B-SDM: A bounding surface stiffness degradation method for modelling the long-term ratcheting response of offshore wind turbine foundations

Long-term cyclic loading from environmental conditions can lead to excessive permanent rotation of offshore wind turbines (OWTs) due the ratcheting response sand. A practical hybrid strain accumulation approach, termed bounding surface stiffness degradation method (B-SDM), for finite element analysis (FEA)-based design OWTs under is presented. This includes a base elastoplastic constitutive model that captures stress–strain relationship in first load-unload cycle and scheme modelling subsequent cycles. The presented approach allows versatile overlay calculates be applied range models. utilised established based on concept considers strain-hardening plastic volume change before failure. has been validated by single test data sand used finitesingle-element monopile loading. When modelled 3D FEA, conventional step-by-step until end regular cycle. Strain cycles using B-SDM, which modulus dilatancy are scaled law.