Vibration-based assessment of the structural integrity of a masonry wall system with single opening subjected to progressive damage induced by out-of-plane loading conditions

Existing masonry constructions often develop a complex mechanical response due to considerable material heterogeneity of the ancient masonry and presence of structural pathologies. The occurrence of severe loading conditions, such as those caused by differential soil settlements and seismic events, can also induce brittle collapse mechanisms in ancient masonry constructions. Operational Modal Analysis (OMA) methods are particularly well-suited Structural Health Monitoring (SHM) approaches for historical masonry constructions. Despite their benefits, low sensitivity of OMA methods to localized damage is often indicated in the literature as major limitation. This paper presents preliminary results of vibration-based structural integrity assessment of a masonry wall system with single opening. Specifically, the wall specimen was subjected to progressive damage induced by increasing out-of-plane displacements. The modal identification of the structure was performed at different steps of the test sequence. Similarly, visual inspections were carried out on the wall specimen to detect the development of damage. Changes in the identified modal features were computed for every step of the test. The obtained preliminary results show clear variations in modal features, consistently with the damage level suffered by the tested structure. Interestingly, mode shapes were found particularly sensitive to damage even under initial levels of out-of-plane deformation.