PSI - Issue 78

Allegretti M. et al. / Procedia Structural Integrity 78 (2026) 852–858

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historical masonry, which still represent one of the most critical aspects of these structures. These criticalities arise from several factors, including the anisotropy of the material, the uncertainty regarding the internal composition of the structure Barros et al. (2023), and the variability of the mechanical properties related to the type of constituent materials Liu et al. (2023). Particular attention is also paid to the interaction between the various parts of the struc ture, especially between the internal fill and the load-bearing elements Conde et al. (2016); Sarhosis et al. (2016). To employ reliable numerical models capable of accurately describing failure modes and optimizing strengthening and maintenance interventions Hou and Xia (2021); Ye et al. (2021), a deep knowledge of the analyzed structure is essential. Several studies have already highlighted the importance of correctly modeling all the constituent elements, which would otherwise lead to an overestimation of the ductility and fundamental periods of the structure, as well as to an underestimation of its sti ff ness and load-bearing capacity Zampieri et al. (2021). In this context, case studies provide a valuable contribution to the scientific literature. Although they do not always introduce radical innovations, they are fundamental to understanding the practical challenges associated with the preservation and rehabilitation of the infrastructural heritage. This article aims to assess the safety of a masonry bridge by analyzing how the results of the structural checks vary depending on the calculation assumptions, which are closely related to the adopted level of detail. To this end, detailed models are employed that capture the interaction between the di ff erent constituent parts of the structure, highlighting and comparing the substantial di ff erences in the results obtained at the various levels of analysis.

2. Description of the Multi-Span Bridge

The analyzed bridge is a historic multi-span masonry arch structure, a view of which is shown in Fig. 1. This study was made possible thanks to the collaboration between the University of Roma Tre and the Regione Lazio (Italy), which led to the development of the project MLAZIO , aimed at formulating new methodologies for the analysis of existing trasnsportation infrastructures. The structure is a masonry arch bridge withf eight semicircular arch spans, each with a span length of 15 m and a rise-to-span ratio of 0.5. The total width of the bridge is 9.3 m, while the thickness of the arch section remains constant

Fig. 1. General view of the multi-span bridge