• Title, Summary, Keyword: Buckling

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Lateral buckling formula of stepped beams with length-to-height ratio factor

  • Park, Jong Sup
    • Structural Engineering and Mechanics
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    • v.18 no.6
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    • pp.745-757
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    • 2004
  • Lateral-torsional buckling moment resistances of I-shaped stepped beams with continuous lateral top-flange bracing under a single point load on the top flange and negative end moments were investigated. Stepped beam factors and a moment gradient correction factor suggested by Park et al. (2003, 2004) were used to develop new lateral buckling formula for beam designs. From the investigation of finite element analysis (FEA), new lateral buckling formula of beams with singly or doubly stepped member changes and with continuous lateral top-flange bracing subjected to a single point load on top flange and end moments were developed. The new design equation includes the length-to-height ratio factor to account for the increase of lateral-torsional buckling moment resistance as the increase of length-to-height ratio of stepped beams. The calculation examples for obtaining lateral-torsional buckling moment resistance using the new design equation indicate that engineers should easily determine the buckling capacity of the stepped beams.

Effect of lateral restraint on the buckling behaviour of plates under non-uniform edge compression

  • Bedair, Osama K.
    • Structural Engineering and Mechanics
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    • v.5 no.1
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    • pp.85-104
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    • 1997
  • The paper investigates the influence of lateral restraint on the buckling behaviour of plate under non-uniform compression. The unloaded edges are assumed to be partially restrained against translation in the plane of the plate and the distributions of the resulting forces acting on the plate are shown. The stability analysis is done numerically using the Galerkin method and various strategies the economize the numerical implementation are presented. Results are obtained showing the variation of the buckling load, from free edge translation to fully restrained, with unloaded edges simply supported, clamped and partially restrained against rotation for various plate aspect ratios and stress gradient coefficients. An apparent decrease in the buckling load is observed due to these destabilizing forces acting in the plate and changes in the buckling modes are observed by increasing the intensity of the lateral restraint. A comparison is made between the budding loads predicted from various formulas in stability standards based on free edge translation and the values derived from the present investigation. A difference of about 34% in the predicted buckling load and different buckling mode were found.

Thermomechanical buckling of rectangular, shear-deformable, composite laminated plates

  • Ge, Y.S.;Yuan, W.X.;Dawe, D.J.
    • Structural Engineering and Mechanics
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    • v.13 no.4
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    • pp.411-428
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    • 2002
  • The B-spline finite strip method is developed for the prediction of the buckling of rectangular composite laminated plates under the combined action of applied uniaxial mechanical stress and increasing temperature. The analysis is conducted in two stages, namely an in-plane stress analysis in the pre-buckling stage to determine the pre-buckling stresses, followed by a buckling analysis using these determined stresses. The buckling analysis is based on the use of first-order shear deformation plate theory. The permitted lay-up of the laminates is quite general, within the constraint that the plate remains flat prior to buckling, and a wide range of boundary conditions can be accommodated. A number of applications is described and comparison of the results generated using the finite strip method is made with the results of previous studies.

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

  • Moon, Jiho;Yi, Jongwon;Choi, Byung-Ho;Lee, Hak-Eun
    • Journal of The Korean Society of Civil Engineers
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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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Simplified method for prediction of elastic-plastic buckling strength of web-post panels in castellated steel beams

  • Liu, Mei;Guo, Kangrui;Wang, Peijun;Lou, Chao;Zhang, Yue
    • Steel and Composite Structures
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    • v.25 no.6
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    • pp.671-684
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    • 2017
  • Elastic-plastic shear buckling behaviors of the web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear force were investigated further using Finite Element Model (FEM) based on a sub-model, which took the upper part of the web-post under horizontal shear force to represent the whole web-post under vertical shear force. A simplified design method for the web-post elastic-plastic shear buckling strength was proposed based on simulation results of the sub-model. Proper boundary conditions were applied to the sub-model to assure that its behaviors were identical to those of the whole web-post. The equation to calculate the thin plate elastic shear buckling strength was adopted as the basic form to build the design equation for elastic-plastic buckling strength of the sub-model. Parameters that might affect the elastic-plastic shear buckling strength of the whole web-post were studied. After obtaining the vertical shear buckling strength of a sub-model through FEM, the shear buckling coefficient k can be obtained through the back analysis. A practical calculation method for k was proposed through curving fitting the parameter study results. The elastic-plastic shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the FEM and test results. And it was more precise than those obtained from EC3 based on the strut model.

