Pervasive sensing and real-time analysis for monitoring potential damage of civil structures

Non-invasive diagnostics have become a cornerstone of safety assessment and intervention design for civil structures, enabling informed decision-making without altering structural conditions. Within this framework, Structural Health Monitoring (SHM) provides local and global information on structural response through sensing systems operating under periodic or continuous acquisition schemes. When properly designed, SHM systems can be tailored to structural typology and expected deficiencies of both new and existing structures. Motivated by the need to safeguard strategic infrastructure and optimize lifecycle maintenance, this thesis investigates SHM from two complementary perspectives: vibration-based monitoring for global assessment and distributed fiber-optic sensing for deformation tracking. The first part focuses on vibration-based SHM through Operational Modal Analysis (OMA), addressing both methodological and experimental aspects. Particular attention is devoted to damage assessment through modal parameter variations, exploiting the relationship between natural frequencies and structural stiffness. Experimental investigations on monitored structures demonstrate that carefully selected global modal indicators allow the detection of controlled stiffness variations under different excitation and operational conditions. To support scalable implementation, automated processing strategies for covariance-driven Stochastic Subspace Identification (SSI-CoV) are discussed, including clustering-based tools (IHCA) developed within the research group for continuous datasets. The reliability of modal tracking is evaluated in relation to signal quality, excitation level, and sensor performance. The experimental campaign further compares sensing technologies for dynamic monitoring, including low-cost MEMS accelerometers and fiber-optic accelerometers based on Fiber Bragg Gratings (FBG). MEMS devices proved suitable for cost-effective and scalable monitoring when acquisition parameters are appropriately selected, while FBG accelerometers offer advantages such as electromagnetic immunity and integrability within existing fiber networks. The second part extends SHM to the static domain through distributed fiber-optic sensing based on Brillouin scattering for strain and temperature measurements, highlighting its potential for long-term deformation monitoring in both embedded and externally bonded configurations.