Semi-rigid Elasto-plastic Post Buckling Analysis of a Space Frame with Finite Rotation

ABSTRACT: In this study, large-deformation and small-strain elasto-plastic analysis of space frames with symmetric cross sections and semi-rigid connections are presented. The effect of axial forces on the bending moment and lateral buckling are included. However, axial-torsional and warping effects are omitted. The Eulerian equations for a beam-column with finite rotation taking into account bowing effects are adopted for an elastic system and are extended to an inelastic system with a plastic hinge concept. The derived tangent stiffness matrix is asymmetric due to the finite rotation. The joint connection elements were introduced for semi-rigidity using a static condensation technique. The arc-length method was applied to trace the post-buckling range of elastic and elasto-plastic problems with semi-rigid connections. Nonlinear buckling and elasto-plastic collapse analyses were carried out for the proposed space frame to demonstrate the potential of the developed method in terms of accuracy and efficiency.