General Info📚
On the 3rd of August 2020 marked the opening and inauguration ceremony of the new replacement structure of the Polcevera viaduct.
The 18 pillars of the new Genoa bridge were illuminated with the colours of the Italian flag days before its inauguration.
Construction of the new Genoa San Giorgio bridge took only 15 months and was designed by the renowned native of the city architect Renzo Piano and built by construction company webuildgroup.
Bridge History 📑
Ponte Morandi officially Viadotto Polcevera, was a road viaduct in Genoa (Italy), constructed between 1963 and 1967 along Italy's A10 motorway over the river Polcevera. The bridge is widely called "Ponte Morandi" after its structural designer, and engineer Riccardo Morandi.
The viaduct was built between 1963 and 1967 by the Società Italiana per Condotte d'Acqua, costing 3.8 billion Italian lire and opened on 4 September 1967.
It had a length of 1,182 metres (3,878 ft), a height of 45 metres (148 ft) at road level, and three reinforced concrete pylons reaching 90 metres (300 ft) in height
The maximum span was 210 metres (690 ft).
The Genoa Bridge was a pioneer and innovative design for its time.
The Ponte Morandi was a cable-stayed bridge characterised by a prestressed concrete structure for the piers, pylons and deck, with only two stays per span, and a hybrid system for the stays constructed from steel cables with prestressed concrete shells poured on.
The concrete was prestressed only to 10 MPa making it susceptible to cracks, water intrusion, and corrosion of the internal steel.
Reason of the Collapse in 2018 💥
The innovations of the Morandi Bridge were the early use of pre-stressed concrete and cable-supported spans. Over the past half-century, we have learned a lot about the use of these technologies.
Two particular design aspects that bridge engineers of today are much more aware of are durability and robustness.
During the period of construction of the bridge in 1960 designers were not aware of the high importance of the interaction of materials and the effects of pollution and climate change on the corrosion of certain material.
It has been reported that the southern stays gave way first explosively due to corrosion and damage of the old bridge.
“A bridge is like a car,” says Luigi Gambarotta, professor of structural mechanics at the University of Genoa. “You can’t overload it, and to keep it working you need to change the broken parts.”
That was difficult in the case of Morandi Bridge: the cables were difficult to inspect, and it was unclear how they were coping with increased traffic loads.
Source: theguardian.com
“They waited 25 years and then the bridge collapsed. This is how things go in Italy – you start something and you never finish it,” says the architect Antonino Saggio, who is leading a campaign to save what remains of the bridge.
Demolition of the remaining Structure
Engineering Lessons Learned
by Institute of Civil Engineers (ICE)
The collapse raised concerns about the general condition of infrastructure in Europe, with studies in Italy, France, and Germany suggesting that a significant number of bridges are in need of renovation or replacement due to corrosion and structural deterioration.
Durability and robustness
Robustness is now a priority in any structure. Modern cable-stayed bridges usually adopt multi-cable arrays, which offer alternative load paths in the event of a loss of capacity of any one cable.
While these developments should make a tragedy such as the one in Genoa less likely, bridge engineers must continue to be aware of time-related deterioration and increased loading conditions.
Improved inspections
The bridge had been subject to continual restoration work from the 1970s on due to an incorrect initial assessment of the effects of creep and corrosion of the concrete and its steel reinforcement. This resulted in the excessive deferred displacement of the vehicle deck so that it was neither level nor flat.
Only after continual measurement, redesign and associated structural work was the vehicle deck considered acceptable, approaching horizontal by the mid-1980s.
On 3 May 2018, the Autostrade company had announced a call for tenders for a structural upgrade of the viaduct to the value of €20,159,000, with a deadline of 11 June 2018. The work on the reinforcement of the stays on pillars 9 and 10 would have needed to be finished within five years.
Workers were installing new heavy concrete barriers on the Ponte Morandi before it collapsed, reducing the already low compressive pre-stress on the concrete of the stays and increasing the loads. Unfortunately, the bridge collapsed on the 14th of Augst 2018.
Source: ICE
New Design ✏️ 🌉
On the 3rd of August 2020 marked the opening and inauguration ceremony of the new replacement structure of the Polcevera viaduct in the presence of the Italian President Sergio Mattarella, prime minister Guiseppe Conte and the bridge architect and native Renzo Piano.
The project cost 200 million euros plus the cost of demolishing the Morandi bridge, which added another 90 million euros to the total expenses of the project.
A joint venture of WeBuild and Fincantieri has delivered the construction of the new bridge, with Rina Consulting as project manager for the programme.
The structure was designed by famous architect Renzo Piano and is 1,067m long that comprises with a steel deck spread over 19 steel and concrete spans, which vary in length from 26m to 100m.
You will also like: Renzo Piano's top 5 designs
General Info 📑
The final days of work on-site have seen the laying of the final layer of asphalt, the installation of horizontal and vertical signage, as well as the setting up of the robotic system that will inspect the structure and allow for any preventive maintenance.
The scheme involved:
220,000 hours of engineering work
Generation of more than 3,200 technical documents
Review of over 1,500 project sheets.
20 live sites were operating simultaneously, 24 hours a day without interruption for almost two years.
Several weeks of load tests were done to ensure the loading capacity of the new bridge were done.
The tests started earlier this month following the recent near completion of the structure in a record 15 months. The series of tests, conducted by state motorways entity Anas and Rina initially consisted of 16 heavy trucks driving along the bridge.
Later, another 56 trucks lorries weighing 44 tonnes each - a combined weight of 2,500 tonnes - put the bridge through further tests. Static load tests continued in the coming day's trucks continued to run along the bridge.
Source: WorldHighways