truncated conical shells are reinforced by single-walled carbon nanotubes which alter according to linear functions of the shell thickness. The nonlinear equations are solved by both the Airy stress function and Galerkin method based on the classical shell theory. In numerical results, the influences of various types of distribution and volume fractions of carbon nanotubes, geometrical parameters, elastic foundations on the nonlinear buckling and post-buckling behavior of FG-CNTRC truncated conical shells are presented. The proposed results are validated by comparing with other authors.