Mechanical Characteristics of Prestressed Concrete Curved Transition Section of Composite Bucket Foundations for Offshore Wind Turbines

Abstract

The composite bucket foundation (CBF) consists of a concrete curved transition section, a concrete beam-slab system, and a suction caisson and is increasingly used as the foundation for offshore wind turbines. The curved transition section transmits the upper load from the tower to the foundation, and its force and transmission characteristics are related to the safety of the entire wind turbine structure. The arced transition section has the characteristics of complex geometry, load conditions, and large curvature. It is difficult to determine its bearing characteristics and force transmission system. In this paper, the boundary conditions and loading device of the CBF model test are designed, and three 1:20 arced transition section model specimens are made. The mechanical characteristic experiments of CBF are used to analyze the failure process, failure characteristics, and seismic performance of the structure. Results show that the cracking effect of the arced transition section after prestressing is obviously better than that of a reinforced concrete arced transition section structure. The arced transition section specimens equipped with prestressed tendons can increase the structural cracking load ratio by about 35% for reinforced concrete members. The energy dissipation capacity of the specimens has been significantly improved, and the material properties can be fully utilized. The failure mode of the arced transition section structure under horizontal reciprocating load shows the characteristics of bending and shear failure.