An accuracy-improved approach to establish design response spectra for wind turbines

Abstract

Onshore and offshore wind power technologies have seen unprecedented growth. For wind farms located in areas prone to earthquake, seismic analysis and design of wind turbines are required to guarantee their safety and economy. This paper proposes a procedure to establish design response spectra for wind turbines by modifying the 5%-damped design response spectra in codes for traditional buildings. This modification entails short service life and low structural damping ratio of wind turbines. The damping modification factors (DMFs) are developed for the quantile spectra to account for the excessive fluctuations of low-damped spectra. Besides, the critical modal periods of the wind turbine are applied in the procedure, leading to much more accurate results of the DMFs at these periods. The design seismic intensity is modified to make an identical seismic risk for the wind turbines and buildings, leading to economical design of wind turbines. A case study is conducted for a monopile-based offshore wind turbine to illustrate and demonstrate the proposed approach. Comprehensive discussions are also included on establishment of DMFs for wind turbines with various damping ratios and different substructures. The results indicate that the proposed DMFs have a high accuracy at the critical modal periods of the wind turbine, and the DMFs corresponding to different damping ratios and various quantile values can be efficiently derived according to the developed regression models.