A Study on Buckling Strengths for Steel Compression Members at High Temperatures (고온 강구조 압축재의 좌굴 강도에 관한 연구)

  • Choi, Hyun-Sik
    • Journal of the Korean Association for Spatial Structures
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    • v.19 no.2
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    • pp.73-81
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    • 2019
  • The high-temperature properties of mild steels were studied by comparing the test results of Kwon and the yield strength, tangent modulus predicted by the design provisions of ASCE and Eurocode(EC3). The column strengths for steel members at high temperatures were determined by the elastic and inelastic buckling strengths according to elevated temperatures. The material properties at high temperatures should be used in the strength evaluations of high temperature members. The buckling strengths obtained from the AISC, EC3 and approximate formula proposed by Takagi et al. were compared with ones calculated by the material nonlinear analysis using the EC3 material model. The newly simplified formulas for yield stress, tangent modulus, proportional limit and buckling strength which were proposed through a comparative study of the material properties and buckling strengths. The buckling strengths of proposed formulas were approximately equivalent to ones obtained from the formulas of Takagi et al. within 4%. They were corresponded to the lower bound values among the buckling strengths calculated by the design formulas and inelastic buckling analysis.

An Approximate Method for the Buckling Analysis of a Composite Lattice Rectangular Plate

  • Kim, Yongha;Kim, Pyunghwa;Kim, Hiyeop;Park, Jungsun
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.3
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    • pp.450-466
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    • 2017
  • This paper defines the modified effective membrane stiffness, bending stiffness considering the directionally dependent mechanical properties and mode shape function of a composite lattice rectangular plate, which is assumed to be a Kirchhoff-Love plate. It subsequently presents an approximate method of conducting a buckling analysis of the composite lattice rectangular plate with various boundary conditions under uniform compression using the Ritz method. This method considers the coupled buckling mode as well as the global and local buckling modes. The validity of the present method is verified by comparing the results of the finite element analysis. In addition, this paper performs a parametric analysis to investigate the effects of the design parameters on the critical load and buckling mode shape of the composite lattice rectangular plate based on the present method. The results allow a database to be obtained on the buckling characteristics of composite lattice rectangular plates. Consequently, it is concluded that the present method which facilitates the calculation of the critical load and buckling mode shape according to the design parameters as well as the parametric analysis are very useful not only because of their structural design but also because of the buckling analysis of composite lattice structures.

Case Study for Buckling Design of Temporary Bridges using System Buckling Analysis (시스템좌굴 해석법을 이용한 라멘형가교 주요부재의 좌굴설계에 관한 사례 연구)

  • Kyung, Yong Soo;So, Byoung Hoon;Bang, Jin Hwan;Kim, Moon Young
    • Journal of Korean Society of Steel Construction
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    • v.19 no.1
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    • pp.87-98
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    • 2007
  • 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 was presented using a 3D system buckling analysis and second-order elastic analysis. Six types of temporary bridges, which can be designed and fabricated in reality, were chosen and the buckling design for them was performed in consideration ofload combinations of dead and live loads, thermal load, and wind load. Effective buckling length of steel piers, transition of 3D buckling modes, and effects of second-order analysis were investigated through a case study involving six temporary bridges.

Reinforcement Effects of Buckling Member for Single-layer Latticed Dome (단층래티스 돔의 좌굴부재 보강효과에 관한 연구)

  • Jung, Hwan-Mok;Yoon, Seok-Ho;Lee, Dong-Woo
    • Journal of the Korean Association for Spatial Structures
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    • v.16 no.4
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    • pp.45-52
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    • 2016
  • The single layer latticed domes have attracted many designers and researchers's attention all of the world, because these structures as spatial structure are of great advantage in not only mechanical rationality but also function, fabrication, construction and economic aspect. But single layer latticed domes are apt to occur the unstable phenomena that are called "buckling" because of the lack of strength of members, instability of structural shape, etc. In the case of latticed dome, there are several types of buckling mode such as overall buckling, local buckling, and member buckling according to the shape of dome, section type of member, the size of member, junction's condition of member and so on. There are many methods to increase the buckling strength of the single layer latticed dome, that is, with the change of geometrical shape of dome, the reinforcement of buckled member, etc. Therefore, the purpose of this study is to verify the reinforcement effect of buckled member when designers reinforce the buckled member to increase the buckling strength of single layer latticed dome with 3-way grid.

Energy approach for dynamic buckling of shallow fixed arches under step loading with infinite duration

  • Pi, Yong-Lin;Bradford, Mark Andrew;Qu, Weilian
    • Structural Engineering and Mechanics
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    • v.35 no.5
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    • pp.555-570
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    • 2010
  • Shallow fixed arches have a nonlinear primary equilibrium path with limit points and an unstable postbuckling equilibrium path, and they may also have bifurcation points at which equilibrium bifurcates from the nonlinear primary path to an unstable secondary equilibrium path. When a shallow fixed arch is subjected to a central step load, the load imparts kinetic energy to the arch and causes the arch to oscillate. When the load is sufficiently large, the oscillation of the arch may reach its unstable equilibrium path and the arch experiences an escaping-motion type of dynamic buckling. Nonlinear dynamic buckling of a two degree-of-freedom arch model is used to establish energy criteria for dynamic buckling of the conservative systems that have unstable primary and/or secondary equilibrium paths and then the energy criteria are applied to the dynamic buckling analysis of shallow fixed arches. The energy approach allows the dynamic buckling load to be determined without needing to solve the equations of motion.