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Commercial of 500-600mm are typical – Fabsec beams in 201 work closely with the structural engineer SOM and Bishopsgate and plated girders in the Broadgate the cladding contractor Josef Gartner to make sure Tower. It all adds up to around 300 pieces of steel all of the steelwork and fixings fit and we have had per floor in the tower and about twice that number to interface with a lot of other trades,” says Mr Day. in each floor of 201 Bishopsgate. “Overall this is a very integrated project, so far “It has all fitted together well. We have had to achieving a smooth follow on of work. Rail extension makes room The raft over the Liverpool Street rail tracks – and now beneath the Broadgate Tower and 201 Bishopsgate – is a 2.5m deep structure of two twin steel framed decks on piled foundations with precast planks and concrete topping. William Hare’s job on first arrival, through a separate contract to the main building steelwork, was to cut through the 300mm top slab and expose the steelwork for adding another 600t of steel for strengthening and extending the raft. The 201 Bishopsgate frame fits on the original raft structure, built in 1999, but the Broadgate Tower extends further out, which necessitated an extension to the raft and the six massive steel A-frames for distributing the tower loads evenly over the raft and down into its piled foundations. “Eight new piles from 3m diameter at the top to 9m in diameter at the bottom were machine dug down to 20m in depth to form the extended foundations,” says Bovis Lend Lease Project Manager Robert Dudley. “The steel trusses of the raft were then extended out on the west side by William Hare with new 2.5m deep girders. Twelve massive steel and concrete node pieces connect the base of the A-frames to the old and new piles.” Profile & Drill Shotblasting website: www.kaltenbach.co.uk/news NSC February 2007 23


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