Torsional, flexural and torsional-flexural buckling of angle section members – an analytical approach (original) (raw)
Related papers
Equal-leg single angle section (SAS) members were analyzed for flexural loading patterns along the geometric axis. Uniform, triangular, double-curvature and parabolic bending moment were produced using loading patterns over the span of member. Variations in orientation as well as in local and global slenderness ratio were considered to plot normalized moment rotation curves. Both material and geometrical nonlinearities with imperfections in member were also incorporated. These curves were compared with the existing provisions of AISC specification to verify the validity of the upper limit on C b , which accounts for the effect of loading patterns on the elastic critical buckling moment of SAS members. Design specifications of Indian Standard (IS 800: 2007) for lateral-torsional buckling (LTB) of doubly and mono-symmetric sections were used to develop the design guidelines for limit state of LTB of SAS members. Moment capacity curves from proposed guidelines were compared with the AISC specification and were found to be safe and conservtive.
An Abridged Review of Buckling Analysis of Compression Members in Construction
Buildings, 2021
The column buckling problem was first investigated by Leonhard Euler in 1757. Since then, numerous efforts have been made to enhance the buckling capacity of slender columns, because of their importance in structural, mechanical, aeronautical, biomedical, and several other engineering fields. Buckling analysis has become a critical aspect, especially in the safety engineering design since, at the time of failure, the actual stress at the point of failure is significantly lower than the material capability to withstand the imposed loads. With the recent advancement in materials and composites, the load-carrying capacity of columns has been remarkably increased, without any significant increase in their size, thus resulting in even more slender compressive members that can be susceptible to buckling collapse. Thus, nonuniformity in columns can be achieved in two ways—either by varying the material properties or by varying the cross section (i.e., shape and size). Both these methods ar...
Torsional Buckling Analysis of a Bar Member
Recent Developments in Sustainable Infrastructure, 2020
During buckling of column, it is assumed that the column would buckle as the cross section bends in the plane of symmetry. But in some problems of buckling failures of column, it would be either due to twisting or due to combined effect of bending and twisting. Such a combined effect of bending and twisting in a structure is known as torsional buckling. In the present work, a thin-walled bar of cross section (b × t) with the length 'l' is studied by applying uniform axial compression. The differential equation for the deflection curve and the differential equation for torsional buckling are presented. The expressions for total moment, torque and torque per unit length are derived and finally the expressions for the critical stresses and critical load for torsional buckling failure are derived. A numerical example is solved. The critical stress and critical load are calculated.
Local Buckling Strength of Uniformly Compressed Octagonal Thin Walled Section Members
Journal of Structural and Construction Engineering (Transactions of AIJ)
Cold-formed steel members are widely applied in columns and other axial members in steel structures. One of the key issues in design of cold formed steel is local buckling strength under axial compression. As a means to avoid premature local buckling, we have paid an attention to the application of octagonal section members. In this paper, we conducted numerical analyses (Finite Strip Analysis and Finite Element Analysis) and stab column tests, to investigate both the elastic and the post buckling strengths of octagonal section members including those where the adjacent plate elements have different width-thickness ratios. These tests and numerical analysis results indicated that the post buckling strengths of the plate elements were affected by the restraining effect from the adjacent plate elements. However, the overall strengths of the members were in line with those estimations by the traditional effective-width method, where simply supported conditions were assumed. This was caused possibly by a trade-off effect between the adjacent plate elements on their local buckling strengths.
A New Approach to Buckling Analysis of Lattice Composite Structures
Journal of Solid Mechanics, 2017
Buckling strength of composite latticed cylindrical shells is one of the important parameters for studying the failure of these structures. In this paper, new governing differential equations are derived for latticed cylindrical shells and their critical buckling axial loads. The nested structure under compressive axial buckling load was analyzed. Finite Element Method (FEM) was applied to model the structure in order to verify the analytical results. The obtained results were validated based upon the results of previous case studies in literature. For the squared type of lattice composite shells, a new formula for the buckling load was developed and its value was compared to the critical load, using FEM with 3D beam elements. The processes were carried out for three different materials of Carbon/Epoxy, Kevlar/Epoxy and EGlass/Epoxy.
