PSI - Issue 78

Antonio Cefalì et al. / Procedia Structural Integrity 78 (2026) 1350–1357

1354

Distributed Fiber Optic Sensors (DFOS), including Distributed Acoustic Sensing (DAS) and Distributed Strain Sensing (DSS), measure strain, temperature, and acoustic vibrations along entire cable lengths, providing continuous spatial data beneficial for long linear infrastructures.Wireless Sensor Networks (WSN) offer a cost-effective and flexible solution for covering large or challenging areas by wirelessly transmitting data to a central hub (Amditis et al., 2010; SNPA, 2021; Torfs et al., 2013). Satellite-based monitoring using Interferometric Synthetic Aperture Radar (InSAR) detects ground surface deformations with millimetric precision over vast areas, particularly effective for slow-moving landslides and large infrastructure (Alatza et al., 2024; Balbi et al., 2021; Bru et al., 2024), with Corner Reflectors (CRs) (Sarabandi and Chiu, 1996) enhancing signal quality. Ground-Based Radar Interferometry (GB InSAR) provides high-resolution deformation measurements over localized areas (Lowry et al., 2024). Photogrammetry, using drones or terrestrial cameras, creates detailed 3D models for precise displacement mapping in landslides and structures. Seismic monitoring networks, such as Italy's National Seismic Network and National Acelerometric Network (Siino et al., 2020), continuously record ground motions, crucial for assessing seismic response, damage, and emergency management (Attolico et al., 2010; Augliera et al., 2011; Çelebi, 2011). Ambient seismic noise analysis, like the H/V spectral ratio, also aids in characterizing site effects and ground property changes over time (Castellaro and Mulargia, 2009). The integration of these diverse technologies into comprehensive monitoring systems enables a multi-layered approach to risk assessment and management. Data fusion from various sensor types yields a more complete and reliable understanding of structural and ground behavior, supporting more accurate predictive models and effective early warning systems, with real-time data transmission being vital for immediate emergency decision-making. 6. Lifecycle of a structure vs monitoring phases A correct design of an SHM does not prescind from the knowledge of the design, construction and vital history of an infrastructure (lifecycle of a structure). By indicating with the general term of model the set of geological, geotechnical and structural characteristics of the structure-soil system, it is possible to identify, with reference to the three phases of the life of the work (design, construction and management), four different models (see Fig. 1): • Designed Model at time t0 – model that takes into account the hypotheses and choices made in the design phase; • Constructive Model at time t1 – model that takes into account the actual construction methods and variations during construction; • Degraded Model at time t2 – model that takes into account all the changes induced by external factors, the degradation and the operating variations to which the work has been subjected; • Post-event Model at time t3 – model that takes into account the variations induced by a disturbance phenomenon not considered in the design and construction phase or considered to be of a different entity. Each phase of the programming and design must have the aim of examining and verifying the different aspects of the various models that constitute the life cycle of the work. It is therefore possible to identify four different phases for the correct design of an SHM (see Fig. 1): • Studies: Analysis of the geological, geomorphological, hydraulic, hydrological, and seismic framework, including geological evolution and a historical-critical analysis of the various design, testing, and intervention phases, in order to define the Designed Model and/or the Construction Model. • Investigations: On-site and laboratory investigations of the structure concerned and its geological, hydrological, seismic, and geotechnical characteristics, to transition from the construction model to the degraded model. In this phase, a preliminary monitoring system will be implemented to integrate the investigations and characterize disturbing phenomena. • First phase monitoring: Verification of the work, along with the planning and design of structural and non structural interventions. Implementation of the interventions and monitoring of the construction phases in order to verify design hypotheses, deepen understanding of the phenomenon, and verify the safety of any other existing works and/or infrastructure.