Data Analysis for Structural Health Monitoring of a Steel Jacket Offshore Platform

This paper presents the long-Term data analysis operated on the steel jacket VEGA-A offshore platform, which has been under continuous monitoring for more than two decades. The system records both environmental and structural data, including wave height, wind speed, and accelerations, enabling the study of dynamic behaviour under real operating conditions. An automated Operational Modal Analysis (OMA) procedure was employed to extract natural frequencies, mode shapes, and damping ratios from ambient responses, and detection of potential anomalies was operated. Results show that the platform's fundamental bending and torsional modes remain stable over time, with short-Term frequency shifts linked to operational interventions or environmental extremes. The extended dataset, along with clustering techniques and correlation analyses, highlights the importance of an approach integrating both structural and environmental data in guiding maintenance and inspection strategies. Future research could be carried out on upgraded versions of the monitoring system, after the incorporation of additional underwater sensors, with the development of modelbased approaches that could further refine damage detection capabilities and optimize service-life extension efforts.