In situ damage assessment and nonlinear modelling of a historical masonry tower

In the present paper the case study of the eighth-century masonry tower called “Torre Sineo” (Alba, Italy) is described. The building has been recently analyzed and monitored because of an emerging damage pattern, and also due to some seismic events during the last few years. Nondestructive evaluation techniques have been adopted to assess the present situation of the tower without perturbations, among them, a detailed geometrical survey and a thermographic analysis. Such investigations reveal the presence of damaged zones concentrated close to the opening regions as well as a deviation of the tower from verticality. In the second part of the paper, the results from a nonlinear analysis are presented, in order to assess the behavior of the tower in the case of increase in the tilt mechanism. Cracking and crushing of the masonry have both been taken into account, as well as the influence of geometrical nonlinearity. The opening of sub-vertical radial cracks suggests compression crushing, while the evolution of the top displacement shows an almost linear evolution with respect to the tilt of the basement. The numerical simulations have also predicted damage in correspondence with the main openings. The numerical analysis has given a valuable picture of possible damage evolution, providing useful hints for the prosecution of structural monitoring.