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The non-linear in-plane stability of pin-ended circular shallow arches is analytically investigated. The arches are made of functionally graded material with the material properties varying along the thickness. The external load is a radial concentrated force in the direct vicinity of the crown. The effect of the bending moment on the membrane strain is included in the one-dimensional model. The equations of the pre-buckling and buckled equilibrium are derived using the principle of minimum potential energy. Analytical solutions are found for both bifurcation and limit point buckling. Extensive parametric studies are performed to find and demonstrate the effect of various parameters on the buckling load and in-plane behaviour. It is found that most arches have multiple stable and unstable equilibria and the number of equilibria increases with the modified slenderness. When the load is applied exactly at the crown, the lowest buckling load is related to bifurcation buckling for most geometries and material compositions but when there is a small imperfection in the load position, only limit point buckling is possible. The position of the load can have quite a huge influence on the buckling load, therefore pin-ended functionally graded shallow arches are sensitive to small imperfections in the load position. • The sensitivity of shallow arches to small loading imperfections is studied. • The arches are made of transversely FGM. • The effect of various geometrical-material parameters is investigated analytically. • Results show that the load position has huge influence on the buckling behaviour. [ABSTRACT FROM AUTHOR]

For compression members with primarily axial forces, steel angles with bolted connections are often used. Due to the eccentric connection on only one leg additional bending moments are acting on the member, leading to a complex load carrying behaviour with flexural and/or lateral torsional buckling phenomena. The paper mainly focuses on the presentation of the influence of realistic end support conditions at the gusset plates on the member capacity in compression. In the first part of the paper, about 300 existing test results for steel angles in compression with bolted connections are prepared in such a way that they can be compared with different design rules. This was achieved through the common representation of all test results as a function of the normalized slenderness λ ¯ v about the weak axis. In the second part, systematic numerical calculations are conducted for limit cases of the stiffness of the boundary condition of the load-introducing gusset plates (rigid/hinged). The results are also presented in dependency of the relative slenderness λ ¯ v . The consolidation of all tests and numerical results shows (besides the well-known difference between one-bolt and two-bolt connections) a very high influence of the end support of the gusset plate. [ABSTRACT FROM AUTHOR]

This paper presents a design proposal for the out-of-plane buckling resistance of prismatic beam-columns subject to axial compression and uniaxial major-axis bending that was developed based on the well-known Ayrton-Perry format. Firstly, the relevant theoretical background is summarized, closely following the theoretical derivation performed by Szalai and Papp (2010). Secondly, the required transformations for the engineering application of the design procedure are detailed and extended to arbitrary bending moment distributions. Appropriate generalized initial imperfection factors for the out-of-plane buckling of beam-columns are defined so as to achieving complete consistency across the stability verifications for columns, beams and beam-columns. The proposed procedure is subsequently validated against a large set of advanced numerical simulations. A good agreement was found between the numerical results and the estimates provided by the proposed design procedure, both in terms of the overall trend and the specific quantitative results. Based on a statistical assessment, the comparison with the interaction expression of Eurocode 3 (2005) (method 2) showed that this proposal slightly outperforms the Eurocode procedure, both in terms of average values and dispersion of results. [ABSTRACT FROM AUTHOR]

In the field of structural engineering the design of cost efficient structures is highly important. This led to the development of cold-formed steel structures (CFS). An advanced CFS structure is introduced in this paper, which uses a special type of polystyrene aggregate concrete (PAC) as bracing material. This material has beneficial insulating and fire protection properties, which makes it a reasonable choice for residential buildings. An experimental program was performed, to gain information on the flexural and axial behaviour of PAC-braced CFS elements and panels. Both unbraced and braced members were tested to gain information on increment of load-bearing capacity. Several different element sizes were used to be able to investigate the different stability failure modes (i.e. local, distortional and global). Results showed that PAC was able to restrain the global and distortional buckling modes of steel elements, thus providing “full bracing” in most practical cases. These results are introduced in two papers (Part I and II), detailing the failure modes, load increments and the effect of composite action. In this paper – Part I – the background and the results of bending tests are presented, and the experiments on the compression elements are detailed in Part II [1] . [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the elastic stability of slender columns weakened by multiple edge cracks subjected to concentrated loads applied at the ends is presented. The analysis is carried out by using the minimum potential energy technique. The cracked section is modeled by a massless rotational spring which causes discontinuity in the rotations due to bending moments. In the present work, columns with various end conditions such as pinned ends, fixed ends, fixed-pinned ends and fixed-free ends are studied. The analysis depends on the assumed deflection function, which satisfies exactly the end conditions. The buckling loads for each case of end conditions for a column with arbitrary number of cracks along the column length are given in simple and practical equations which also gave accurate results. A comparison between the results of the present analysis and that of some previous studies shows the accuracy and the simplicity of the developed method to find the critical load in such cases. [Copyright &y& Elsevier]

