Behavior of PCFCST Gusset K-Joints with Arc-Shaped Endplates in Wind Turbine Towers

Under the evolving trend of ultralong blades, ultrahigh towers, and large-capacity units in wind turbine systems, concrete-filled steel tubular (CFST) lattice towers demonstrate prominent advantages in terms of structural efficiency, material consumption, and degree of industrial construction. As a critical component of the tower structure, the joint is subjected to a highly complex stress state. This paper presents experimental and numerical investigations on a novel prefabricated K-type gusset joint with arc-shaped endplates for concrete-filled circular steel tubular (PCFCST) members. The results indicate that the primary failure modes of the proposed joint involve buckling of the compression web and buckling of the gusset plate, while the arc-shaped endplates and blind bolts remained intact throughout the tests. The load-bearing capacity of the joint is closely associated with its failure mode, which is primarily influenced by the gusset-to-web thickness ratio (μ) and the arc-shaped endplate-to-gusset thickness ratio (β). To ensure reliable force transfer through the gusset and the arc-shaped endplate in practical engineering, it is recommended that μ>2 and β>1.5.