Shake table testing and computational framework for seismic response of utility-scale bucket foundation offshore wind turbines

Shake table testing was conducted to document the seismic response of a bucket foundation offshore wind turbine (OWT) system. Salient response of the system's soil-structure interaction effects is presented and dis-cussed. Among the observed response characteristics, excess pore pressure fluctuation within and around the soil-bucket domain is thoroughly addressed, including the strong tendency for the soil dilation excursions driven by the induced cyclic strains. The experimental data is used to calibrate a numerical model with dynamic soil response simulated by a coupled solid-fluid formulation. The calibrated model is extended to investigate seismic response of a prototype utility-scale OWT, with and without added wind loading effects. Overall, the research outcomes indicate that: i) excess pore pressure fluctuations in the vicinity of the bucket play an important role in dictating the extent of potential permanent base rotation, ii) consideration should be given to wind loading that might further exacerbate this base rotation, and iii) it is of importance to model the turbine tower as a system of discrete masses rather than the simplified proposed for practice equivalent top mass idealization.

Automated summary

Shake table testing was conducted to investigate the seismic response of a bucket foundation offshore wind turbine (OWT) system. The study focuses on the soil-structure interaction effects, particularly the excess pore pressure fluctuations and soil dilation excursions driven by induced cyclic strains. The experimental data is used to calibrate a numerical model, which is further extended to analyze the seismic response of a utility-scale OWT with and without wind loading effects. The research outcomes highlight the importance of excess pore pressure fluctuations, the exacerbating effect of wind loading on base rotation, and the need to model the turbine tower as a system of discrete masses.