Diagnosis of monumental structures considering history-related phenomena: a systematic operating method applied to the Baptistery of Pisa

The study of historical constructions poses several challenges due to complex geometries, poor knowledge of material properties, historical stratifications, and damage patterns deriving from past events. All these history-related phenomena are usually investigated through historical research, topographical surveys, as well as tests and inspections. These multiple and multidisciplinary aspects provide real data to build and calibrate structural models. Despite that, the potential for reaching an enhanced knowledge by their integration is not yet being exhaustively exploited. This paper presents a systematic operating method accounting for different sources of knowledge and building their synthetic and effective representation into an informative model. It is conceived as the first step of a broader framework aimed at better understanding masonry heritage structures considering historyrelated phenomena. The method is applied to study the Baptistery of San Giovanni in Pisa which presents an interesting crack pattern. A geometrical model capable of adequately representing the complexity of the monument has been obtained by means of a detailed 3D laser scanner point cloud. A monitoring system based on the measurement of the relative displacements of a set of key points on the monument has been set up to detect potential soil settlements, and additional data have been collected thanks to documents and historical representations. The informed three-dimensional model of the Baptistery shows the adequacy of this strategy to integrate the collected information and allows for collecting data-driven assumptions about the construction stages and the current state of the structure. These considerations can be used to build models to predict the structural behavior of the monument based on the availability of data.