Masonry heritage buildings are typically vulnerable under seismic forces, due to the original design based on gravity load and, at the same time, the long-term decay effects. Nowadays, the computation of the vulnerability index is crucial for seismic evaluation and conservation strategies. An accurate geometric survey is a keystep for the knowledge process, especially in geometry-governed structural elements (e.g. in vaults, members with variable cross-section, etc.). In the case of a huge building, scaffolding is commonly assessed in order to touch the structure for measuring or sensors installing (e.g. laser scanner). Minor damages are accepted when scaffoldings are fixed to the structure even in case of cultural heritage. In the present study, an innovative drone-based technique for the geometric survey, which aims to be fully non-destructuve, is proposed. A drone is equipped with a high-resolution camera (3D rotating) and GPS-system for the spatial positioning. By reaching a sufficient number of photos, the whole surface of the building can be covered. The database is then processed in order to compute a points cloud. Consequently, the points are linked and the wireframe model is reached. Finally, surfaces are generated between the edges and the meshed model is made by a proper visual code. The procedure is intended to be reproduced over time for monitoring potential crack or local instability. In order to demonstrate the validity of the proposal, a pilot building was selected. It is a masonry church with a large dome on the top (about 15 m diameter) and the variable thickness of the walls (about 50%). The indoor and outdoor photos were acquired by drone. Finally, the solid model was met by means of a specific designed Grasshopper-based code. In addition, the solid model was imported in a finite elements environment.
Innovative Non-destructive Technique for the Structural Survey of Historical Structures
Cascardi Alessio
;
2021-01-01
Abstract
Masonry heritage buildings are typically vulnerable under seismic forces, due to the original design based on gravity load and, at the same time, the long-term decay effects. Nowadays, the computation of the vulnerability index is crucial for seismic evaluation and conservation strategies. An accurate geometric survey is a keystep for the knowledge process, especially in geometry-governed structural elements (e.g. in vaults, members with variable cross-section, etc.). In the case of a huge building, scaffolding is commonly assessed in order to touch the structure for measuring or sensors installing (e.g. laser scanner). Minor damages are accepted when scaffoldings are fixed to the structure even in case of cultural heritage. In the present study, an innovative drone-based technique for the geometric survey, which aims to be fully non-destructuve, is proposed. A drone is equipped with a high-resolution camera (3D rotating) and GPS-system for the spatial positioning. By reaching a sufficient number of photos, the whole surface of the building can be covered. The database is then processed in order to compute a points cloud. Consequently, the points are linked and the wireframe model is reached. Finally, surfaces are generated between the edges and the meshed model is made by a proper visual code. The procedure is intended to be reproduced over time for monitoring potential crack or local instability. In order to demonstrate the validity of the proposal, a pilot building was selected. It is a masonry church with a large dome on the top (about 15 m diameter) and the variable thickness of the walls (about 50%). The indoor and outdoor photos were acquired by drone. Finally, the solid model was met by means of a specific designed Grasshopper-based code. In addition, the solid model was imported in a finite elements environment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
