Comparative study between S-N and fracture mechanics approach on reliability assessment of offshore wind turbine jacket foundations

This paper investigates from a structural reliability assessment (SRA) perspective the fatigue using S-N curve approach compared with fracture mechanics (FM) for typical welded offshore wind turbine (OWT) jacket support structure. A non-intrusive formulation was developed an OWT structure in 50 m deep water, consisting of sequence steps. First, stochastic parametric 3D (three-dimensional) Finite Element Analysis (FEA) simulations are performed, taking into account variables such as loads, wave loads and soil properties facilities within software package ANSYS. Secondly, FEA results post-processed Artificial Neural Network (ANN) response surface modelling technique deriving performance functions expressed terms variables. Finally, First Order Reliability Method (FORM) is applied calculating index values components. The framework to elucidate damage process, including small long crack transition amongst other stages, steels used applications. FM investigated includes growth based on bilinear law, considering both segments law non-correlated correlated (RI). Sensitivity analysis showed strong dependence structure's levels uncertainties constants measured coefficient variation (COV). Also investigated, reassessed updated presence assumed health monitoring/ condition monitoring (SHM/CM) data. case study revealed that highly sensitive initial size. It recommended apply method at design stage while towards end life approaches failure.