Nonlinear analysis and design of concrete-filled dual steel tubular columns under axial loading

Abstract

A new unified design formula for calculating the composite compressive strength of the axially loaded circular concrete filled double steel tubular (CFDST) short and slender columns is presented in this paper. The formula is obtained from the analytic solution by using the limit equilibrium theory, the cylinder theory and the "Unified theory" under axial compression. Furthermore, the stability factor of CFDST slender columns is derived on the basis of the Perry-Robertson formula. This paper also reports the results of experiments and finite element analysis carried out on concrete filled double steel tubular columns, where the tested specimens include short and slender columns with different steel ratio and yield strength of inner tube; a new constitutive model for the concrete confined by both the outer and inner steel tube is proposed and incorporated in the finite element model developed. The comparisons among the finite element results, experimental results, and theoretical predictions show a good agreement in predicting the behavior and strength of the concrete filled steel tubular (CFST) columns with or without inner steel tubes. An important characteristic of the new formulas is that they provide a unified formulation for both the plain CFST and CFDST columns relating to the compressive strength or the stability bearing capacity and a set of design parameters.

Experimental and numerical studies of square concrete-filled double steel tubular short columns under eccentric loading

“…Little research has been reported on the structural behavior of thin-walled CFDST square columns that are subjected to eccentric loads. This paper Most of the investigations on CFDST columns reported previously has focused on circular cross-section [1][2][3][4][5][6][7][8][9][10][11][12] and tests on short square CFDST columns consisting of an inner circular steel tube have been very limited [13][14][15][16]. Pei [13] performed tests to determine the structural performance of stub CFDST square columns under axial and eccentric loads.…”

Numerical analysis of axially loaded circular high strength concrete-filled double steel tubular short columns

“…In comparisons with experimental studies on CFST columns, only limited experimental investigations on CFDST columns with circular sections were performed by researchers, such as Xiong et al [6], Peng et al [8], Liew and Xiong [9], Romero et al [10], Wan and Zha [11], Ekmekyapar and Al-Eliwi [12]and Ibañez et al [13]. Peng et al [8] Experimental observations indicated that the column ultimate strengths were reduced by increasing the / o o D t ratios of the outer tube.…”

“…Numerical studies on circular CFDST short column constructed by carbon steel tubes have been extremely scare [11,27]. Wan and Zha [11] proposed a confining pressure model and a softening reduction factor as a function of confining factors for determining the post-peak responses of concrete in CFDST columns. However, it was found that the computed axial loadstrain curves deviated considerably from experimental data.…”

Nonlinear analysis of rectangular concrete-filled double steel tubular short columns incorporating local buckling

“…Computational and experimental investigations on the responses of circular short CFDST columns subjected to axial loading have been undertaken by researchers, such as Peng et al [9], Hassanein et al [10], Wan and Zha [11], Xiong et al [12], and Ekmekyapar and Al-Eliwi [13].…”