Simplified Second-Order Inelastic Analysis for Steel Frames

The aim of the work described in this paper is to provide a practical method for second-order inelastic analysis for frame design. To this end, it is shown that gradual bending stiffness degradation of beam-columns before the attainment of the full
loadcarrying capacity can be simulated by decreasing the stiffness of the pseudo end-rotational springs which are assembled to the beam-column stiffness matrix. The analysis is carried out by a simple incremental method. The modified stability-function-based equations with the presence of the end springs are used with one iteration for each load increment. The method showed excellent results and a noticeable
improvement over the plastic-hinge method. The simplicity of the proposed method, and the low computer capacity and time needed, make it possible to use the program on personal computers without any special requirements.

F. Al-Mashary and Professor W.F. Chen