Nonlinear numerical modelling of onshore wind turbine foundations validated with experimental data

This paper presents a detailed and comprehensive modelling strategy for reproducing the behaviour of onshore wind turbine foundations, incorporating the details of the tower-to-foundation connection. The study focuses on comparing the performance of the two most common solutions for this connection: prestressed anchor cage (AC) and embedded tower foundation section (TFS). In the latter case, modelling strategies are developed to account for the presence of gaps (or voids) between the steel flange and the surrounding concrete, a common occurrence in this type of solution, and to access their impact on the overall performance of the system. The analysis examines the behaviour of these systems under service conditions and at the ultimate limit state with different levels of modelling complexity, providing insights into their operational performance and load-bearing capacities. Furthermore, the developed models are validated with experimental results collected in two wind turbines continuously monitored during more than one year to ensure that the simulations accurately reflect the real behaviour and to enhance the reliability of the findings. The combination of advanced modelling with rarely available monitoring results permitted the proposal of a dully validated and original modelling strategy with great relevant for the evaluation of a large number of ageing wind turbines with issues at the connection tower-foundation. • Validated numerical models for onshore wind turbine foundations. • Detailed comparison of foundations with anchor cage (AC) and tower foundation section (TFS) solutions. • Comprehensive analysis of how gaps in TFS foundations impact the moment-rotation relationship of the tower base. • Examination of system behaviour under service conditions and Ultimate Limit State (ULS). • Use of experimental validation to ensure model accuracy and reliability.