PSI - Issue 62

Francesco Bencardino et al. / Procedia Structural Integrity 62 (2024) 972–982 Bencardino/ Structural Integrity Procedia 00 (2019) 000 – 000

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The main causes include: •

exposure to moisture and chloride ions (e.g., from deicing salts or seawater); • low concrete cover or poor-quality concrete; • lack of proper protective coatings or cathodic protection systems.

Moreover, the concrete developed cracks due to various factors, including shrinkage, temperature changes, and structural overloads, which also caused spalling. The latter is the chipping or breaking off of concrete from the surface. It is often a result of the corrosion of the reinforcing steel, as rusting steel expands and causes the concrete to crack and break. Lastly, carbonation occurred when carbon dioxide from the atmosphere reacted with the calcium hydroxide in concrete to form calcium carbonate. This reduced the alkalinity of the concrete, potentially leading to corrosion of the reinforcing steel. In addition to these common forms of decay, other factors like seismic activity, fire exposure, and improper maintenance could also have a detrimental impact on the integrity of the structures.

Fig. 3. State-of-the-play ( left ) and detail of the steel reinforcement ( right ).

3. Structural analysis The calculation scheme considers the bridge to be made up of three girders arranged consecutively, each according to the static scheme of a double simply supported beam (Fig. 4). Each girder is made up of four rectangular beams, two internal and two on the edge, connected by a 200 mm thick upper slab. Specifically, the calculations concern the operations of resistance verification in the current state of the normal RC beams, subjected to bending and shear stress, and the strengthening design and verification interventions of the same elements for which the use of FRPs is proposed.

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Fig. 4. Geometry: cross-section ( top ) and static scheme ( bottom ) – dimension in meters.