Reverse Engineering for the Structural Analysis of Heritage Constructions

Reverse engineering is a process in which an existing object is studied to understand how it works and potentially improve it. In the Cultural Heritage (CH) sector, 3D scanning and parametric modeling tools have made reverse engineering a viable approach for studying and understanding historical buildings. This paper presents a method for studying the displacements and deformations in historical masonry buildings over time using reverse engineering techniques, such as Terrestrial Laser Scanning (TLS) and parametric 3D modeling. The proposed workflow is divided into three phases. First, a digital survey is conducted to create a 3D point cloud that accurately represents the current condition of the building's structural elements. This point cloud is called the Basic 3D Model (B3M). Next, the point cloud is reconstructed as a 3D NURBS topological model, and specific visual programming algorithms are used to cancel out the hypothetical deformations that have occurred over time. This model is called the Ideal 3D Model (I3M) because it represents the theoretical, undeformed configuration of the structures. Finally, the I3M is compared to the B3M to identify the deviation between the deformed and undeformed configurations. This comparison allows for determining the structural behaviour of the building's parts and evaluating the overall condition of the building to guide interventions for structural improvement. The method has been applied to several case studies in Italy, including masonry columns, façades, and timber trusses.