Stochastic dynamic stiffness of surface footing for offshore wind turbines:Implementing a subset simulation method to estimate rare events

Highlights•This study concerns the stochastic dynamic stiffness of foundations for large offshore wind turbines.•A simple model of wind turbine structure with equivalent coupled springs at the base is utilized.•The level of uncertainties is quantified through a sensitivity analysis.•Estimation of rare events of first natural frequency applying subset simulation is discussed