To support the unprecedented height of the building,
the engineers developed a new structural system called
the buttressed core, which consists of a hexagonal
core reinforced by three buttresses that form the ‘Y’ shape.
Each wing, with its own high performance concrete corridor
walls and perimeter columns, buttresses the others via a
six-sided central core, or hexagonal hub. The result is a tower
that is extremely stiff laterally and torsionally. SOM applied a
rigorous geometry to the tower that aligned all the common
central core, wall, and column elements.
Each tier of the building sets back in a spiral
stepping pattern up the building. The setbacks are organized
with the Tower’s grid, such that the building stepping
is accomplished by aligning columns above with walls
below to provide a smooth load path. This allows the
construction to proceed without the normal diffi culties
associated with column transfers.
The setbacks are organized such that the Tower’s
width changes at each setback. The advantage of the
stepping and shaping is to ‘confuse the wind’. The wind
Thestructuralsystem
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