Vibration-based damage detection in masonry structures: a case study of an AAC arch

• Vibration-based damage detection was applied to a masonry arch made of autoclaved aerated concrete (AAC) • Numerical simulations were used to predict damage locations and assess indicator sensitivity in AAC masonry. • Experimental modal analysis confirmed that local damage in AAC structures affects modal parameters. • Curvature-based indicators (MSC, MSCS, DI) proved effective in detecting and localizing AAC arch damage. • The proposed methodology is suitable for AAC and aligns with validated approaches used for other masonry structures. This work presents vibration-based damage identification methods as a non-destructive testing approach commonly employed in structural health monitoring (SHM) to ensure the safety and reliability of building structures. Structural damage causes local changes that influence dynamic parameters such as eigenfrequencies and mode shapes. The primary aim of this research is to detect and localize damage in a masonry arch made of autoclaved aerated concrete (AAC) by analysing dynamic parameters derived from experimental vibration methods. Initially, a numerical static response analysis using a finite element model of the arch was performed to predict the location of cracks during the failure process. The simulation accurately pinpointed the location of the first crack, which was then used to guide damage induction in the experimental phase. Additionally, a modal analysis was conducted on a simplified numerical model of the AAC arch to preliminarily evaluate the sensitivity of vibration-based damage indicators to modeled stiffness reductions. Dynamic impulse tests were conducted on both the undamaged and damaged states of the arch, and experimental modal analysis (EMA) was employed to extract eigenmodes in both cases. A comparison of mode shapes and their curvatures between the two states allowed the application of several damage detection indicators, including the Modal Assurance Criterion (MAC), Coordinate Modal Assurance Criterion (COMAC), Mode Shape Curvature Square (MSCS), and Damage Index Method (DIM). The combined numerical and experimental approach confirmed the effectiveness of curvature-based indicators (MSCS, DI) in detecting and localizing structural damage in AAC masonry arches. These findings demonstrate the potential for broader applicability of vibration-based diagnostics to lightweight masonry structures, even those constructed from less conventional materials.