Experimental Study on the Axial Compression High-Cycle Fatigue Performance of Concrete-Filled Double-Skin Steel Tubular Columns

Concrete is widely used in the field of wind power generation. Under design conditions, concrete in wind turbine towers is often subjected to compressive cyclic fatigue loading. In this study, 10 specimens were experimentally investigated to clarify the high-cycle fatigue behavior of plain concrete (PC), steel-reinforced concrete (SRC), and concrete-filled double-skin steel tubular (CFDST) members. The specimens were designed based on a scaled-down model of the corner columns from an actual lattice tower structure, considering the most unfavorable fatigue load scenario. The fatigue life and failure modes of the different member types were analyzed. The results indicate that, in terms of fatigue life, CFDST members are superior to PC and SRC members. Experimentally, the mean fatigue lives were 31,008 cycles for PC members and 85,374 cycles for SRC members, whereas all CFDST specimens survived beyond 100,000 cycles without failure. The fatigue failure of these specimens is characterized by localized failure leading to global collapse. Under axial cyclic loading, the confinement effect provided by the double-skin steel tubes significantly enhances the fatigue life of the concrete core. Furthermore, the axial compressive capacity of the CFDST specimens with a low steel ratio still generally meets the requirements of relevant design codes. Finally, design recommendations for the corner columns of lattice wind turbine towers are proposed.