Axial compressive behavior of concrete-filled double skin steel tubular columns with different stiffening constructions for wind turbine towers

In recent years, substantial interest has been directed toward concrete-filled double skin steel tubular columns with large hollow ratios (LHR-CFDST). Applications for thin-walled LHR-CFDST in wind turbine towers are seen to have a great deal of promise. In order to better investigate the design method of this type of structure, a refined finite element (FE) model is developed, drawing upon prior experimental investigations. Then the mechanism, including the properties of the axial stress distribution in concrete, is analyzed using the model validated by the experimental data. Subsequently, an extensive parametric analysis is conducted to verify the impact of various factors on the axial compressive performance of the structure. These variables include the material strength, the diameter-to-thickness ratio of the tube, the hollow ratio, the number of stiffened ribs, and the spacing between the studs. Ultimately, based on the conclusions gained from the parametric study, a predictive formula for the compressive peak load of stiffened LHR-CFDST is established, conforming to AISC 360-16. The agreement with the experimental and FE analysis results verifies the prediction accuracy of the formula.