Researchers from the University of Technology Sydney (UTS) have developed a new cable stay reinforcement system that could make large offshore wind turbines more resilient against the combined impacts of earthquakes, strong winds and ocean waves.
The study, led by Professor Behzad Fatahi and conducted by PhD researcher Nadeem Fairley with support from engineering firm Arup, focused on a 15 MW offshore wind turbine supported by a monopile foundation. The researchers compared a conventional turbine tower with a newly designed cable-stayed tower using advanced numerical modelling.
Improving Structural Resilience
The proposed design uses high tensile steel cables and supporting struts to strengthen the turbine tower. The added reinforcement increases structural stiffness, helping the tower better withstand multiple hazards while reducing excessive movement during extreme loading conditions.
Simulation results showed that the cable stayed tower significantly reduced tower acceleration, stress, and deformation. In several scenarios where the conventional tower experienced yielding or buckling, the reinforced design remained structurally stable.
Addressing Multiple Hazard Risks
Researchers noted that many promising offshore wind locations, particularly across the Asia Pacific region, are also situated in earthquake prone areas. As offshore wind turbines continue to grow in size, ensuring they can withstand earthquakes alongside wind and wave forces has become a major engineering challenge.
The study found that the cable stay system reduced internal forces in the upper sections of the tower, minimized vibration and prevented sectional ovalisation a deformation that can lead to buckling in thin walled turbine towers.
Supporting future offshore wind projects
According to the researchers, offshore wind turbines rarely face hazards individually, making it important to consider combined earthquake, wind and wave loading during design. They believe the proposed reinforcement system could improve the safety and long term reliability of future offshore wind farms.
The team also suggested that the technology could be used to strengthen existing offshore wind turbines, extend the lifespan of ageing structures, and support future upgrades with larger turbine models.