Abstract
The objective of this study is to investigate the mechanical properties and the composite action of circular concrete-filled steel tube (CFST) columns subjected to compression-torsion load using finite element model analysis. Load–strain (T–γ) curves, normal stress, shear stress, and the composite action between the steel tubes and the interior concrete were analyzed based on the verified 3D finite element models. The results indicate that with the increase of axial force, the maximum shear stress at the core concrete increased significantly, and the maximum shear stress of the steel tubes gradually decreased. Meanwhile, the torsional bearing capacity of the column increased at first and then decreased. The torque share in the columns changed from the tube-sharing domain to the concrete-sharing domain, while the axial force of the steel tube remained unchanged. Practical design equations for the torsional capacity of axially loaded circular CFST columns were proposed based on the parametric analysis. The accuracy and validity of the proposed equations were verified against the collected experimental results.
Highlights
Concrete-filled steel tube (CFST) structures are widely used as compression members in bridges and building structures
There have been many experiments, theoretical models, finite element models, and design methods based on the compression-bending and tensile-bending performance of CFST columns [13]
2, the finite element model used in this study is introduced and its the composite action and load sharing ratio of the steel tubes and the core concrete are validity is examined; and in Section 3, the effect of the loading path is studied
Summary
Concrete-filled steel tube (CFST) structures are widely used as compression members in bridges and building structures. Wang et al [31] conducted experimental research on concrete-filled steel tube columns under pure torsion, bending-shear, and combined bending-shear–torsion; they compared and analyzed the mechanical properties and working mechanism of specimens under different loads and provided a formula for calculating the bearing capacity of columns under complex bending, shear, and torsion. 2, the finite element model used in this study is introduced and its the composite action and load sharing ratio of the steel tubes and the core concrete are validity is examined; and, the effect of the loading path is studied.
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