Axial hysterestic behavior of prestressed CFDST columns for lattice-type wind turbine towers

The escalating power outputs of wind turbines necessitate enhanced load-bearing capabilities in their support structures. A new type of prestressed concrete-filled double skin steel tubular (CFDST) lattice-type wind turbine tower has been proposed to replace the original steel-concrete hybrid tower. The corner columns of the tower are made of prestressed CFDST columns, with the prestressing steel strands situated within the hollow area. While numerous studies have researched the axial characteristics of concrete-filled steel tubular (CFST) columns, investigations into prestressed CFDST columns subjected to axial cyclic loading remain sparse. To address this research gap, this study carried out the experimental and finite element studies of eight prestressed CFDST columns under axial tensile, axial compressive, and tensile-compressive cyclic loads. Detailed analyses of failure modes, hysteresis curves, stiffness degradation, skeleton curves and ductility were conducted. The test results indicate that the prestressing enables the concrete to establish good contact with the steel tubes, thereby preventing the premature cracking. At a cost of approximately 6.8 % reduction in axial compressive load, the axial tensile load of the structure is enhanced by about 47.2 %. Furthermore, an advanced finite element (FE) model, refined based on the test, closely matched the experimental data, thereby validating its accuracy for subsequent mechanism and parameter investigation.