The safe and economical design of curved spatial frames necessitates a geometrical nonlinear analysis of the structure. In this report, the nonlinear equations governing such structural behaviour are derived. Solution strategies which are capable of analysing the post-buckling behaviour of structures are also critically reviewed. In addition, an extrapolation stiffness method that lends itself to a more efficient solution of the nonlinear equations than conventional Newton-Raphson methods is presented.
The post-buckling responses of various spatial frames are analysed and the results found to be in good agreement with available published work.