VULNERABILITY ANALYSIS OF HISTORIC MASONRY TANK-TOWER USING THE PHOTOGRAMMETRIC SURVEY: A CASE STUDY

The structures built in forms of tower demonstrated to be flexible when involved in earthquake shaking and reacting against the seismic loads. On the other side, the collapse of masonry due to its fragility needs to be prevented. For this reason, an accurate mechanical and geometrical survey is a crucial aspect to be performed for a correct structural vulnerability analysis. Although the diagnosis of existing masonry buildings is now strongly supported by modern technologies (e.g. flat-jacks, ultrasonic pulse, hammer, penetrometer, etc.), the geometrical survey results still timeand cost-consuming, and therefore it is often made with dangerous approximation. The present case-study concerns with a historical masonry tank-tower located in southern Italy. The structural geometry was assessed by digital photogrammetry supported by a drone able to remote-fly all around the tower while taking a set of photos. After the first phase of aerophotography, the point cloud was computed for a further digital elaboration, able to create the meshed surfaces. Furthermore, the geometrical model has been converted into a structural model, able to be processed through numerical analyses. In such a way, a static analysis, a modal analysis and a non-linear static analysis have been carried out by means of Finite Element Method (FEM). Two scenarios were considered, i.e. assuming the tank to be full or empty. The top-displacement versus the base-shear law was so-simulated. Lastly, the crack patterns were also compared in order to evaluate the influence of the tank on the damage of the tower.