It’s a lift off

The Nelson Mandela Bay Multi-Purpose Stadium in Port Elizabeth entered the final phase of construction when the impressive roof with its white leaf-shaped colonnades, began being erected mid October. The process is being carried out by TMC, Subcontracting to the Grinaker-LTA/ Interbeton Ibhayi Joint Venture.

Construction of this 6-level, 45 900 seater stadium at a cost of just over R1 billion is well advanced and additional temporary seating will be installed for the 2010 FIFA World Cup.

The superstructure, pre-cast seat elements and raking beams are finished and the brickwork and plastering are nearing completion. Installation of the services is progressing well and the finishes to floors, walls and ceilings began in August. The final phase will include items such as access walkways and roads, parking and turnstiles.

“We have had particular success with the pre-cast raking beams, which are of a high standard and have achieved good tolerances,” said Mark Bicknell, Project Director for the JV. A pre-cast yard was established on site for this purpose.

“One of the major challenges so far has been the complexity of fixing the anchors. We took enormous trouble to ensure the extremely high tolerances, specified by German consulting engineers SBP, were achieved,” added Bicknell. “But erecting the roof, which is being assembled on the ground and lifted into position, is proving to be a testing period for the site team.”

"We are working well ahead of FIFA deadlines and the current projected completion date is set for the end of May."

The roof, which appears to be levitating over the base of the stadium, has a structural steel frame covered with aluminium cladding and with a PTFE- fabric spanning between the girders. It was designed by GMP Architects to provide maximum protection from wind and rain to the spectators on the upper concourse and upper tier in particular.

The steel girders were manufactured by ABJ in Kuwait and the three shipments required to transport the various components arrived in September 2008. Assembly began mid September.

The 36 girders, which arrived in pieces, are being assembled on the ground in four jigs and each assembly is done with two mobile cranes. Each 45m long, assembled girder weighing 56t will then be lifted to a height of 40m out of the jig and placed on the structure using a 400-ton crawler crane to create a 35m cantilever over the stadium. A road will be constructed with lifting platforms to carry the crawler cranes. Part of the road will be demolished once the roof is in place, while other parts will be retained as an access road.

A team of erecters will use scissor lifts and cherry pickers as working platforms for tightening the bolts in the jig before the girder is lifted into position.

Port Elizabeth is notorious for its high winds, and calm conditions will be essential during each lift, so provision has been made to erect the roof at night if necessary.

Cladding the girders takes place in the air using rope access systems. Ropes are attached to support brackets temporarily fixed to the structure and the roof sheeting erectors are suspended from these by lifelines whilst they install the sheeting over the girders.

Another complex aspect is the interface of the roof and the highly sensitive pitch operations. The front girders need to be erected from the pitch area, which will be challenging because of the space limitations. A compression ring is being installed in front of the girders, to provide lateral support for all 36 girders, as well as a catwalk and to which various services including the stadium lights will be attached. All this takes place as the roof girders are bolted and welded in position.

The joint venture includes Grinaker-LTA and Interbeton bv, with HBM Stadien-und-Sportstattenbau, a German construction company that specializes in sports stadia, as advisers. In addition 39 consultants headed up by the BKS/BTKM-PMSA Joint Venture are combining their expertise to create this world-class stadium, which will not only be used for soccer but many other sporting and entertainment events as well.