Showing papers in "Thin-walled Structures in 1983"
TL;DR: For elastic-plastic cylindrical shells with initial axisymmetric imperfections, a phenomenological plasticity theory was proposed in this article to account for the formation of a vertex on subsequent yield surfaces.
Abstract: For elastic-plastic cylindrical shells with initial axisymmetric imperfections bifurcation into a non-axisymmetric shape is analysed. The shell material is represented by a phenomenological plasticity theory that accounts for the formation of a vertex on subsequent yield surfaces. The influence of various geometric and material parameters is investigated for a wide range of radius-to-thickness ratios. It is shown that for the thicker shells bifurcation generally occurs beyond the maximum axial compressive load. A few analyses for shells with additional non-axisymmetric imperfections show the unstable post-bifurcation behaviour and the sensitivity to imperfections of more general shapes.
74 citations
TL;DR: Theoretical analyses for nonlinear vibrations of a clamped rectangular plate under a uniformly distributed periodic load, with the effect of both initial deflection and initial edge displacement taken into consideration, are presented in this paper.
Abstract: Theoretical analyses are presented for nonlinear vibrations of a clamped rectangular plate under a uniformly distributed periodic load, with the effect of both initial deflection and initial edge displacement taken into consideration The dynamic analog of the Marguerre equations is used and the steady-state solutions are obtained by first applying the Galerkin method and then the harmonic balance method Actual calculations are carried out for the square plate under the assumption of the three degrees-of-freedom system and the frequency response characteristics and typical waveforms are determined under various initial edge displacements including initially buckled cases Effects of both initial deflection and initial edge displacement on the static deflection as well as the lower natural frequencies are also clarified
58 citations
TL;DR: In this article, a theoretical study of elastic buckling modes of I-section beams under various loading conditions is presented, based on energy considerations and the energy equations governing instability are derived using plate theory to allow for distortion of the cross-section.
Abstract: A theoretical study of the elastic buckling modes of I-section beams under various loading conditions is presented. The analysis is based on energy considerations and the energy equations governing instability are derived using plate theory to allow for distortion of the cross-section. The resulting analysis is able to predict lateral, local and distortional buckling modes. The results are compared with classical lateral buckling solutions based on beam theory.
49 citations
TL;DR: In this paper, the authors present a formulation of a curved thin-walled box beam finite element having a variable cross-section with at least one vertical axis of symmetry, and three degrees of freedom have been included in the formulation to allow for the effects of warping and distortion.
Abstract: The purpose of this paper is to present a formulation of a curved thin-walled box beam finite element having a variable cross-section with at least one vertical axis of symmetry. To allow for the effects of warping and distortion, three degrees of freedom have been included in the formulation. These degrees of freedom have been designated as the rate of change of twisting angle, the distortional angle of the cross-section, and the rate of change of distortional angle. The effect of shear lag has also been included. The element may be used for the elastic analysis of a variety of thin-walled structures and in particular for the preliminary analysis of box bridge decks where a three-dimensional analysis may be unnecessary. The accuracy of the element has been demonstrated by comparison of the results obtained with known results from other methods for some examples.
26 citations
TL;DR: In this paper, the effect of column axis imperfection on the equilibrium behaviour and ultimate carrying capacity of thin-walled lipped channel columns is investigated. But the analysis is restricted to columns with a single axis imperfections.
Abstract: An analytical investigation is made of the effect of column axis imperfection on the equilibrium behaviour and ultimate carrying capacity of thin-walled lipped channel columns. The Rayleigh-Ritz method is used to obtain local buckling loads and a semi-energy method is employed to describe post-buckling interaction behaviour. In the analysis a facility of allowing the locally deflected form to change after buckling is provided, resulting in asymptotic equilibrium curves tending towards continually changing reduced Euler loads as opposed to fixed reduced Euler loads based on an unchanging locally deflected form. The imperfection sensitivity of column designs which produce stable and unstable equilibrium behaviour after local buckling is investigated as is that of columns which exhibit neutral equilibrium behaviour before local buckling. Results are presented in the form of non-dimensional load-deflection equilibrium curves and ultimate load-slenderness plots covering these three equilibrium states. A comparison of the theory with independent experimental work is also included.
