PSI - Issue 84

Marianna Crognale et al. / Procedia Structural Integrity 84 (2026) 898–905

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2. Case Study and Numerical Modelling 2.1. Case Study Viaduct

The case study concerns the Vicende Viaduct, located near the town of Fiamignano (RI) along the SS578 Salto Cicolano Road. The bridge crosses a small valley and connects the hamlet of Peschieta to the main route toward the Salto valley. It consists of three equal spans, each approximately 44 m long, resulting in a total bridge length of about 135 m. The deck contains two traffic lanes with an overall width of roughly 12 m, including side barriers and secondary elements (see Fig. 1). The superstructure comprises five simply supported prestressed concrete double T girders per span, connected by a cast-in-place reinforced-concrete slab. The substructure consists of reinforced-concrete piers and abutments, with elastomeric bearings supporting the girders on rectangular pier caps. Visual inspections identified drainage pipes at the pier–deck interfaces and localized surface degradation in these regions.

Fig. 1. Vicende Viaduct: (a) general view of the structure; (b) detail of a pier–deck connection; (c) dimensionless schematic elevation showing spans, piers, and abutments.

2.2. Traditional FEM Pushover Analysis The baseline seismic performance of the viaduct is evaluated through a conventional nonlinear static (pushover) analysis implemented in OpenSees (McKenna et al., 2000). The structure is modeled using beam–column elements for both the superstructure and substructure. Prestressed concrete girders are represented by equivalent elastic sections, while reinforced-concrete piers are modeled using force-based beam–column elements with fiber-discretized cross sections, allowing the progressive spread of plasticity along the pier height. It should be noted that the dimensions of the structural elements, as well as the design reinforcement, are not precisely known, as no project documentation or detailed inspections (beyond visual surveys) are available. For this reason, a preliminary simulation of the structural sections was carried out. Concrete and reinforcing steel fibers are described using standard constitutive laws, with material properties kept constant throughout the analysis, i.e., without accounting for degradation effects. Gravity loads are applied first, followed by displacement-controlled lateral loading in the longitudinal direction, corresponding to the governing seismic response of the viaduct; P– Δ effects are included at this stage to describe geometric nonlinearities. The resulting global capacity curves and pier deformation demands provide the reference response for comparison with the proposed degradation-aware interpretation framework. Fig. 2 shows the pushover curve in terms of base shear and displacement of a top control point. The response is linear up to a shear force of about 4,000 kN, after which nonlinearity appears, reaching a maximum value of approximately 11,000 kN at a displacement of 25 cm.