Experimental and numerical investigations into the behavior of circular concrete-filled double steel tubular slender columns

Abstract

This paper describes experimental and numerical investigations into the structural behavior of circular concrete-filled double steel tubular (CCFDST) slender columns loaded concentrically to failure. Test results on 8 specimens including 6 CCFDST slender columns and 2 CCFDST short columns are reported in this study that demonstrate the influences of column slenderness ratio and the thickness of the internal steel tube on the responses of CCFDST columns. A numerical model based on fiber analysis is developed to predict the axial load–deflection responses of CCFDST slender columns. The numerical model of CCFDST columns accounts for the effects of initial imperfection, concrete confinement, material nonlinearities and the interaction between axial load and deformations. A parametric study is performed by means of employing the verified computational technique to ascertain the sensitivity of the performance of CCFDST slender columns to various important parameters. Comparative analyses are undertaken to evaluate the applicability of Eurocode 4 and AISC 360–16 for conventional concrete-filled steel tubular columns (CFST) to CCFDST slender columns. It is shown that the developed numerical modeling technique simulates well the structural behavior of CCFDST slender columns and is an efficient computer simulation tool for the analysis and design of such composite columns. Moreover, the current design codes need to be modified to be utilized for designing CCFDST columns.