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

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%o 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.