• Title, Summary, Keyword: Lateral 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.

Elastic lateral-distortional buckling of I-beams and the Meck Plot

  • Zirakian, Tadeh;Nojoumi, Seyed Ali
    • Structural Engineering and Mechanics
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    • v.37 no.3
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    • pp.297-307
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    • 2011
  • Meck Plot is an adapted version of the well-known Southwell method to the case of lateral-torsional buckling, which indeed reflects the physical inter-dependence of lateral flexure (lateral displacement) and torsion (rotation) in the structure. In the recent reported studies, it has been shown experimentally and theoretically that lateral displacement of an I-beam undergoing elastic lateral-distortional mode of buckling is interestingly directly coupled with other various deformation characteristics such as web transverse strain, web longitudinal strain, vertical deflection, and angles of twist of top and bottom flanges, and consequently good results have been obtained as a result of application of the Meck's method on lateral displacement together with each of the aforementioned deformation variables. In this paper, it is demonstrated that even web transverse and longitudinal strains, vertical deflection, and angles of twist of top and bottom flanges of an I-beam undergoing elastic lateral-distortional buckling are two-by-two directly coupled and the application of the Meck Plot on each pair of these deformation variables may still yield reliable predictions for the critical buckling load.

Analytical and Parametric Investigations on Lateral Torsional Buckling of European IPE and IPN Beams

  • Yilmaz, Tolga;Kirac, Nevzat
    • International journal of steel structures
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    • v.17 no.2
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    • pp.695-709
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    • 2017
  • Lateral torsional buckling is one of the main failure modes controlling the strength of the slender thin-walled members. A transversely or transversely and axially combined loaded member that is bent with respect to its axis of greatest flexural rigidity may buckle laterally and twist as applied load reaches its critical value unless the beam is provided with a sufficient lateral support. This study intends to present a unique convenient equation that it can be used for calculating critical lateral-torsional buckling load of simply supported European IPE and IPN beams. First, an analytical model is introduced to describe lateral-torsional buckling behavior of beams with monosymmetric cross-section. The analytical model includes first order bending distribution, load height level and monosymmetry property of the section. Then, parametric study is carried out using the analytical solutions in order to establish a simplified equation with dimensionless coefficients. The effect of slenderness and loading positions on lateral-torsional buckling behavior of IPE and IPN beams are studied. The proposed solutions are compared to finite element simulations where thin-walled shell elements and beam elements including warping are used. Good agreement between the analytical, parametric and numerical solutions is demonstrated. It is found out that the lateral-torsional buckling load of European IPE and IPE beams can be determined by presented equation and can be safely used in design procedures.

Inelastic distortional buckling of hot-rolled I-section beam-columns

  • Lee, Dong-Sik
    • Steel and Composite Structures
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    • v.4 no.1
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    • pp.23-36
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    • 2004
  • The inelastic lateral-distortional buckling of doubly-symmetric hot-rolled I-section beam-columns subjected to a concentric axial force and uniform bending with elastic restraint which produce single curvature is investigated in this paper. The numerical model adopted in this paper is an energy-based method which leads to the incremental and iterative solution of a fourth-order eigenproblem, with very rapid solutions being obtained. The elastic restraint considered in this paper is full restraint against translation, but torsional restraint is permitted at the tension flange. Hitherto, a numerical method to analyse the elastic and inelastic lateral-distortional buckling of restrained or unrestrained beam-columns is unavailable. The prediction of the inelastic lateral-distortional buckling load obtained in this study is compared with the inelastic lateral-distortional buckling of restrained beams and the inelastic lateral-torsional buckling solution, by suppressing the out-of-plane web distortion, is published elsewhere and they agree reasonable well. The method is then extended to the lateral-distortional buckling of continuously restrained doubly symmetric I-sections to illustrate the effect of web distortion.

