Nonlinear P-A analysis of steel frames with semi-rigid connections

摘要

This paper presents the formulation for a novel force-based 1-D compound-element that captures both material and second order P-A nonlinearities in steel frames. At the nodal points, the element is attached to nonlinear rotational and a translational springs which represent the flexural and axial stiffiiess of the connections respectively. By decomposing the total strain in the material as well as the generalised displacements of the flexible connections to their elastic and inelastic components, a secant solution strategy based on a direct iterative scheme is introduced and the corresponding solution strategy is outlined. The strain and slope of the deformed element are assumed to be small;;however the equilibrium equations are satisfied for the deformed element taking account of P-A effects. The formulation accuracy and efficiency is verified by some numerical examples on the nonlinear static, cyclic and dynamic analysis of steel frames.