An integrated approach to the structural assessment of historic buildings: The case of St. Angelo Church in Anagni

This paper tackles the problem of the safety assessment of St. Angelo church in Anagni (Italy) through an integrated approach linking geometrical survey with structural analysis. A historic analysis is first performed collecting information from ancient drawings and on-site observations identifying the main construction phases and interventions executed throughout the centuries and highlighting the different materials adopted in the construction. Terrestrial and aerial close-range photogrammetry is executed to reconstruct the geometry of both the interior and the exterior of the building, resulting in a fully three-dimensional digital model of the building and its surroundings. From this model, the main structural elements of the structure were identified, and a structural assessment was performed adopting the lower-bound theorem of limit analysis. The main vaults are analysed through a graphics slicing technique and the overall geometric safety factor of the representative structural section of the church is obtained. The paper illustrates a pipeline adapted to the assessment of existing structures, where safety factors can be obtained in a relatively short time directly from the data obtained through the survey and with fair compromise between complexity and accuracy. Coherent and appropriate use of modern technologies for geometrical survey and simple and clear mechanical theories allowed a multidisciplinary group of architects, conservators, and structural engineers to carry out a preliminary structural assessment of St. Angelo Church under gravitational loads. The conclusions drawn in light of the results of this analysis is that the Church can be considered safe.