PSI - Issue 78

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

854

along its entire length, equal to 60 cm. The supporting piers have a truncated-pyramidal section with a rectangular base tapering upwards, with heights ranging from a minimum of 9.0 m to a maximum of 15 m, giving the bridge a significant vertical development. Above the intrados of the arches lies a continuous concrete slab, with a considerable thickness of 1.0 m. This element plays a fundamental role in the analyses, which will be discussed later in Sections 2.1 and 4. The morphology of the structure reflects traditional load-bearing masonry arch construction techniques, employing regular blocks of soft tu ff stone and mortar joints in the external facings, while the interior consists of irregular rubble stone. The main characteristics and parameters are summarized in Table 1.

Table 1. Geometric data of the multi-span bridge. Parameter

Value

Total span

150m 9.3m

Width

Number of arches 8 Arch and tympanum thickness 60 cm Single arch span 15m Rise-to-span ratio 0.5 Pier heights

9 – 11.5 – 15 – 15 – 12.5 – 12.5 – 12.5 m Regular tu ff blocks and mortar joints

External material Internal material Deck slab thickness Deck slab material

Irregular rubble stone

1.0m

Reinforced concrete

2.1. Levels of knoledge

A thorough understanding of all the constituent components of a structure is fundamental for the development of numerical models capable of realistically describing the structural behavior of the asset. The aim of this study is to analyze the variability of the results obtained and the modeling choices as a function of the level of available documen tation and the quantity and quality of the information progressively acquired for the case study under investigation. In particular, the outcomes of the seismic assessment, carried out through nonlinear static analysis (pushover), are evaluated by considering three di ff erent levels of knowledge, hereinafter referred to as: • LV0: initial level, based on design documentation and visual inspection; • LV1: advanced level, obtained by confirming and refining the understanding of the structure and its materials through data acquired from experimental investigations; • LV2: level that includes the e ff ect of a strengthening intervention with a reinforced concrete (RC) slab. The analysis starts from the minimum level of knowledge (LV0), where only the main geometrical features and the type of materials of the load-bearing structures are available, and progresses with a gradual increase in information thanks to experimental testing campaigns. These tests allowed to: • confirm the geometries of the structure by means of Laser Scanner surveys; • determine the mechanical parameters of the masonry and mortar through double flat-jack tests, penetrometric and tomographic tests; • investigate the internal configuration of the structural elements through tomography and endoscopy. Finally, the contribution of the post-construction intervention was analyzed, consisting in the realization of a RC slab cast on the extrados of the arch, for which cores were extracted to determine the mechanical parameters of the concrete. In this phase (LV2), the mechanical and geometric parameters defined at the LV1 level were kept unchanged; the analysis thus focused exclusively on evaluating the structural e ff ect of the intervention.