PSI - Issue 84

Federico Scafati et al. / Procedia Structural Integrity 84 (2026) 25–32 F. Scafati et al. / Structural Integrity Procedia 00 (2026) 000–000

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In the previous bridge configuration, the first vibration period was 0.8 s. The introduction of the isolation system shifted it up to 2.0 s. A dynamic linear analysis was performed. The maximum displacement at the collapse limit state, evaluated according to the Italian technical standards (MIT, 2018) in seismic conditions is ±325 mm. For this value, the maximum horizontal force on the devices is V max = 706 kN. At the ultimate limit state in static conditions, the maximum vertical load on the bearings is N ULS = 5800 kN. Some of the main challenges of the project were the particular geometry of the bridge, which has a curvature radius of 50 m that introduces non-negligible contributes as the centrifugal force, the presence of a railway and a river under the bridge, which determined an increase in the attention level during each phase of the seismic retrofitting intervention. The Rivi Freddi bridge, located in Berceto, is part of the A15 Parma-La Spezia highway. The bridge is composed of two separate and slightly curved carriageways. Each of them has three simply supported spans, 41 m long, considering the distance between the bearings. The total lengths are 131.8 m for the external carriageway and 130.5 m for the internal one. The deck consists of four prestressed and reinforced concrete beams, 2.4 m high, with 2.8 m interaxis. They are connected by reinforced concrete elements: an upper slab 23 cm thick cm and six cross beams for each span (Fig. 5a). Piers have a hollow reinforced concrete section, ranging in height from 11.9 to 21.1 m, with a pier cap. Their shaft foundations have depths ranging from 10 to 12 m. To realize the seismic retrofitting according to the current seismic hazard standards (MIT, 2018), the intervention consisted in: i) Replacing of the existing steel bearings (Fig. 5b) with double curved surface sliders (DCSS), with an equivalent radius of 3700 mm and a nominal friction coefficient of 7.2%, calibrated for the quasi-permanent load of N sd =1071 kN (Fig. 5c and Fig. 5d); ii) Installation of the shock transmitters devices on the underside of the deck, in correspondence of the piers. This solution allows connecting adjacent spans, realizing the kinematic chain to make continuous the deck in seismic conditions (Fig. 6a and Fig. 6b); iii) Substitution of existing joints on piers and abutments; iv) Adaptation intervention on abutments to permit the installation of the new joints; v) Concrete jacketing with additional steel bars in piers (Fig. 5a); vi) Seismic retrofitting of the foundations. 4.2. The Rivi Freddi bridge

(a)

(b)

(c)

(d)

Fig. 5. Rivi Freddi bridge: (a) Pier reinforcement; (b) Existing bearings; (c) new DCSS devices during installation and jacks; (d) new housing for a DCSS before casting (Freyssinet Product Company Italia S.p.A).