PSI - Issue 84

Davide Caliò et al. / Procedia Structural Integrity 84 (2026) 513–520

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sediments ranging from blocks to gravels and sands, with clasts mainly of carbonate and volcanic origin. These deposits are confined to the streambed crossed by the viaduct and are related to episodic high-energy runoff. Their thickness is limited and is estimated to be generally less than 2 m. The viaduct abutments are founded on carbonate formations belonging to the Lentini (LEI1) and (LEI2) synthems (Fig. 1). The most widespread unit, LEI1, consists of calcarenites and fossiliferous sands deposited in a shallow-marine environment. These lithotypes are characterized by medium- to coarse-grained textures, abundant bioclastic content and planar-parallel bedding with decimetric to metric thickness. A low degree of cementation is common, resulting in weak and friable rock masses locally alternating with more cemented and mechanically competent layers. Overall, the local geological and lithological conditions represent a primary controlling factor on the site’s susceptibility to erosional processes and on the morphological evolution of the area.

Figure1 Location of the Cantera viaducts in eastern Sicily and simplified geological map showing the main lithostratigraphic units.

2.2. Structural characteristics of the viaduct. The Cantera viaduct is part of the SS114 road network, left carriageway, and is located within the municipality of Augusta (Siracusa Province). The structure consists of a five-span viaduct supported by vertical piers founded within the fluvial corridor of the Cantera stream. A twin bridge is parallel and adjacent to that here investigated. The viaduct is constructed using a composite steel–concrete system, with a simply supported–simply supported static scheme of the deck of each span. Each span has a length of 44.8 m, for a total length development of 224 m. Each deck is composed of three main steel longitudinal beams, each transversally connected at five locations by steel cross-trusses (10 per deck). All the cross-trusses have the same dimensions, including those located in the bearing zones. Each deck is supported by six bearings (three per side), for a total of 30 bearing devices (six at the two abutments and 24 at the four piers). The deck slab appears to be made of cast-in-place reinforced concrete, constructed using self-supporting precast slabs (predalles) resting on the flanges of the longitudinal beams. The abutments are made of cast-in-place concrete. The abutments have a single structural configuration for the two twin viaducts. The viaduct decks are supported by piers with maximum height of about 32 m entirely made of reinforced concrete, whose cross-section has a hollow irregular octagonal shape with thickness of about 30 cm. Based on the static scheme, six expansion joints separate the decks. No original design documentation for the viaduct could be retrieved. However,