Numerical modelling of concrete-filled steel tubular short columns under axial compression

Abstract

The paper presents three-dimensional numerical models of short concrete-filled steel tubular circular columns that can successfully describe the column behaviour under axial compression. Several of the most commonly used material models for the steel part and a concrete portion of the column are evaluated in the models. In addition, the paper presents a new proposal for the extension of the Eurocode 2 stress-strain relation to make it suitable for describing the complex behaviour of concrete inside the steel tube. This model overcomes the current limitations of the Eurocode 2 design guide, referring to the limitation for the concrete curve in compression to 3.5‰ strain. The ultimate axial column strength obtained by the proposed model is compared to the ultimate column capacity calculated by a simplified method provided in Eurocode 4. All presented numerical models are validated on a set of experiments from the literature and demonstrate good agreement. The comments about the accuracy of each model are provided, along with the identified limitations.

Experimental Investigation and Numerical Analysis of the Axial Load Capacity of Circular Concrete-Filled Tubular Columns

“…S4R finite shell elements (4-node general-purpose shell, reduced integration with hourglass control, finite membrane strains) were used to model the steel profile. An element size of 10 mm was chosen for both concrete and steel components based on the mesh sensitivity analysis [2]. The material nonlinear stress-strain relations are included within the constitutive materials.…”

“…For the tangential direction, the "Columb friction model" was adopted, whereby the coefficient of friction was set at 0.47 [55]. According to numerous authors, this coefficient is usually in the range of 0.2-0.6 [3,13,19], although it has little impact on axial response [2].…”

“…Numerical analyses are mostly conducted using available finite element method (FEM) software. The majority of studies employed ABAQUS, as in [1][2][3][4], while certain studies utilized ANSYS [5][6][7] or LS-DYNA [8][9][10]. Further, many researchers provided a comparative analysis of their results with current design codes.…”