Concrete-filled Tubular Columns: Part 2 — Column Analysis

This paper is concerned with an analytical model for column analysis of concrete-filled tubular beam-columns subjected to the combined action of axial load and monotonic or cyclic bending. A method of segmentation is adopted in the analysis of beam-columns. The flexural and axial rigidities of the beam-column segments are derived from M–P–φ and M–P–ε relations obtained through fibre-analysis explained in Part 1¹of the paper. Geometric and material nonlinearities are taken into account and incremental equilibrium equations are formulated based on an updated Lagrangian formulation. An incremental-iterative Newton–Raphson iteration technique is adopted to obtain the solution of the equations. The limitation of Newton–Raphson technique in approaching the limit points is overcome by using a generalized stiffness parameter, thereby tracing the post-buckling response. The accuracy of the model is verified by comparing the results with the experimental values available in published literature.