Steel-concrete composite adapter for wind turbine hybrid towers: Mechanism and ultimate capacity prediction under compression

Abstract

The adapter is an essential part of the wind turbine hybrid tower since the steel and the prestressed concrete segments are connected by the adapter. Due to the large designed prestress, the adapter is prone to fail under compression. Consequently, the ultimate capacity of the adapter under compression is critical to the safe operation of the wind turbine. Previously, the steel–concrete composite adapter (SCCA) was presented and a relevant compressive test was conducted. It is necessary to further explore the ultimate behavior and develop the calculation method of SCCA. Therefore, a comprehensive analytical investigation on the ultimate compressive capacity of SCCA is conducted in this paper. Refined finite element models are built and validated based on the former test results. The mechanism analysis in terms of the stress distribution and the contact stress between steel tubes and sandwich concrete is carried out to reveal the ultimate compressive behavior of SCCA and the effects of studs, stiffened plates, and circumferential rebars. The accuracy and applicability of five existing calculation methods for the ultimate compressive capacity are evaluated. Lastly, a simplified practical method for predicting the ultimate compressive capacity of SCCA is proposed and it can provide reasonable predictions within the common range in wind turbine engineering.