Lateral buckling of thin-walled members with openings considering shear lag

  • Wang, Quanfeng
    • Structural Engineering and Mechanics
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    • v.5 no.4
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    • pp.369-383
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    • 1997
  • The classical theory of thin-walled members is unable to reflect the shear lag phenomenon since it is based on the assumption of no shearing strains in the middle surface of the walls. In this paper, an energy equation for the lateral buckling of thin-walled members has been derived which includes the effects of torsion, warping and, especially, the shearing strains which reflect the shear lag phenomenon. A numerical analysis for the lateral buckling of thin-walled members with openings by using Galerkin's method of weighted residuals has been presented. The proposed numerical values and the predictions by experiment for the lateral buckling loads are to agree closely in the paper. The results from these comparisons show that the proposed method here is capable of predicting the lateral buckling of thin-walled members with openings. The fast convergence of the results indicates the numerical stability of the method. By the study, a very complex practical eigenvalue problem is transformed into a very simple one of solving only a linear equation with one variable.

Buckling Length Analysis for Compression Chord in Cold-Formed Steel Cantilever Truss

  • Konkong, Nirut;Aramraks, Trakool;Phuvoravan, Kitjapat
    • International journal of steel structures
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    • v.17 no.2
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    • pp.775-787
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    • 2017
  • The lateral buckling of a cold-formed steel truss structure was investigated. Both an experimental test and finite element analysis presented a good correlation in the failure mechanism of specimens. The critical buckling load of the compression truss chord was analyzed using a South well plot and the analytical method. The transfer matrix method and the governing equation of an Euler column were used to analyze the critical buckling load of a multi-step, uniform chord member with lateral spring supports. Expressions for the buckling length factor presented according to AISI (2012) and the EN 1993-1-3 (2006) specification were compared by experimental testing and the analytical method. The buckling length factor of the experimental test and the analytical model confirmed that the buckling length of a compressed truss chord was less than the distance between the lateral bracing.

Numerical Study on Lateral Buckling of Fully Bonded Sandwich Pipes

  • Wang, Zhe;Chen, Zhihua;He, Yongyu;Liu, Hongbo
    • International journal of steel structures
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    • v.17 no.3
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    • pp.863-875
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    • 2017
  • Sandwich pipes (SP) are promising subsea pipelines for deep-water applications. Thus, their lateral buckling response is a significant design aspect. The temperature field of SP denotes the load in lateral buckling analysis, and it is calculated using the heat transfer differential equation in this study. A general temperature field formula is proposed for an arbitrary multilayer SP, and this formula is verified by finite element models. Another finite element model based on the fiber shell element is then constructed to investigate the lateral buckling response of SP. They are validated by existing experimental and numerical results. The evolution of the lateral buckling profiles and of stress distribution are studied in consideration of nonlinear pipe-soil interaction and nonlinear material constitutive law. Moreover, the influence of initial imperfections and pipe-soil interaction on lateral buckling response is examined. Finally, a formula is approximated for a SP with a half-wave sinusoidal imperfection profile on the basis of dimensionless analysis and numerical results. This formula is convenient for engineering applications.

A Study On Lateral Buckling Of H-Section Steel Beams (H형(形) 강(鋼) 보의 횡좌굴(橫挫屈)에 관(關)한 연구(硏究))

  • Kim, Seok-Jung
    • Journal of Industrial Technology
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    • v.4
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    • pp.29-35
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    • 1984
  • Buckling is a significant behavior to be considered whenever we design steel structures. In the case of H-shape beams, the lateral buckling occured by bending moment must be considered. Because of the lateral buckling of H-shape beams, the bending strength of the beams are determined by the lateral buckling stress instead of the allowable bending stress. Lateral buckling stress equation, consisting of two terms, i. e. ${\sigma}_{cr}({\nu},{\omega})={\sqrt{[{\sigma}_{cr}({\nu})]^2+[{\sigma}_{cr}({\omega})]^2}}$ has been using, but for the practical purpose of use the following equations are using two, i. e. ${\sigma}_{cr}({\nu})={\frac{0.65E}{{\ell}_h/A_f}}$, ${\sigma}_{cr}({\omega})={\frac{{\pi}^2E}{({\ell}_b/i_b)^2}}$. When we use the above equations, the results are different according to the shape of beam section, and they a re rather complex. In this study lateral buckling stress equation is derived, and the proposed formula$({\sigma}_{cr}(t))$ is compared with above mentioned two basic and practical equations. To verify the proposed formula experimentaly, 16H-shape beams which have different slender ratios arc tested by applying pure bending momet. Through the experiments the buckling behavior of H-shape beams is clarified, and the results shows that the proposed formula$({\sigma}_{cr}(t))$ is accurate enough for practical purpose.

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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.

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.