The bridge is an existing three-span reinforced concrete bridge with a total length of 103.10 m. The static diagram is isostatic: the central span is in fact interrupted by two Gerber saddles, 21.50 m apart. The parts of the beam overlapping the piles are made with a three-cell box, while the remaining parts have an open section with four webs connected to the slab.

The intervention to be carried out consists in positioning a metal beam under each web of the box and the open part. Each metal beam has the function, in the event of the Gerber saddle collapsing, of supporting the central span by levering on a pair of bars suspended from the web of the box section, which also serves as a point of support for the lever itself.

The design of the metal structures supporting the existing runway of an overhead crane was carried out in the Ferro Berica factory in Vicenza, following the appearance of severe cracks and detachments of concrete parts of the BAP beam that supports the crane track within a specific span of the plant.

The metal load-bearing structure was designed with a metal crosspiece consisting of a box section supported by two vertical columns arranged at a slight inclination.

A layer of non-shrink mortar was also interposed between the upper edge of the steel frame and the bottom edge of the damaged PRC beam to restore the damaged concrete cover, guaranteeing the contact between the two structural elements and allowing the metal frame to get charged when the overhead crane passes.

The job was part of the study of the reinforcement of the existing preheating tower and the definition of reinforcing solutions, in order to adapt to a series of new loads expected on the structure. The object of this work is the reinforcement of the beam named 4F_04, located on the 4th floor.

The current section of the 4F_04 beam is a symmetrical I-section with a height of 2520 mm, a bottom and top flange of 400×45 and a web thickness of 20 mm, in S235 steel.
This section is enhanced by:
– a T welded to the lower flange of dimensions: h = 500mm, flange 400×50, web 20mm
– longitudinal rectangular-shaped stiffeners 250×20 at a distance of 700mm and 1400mm from the upper face of the beam.

The bridge at km 8 + 382.172 on the road axis called Guba Road is composed of several spans in a single support scheme with variable length: the free spans are 15 + 20 + 15 m.

The deck, entirely made of reinforced concrete poured on site, is composed of 4 longitudinal beams 1400×360 mm and an inclined slab 200 mm thick.
During the loading test, abnormal deflections were measured and diagonal shear cracks appeared due to the poor quality of the materials used.

It was therefore necessary to carry out the shear reinforcement of the longitudinal beams, which was carried out by “lining” the beams themselves with very high strength concrete (Rck 65 MPa) to a thickness of 50 mm, after removal of the concrete cover.

Work carried out after the failure caused by the flooding of the Magra river in December 2009. The left abutment is statically independent of the reinforced concrete bridge so that its failure did not affect the statics of the bridge itself.

On the occasion of the reconstruction of the abutment in high emergency mode, a seismic reinforcement was also carried out to constitute an effective longitudinal constraint for the deck before its final reconstruction.