THE EFFECTS OF MODELLING TOWER-FOUNDATION CONNECTION STIFFNESS IN A FINITE ELEMENT WIND TURBINE CONCRETE FOUNDATION MODEL

Resumo

Nowadays, one of the main challenges regarding the design of concrete wind turbine
foundations is the search of reliable structural numerical models, which allows concrete and steel
volume reduction, providing more cost benefit solutions. Due to the necessity of modelling the physical
situation in a trustworthy manner, it’s imperative to consider not only the soil-structure interaction, but
also the stiffness of support structure (wind turbine tower). Therefore, the present paper aims to analyse
the effects of tower-foundation connection stiffness in the internal stresses of foundation element (pile
group foundation with a pile cap), as well the global rotational stiffness provided to the system, that
being an essential parameter to guarantee dynamic stability to the wind turbine. The foundations were
model using the SAP 2000, a finite element software. Shell (thin and thick) and solid elements were use
in the foundation model, whilst thin shell elements were designate to represent the tower behaviour. The
results show that the anchor bolt cage provide a high stiffness to the foundation core modifying the stress
distribution along all the pile cap.