PSI - Issue 78

Alessia Furiosi et al. / Procedia Structural Integrity 78 (2026) 753–760

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1. Introduction A significant portion of the existing masonry arch bridges in Italy and Europe were built over a century ago, before the widespread adoption of modern construction materials such as steel and reinforced concrete. Despite their age, these structures are still operating, constituting a significant part of road and railway network systems, while representing valuable examples of architectural and cultural heritage (Melbourne et al. 2007, Page 1993). Their long-term structural stability is increasingly challenged by material degradation, increased axle loads, lack of maintenance, and the rising frequency of hydrological hazards driven by climate change. In earthquake-prone regions, the seismic vulnerability of masonry arch bridges is a critical issue, as they were not designed for dynamic loads. Recent seismic events highlighted specific damage patterns, such as out-of-plane overturning of spandrel walls and hinge formation within the arch vaults (Di Sarno et al. 2019, Oliveira et al. 2010). The assessment of the seismic vulnerability of masonry arch bridges is essential to evaluate their current safety and to plan potential retrofit interventions. Various modeling approaches have been proposed in the literature to simulate their seismic behavior. Traditional methods, such as limit analysis, offer simplified approaches with low computational cost (Heyman, 1995). More advanced techniques, such as finite element modeling, enable detailed analysis of masonry arch bridges but are challenged when large relative displacements are considered (Pelà et al. 2013). Conversely, discontinuum-based approaches have proven highly effective in accurately capturing the nonlinear dynamic response and failure mechanisms of masonry arch structures (Furiosi et al. 2025, Sarhosis et al. 2020, Pulatsu et al. 2019) . In this contribution, a discontinuum-based approach, namely distinct or discrete element method (DEM), is employed to assess the seismic behavior of an existing multi-span masonry arch bridge, located in the North-East part of Itay. The three-dimensional seismic response of the masonry bridge, explicitly accounting for all structural and non structural components (i.e., piers, abutments, arches, spandrel walls, and backfill), is simulated. A substructural modeling strategy was adopted to isolate the critical segments of the bridge, allowing quasi-static simulations to be performed within a reasonable computational timeframe for the assessment and validation of different modeling approaches. The resulting analyses aim to provide valuable insights into the most vulnerable regions, typical damage patterns, and failure mechanisms characteristic of masonry arch bridges. 2. Overview of the bridge case study This study investigates the behavior of critical sections of a vehicular masonry arch bridge, whose model was inspired by the bridge spanning the Gresal stream in Northern Italy (Fig. 1) whose seismic vulnerability was recently investigated by Furiosi et al. (2025) through the development of fragility curves. The bridge, which connects the cities of Belluno and Mas, is characterized by three consecutive arch barrels, each with an average span of approximately 15.0 meters. It spans a total length of 67.0 m and has a transverse width of 7.0 m. The analyzed segment of the bridge structure extends from mid-pier to mid-pier and includes a semicircular arch vault and two tapered piers, with respective heights of 13.0 meters and 11.3 meters (Fig. 2).

Fig. 1. Location of the studied masonry arch bridge (Furiosi et al. 2025).