Numerical Approaches to the Nonlinear Stability Analysis of Single Layer Reticulated and Grid-Shell Structures

Abstract

The paper illustrates the characteristics of a procedure for evaluating the buckling and post-buckling behaviour and the influence of imperfections on reticulated and grid-shells structures. The presentation is composed by two steps: firstly, a simple way to comprehend the effects of initial imperfections by means of an “equivalent” fictitious load vector, acting on the ideal design structure, is presented. The fictitious load's characteristics are evaluated so to qualitatively reproduce the behaviour of an unknown structure, affected by an arbitrary distribution of small geometry variations with respect to the design structure. The second step allows to detect exactly the position of critical points and to trace the secondary equilibrium paths by means of a perturbation technique. Numerical examples illustrate the characteristics and performances of the approaches and suggest practical applications.