Seismic uncoupled analyses for offshore wind turbines

For seismic assessment of wind turbines in seismically active areas, International Standards and Guidelines allow combining two separate analyses under environmental and earthquake loads, respectively. Time-domain or response-spectrum based analyses are prescribed to compute the separate earthquake response. While some work has already been done to estimate the accuracy of uncoupled analyses for land-based wind turbines, to date no similar studies have been carried out for offshore ones. This paper investigates two different implementations of uncoupled analyses for seismic assessment of offshore wind turbines, considering the case study of a 5 MW wind turbine mounted on a tripod in intermediate waters.