Simplified method for performance-based seismic design of suction caissons supporting jacket offshore wind turbines

The paper studies the performance of Offshore Wind Turbines (OWTs) founded on Suction Bucket Jackets (SBJs) in clay under combined wind and seismic loading. A detailed 3D FE model soil–foundation–structure (SFS) system is developed used as a benchmark to assess efficiency an enhanced Winkler-based "Caisson-on-Winkler-Soil" (CWS) model, where soil replaced by nonlinear hysteretic elements. proposed CWS captures residual deformations hysteresis offers physical coupling between vertical moment It allows excellent prediction H–M failure envelope most relevant first quadrant space, loads act same direction. Despite its successful application for simulation inertial loading, fails reproduce dual shearing mechanism that develops at caisson shaft during shaking, stemming from combination kinematic due vertically propagating shear waves, superstructure response, thus underpredicting co-seismic settlements. For latter, research utilizes spectrum compatible input motions models varying geometric material properties derive linear regression equations correlate dimensionless settlement caissons (wE/D) with characteristic dimensional variables problem investigation Arias Intensity (IA) surface ground motion. As final step, proposes hybrid method performance-based assessment SBJ OWTs. employs simplified calculate VHM approximately estimate horizontal displacements rotations jacket legs, followed preliminary settlements using correlations wE/D IA, basis spectrum-compatible motions.