Mechanical behavior of steel-fiber-reinforced self-stressing concrete filled steel tube columns subjected to eccentric loading

Abstract

Initial self-stress contributes to the pre-peak properties of concrete filled steel tube (CFST) columns, but brings salient brittleness at the post-peak stage. Adding steel fibers can alleviate the friability of concrete, helpful in the post-peak behavior of CFST columns. This study aims to investigate the coupling effect of initial self-stress and steel fibers on the mechanical behavior of CFST columns under eccentric loads. 42 eccentrically loaded specimens are conducted with various levels of self-stress, eccentricity ratio, steel fiber volume percentage, concrete strength grade and steel tube thickness. Moreover, a numerical analysis model is developed to capture the eccentrically loaded behavior of steel-fiber-reinforced self-stressing concrete filled steel tube (SSCFST) columns. The results show that the increases in the ultimate load (Nu) and the corresponding bending moment (Mu) are obtained by the self-stress. Adding steel fibers leads to a slight growth of Nu, but the bending moment shows an obvious growth after the ultimate state, indicating adequate safety margin. The axial-flexural interaction curves possess a more obvious convexity as steel fiber dosage is increased. Based on the numerical results, a new axial-flexural interaction model is proposed, which is capable of considering the influence of steel fiber dosage.