Nonlinear analysis of tubular steel framed structures

This paper presents a method for the analysis of inelastic tubular steel framed structures. A previously proposed member tangent stiffness matrix subjected to elastic-plastic bending and derived from moment-thrust-curvature equations is adopted for the nonlinear analysis of tubular steel frames. Approximate moment-thrust-curvature expressions for tubular sections are used in constructing the member tangent stiffness matrix. For inelastic frame analyses, an incremental loading procedure is used to trace the load-displacement curves for the frames. The ultimate strengths of the frames are determined at the limit points of the load-displacement curves where the determinants of the structure tangent stiffness matrices become singular. Several examples are given to demonstrate the applications of the proposed method.