23 citations
TL;DR: In this article, a new method for the design of stiffened compression flanges of large steel box girder bridges is presented, based on the orthotropic plate approach, but the mathematical formulation and its use are more simple in addition, it allows for account of a non-uniform stress distribution in the flange and thus enables the analysis of the shear lag effects on the plate buckling.
Abstract: A new method for the design of stiffened compression flanges of large steel box girder bridges is presented It is based, like that presented 10 years ago by Maquoi and Massonet, on the orthotropic plate approach, but the mathematical formulation and its use are more simple In addition, it allows for account to be taken of a non-uniform stress distribution in the flange and thus enables the analysis of the shear lag effects on the plate buckling The physical differences between plate buckling under uniform and non-uniform compression, respectively, are clearly shown Finally it is found that the collapse ultimate state is little influenced by shear lag
14 citations
TL;DR: In this paper, two finite element methods for analysing geometrically imperfect cooling tower shells are presented, where the geometry of the imperfection is modelled by the elements and the imperfections are represented by an equivalent load on the shell.
Abstract: Two finite element methods for analysing geometrically imperfect cooling tower shells are presented. In the first the geometry of the imperfection is modelled by the elements; in the second the imperfection is represented by an equivalent load on the shell. Axisymmetric and general shell elements have been considered. Results are given which show that the first approximation to the equivalent load is sufficiently accurate and that it is possible to represent local imperfections by axisymmetric imperfections which require less computation. It is also shown that axisymmetric elements should be used wherever possible, because of their greater efficiency, following the geometry of an axisymmetric imperfection but representing local imperfections by equivalent loads.
12 citations
TL;DR: In this article, an approximate method for the analysis of axially loaded plates with initial imperfections is presented, where all the boundary edges are constrained to remain straight in-plane, except when one of the edges is free to wave out-of-plane.
Abstract: An approximate method for the analysis of axially loaded plates with initial imperfections is presented. Formulae for the computation of effective widths of rectangular plates having nine different combinations of boundary conditions have been derived using the energy method; all the boundary edges are constrained to remain straight in-plane, except when one of the edges is free to wave out-of-plane. Design curves have been presented for each set of support conditions, and these can be employed to obtain solutions within acceptable engineering accuracy for practical structures having small imperfections.
10 citations
TL;DR: In this paper, a study of a simple channel cantilever with an eccentrically located end load is presented. But the authors focus on the three stages of the failure process of the structure, i.e., elastic, elasto-plastic and plastic failure.
Abstract: With small applied loads thin-walled steel structures behave in a linear elastic manner until they start to buckle in an elastic or in an elasto-plastic mode Finally beyond the maximum load they develop a plastic failure mechanism Although there are many papers which deal with these three aspects separately there have been relatively few attempts to trace the history of a structure through all three stages This paper describes a study of a simple channel cantilever with an eccentrically located end load
8 citations
TL;DR: The instability behavior of thin-walled horizontal cylindrical vessels supported by means of ring girders, or from rigid end plates, is examined experimentally during liquid filling as mentioned in this paper.
Abstract: The instability behaviour of thin-walled horizontal cylindrical vessels supported by means of ring girders, or from rigid end plates, is examined experimentally during liquid filling. Selected results from a horizontal test on a large stainless steel horizontal storage vessel are presented to illustrate the way in which thin-walled vessels, of large radius/thickness ratios (300–650), behave during fill. Such results have provided the motivation for some 26 polyester film model cylinder tests. The models cover three different radius/thickness ratios (300, 400 and 500) and a range of length/radius ratios. They were supported at their ends and progressively filled with liquid. In each case the onset of instability was noted. In Part II 1 of this paper a theoretical approach is presented and compared with the experimental values in an effort to assess the validity of design methods currently in use.
