What structural system is used in the Burj Khalifa?

The Burj Khalifa uses a buttressed core structural system.

Developed by engineer Bill Baker at Skidmore, Owings & Merrill, the system centers on a hexagonal reinforced-concrete core with three projecting wings arranged in a Y shape. The wings buttress the core, helping the tower resist gravity loads, wind forces, and twisting.

This arrangement allowed the Burj Khalifa to rise far higher than conventional framed systems while using a relatively efficient amount of material. Its setbacks spiral upward, reducing the building’s exposed width and disrupting wind vortices that could produce dangerous oscillations.

A common mix-up is calling the system a “diagrid,” since the tower’s exterior has a strongly engineered appearance. A diagrid relies on diagonal exterior members; the Burj Khalifa’s defining system is instead the reinforced-concrete buttressed core and its three wings.