Numerical investigation on slender concrete-filled steel tubular columns subjected to biaxial bending

Abstract

[EN] The behaviour of concrete-filled steel tubular columns under axial compression or combined compression and uniaxial bending has been deeply investigated in past years by means of experimental testing and numerical simulations. However, the behaviour of these columns under biaxial bending has been scarcely investigated, in fact, a very limited number of experimental tests are available for this loading situation. Additionally, the current provisions in EN1994-1-1 for biaxial bending need to be revised, in order to be aligned with the new methods that are being proposed for the new generation of Eurocodes. This paper presents the outcome of a numerical investigation on the load-bearing capacity of slender concrete-filled steel tubular columns subjected to biaxial bending. The focus is on creating and validating a numerical model for room temperature that can predict the behaviour of this type of columns under biaxial bending, which may be used for evaluating the current design guidelines in EN1994-1-1. The numerical model is validated by comparison against experimental tests from the literature, proving that it predicts the ultimate load of slender columns with good accuracy. Different eccentricities about the minor and major axis and different moment ratios are considered, so that this investigation contains cases for both uniaxial and biaxial bending. With the help of this numerical model, the experimental results are extended to generate more cases, in order to assess the accuracy of the current provisions in EN1994-1-1 for concrete-filled steel tubular columns subjected to biaxial bending.