An introduction to geometrically nonlinear finite element stiffness analysis using the incremental step and equilibrium methods

The derivation of the beam-column element matrices and development of the incremental step method and of the equilibrium method are abstracted from other authors. Emphasis is placed on the consistency of the assumptions and restrictions imposed upon the element and the two methods. Two algorithms are developed describing the two methods and are compatible with the element. Three example problems are solved illustrating the features of the two methods. A comparison of the solutions obtained for each method is made.