Special Issue on "Optimal Design and Control of Onshore, Offshore and Floating Wind Turbine Supporting Structures"

Structural design of wind turbine support structures that focuses on optimal structural system performance and at the same time cost reduction is crucial to achieve economic competitiveness for the development of wind turbine technology. An important challenge, particularly for civil and structural engineers, arises from the increase in turbine diameter and power output, which increases the loads on the support structures. Specifically, three aspects are pivotal in their design and optimization process: a) the ultimate limit state strength for extreme load conditions; b) the fatigue strength under cyclic loads in operational conditions; c) the structural control for resonance in operational and extreme conditions. Within a design optimization approach based on global limit states, structural characteristics and details of the support structures are modified to enhance the global system performance in onshore and offshore wind turbines installations. Moreover, structural health monitoring for wind turbine installations, also based on digital-twin models, is a key factor to extent their durability. Finally, the application of design approaches based on passive or semi-active vibration control strategies is also considered, to reduce resonance and fatigue effects. This Special Issue is devoted to present recent advances in structural design and control of wind turbine supporting structures and their impacts on the advancement of wind energy industry. In particular, general and specific aspects are investigated, including the effects of structural details and control devices on the dynamic response of wind turbine supporting structures, the lessons gained by oil and gas installations, the use of Artifical Intelligence in health monitoring approaches for maintenance. Within this special edition, these array of topics related to optimal design of wind turbine supporting structures are covered. Sorge et al. (2025) analyzed the effective performance of a special passive control device (HSFD, Hinge-Spring Friction Device) for mitigating the dynamic effects on wind turbine towers in on-shore installations. They validated a specific design procedure to assess the perfomance of the control system against several wind loads associated to different operating scenarios. The results represent a significant advancement in the development of a vibration control strategy for horizontal axis wind turbines, and a key factor to extend their durability. Chuah et al. (2025) in their review explored the innovations and lessons learned from offshore oil and gas floating systems and their possible applications in floating wind turbine technology. Their findings provide valuable insights for the development of next-generation floating wind turbines, offering a pathway to expand renewable energy production and accelerate the technological advancement to the global transition towards sustainable energy sources. Ali et al. (2025) presented a high-fidelity Digital Twin framework for the prognostic health management of Offshore Wind Turbines subjected to synergistic Corrosion-Fatigue, which compromises the structural integrity of turbines. They proposed a novel methodology that integrates a coupled-physics degradation model with an AI driven physics-informed machine learning engine, establishing that such an integrated approach is essential for the reliable and economically viable management of offshore assets. Tekantappeh and Rebelo (2025) investigated the impact of varying Inter-Module Connections (IMCs) stiffness on the natural frequencies of Self-erected tower, that is a modular system composed of post-tensioned steel-concrete composite panels. The IMCs play a crucial role in the dynamic behaviour of this newly developed type of towers in wind turbines. The presented results show that a properly estimation and optimization of IMCs stiffness is essential for the design and performance of such modular tower structures. Hu et al. (2025) developed a Tuned Liquid Multi-Column Damper (TLMCD) system model integrated into a floating offshore wind turbine (FOWT) for the vibration control of flexible tower and platform motions. The results show that the platform motion parameters are significantly reduced with the TLMCD control system. In addition, the integration of a linear quadratic regulator control algorithm further enhances the structural performances under windy conditions.