Compressive Behaviour of Diagonally Stiffened Concrete Filled Steel Tubular Stub Columns with Reinforcement Stiffeners

Abstract

Due to its superior strength and ductility, the utilisation of concrete-filled steel tube (CFST) columns has grown over the last few years. However, due to unequal lateral inflation properties, infill concrete and steel tube slip against one another during early loading phases. This paper presented a novel type of CFST section, a diagonally stiffened CFST column as a solution to this problem. It consists of a circular steel tube with stiffening bars installed inside the outer steel tube from one top end to the diagonally opposite bottom end. The suggested section is presented using various stiffening strategies, including binary, tertiary, and quaternary arrangements. The effectiveness of the suggested column section under an axial load is examined using finite element (FE) modelling, and the validation of the FE model was established using experimental testing carried out by previous researchers on unstiffened and stiffened CFST columns. Analysis was done on specimens of diagonally stiffened CFST columns to evaluate the load-carrying capacity, load vs deformation behaviour, stress distribution, and failure pattern. According to the findings of this study, CFST sections with diagonal stiffeners have higher ultimate load capacity than unstiffened CFST columns. Stiffening bars increase the ductility of brittle infill concrete and eliminate localised steel tube buckling. It was recommended that the number of stiffeners be altered to even numbers since odd numbers of stiffeners can cause asymmetry in the section, which can increase the concentration of stress.