Protecting cultural heritage buildings poses significant research challenges. Effective damage prevention hinges on a thorough understanding of structural behavior and the continuous monitoring of its changes over time. Advanced visualization tools are essential to provide adequate awareness of the monitoring systems installed over the years while guaranteeing a quick, basic analysis of their data. This paper addresses a crucial gap in structural health monitoring (SHM), particularly in managing complex structures and systems, by responding to the growing need for tools that not only represent 3D models enriched with heterogeneous data and metadata but also facilitate detailed analysis of sensor recordings. In response to this challenge, it proposes the integration of a 3D informational model and an interactive web-based platform for monitoring data, creating a comprehensive management tool. Piazza del Duomo UNESCO Site in Pisa serves as an ideal test case due to its historical significance, structural complexity, and the wealth of monitoring data collected over time. With their interactive architecture, the two developed integrated visualization tools that could offer an effective solution for data management and visualization in other heritage contexts, particularly in cases where the monitoring system consists of numerous sensors and has evolved substantially over the years.

The structural diagnosis of monumental buildings necessitates organizing diverse cross-disciplinary data. The H-BIM procedure employs 3D digital models to create a comprehensive virtual repository, offering advantages in documentation access, interoperability, intervention design, cost evaluation, and maintenance management. This work proposes an approach to combining different models while addressing interoperability challenges by best exploiting their positive characteristics. After evaluating the advantages and limitations of textured-mesh and NURBS-based models, and virtual reality environments based on specific comparison criteria, an integrated system of these models within the H-BIM framework is proposed. The latter is applied to study the relevant case of the Baptistery of San Giovanni in Pisa, Italy. The integrated H-BIM model is designed primarily to facilitate the structural diagnosis of the monument, and illustrates how combining different 3D representations, each providing multiple information with different levels of detail, enhances its capabilities. This integration results in a more effective tool for the multidisciplinary conservation of cultural heritage, accommodating a wide range of data beyond structural aspects, thus fostering collaboration among professionals from various fields of expertise.

Historic constructions are affected by several uncertainties, among which those on mechanical parameters of masonry, because of reduced knowledge given by the limitation imposed on performing extensive destructive tests not to jeopardize the structural integrity. Besides, uncertainties on soil characterization can play a significant role in the evaluation of structural response, however is often neglected. Finite Element Models (FEM) often represent a good compromise given the possibility of reproducing the complex geometry of historical structures while requiring relatively limited material parameters from experimental tests (to feed models). However, the computational burden can become prohibitive when the evaluation of the effects of the variation of input mechanical properties for the assessment of the current behavior of the structure and potential design of adequate interventions and definition of monitoring systems requires running several analyses. In this work, modal analyses of a monumental Medieval construction such as the Baptistery of Pisa are carried out within a probabilistic framework including material uncertainties on both mechanical parameters of soil and masonry, which are assigned suitable probability distributions based on the limited data from in-situ campaigns combined with engineering judgment. A gPCE-based surrogate model is employed to transform the onerous numerical runs into speeded-up analytical evaluations for the computation of Sobol’ indices to assess the influence of input variability on the first ten natural frequencies of the monument at issue. The method leads to the identification of the most relevant soil and masonry parameters and highlights which frequencies are primarily controlled by either the stiffness of the soil or that of the aboveground historical structure. In this sense, this work provides a first clue for designing a SHM of the Baptistery of Pisa with a view to assessing minimum detectable parameter change while monitoring natural frequencies.