World-class soccer wasn’t the only spectacle at The Nelson Mandela Bay Stadium in Port Elizabeth, South Africa, during the 2010 FIFA World Cup. The aesthetically unique stadium features a tensioned membrane roofing system to protect the 50,000-seat venue from the sun and intense winds prevalent in the region.
The roof structure utilizes 36 aluminum-clad cantilevered trusses each 150 feet long, supporting the edges of the 230,000-square-foot PTFE coated fiberglass fabric panel system without obstructing spectators’ sight-lines. The change between opaque and transparent materials results in the roof’s dynamic, sunflower-like shape and naturally illuminates the stadium during the day while allowing the upper exterior to glow at night. Additionally, the cable system on which the panels are suspended helps reinforce the pattern of ribbed shapes and hollows which serve to shelter spectators and drain rainwater. The trusses comprise 2,500 tons of steel and were able to be transported in pieces to the construction site where the structure then was assembled.
“No other fabric materials could offer the life expectancy, translucency and clean appearance of the lightweight PTFE fabric membrane,” says Joseph Gray, project manager at Birdair Inc., the roofing sub-contractor on the project. “Any other solid metals would have required a substantial increase in structure weight and complexity to support an increased load and provide the necessary attachment points. Additionally, the compound curvature of the roof structure would have been compromised by replacing the fabric with solid material.”
CADMAX Steel Detailers in Boisbriand, Quebec, Canada, performed much of the steel shop detailing for the project. GMP Architects, Berlin, served as the architects on the project and additionally received building contracts for three other 2010 World Cup stadiums. Birdair also received roofing contracts for three of the five new stadiums built in South Africa for the World Cup.
The roof was designed in two stages, a non-deformed geometry to distinguish the design of the frames and girders and a deformed geometry to represent the structure under the stresses provided by the existence of the building’s other elements. To ensure that the roof, which does not incorporate any right angles, could be assembled error-free on the job site, the team used a three-dimensional pattern system and numbered each of the preassembled pieces.
In addition to dealing with the structure’s complexity, the design-build team was required to finish it within a short time-frame and amidst other infrastructural preparations for the international tournament.
“The aggressive schedule was the most difficult challenge to overcome throughout the project, requiring the need to do many items in parallel that would normally be handled sequentially,” says Gray. “Although this did create some relatively minor problems, it enabled the design and construction to make the most of the limited available schedule.”
Going forward, the structure will be used for multiple purposes, per its design. “It is only limited by the imagination and ingenuity of the operators of the building,” he says. “In addition to sporting events, concerts, plays and other events requiring large capacity seating, the large clear span and open field allow for huge participatory events, rallies and displays while offering protection from the wind.”
An international cast collaborated to design and build the structure. GMP Architects, Berlin, were the architects on the project. Buffalo, N.Y.-based Birdair Inc. was the roofing contractor along with Pfeiffer Seilbau, Memmingen, Germany. Schlaich Bergermann & Partner of Stuttgart, Germany, was the structural engineer. A joint-venture of Arbeitsgemeinschaft Grinaker –LTA, Boksburg, South Africa; Interbeton, Gouda, Netherlands; and HBM Stadien – und Sportstattenbau, Dusseldorf, Germany, served as the general contractors. CADMAX Steel Detailers, Boisbriand, Quebec, Canada, performed much of the steel detailing.
For more information, visit www.birdair.com.