Location: Sondrio, Italy
Owner Builder: Sondrio Municipality
Contractor: Quadrio Di Morbegno
Designer: Ing. Beltrami - Lombardi Ingegneria
Problem / Solution
The new bridge over the river Mallero in Sondrio is designed to improve traffic in the capital of the Valtellina area of the city of recent urban development. The structure is characterized by the particular structural setting of the bridge decks which make the two spans, each of a lenght of 50 m. These, in fact, are constituted by concrete plates prestressed in work with post tensioned cables, from 1.15 to 2.8 m but variable thickness, which form two almost symmetrical spans and connect two roads crossing the new residential area.
Strength, lightness and durability.
Why expanded clay?
The particular static configuration of the structure made it necessary to find a solution to lighten the total weight of the bridge decks, which in places reaches remarkable thicknesses. For the casting of the structures it was then employed a lightweight expanded clay concrete with a mechanical resistance to compression of 45 MPa. The experiments conducted have led to the identification of a formulation able to guarantee the strength requirements, lightness (1.850 kg /m3), predetermined elastic modulus, and can reduce the values of precompression than those normally used for structures built with traditional concrete.