The home of Real Madrid FC, Estadio Santiago Bernabéu, has undergone multiple phases of reconstruction work including a new roof that is made with lightweight steel structures.
The pre-assembled components were raised above the stadium using a 600-ton crawler crane. The pre-assembled components were raised above the stadium using a 600-ton crawler crane. Image: Dillinger
The new stadium design is a joint development of German-based architecture firm Gerkan, Marg und Partner, Spanish project partner L35 Arquitectos, Ribas & Ribas Arquitectos, as well as the schlaich bergermann partner engineering office and INES Consulting Engineers.
Beside the sculptural facade, comprising sweeping diagonal stainless steel ribs with varying degrees of transparency, the retractable pitch, and a 360-degree LED screen that runs along the edge of the roof, the new Bernabéu Stadium also includes the seemingly ‘floating’ roof structure with fully retractable inner roof.
Spanish steelwork fabricator Horta Coslada was commissioned to perform the construction work for three of these design elements. The company specialises in large and complex projects such as bridges, stadiums, infrastructure, and high-rise buildings.
For the roof of the Santiago Bernabéu Stadium, Horta Coslada processed a total of 13,000 tons of steel, 3,100 tons of which were S690QL1 high-strength steel from Dillinger in plate thicknesses of 10 to 120mm. This higher strength means that lighter and more slender designs can be produced that would otherwise not be structurally possible.
The main cross members, each measuring 6m wide, were lifted into the stadium and then bolted together to create a total span of 176m The main cross members, each measuring 6m wide, were lifted into the stadium and then bolted together to create a total span of 176m. Image: Dillinger
According to Dillinger, the lower weight of the components not only allows use of larger structural elements, but also opens up new architectural opportunities. The roof of the Santiago Bernabéu Stadium used steel known as S690 which is commonly used in the field of crane construction. However, it is not used very often in steel construction applications and – even then – only in small tonnages. Based on estimates provided by Alejandro Otero Gutièrrez, CEO at Horta Coslada, no European project has ever processed such a large quantity of S690 as was used for this project.
Roof construction strategy
The general contractor commissioned by Real Madrid, Fomento de Construcciones y Contratas (FCC) collaborated with Horta Coslada to develop a construction strategy involving assembly of the huge cross members required for the roof structure outside the stadium. The core element of this strategy was a six-meter-high temporary platform, positioned in front of the west stadium entrance, on which all components of the roof were pre-assembled.
The original plans of the engineers for the main roof were based on the lightweight spoked-wheel principle. This comprises an inner tension ring that is to be connected via 44 radial cables to an outer pressure ring and rest on steel outriggers of the existing perimeter structure.
Joining the components of the cross members above the stadium. Imag Joining the components of the cross members above the stadium. Image: Dillinger
However, FCC decided to dispense with this lightweight cable construction and instead replace it with a more conventional system that uses four latticed main trusses made of steel which support the entire stadium roof. The main supports are the north and south cross members, each measuring 6m wide and spanning some 176m.
These key elements of the roof also played a vital part for the entire assembly process. During the construction work, they made it possible to pre-assemble the other roof components on the platform outside the stadium. The two main trusses were produced in full from S690 high-strength steel in a lattice structure and each weigh almost 1,500 tons. They rest on just four points, or rather columns, two of which were newly constructed.
“This structure was only possible thanks to use of the S690 steel grade, a lightweight steel with extremely high yield point,” said Alejandro Otero Gutiérrez, CEO at Horta Coslada.
The roof structure of the Santiago Bernabéuwas only made possible thanks to use of the high-strength S60QL1 premium steel. The roof structure of the Santiago Bernabéuwas only made possible thanks to use of the high-strength S60QL1 premium steel. Image: Dillinger
“The weight saving, which could only be achieved in this way, was the key to success of the entire structure. Compared with other solutions, we were able to use around 40% less steel thanks to the properties of this special grade.”
Around a third of the entire roof structure at the Santiago Bernabéu Stadium was produced from S690 supplied by Dillinger. Due to the use of the S690 material the roof used steel that weighed 12,000 tons rather than 20,000 tons.