Survey and seismic vulnerability assessment of the Baptistery of San Giovanni in Tumba (Italy)

For the assessment of the seismic vulnerability of a historical building, knowledge is a fundamental prerequisite for a reliable assessment of the current seismic safety and for the choice of an effective action of improvement. Nowadays, thanks to the available technology used in the field of architectural surveying, laser scanning and digital photogrammetry, it is possible to define the exact geometry of any case study. The main aim of the research is to highlight the relationship between the architectural survey, performed using 3D laser scanner methodology, and the structural analysis based on the finite element method (FEM). The case of study consists of an important and unique construction, which is the baptistery of San Giovanni in Tumba (Italy). After data acquisition, developed by using optical 3D measurement techniques, the proposed procedure sought to generate a NURBS model starting from very dense outlines obtained by point cloud slices. Subsequently, the analysis was developed in a nonlinear framework, in which the behavior of the structure under seismic loads is investigated. In particular, the modal characteristics of the structure allow the use of a nonlinear analysis based on the pushover methodology. In addition, structural behavior has been analyzed by means of a nonlinear response history analysis, in which consistent ground motions were adopted to reproduce seismic loads.