Creep behavior of masonry in cultural heritage by "structure from motion method"

Abstract

Masonry structures demonstrated to be vulnerable against both seismic actions and long-term effect in past decades. In particular, the creep effects are dangerous since they may produce the brittle collapse of the structure without any warning. The case of the San Marco bell tower in Venezia that happened in 1902 is a well known event; it suddenly collapsed even if cracks were not visible. This particular failure is strongly related to the global deformation of the structure. For this reason, the monitoring of the safety level is strongly linked to the geometric survey. The "structure from motion" method (SFM) is based on the photo's elaboration of the building for computer graphic processing. The outcome is the accurate geometry relief, as largely demonstrated in literature. The present study reports on an SFM application referring to an ancient masonry church. The innovative contribution consists of the indoor and outdoor surveying that were aligned and matched in order to build the 3D geometry of the building. The main result was the solid model of the building, which was compared with an available survey in order to monitor the creep-state. The proposal can be considered a pilot-case for the "building watch" programming aimed to the cultural heritage preservation.