Compressive behavior of the steel-concrete composite adapter for wind turbine hybrid towers

Adapter is one of the most important components in wind turbine hybrid towers. It allows the upper steel segments to connect reliably with the lower concrete segments and thus they can work well as a whole structure. However, traditional reinforced concrete adapters (RCAs), which have been commonly used in engineering practice, encounter many shortcomings such as complicated construction processes and strength/stiffness degradation after the concrete cracking. In this paper, a novel type of steel-concrete composite adapter (SCCA) was proposed. Experimental and numerical studies on its compressive behavior were conducted. Six SCCA specimens and one RCA specimen were tested under axial compression. The tested parameters include the stud spacing, the thickness of stiffened plates, and the amount of bottom circumferential rebars. By revealing the failure modes, load-displacement relations, ultimate strength, deformability, and strain relations of SCCA, the superiority of SCCA over RCA was proved. To extend the scope of the experiment and conduct parametric an-alyses, finite element models were established and validated with test results. Sensitive parameters related to the ultimate capacity of SCCA were investigated. Additionally, reasonable studs spacing which is beneficial for enhancing the ultimate capacity of SCCA was obtained.