Bridge over the River Adda (Italy)

The bridge in question, with a total length of about 90.0m, was designed around the mid-1950s by Prof. Ing. Giulio Krall and is entirely made of reinforced concrete according to the static scheme of the lower arch. The slightly oblique deck has a longitudinal slope of about 2.5% and is hung by means of a series of inclined hangers from two large arches with a parabolic axis. The supporting arches are characterized by a 90.0m tax string and a height in key of about 14.5m.

In the design phase, to remedy the structural deficiencies identified by the analysis of the SdF, the following improvement interventions were envisaged: (1) reinforcement of the upper deck slab through the construction of a collaborating hood having a thickness of 60mm, reinforced with a net Ø16 / 20/20 thickened transversely with Ø16 / 20 close to the central spine beam; (2) shear reinforcement of the end parts of the arches by means of fiber-reinforced composites; (3) pressure – flexion reinforcement of the end parts of the arches by means of tackles; (4) replacement of the existing hangers with high resistance bars, Ø70 and Ø90, made of S460N steel.