KOITERS ANALYSIS OF THIN-WALLED STRUCTURES BY A FINITE-ELEMENT APPROACH

This paper refers to the analysis of the postbuckling behaviour of thi n-walled structures by means of an asymptotic approach based on a fini te element implementation of Koiter's non-linear theory of instability . The analysis has been accomplished by using the following assumption s: (i) the structure is described as an assemblage of flat slender rec tangular panels; (ii) a non-linear Kirchhoff-type plate theory is used to model each panel; (iii) HC finite elements discretization is used; (iv) linear and quadratic extrapolations are assumed for the fundamen tal and the postbuckling paths, respectively; (v) multimodal buckling is considered; and (vi) imperfection sensitivity analysis is performed in both multimodal and monomodal form based on the steepest-descent p ath criterion. Several numerical results are presented and discussed. Comparisons with numerical solution obtained by standard incremental c odes are given, which show the accuracy and reliability of the propose d approach.