Feasibility study of new hybrid piled concrete foundation for offshore wind turbine

Abstract

Offshore wind turbine energy has recently attracted significant attention and many researchers have attempted to develop cost-efficient offshore wind turbine support structures to reduce capital costs. This paper proposes a new hybrid support structure using driven piles that eliminates the disadvantages of conventional support structures for offshore wind turbines. The hybrid support structure proposed here is a piled concrete foundation (PCF) structure, which combines a concrete base with a steel shaft and is supported not only by gravity type foundations but also by driven piles. The soil was modeled as an elastic foundation, and the added mass was calculated using the Added mass method to determine the effects of water surrounding the support structure. To evaluate the feasibility of the PCF, quasi-static analysis, natural frequency analysis and seismic analysis were performed using environmental conditions at the Southwest Coast of Korea. In quasi-static analysis, the lateral displacement did not exceed the allowable displacement, and natural frequency analysis confirmed the superiority of the dynamic behavior of the PCF. Seismic evaluation through response spectrum analysis and time-history analysis demonstrated that the PCF is safe. The proposed PCF was confirmed to have sufficient structural stability for applications in real-site conditions in Korea. Optimization of the structure using the preliminary design resulted in an efficient structure that reasonably reduces fabrication costs.