Flexural-torsional elasto-plastic buckling analysis of stiffened plates using dynamic relaxation. Part 2: Comparison with test results and other formulations (original) (raw)
Related papers
2021
In the framework of the ongoing revision of EN 1993-3-1, the RCFS funded research project ANGELHY is currently performing experimental, numerical and theoretical studies on angle sections and lattice towers. This paper presents a particular aspect of the ANGELHY project and focusses on a theoretical study concerning the behaviour of angle section members. First, the elastic second order equation of such members subjected to axial compression is established. Then, this differential equation is solved based on different assumptions concerning geometric imperfections to determine second order displacements, rotations and internal forces and moments. The analytical second order solution is validated through comparisons to a numerical elastic second order analysis. Based on the validated ana lytical solution, it is then shown, that even if torsional/torsional-flexural buckling of angle sec tion members was relevant according to the elastic critical loads, the member rather fails by flexural buckling only. The reason for this unexpected conclusion may be directly derived from the second order internal forces and moments as shown in the last part of this paper.
Buckling of stiffened curved panels under uniform axial compression
Journal of Constructional Steel Research, 2014
In bridge construction, the use of stiffened plates for box-girder or steel beams is common day to day practice. The advantages of the stiffening from the economical and mechanical points of view are unanimously recognized. For curved steel panels, however, applications are more recent and the literature on their mechanical behaviour including the influence of stiffeners is therefore limited. Their design with commercial finite element software is significantly time-consuming, which reduces the number of parameters which can be investigated in an optimization procedure. The present paper is thus dedicated to the study of the behaviour of stiffened curved panels under uniform longitudinal compression. It addresses the linear buckling and the ultimate strength which are both influenced by the coupled effects of curvature and stiffening. It finally proposes a design methodology based on that for stiffened flat plates adopted by European Standards and a column-like behaviour.
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.
Interactive shear buckling of corrugated webs (Exprimental work).pdf
Asmaa Yasseen Hamed, 2016
This paper focuses on behaviour of the interactive shear stress of corrugated steel webs with trapezoidal corrugations experimentally and analytically Proposed interaction equation, which based on local buckling of the corrugation fold as isotropic flat plates, global buckling of the entire web panels as an orthotropic plate, and steel yielding of the web is presented. Four beams with corrugated steel webs were tested to failure under shear; the failure was due to buckling of the web. Finite element method (FEM) was used to perform nonlinear analysis to the models of the test specimens to determine ultimate load of these girders. Comparisons between the results from the proposed equation, the finite element analysis, and the tests are satisfactory. A new formula by the author is developed, which considers interaction among the various shear failure modes. The conditions of many of these tests are found to be inconsistent with the theoretical conditions assumed in deriving the shear strength formulas. The various formulas for predicting critical shear stress are then compared with selected test results.
Experimental verification of buckling of curved web close steel section
2018
Today, bridge girders with curved flanges and webs are becoming common in order to increase the aesthetic value and to improve the quality of the structure. Despite the use of these new shapes, not much research has been done in this field. The aim of the present research is to develop an experimental test setup, during which box girders with changing web curvature are subjected to a constant shear force. The specimens were made from plastic sheets (with thickness 0.125 mm) to create the webs and flanges, and MDF wood to create the external stiffeners. In a later phase, numerical models are created, which have the same properties and characteristics as the experimental specimens. These include a height of 70 mm, a width of 30 mm, and curvature radii of 1500, 5, 3, 5/3, 1 and 0.55 times the web height. The aim of the test is to analyse the elastic buckling behaviour of the webs and the failure condition of the specimen. The experimental results are analysed and compared with numerical results, for which no imperfections were included. Tests indicate that the elastic buckling load is increasing with increasing curvature, whereas for the failure load the opposite happens. The numerical models show identical behaviour, with higher loads. The failure load behaviour changes according to flat web or shell behaviour of the specimen. The results showed that flatter webs have much more postbuckling capacity than the most curved webs. The deformation pattern of the web is also different for both categories. Where the flatter webs had diagonal tension lines, the most curved webs had more horizontal bulges, shifting to the upper web-flange juncture. The difference between the numerical and experimental results can be blamed to the lack of imperfections implemented in the first approach. Earlier numerical research 1 with closed steel sections, show that the failure load line is increasing with growing curvature. The high web slenderness for the experimental specimen causes opposite results for the failure load. For an increasing curvature, the post-buckling capacity is decreasing, while the elastic buckling capacity is increasing. This all results in an increasing or decreasing failure load curve.
2012
The aim of this paper is to clarify the influence of different levels of initial imperfections and the effect of web dimensions for T stiffener on the estimation of the critical buckling stress of stiffened panels under axial and combined loads using Ansys software. The post buckling behavior of the plate-stiffener combination consisting of a Tgirder with the attached effective plating between two adjacent transverse frames is investigated in case of longitudinal axial load and of combined longitudinal axial load and lateral pressure as normally encountered in bottom and deck panels. To accomplish the intended parametric study, the sections modeled have been classified into two sets according to different values of web depth and different values of web thickness. Two different levels of initial imperfections attributed to the plate and to the web were taken into account. The finite element model is attempted using the element SOLID45 for its advantages in the non-linear analysis. The square deflection method is used to estimate the critical stress for the FEM models; the results are seen to be in good agreement with Perry-Robertson formulation. It has been concluded that the web depth of T-section greatly affects the value of critical buckling stress in case of combined load. The proposed model can be useful to determine the minimum web depth to be adopted if a minimum value of the critical stress is intended. The influence of the level of initial imperfections on the post buckling behavior of the plate-stiffener combination is assessed.
Interactive shear buckling of corrugated webs
his paper focuses on behaviour of the interactive shear stress of corrugated steel webs with trapezoidal corrugations experimentally and analytically Proposed interaction equation, which based on local buckling of the corrugation fold as isotropic flat plates, global buckling of the entire web panels as an orthotropic plate, and steel yielding of the web is presented. Four beams with corrugated steel webs were tested to failure under shear; the failure was due to buckling of the web. Finite element method (FEM) was used to perform nonlinear analysis to the models of the test specimens to determine ultimate load of these girders. Comparisons between the results from the proposed equation, the finite element analysis, and the tests are satisfactory. A new formula by the author is developed, which considers interaction among the various shear failure modes. The conditions of many of these tests are found to be inconsistent with the theoretical conditions assumed in deriving the shear strength formulas. The various formulas for predicting critical shear stress are then compared with selected test results.