Being part of the Three Bridges project, Mulazzo Suspension Bridge over Mangiola river is now under construction. The original old bridge, in bricks and stone with small spans and supports in the riverbed, was destroyed during the 2011 flood, that exceeded the 200 years return level and took the entire bridge down (video of the 2011 flood).
The new Bridge flies over the entire riverbed by a 100 m main span and a 24 m side span, both of them suspended to the main cables: the total length between the joint is 124 m.
There are four towers, two of them in steel structure and two in reinforced concrete, at different altitudes since the bridge has a longitudinal 5% slope.
The deck has a steel structure 11m wide and carries two highway lanes and two footpaths. The deck structure is composed by a central stiffening steel box girder and transverse steel I-beams. The central box girder provides strength and the rigidity in the vertical plane. In service the deck works together with the reinforced concrete slab as composite structure, making an element with high flexural stiffness. The transverse I-beams have tapered profile and they cross the central beam, support the slab and connect the deck structure to the cables.
The hangers are vertical cables which suspend the deck from the main cables by means of steel fabricated clamps. They have hinge connections at both ends, making assembly of the connections, and hence the deck, easy and fast.
Now the four masts are completed, the main cables are being installed, and soon the deck will be assembled.
De Miranda Associati Consulting Engineers is the Designer of the Bridge on behalf of Regione Toscana; Ici Coop is the Contractor with steel works from MBM, and cables from Redaelli.