Advanced plastic hinge analysis for the design of tubular space frames

The basic theory of a two-surface plastic hinge analysis program is presented, focusing on the inelastic stiffness formulation of a three-dimensional beam–column element. Material non-linear behaviour is considered by allowing yielding to occur at the element end and mid-length sections. Simple beams and columns were analysed to demonstrate the capability of the analysis model in predicting the bending and buckling behaviour of frame members. Several tubular space frame structures, including tubular braced frames, a lattice dome and a barrel vault with pre-tensioned cables, were analysed to illustrate the qualities and limitations of the analyses in predicting the systems' strength and behaviour. The design implication of geometrical imperfections on the limit load of the system is also highlighted.