Torsional behaviour of horizontal joints in prestressed concrete towers for wind turbines

The horizontal joint is a critical part in the prestressed concrete towers for wind turbines ; however, the design methods in existing codes fail to accurately predict its torsional capacity under combined bending and shear actions. This study aims to improve the design accuracy of the horizontal joint in prestressed concrete towers for wind turbines. An experimental investigation was conducted on four horizontal joint specimens subjected to combined compression-torsion or compression-bending-shear-torsion loads. The results indicated that the torsional capacity of horizontal joints was primarily attributed to the friction between the upper and lower segments, and the torsional capacity of horizontal joints was significantly influenced by the bending moment and shear force applied to the horizontal joint. Furthermore, a finite element (FE) model was developed and validated against the experimental results, and a parametric study was conducted to investigate the influence of key parameters including the material strengths , cross-sectional dimensions, prestressing force and transverse loads. Subsequently, the applicability of the existing design methods of torsional capacity for horizontal joints was evaluated and found to be inadequate due to their neglect of the bending moment and shear force. Finally, a modified method is proposed and validated through the experimental and numerical results obtained in this study. Results demonstrate that the proposed design method is more accurate and consistent for predicting the torsional capacity of horizontal joints in prestressed concrete towers for wind turbines. • An experimental investigation was conducted on four horizontal joints in prestressed concrete towers for wind turbines. • The effect of horizontal joint cracking on its torsional behaviour is considered in this study. • A torsional calculation method considering the effect of horizontal joint cracking is proposed.