Inverse modeling of damping and soil–structure interface for monopiled offshore wind turbines

Abstract

There have been many articles contributed to the finite element modeling for the dynamic analysis of monopile offshore wind turbine (OWT) systems. However, the accuracy of the parameter values used in the finite element model has always been a major concern. Mathematically, the design and analysis based on a finite element model is classified as a “forward” problem, while correcting the parameter values of the baseline finite element model based on measured response data is an “inverse” problem. This paper is the first article devoted to the concurrent correction of parameter values of both soil–structure interface and damping of a monpile OWT based on measured response data. While adopting a lumped parameter model (LPM) – which consists of one rotational spring, one horizontal spring and one rotational dashpot – for the soil–structure interface and a Rayleigh damping model for the energy-loss of the tower/substructure, this study develops a novel method for simultaneously updating the Rayleigh damping coefficients and soil–structure interface stiffness/damping parameters based on only a few measured natural frequencies and damping ratios. In the numerical studies, computer simulations with the National Renewable Energy Laboratory 5-MW (NREL 5-MW) reference turbine are carried out to demonstrate the effectiveness of the proposed method.