Seismic considerations in design of offshore wind turbines

• Published in: Soil dynamics and earthquake engineering (1984) Vol. 124; pp. 399 - 407
• Main Author: Kaynia, Amir M.
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01.09.2019; Elsevier BV
• Subjects: Clean energy; Damping; Design; Dynamic loads; Earthquake dampers; Earthquake loads; Earthquake response; Earthquakes; Hysteretic damping; Nonlinear systems; Offshore; Offshore energy sources; Permanent tilt; Radiation; Radiation damping; Renewable energy; Resonant frequencies; Seismic activity; Seismic design; Seismic engineering; Seismic performance; Soil-structure interaction; Tripods; Turbines; Wind; Wind power; Wind turbine; Wind turbines; Hysteretic damping; Soil-structure interaction; Earthquake response; Permanent tilt; Wind turbine; Seismic performance; Radiation damping
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2018.04.038

Interest in renewable and clean energy over the past decade has motivated immense research on wind energy. The main issues in design of offshore wind turbines in regions of recent development have been aero- and hydro-dynamic loads; however, earthquake is a design concern in seismic areas such as East Asia and Western United states. This paper reviews the state of practice in seismic design of offshore wind turbines. It is demonstrated that wind turbines are in particular vulnerable to vertical earthquake excitation due to their rather high natural frequencies in vertical direction; however, inclusion of the radiation damping could contribute considerably reduce the earthquake loads. Moreover, it is demonstrated how soil nonlinearity could lead to settlement and permanent tilting of offshore wind turbines on caisson foundations or tripods. Using these cases, the paper demonstrates that the design of offshore wind turbines for earthquake loading is driven by performance-based considerations. •Effect of combined environmental and earthquake loads on offshore wind turbines, highlighting the issue of permanent tilt.•Nonlinear foundation springs with reduced/controlled hysteretic damping for soil-structure interaction analysis.•Rigorous modelling of radiation damping and its role in reduction of vertical seismic response of wind turbines.•Harmonization of earthquake hazard requirements in design of wind turbines.•Review of key issues in earthquake design of offshore wind turbines.