The ‘diagrid’ responds to the building's curved shape and provides vertical support to the floors thus allowing large internal column free office space.
The central core is required only to act under vertical load and is free from diagonal bracing.
In addition to being highly efficient in resisting wind forces, the ‘diagrid’ frames the communal light wells which spiral up the building enabling occupants to enjoy natural light over a larger area of floor.
The internal structure of the building comprises conventional steel beams and columns with composite profiled decking floors.
The total weight of steel used is approximately 11,000 tones.
Arup’ engineers addressed the building’s radical form by creating the efficient external ‘diagrid’ system (diagonally braced structure) of intersecting steel sections around the tower's perimeter.
Cives Steel prefabricated wide-flange rolled steel sections into intricate 6-ton node con
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nectors. In what the engineers called a “bird’s mouth” geometry at the building’s corners,
these complex nodes bolted into six different 12-inch, H-column-type diagrid elements. To
achieve additional fine tolerances within the gutters and ridges of the stainless steel clad
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ding at the nodes, ironworkers had to flip the heads and shafts of bolts on a case-by-case
basis