Digital Healthcare Engineering System for Enhancing the Safety and Sustainability of Aging Monopile Offshore Wind Turbines in Storm Conditions

Monopile foundations dominate offshore wind turbine installations in shallow waters but are increasingly challenged by structural degradation as assets age. Cumulative damage mechanisms (including corrosion, fatigue cracking and denting) are exacerbated by intensifying metocean conditions, posing significant risks to safety, reliability and operational performance. Conventional maintenance strategies often prove inadequate, particularly under severe storm events. This study presents a Digital Healthcare Engineering (DHE) system that integrates high-fidelity numerical simulations, real-time environmental monitoring and Artificial Intelligence (AI)-driven diagnostics to assess and predict structural health continuously. By transitioning asset management from a reactive to a proactive paradigm, the DHE system enhances early failure detection, optimizes maintenance planning and mitigates the risk of catastrophic failures. Beyond monopile-supported turbines, the framework demonstrates scalability for broader application to ageing offshore and marine structures, contributing to safer and more sustainable operations. INTRODUCTION Offshore wind turbines have become essential in the global transition to clean energy, with projected global capacity rising from 75 GW to 2,000 GW by 2050 (World Economic Forum, 2025). Monopile foundations, which currently support approximately 63% to 81% of these installations, remain the predominant foundation type for fixed-bottom OWTs due to their simplicity, cost-efficiency, and established installation procedures (Fabricius, 2023; Vidal et al., 2020). However, as turbine sizes increase and wind farms are developed in deeper waters, these structures face heightened design demands and operational challenges (Fabricius, 2023; Horwath et al., 2020). Offshore wind turbines are continually exposed to harsh marine conditions, including wind, waves, and currents, which induce significant cyclic and extreme loading over their lifetimes. These loads are compounded by environmental degradation mechanisms such as general and localized corrosion, fatigue cracking, and accidental mechanical damage (TNO, 2023; Xie et al., 2025; Sindi et al., 2024b). Fig. 1 illustrates these challenges in real-world offshore conditions and their impact on OWT structural integrity. Corrosion, especially in splash zones and internal compartments exposed by failed seals, reduces material thickness and load-carrying capacity (Sunday and Brennan, 2021; Sindi et al., 2024a) Fatigue, triggered by wind and wave-induced cyclic loading, leads to crack initiation and propagation, particularly at welds or other stress concentrators (TNO, 2023; Oyeniran and Aziaka, 2020). Moreover, mechanical damage from vessel collisions or dropped tools can introduce local denting, reducing structural integrity and potentially initiating further fatigue failure (Xie et al., 2025; Amdahl et al., 2013). These degradation mechanisms often interact synergistically, as seen in corrosion-fatigue (CF), where pitting corrosion accelerates fatigue crack growth and significantly shortens fatigue life (TNO, 2023; Okenyi et al., 2022; Li et al., 2022). At the same time, environmental factors such as scour erosion reduce effective pile embedment, changing soil-structure interaction and diminishing the foundation's lateral stiffness and capacity under extreme storm loading (Wei et al., 2024). Inspection and maintenance are further complicated by the offshore environment. Traditional condition assessment approaches—typically based on periodic inspections or predefined maintenance schedules—are logistically intensive, hazardous, and often insufficient for managing aging structures that exceed their initial 20–25 year design life (Sindi et al., 2024b). In this context, conventional SHM techniques may fail to offer the real-time insight or longterm degradation forecasting necessary for life extension and safe operation. Furthermore, the rapid upscaling of monopile dimensions introduces a "proven technology paradox," whereby experience with smaller, shallower designs does not adequately inform performance expectations for larger piles in deeper waters, especially under extreme loads (Sunday and Brennan, 2021; Horwath et al., 2020; Andrić et al., 2017). These compounding challenges underscore the urgent need for advanced, integrated, and predictive structural health management solutions tailored to aging monopile foundations.