Advances in Mechanical Engineering, 2019
This article investigates the elastic compound buckling behavior of latticed columns with three lacing systems under two boundary conditions. Valid numerical method named SEM, that conducts buckling analysis using strain energy of bars and potential energy of chords, was built to address flexural, torsional, and flexural-torsional buckling loads along with their overall and local buckling deformations. Eurocode 3 and finite element software ABAQUS were used to validate the auxiliary of SEM. Through the research on X-lacing, E-lacing, and K-lacing latticed columns under two boundary conditions, the rigidity of bars was found to exceed a threshold value affecting the linear buckling load. When the cross-sectional area of lacing bars tends to 0 or threshold value, Eurocode 3 guidelines were imprecise in forecasting the linear buckling load. Eccentricity and geometric imperfections would decrease the buckling capacity of built-up columns substantially. The K-lacing columns respond more sensitively on local imperfections than the Xlacing and E-lacing columns under simply supported condition. However, for the columns under cantilever state, local imperfections have no significant impact for the three lacing columns. In addition, the numerical results of nonlinear buckling load and equilibrium path from SEM considering geometric imperfections are close to the output of finite element method, validating the accuracy of SEM.
Thin-walled Structures, 2019
In this work, an appraisal of the influence of the residual stresses and geometric imperfections is carried out for thin-walled I-shaped sections covering both hot-rolled and welded profiles based on a numerical study using the Finite Element Method. The Eurocode 3 design provisions for local buckling are presented and evaluated in comparison to the numerical results. Several residual stress patterns and geometric imperfection's amplitude and shape are considered to determine their effect on the ultimate strength of the cross-sections. Additionally, it is described a procedure to assess the flange and web interaction under different imperfection assumptions, and its influence investigated. The conclusions from this study are that the Eurocode 3 design provisions for hot-rolled sections are appropriate, but should be further improved for welded sections, mainly because the influence of the welded residual stresses is detrimental for the cross-section capacity and its effect is not to accounted for adequately. Finally, this study provides relevant information for the numerical modelling of thin-walled I-shaped sections concerning the consideration of geometrical imperfections and residual stresses. Regardless of the efforts of Winter in providing a lower bound resistance curve, that included the experimental results, like the one preconized by Eq. (1), due to the lack of information about the imperfections and residual stresses of the tested specimens, it is difficult to
Cyclic Behaviour of Hollow and Filled Axially-Loaded Members
Hollow section members are often employed as bracing elements, for both structural and aesthetic reasons. This paper describes an investigation of the response of such members to cyclic axial loading. The influences of concrete or mortar infill and of member slenderness are addressed.
