<p>This paper presents
and illustrates the application of an elastic-plastic Generalised Beam Theory
(GBT) formulation, based on J<sub>2</sub>-flow plasticity theory, that makes
it possible to perform physically and geometrically non-linear (post-buckling) analyses of prismatic thin-walled members (i) with arbitrary cross-section shapes,
(ii) exhibiting any type of
deformation pattern (global, local, distortional, warping, shear), (iii) made
from non-linear materials with isotropic strain-hardening and (iv) containing
initial imperfections, namely residual stresses and/or geometric imperfections, having generic distributions. After
providing a brief overview of the main GBT assumptions, kinematical relations and
equilibrium equations, the development of a novel non-linear beam finite
element (FE) is addressed in some
detail. Moreover, its application is illustrated through the presentation and
discussion of numerical results concerning the post-buckling behaviour of
a fixed-ended I-section steel column exhibiting local initial geometrical imperfections, namely (i) non-linear
equilibrium paths, (ii) displacement profiles, (iii) stress diagrams/distributions and (iv) deformed configurations.
For validation purposes, the GBT results are also compared with values
yielded by Abaqus rigorous shell FE
analyses.</p>
POST-BUCKLING AND DETERIORATING BEHAVIOR OF BOX-SECTION STEEL MEMBERS
