Cable-stayed bridge over the Po River

Location
Piacenza
Country
Italia
Year
2000 – 2003
Client
CEPAV1
Area
Infrastructures
Services offered
Geotechnical Engineering, Structural engineering
Concept Design
Mario Petrangeli & Associati s.r.l.

Project description

The cable-stayed bridge over the Po River, finished in 2006, set a world record in its kind, since it is completely made of concrete and it serves a railway line with design speed of 350 Km/h.

The high speed train crosses the bridge at about 1,500 metres downstream of the A1 motorway, near Piacenza, in a part where the minimum flow river bed is about 350 metres wide but the distance between the embankments is higher than a kilometre.

The cable-stayed bridge is founded on two piers in the minimum flow river bed. The central span is equal to 192 m, while the two side spans are equal to 104 m. The bridge has also 20 secondary access spans between about 33 and 66 m.

The structural design entrusted to CEAS concerned the 24 foundation piling of the viaduct and some ancillary works for the work construction, while Mr Mario Paolo Petrangeli of Rome designed the elevated structures. The alluvial soil characterization and the approach to the general criteria of the geotechnical project were carried out on the advice of Mr Roberto Nova of the Structural Engineering Department of the Polytechnic University of Milan.

In particular, the foundations of the two central piers consist for each tower of a slab suitably shaped for hydraulic reasons resting on 28 2 m piles about 63 metres long.

These two important works were built in the river bed after installing some vibrated reinforced concrete sheet piles. Then a temporary work surface was built, supported by the sheet piles where the machines to perform piers were positioned.

The piers were finished in 2003 with the load tests, using the Osterberg cell technology.

The numbers

5.000 t of load for loading and breaking tests

24 piles in the river bed

63 depht of the foundation piles

ACTIVITIES CARRIED OUT

Structural and geotechnical design of the pile foundation works.
Structural design of the ancillary works in the river bed (quays, metal gangways, sheet piling and waterproof invert).
Worksite assistance during execution.

IMPORTANT ASPECTS OF THE PROJECT

Intervention within an important infrastructural project for the country carried out in very complex and difficult environmental conditions.
The capacity of the foundation piles is between 10 and 16 MN. They are bored with a diameter of 2,000 mm, they are between 35 and 62.5 m long, according to the loads and the stratigraphic conditions and undermining imposed by the hydraulic project.
Two loading and breaking tests were carried out in Autumn 2001. 50 MN test loads were reached thanks to the use, for the first time in Italy, of the Osterberg cell technology (supplied by Loadtest., Inc). This method allows reaching very high load levels without moving great reference structures. The test results were consistent with the project assumptions.