Olympics Aquatics Centre reaches half-way point - VIDEO

Construction of the wave-shaped roof of the London 2012 Olympics Aquatics Centre has reached the half way point.

The 'big lift' of the 160m-long 2,800t roof started three months ago. The roof frame, which is being supported by just three concrete piers, is on track to be completed this summer.

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The steelwork on the Aquatics Centre is being fabricated by Newport-based Rowecord Engineering. Main contractor on the project is Balfour Beatty.

When complete, the 160m-long and upto 90m-wide roof will rest on two concrete supports at the northern end and a 28m-long and 5m-wide supporting ‘wall’ at its southern end.

A huge 30m-long steel truss weighing over 70t has been lifted into place on top of the southern wall and this been connected to 10 steel trusses each made up of four sections which in total will span upto 120m to the two northern roof supports.

The steel trusses are being assembled on the Aquatics Centre site and connected together 20m off the ground on three rows of temporary support trestles.

All of the support has been provided by RMD Kwikform, in the form of its Megashor Heavy Duty propping system. RMD Kwikform engineers have been working with the Aquatics Centre construction team to develop a series of Megashor towers of various heights to temporarily support the steel roof structure during this phase of the construction.

Some 26 trusses are now in place and once the huge steel roof frame is complete this summer it will be lifted up to two metres at its southern end, turning on complex rotating joints in the northern roof supports. The temporary trestles will then be removed and the 160m-long roof frame lowered on to its three permanent piers.

As the full weight of the roof rests on its supports it will slide approximately 20cm into its joints on the southern wall. The roof has been designed, through wind tunnel testing and computer modelling, to stretch, twist and contract in response to the effects of snow, wind and changing temperatures.

Once the steel roof is in place this summer work will begin on the aluminium roof covering. Installation will then start next year on the timber cladding of the ceiling which will cover the northern roof supports.

The foundations of the permanent venue are complete and work will begin on the pool structure once the steel roof is complete.