Advanced Structural Health Monitoring and Predictive Maintenance of the Parchi Viaduct Using Distributed Fiber Optic Sensors and Digital Twin Technology

Aging infrastructure poses significant challenges in ensuring safety, reliability, and long-term serviceability. The Parchi Viaduct, a 3-km multi-span structure on Milan’s A51 Eastern Ring Road, experienced critical degradation in its Gerber saddles, necessitating temporary closure for safety assessments. In response, Milano Serravalle Milano Tangenziali S.p.A. and CAEmate S.R.L. deployed an advanced Structural Health Monitoring (SHM) system, integrating distributed fiber optic sensing (DOFS) and a physics-informed digital twin (PINN) to enable real-time load-bearing capacity evaluation and predictive maintenance. This paper presents the implementation of the WeStatiX SHM platform, utilizing DOFS to capture strain, temperature, and vibration data while dynamically updating a finite element model (FEM) through inverse analysis and multi-objective optimization. By continuously refining modal parameters such as natural frequencies, mode shapes, and damping ratios, the system enables early detection of structural anomalies and degradation trends. The validated digital twin successfully predicted real-world structural behavior, confirming residual load-bearing capacity despite saddle deterioration and supporting the safe reopening of the viaduct under real-time monitoring per Italian NTC standards. Load test results and FEM simulations demonstrated excellent agreement, with taller piers exhibiting ~20% greater deflection, emphasizing pier height's impact on load distribution and deformation patterns. These findings enhance predictive maintenance planning, improve stress redistribution modeling, and contribute to prolonging the structural lifespan of aging infrastructure assets.