The objective of this study was to deploy an autonomous real-time Digital Twin (DT) Structural Health Monitoring (SHM) system on offshore platform to enable continuous real-time monitoring and automated evaluation of the structural integrity based on the offshore feeding data of a 4-legged fixed substructure which has experienced vessel collision earlier. The collaboration between asset owners, asset operators, and academic researchers aimed to develop an advanced DT SHM system for this purpose. The SHM system implemented a comprehensive framework that integrated software and hardware components with Internet of Things (IoT) capabilities. The hardware facilitated the collection of raw data, while a proprietary physics engine was developed to enable autonomous structural analysis for calibration and subsequent integrity assessment to identify the most probable source of structural anomalies. Real-time data acquired online were used to derive useful structural engineering parameters, forming a digital twin that emulated the actual offshore condition of the structure. The deployment of the autonomous SHM system provided asset operators with valuable insights into the structural performance of the substructure in real-time. This enabled fast decision-making aiming to improve the efficiency of engineering manhours as well as optimisation of inspection and maintenance practices. The system outperformed conventional methods by timely quantifying the influence of assessed damages on the global substructural integrity, allowing for more accurate benchmarking and up-to-date information. This case study emphasizes the significance of adopting autonomous Digital Twin SHM systems for offshore structures, particularly when compared to manual assessments. The implementation of the autonomous system reduces both time and effort while providing reliable benchmarking and up-to-date information on the structural integrity of the monitored structure. This highlights the importance of utilizing advanced SHM technologies to optimise the inspection and maintenance practices of offshore structures. The objective of this paper is to present the framework for a Digital Twin SHM system that is designed for real-time global structural monitoring. Copyright © 2024, International Petroleum Technology Conference.