Behaviour and design of combined sections steel beam columns

Abstract

Abstract Combined-section steel columns (also referred as built-up steel columns) which are composed of two separate sections present an ideal and economic design for long columns subject to high values of bending moment and axial forces. Research dealing with the design of these columns is currently insufficient. At present, most codes of practice consider each column’s component to behave either separately or rigidly connected. As such, the main objective of this research is to scrutinize the behaviour of the combined-section columns which are subjected to eccentric loading and propose design criteria for them. A nonlinear numerical model for these columns is developed based on the finite element method. The results of the numerical model are first verified against the outcomes of experimental investigations which are available in literature. Then, the numerical model is adopted to simulate the behaviour and the capacity of the combined columns. The numerical model includes accounts for the effects of both the geometric and materials nonlinearities along with the effect of the initial imperfections. A parametric study is performed to investigate the effect of various parameters on the behaviour, failure modes and capacity of the columns.