On-site diagnosis of masonry structures via sonic tomography: The case of the ex-church of San Barbaziano

The knowledge of the health-state conditions of a masonry structure is a prerequisite both for a reliable assessment towards seismic risk and for selecting proper maintenance and restorations interventions. This is particularly challenging for historic constructions which, due to preservation requirements, should be tested by as less invasive techniques as possible. Non-destructive acoustic methods are increasingly applied for evaluating masonry structural elements. Sonic tests proved reliable in assessing masonry layout, in detecting hidden defects, voids, heterogeneities or degradation and also in estimating characteristic mechanical properties of construction materials. In the ex-church of San Barbaziano in Bologna, Italy, sonic tomography tests were carried out in masonry piers of irregular shape and walls in addition to more traditional direct and superficial sonic tests, to evaluate and visualize the internal conformation of masonry sections. The results presented in this paper are aimed at showing the methodology, its reliability, efficiency, advantages and limits.