Burj Khalifa Tower, Dubai, UAE

The Outstanding Structure Award Committee, chaired by William J. Nugent, USA, presented the 2011 Outstanding Structure Award  to the Burj Khalifa Tower, Dubai, UAE, for being:

“an aesthetically striking super tall building that utilises a Y-shaped, buttressed concrete core and a stepped, spiraling vertical shape to address never before seen structural requirements and achieve a record setting height”.

At 828 meters, the Burj KhalifaTower is the world’s tallest structure. Remarkably, its height eclipses the previous tallest buildingstructure by more than 60 percent and the previous tallest structure of any type by more than 30 percent. To achieve this record setting height, it was necessary to push the limits of current analytical, materials, and construction technologies. The Tower’s designers utilized a y‐shaped, buttressed concrete core and a spiraling vertical, exterior shape with strategically placed set‐backs to “confuse the wind” and address never before seen structural requirements.

In doing so, they created an aesthetically pleasing and functional super tall building that achieved the project’s goal to not simply be the world’s highest building, but to embody the world’s highest aspirations.

Structural System Description

Each of the wings buttress the others via a six-sided central core, or hexagonal hub. This central core provides the torsional resistance of the structure, similar to a closed pipe or axle. Corridor walls extend from the central core to near the end of each wing, terminating in thickened hammer head walls. These corridor walls and hammer head walls behave similar to the webs and flanges of a beam to resist the wind shears and moments. Perimeter columns and flat plate floor construction complete the system. At mechanical floors, outrigger walls are provided to link the perimeter columns to the interior wall system, allowing the perimeter columns to participate in the lateral load resistance of the structure; hence, all of the vertical concrete is utilized to support both gravity and lateral loads. The result is a tower that is extremely stiff laterally and torsionally.

It is also a very efficient structure in that the gravity load resisting system has been utilised so as to maximise its use in resisting lateral loads. As the building spirals in height, the wings set back to provide many different floor plates. The setbacks are organised 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. As such, the tower does not contain any structural transfers. These setbacks also have the advantage of providing a different width to the tower for each differing floor plate. This stepping and shaping of the tower has the effect of “confusing the wind”: wind vortices never get organised over the height of the building because at each new tier the wind encounters a different building shape.

The Outstanding Structure Award Finalists were:
Moses Mabhida 2010 Soccer Stadium, Durban, South Africa
Pont Gustave Flaubert Lift Bridge, Rouen, France
Stonecutters Bridge, Hong Kong, China