Drawing showing the sequential construction of the Burj Khalifa spire. Courtesy of Samsung C & T.
It is one thing to draw a spire that reaches 828 meters into the air and to engineer the structure to support that height, but it is an added level of complication to figure out how it can be constructed.
Burj Khalifa is built of concrete with a jump-form system, up to level 156, where the tower is constructed of structural steel. As this drawing sequence from SOM illiterates, the steel was lifted and erected by a crane and derrick that was attached to the concrete core. The final 136 meters of the spire, a steel pipe weighing 350 tons, had to be assembled in sections within the tower, then jacked up into place. This method recalls the system used in the Chrysler Building in 1929, but at a much larger scale.
The following technical description of the erection of the spire prepared and executed by Samsung C & T, was provided by the construction project managers from Turner:
The spire at the Burj Khalifa is comprised of over twenty sections welded together to form a hollow steel structure over 110 meters long (inside the building and exposed). These steel sections were assembled within the main tower structure while it was being erected, and the completed spire pipe was then hydraulically jacked into final position over the course of eight separate lift cycles. The main construction sequence allowed for various tower structural members to be temporarily left out to accommodate the lifting equipment, which included three hydraulic strand jacks and a series of roller guides. The exposed portion of the spire’s exterior is equipped with stainless steel fins, which maintain the tower’s spiral geometry and optimize the wind flow across the structure.