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From:
Pedro B. Dinis and Dinar Camotim,
“On the Use of Shell Finite Element Analysis to Assess the Local Buckling and Post-Buckling Behaviour of Cold-Formed Steel Thin-Walled Members”, III European Conference on Computational Mechanics, p. 689, 2006, DOI: 10.1007/1-4020-5370-3_689
ABSTRACT: This paper deals with the use of shell finite element analyses to assess the (i) elastic bifurcation and (ii) elastic and elastic-plastic local-plate and distortional post-buckling behaviours of cold-formed steel thin-walled members (mostly columns, i.e., uniformly compressed members) all the geometrically and physically non-linear analyses are performed using the code ABAQUS and adopting 4-node isoparametric shell elements to discretise the members. First, one addresses several relevant issues concerning (i) the member discretisation (shell element type and mesh refinement), (ii) the simulation of the member end support conditions (a key aspect in numerical structural analysis), (iii) the modelling of the applied loading and material behaviour, (iv) the incorporation of member initial geometrical imperfections and residual stresses, (v) the assessment of buckling mode interaction effects and (vi) the methods employed to solve either the eigenvalue problem or the system of non-linear algebraic equilibrium equations. Then, in order to illustrate the concepts and issues mentioned above and, at the same time, illustrate the power and versatility of the shell finite element analyses, one presents and thoroughly discusses a fairly large number of numerical results concerning the buckling and post-buckling behaviour of lipped channel (mostly), Zed-section and Rack-section cold-formed steel members some of the post-buckling analyses include interaction effects between local-plate and distortional buckling modes. These results consist of (i) buckling curves providing the variation of the critical stress with the member length (see Fig. 1(a)), (ii) elastic and elastic-plastic non-linear (post-buckling) equilibrium paths (see Figs. 1(b)-(c)), (iii) figures providing the evolution, along those equilibrium paths, of the elastic and elastic-plastic member deformed configurations, and (iv) figures showing the spread of plasticity along the members up to failure (see Fig. 1(d)) and conveying relevant information about the nature of their collapse mechanisms.
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