5 citations
TL;DR: In this article, the buckling behavior of a liquid storage tank built up of circular cylindrical shell-sections with different thicknesses is investigated and the critical vacuum for bifurcation is determined taking into account the weight of the structure.
Abstract: The buckling behaviour of a liquid storage tank built up of circular cylindrical shell-sections with different thicknesses is investigated. In any partially filled state the critical vacuum for bifurcation is determined taking into account the weight of the structure. For a storage tank with small geometrical imperfections the behaviour is analysed asymptotically using Koiter's general post-buckling theory. The initial post-buckling analysis based on the assumption of linear pre-buckling behaviour indicates that the storage tank is imperfection-sensitive in any partially filled state. Finally, bifurcation analyses accounting for nonlinear pre-buckling show that the assumption of linear pre-buckling is a good approximation even at high liquid levels.
TL;DR: In this article, a simplified theoretical approach to the problem of the stability of horizontal cylindrical vessels filled with liquid is proposed and is compared with the experimental results presented in Part I of this paper and with those of other investigators.
Abstract: A simplified theoretical approach to the problem of the stability of horizontal cylindrical vessels filled with liquid is proposed and is compared with the experimental results presented in Part I of this paper and with those of other investigators. In view of these comparisons certain design considerations are proposed for liquid storage vessels.
TL;DR: In this article, some results relative to the stability and postbuckling behavior of elastic beams are presented. But the model used to describe the beam behaviour is the monodimensional one, based on the assumption of plane bending and shear indeformability.
Abstract: In this paper, some results relative to the stability and postbuckling behaviour of elastic beams are presented. The mechanical model used to describe the beam behaviour is the monodimensional one, based on the assumption of plane bending and shear indeformability. A linear relationship between moments and curvatures of the beam is assumed according to the hypothesis of large displacements-small strains. By means of the perturbative method, the flexural-torsional postbuckling behaviour of simply supported and cantilever beams is studied; the stability, in the Liapunov sense, of the prebuckling and bifurcated equilibrium configuration is also discussed. Finally, some experimental results are presented for the case of the cantilever beam, showing the accuracy of the theoretical predictions.
TL;DR: In this article, the effect of a bulge in a hyperboloidal cooling tower on the stresses due to gravity and prescribed wind load is studied, by means of shell membrane theory.
Abstract: The effect of a bulge in a hyperboloidal cooling tower on the stresses due to gravity and prescribed wind load is studied, by means of shell membrane theory. The geometry of a slightly out-of-round shell is derived, and the equilibrium equations are modified to include the effects of out-of-roundness. An iterative procedure is employed to solve the equilibrium equations numerically. Tables of stresses are given for a specific shell subjected to various moderate-sized bulges. The effect of a moderate-size bulge on the stresses in a cooling tower subjected to wind load and self weight is relatively small. The main effect of the out-of-roundness is to redistribute the stresses in the shell by a process of shedding load in the neighborhood of the bulge.
TL;DR: In this paper, a finite element program with large deformations and plasticity is used to analyse the behavior of stiffened compression flanges of box girders and to investigate the diminishing of the shear lag effect at collapse.
Abstract: A finite element program with large deformations and plasticity is used to analyse the behaviour of stiffened compression flanges of box girders. Simulations are performed for pure bending and for bending with shear in order to investigate the diminishing of the shear lag effect at collapse. It is concluded that at the actual ultimate load, shear lag has largely disappeared but that a design at ultimate load without consideration of the shear lag may entail an inelastic behaviour under service load. First yielding occurs in the centre of the stiffened panel for pure bending and in the middle of the unloaded edges when elastic shear lag becomes important. A substantial increase of the ultimate load can be expected from an increase of the stiffener rigidity.