Abstract: Eurocode 3 provides several methods for the stability verification of members and frames. However, several inconsistencies and difficulties have been noticed in the case of non-uniform members regarding in what concerns stability verification. In this paper, the case of web-tapered beams is studied. In a first step, available methods for stability verification of web-tapered beams are discussed. A second order analytical model based on an Ayrton–Perry approach is then derived for the case of tapered beams with uniform bending moment and further extended to other bending moment distributions. Several consistent simplifications are carried out in order to build a simple but coherent design model for the stability verification of tapered beams subject to linear bending moment distributions and to parabolic bending moment. More than 3000 numerical simulations are carried out for calibration and analysis of the results. Throughout the paper, specific issues such as the presence of shear or the codified imperfections for welded cross-sections are brought in and taken into account. Finally, it is noted that the proposed model is consistent with recently proposed design models for the stability verification of prismatic beams. [Copyright &y& Elsevier]

Abstract: In this paper, linear buckling analyses of plates with longitudinal stiffeners having various shapes and positions and subjected to axial force, in-plane bending and shear are developed. The aim is to give some new practical insights about the shape and optimum position of longitudinal stiffener in webs when axial force, bending moment and shear act. By means of a comprehensive numerical investigation, some practical issues for buckling phenomena in stiffened plates, taking into account (a) dimensions and shape (square and rectangular) of the plate, (b) dimensions and shape of the stiffener (with open and closed cross-sections), (c) location of the stiffener, and (d) load configuration (uniform compression, pure bending, combinations of axial compression and bending, and shear) are developed. [ABSTRACT FROM AUTHOR]

Abstract: In this paper linear buckling analyses of square and rectangular plates with circular and rectangular holes in various positions subjected to axial compression and bending moment are developed. The aim is to give some practical indications on the best position of the circular hole and the best position and orientation of rectangular holes in steel plates, when axial compression and bending moment act together. Two different orientations are considered for rectangular holes: holes with major dimension parallel to the vertical plate axis (RS holes) and major dimension parallel to horizontal plate axis (RL holes). The effect of bending moment on the stability of the plate is studied and some differences with respect to the uniform compression load case are shown. Some design suggestions on the best orientation of rectangular for stability purposes are given. The influence of dimension and position of perforations on linear buckling behaviour and, in particular, on buckling coefficient of the plate is observed. Some practical design formulations for the calculation of the buckling coefficient, taking into account (a) dimensions and shape (square and rectangular) of the plate, (b) dimensions and shape (circular and rectangular) of the hole, (c) position of the hole (centre in the “maximum” and in the “nodal” point), (d) orientation (RS and RL) of the rectangular hole, and (e) load configuration (uniform compression, combinations of axial compression and bending and pure bending) are finally proposed. [Copyright &y& Elsevier]

Abstract: In this study, linear buckling analysis of unstiffened plates under interacting patch loading and bending moment is developed. The study focuses on estimation of the elastic critical load due to patch load, and concomitant linearly variable compressive stress in the normal direction, with analysis of mechanisms of plate instability. The present work proposes simple design equations for the elastic critical load of rectangular plates subjected to both patch load, and uniform compressive stress, and also patch load with linearly varying compressive stresses for the serviceability limit state. The proposed analytical relationship, obtained on the basis of parametric numerical analyses, is validated by comparing analytical predictions with experimental tests from the literature, and full numerical models; good agreement was obtained for practical situations in steel bridge design, such as the erection of steel bridges with the launching construction technique. In the launch phase, web panels of the open-section girders are subjected to concentrated loads applied to the lower flange, and considerable bending moment. [Copyright &y& Elsevier]