PSI - Issue 78

Giuseppina Uva et al. / Procedia Structural Integrity 78 (2026) 1048–1055

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1. Introduction The structural assessment of existing masonry arch bridges, particularly those of historical value, presents significant challenges due to multiple sources of uncertainty. These include limited knowledge of original geometry and construction details, variability in material properties due to aging and degradation, and the complex nature of loading conditions - especially under seismic actions. Furthermore, the inherently non-linear behavior of masonry and the lack of standardized experimental data increase the difficulty of accurate modelling. Capturing these uncertainties within numerical simulations typically requires highly detailed models, capable of representing damage evolution and structural interactions. However, such models are computationally intensive and often impractical for extensive analyses, especially in a professional or decision-making context (Casolo and Sanjust, 2009; D’altri et al., 2020; Modena et al, 2015). To overcome these limitations, an efficient strategy should use simplified numerical models calibrated to reproduce the key features of structural response so to make large-scale parametric studies feasible with a reduced effort while retaining a sufficient accuracy. This paper introduces such an approach, that is applied to the case study of the San Marcello Pistoiese masonry bridge in Italy. Two FE models are developed in Abaqus: a comprehensive three-dimensional Solid Model, and a simplified Shell-Box Model based on shell elements. The latter is calibrated against the full model and validated across several performance metrics, including inertial and modal characteristics, spectral accelerations, capacity curves, and damage distribution. Both models adopt a Concrete Damage Plasticity formulation to capture the non-linear response of masonry under loading, allowing for a realistic simulation of progressive damage. The proposed strategy offers a computationally feasible pathway for the analysis of existing masonry bridges, particularly in contexts where uncertainty quantification and extensive simulations are required. 2. Case study: San Marcello Pistoiese masonry bridge As a case study for the definition of the modelling strategy, we have selected the San Marcello Pistoiese Bridge, located in the province of Pistoia (Tuscany, Italy), that was widely studied in the literature (Leprotti et al., 2010; Pelà et al, 2013).

Fig. 1. Longitudinal and transversal drawings of San Marcello Pistoiese Bridge (measures in m).

The bridge was built after the Second World War to cross the Lima River using different types of masonry materials and arrangements (Figure 1, Table 1) and is characterized by the presence of an infill consisting of waste material obtained from the excavation of the foundations.