IJERT-Flexural Buckling Analysis of Thin Walled T Cross Section Beams with Variable Geometry
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/flexural-buckling-analysis-of-thin-walled-t-cross-section-beams-with-variable-geometry https://www.ijert.org/research/flexural-buckling-analysis-of-thin-walled-t-cross-section-beams-with-variable-geometry-IJERTV3IS031854.pdf Thin walled structure is a structure whose thickness is small compared to its other dimensions but which is capable of resisting bending in addition to membrane forces. Which is basic part of an aircraft structure, the structural components of an aircraft consist mainly of thin plates stiffened by arrangements of ribs and stringers. Thin plates (or thin sections or thin walled structures) under relatively small compressive loads are prone to buckle and so must be stiffened to prevent this. The determination of buckling loads for thin plates in isolation is relatively straightforward but when stiffened by ribs and stringers, the problem becomes complex and frequently relies on an empirical solution. The buckling of the thin plates is a phenomenon which could lead to destabilizing and failure of the aircraft; in this paper it is considered T cross section with variable geometry and length. The critical buckling stresses have been studied for several combinations of the geometry parameters of the beam with the help of ANSYS and drown the result plots Keywords: Thin walled beams, buckling analysis, Finite element analysis I INTRODUCTION A great deal of attention has been focused on plates subjected to shear loading over the past decades. One main fact in design of such elements, which fall in the category of thin-walled structures, is their buckling behavior. Plate girders and recently shear walls are being widely used by structural engineers, as well as ship and aircraft designers. The role of stiffeners is proved to be vital in design of such structures to minimize their weight and cost. Xiao-ting et al [1] presented an analytical model for predicting the lateral torsional buckling of thin walled channel section beams restrained by metal sheeting when subjected to an uplift load. And calculated the critical load from critical energy theory and showed that the critical buckling moment in the pure bending case is less than half of the critical moment, it is more effective to use the anti sag bars in the simply supported beams than in the fixed beams, the closer the loading point to the centre the lower the critical load. M.Ma et al [2] developed energy method for analyzing the lateral buckling behavior of the monosymmetric I beams subjected to distributed vertical load, with full allowance for distortion of web. the method assumes that the flanges buckle as rigid the rectangular section beams, but the web distorts as an elastic plate during buckling. it is shown that the disparity between the distortional and classical critical load increases as h/l increases and that for short beams the classical method seriously over estimates the critical load. B. W. Schafer [3] worked on cold-formed thin-walled open cross-section steel columns and provided local, distortional, and flexural-torsional buckling. Experimental and numerical studies indicated that post buckling strength in the distortional mode is less than in the local mode. In pin-ended lipped channel and zed columns, local and Euler interaction is well established. A direct strength method is proposed for column design. The method uses separate column curves for local buckling and distortional buckling with the slenderness and maximum capacity in each mode controlled by consideration of Euler equation. Attard Mario et al [4] investigated lateral-torsional buckling behavior of open-section thin-walled beams based on a geometrically nonlinear formulation, which considers the effects of shear deformations, also made Comparisons between the results based on fully nonlinear analysis and linearized buckling analysis in order to illustrate the effects of pre-buckling deformations as well as the shear deformations on the buckling load predictions. Ing. Antonin pistek,[5] analytical method for limit load capacity Calculation Of thin walled aircraft structures focused on description and Comparison of different methods for limit load Capacity calculation of thin walled aircraft Structures-considering all possible forms of Buckling and failures on nonlinear behavior of The structure under gradually increased Loading. Carine Louise Nilsen, et al [6] found that the behavior of thin-walled steel sections, including local buckling, distortional buckling, global buckling and shear buckling have been well understood and appropriate design methods existed. Foudil Mohria et al [7] derived analytical solutions Based on a non-linear stability model, for simply supported beam-column elements with bi-symmetric I sections under combined bending and axial forces. Jaehong Lee et al [8] explained lateral buckling of thin-walled composite beams with monosymmetric sections. A general geometrically nonlinear model for thin walled laminated
Compression member response of double steel angles on truss structure with member length variation
IOP Conference Series: Materials Science and Engineering, 2018
One type of structures that implements steel angles as its members is truss system of telecommunication tower. For this structure, reinforcements on tower legs are also needed when antennas and microwaves installation placed on the peak of tower increases in quantity. One type of reinforcement methods commonly used is by increasing areas section capacity, where tower leg consisted of single angle section will be reinforced to be double angle sections. Regarding this case, this research discussed behavior two types of double angle steel section 2L 30.30.3 that were designed identically in area section but vary in length: 103 cm and 83 cm. At the first step, compression member together with tension member was formed to be a truss system, where compression and tension member were met at the joint plate. Schematic loading was implemented by giving tension loading on the joint plate, and this loading was terminated when each specimen reached its failure. Research findings showed that implementing shorter double angle (83 cm) sections, increased compression strength of steel angle section up to 13 %. Significant deformation occurring only on the flange for both of specimens indicated that implementing double angle is effective to prevent lateral-torsional buckling.