its height. The Y-shape plan is ideal for residential
Gulf. Viewed from above or from the base, the form
and hotel use in that it allows the maximum views
also evokes the onion domes of Islamic architecture.
outward without overlooking a neighboring unit. The
To support the unprecedented height of the building,
wings contain the residential units and hotel guest
the engineers developed a new structural system
rooms, with the central core housing all of the
called the buttressed core, consisting of a hexagonal
elevators and mechanical closets. The tower is
core reinforced by three buttresses that form the ‘Y’
serviced by five separate mechanical zones, located
shape, enabling the building to support itself laterally
approximately 30 floors apart over the height of the
and keeps it from twisting. The result is a tower that
building. Located above the occupied reinforced
is extremely stiff laterally and torsionally. It is also a
concrete portion of the building are the structural
very efficient structure because the gravity load-
steel spire, housing communication, and mechanical
resisting system has been used to maximize its use
floors, and completing the architectural form of the
in resisting lateral loads also.
tower. The result is an efficient building in terms of its
Most of the tower is
functionality,
a reinforced concrete
structural system,
structure, except for
and response to the
the top, which
wind, while still
consists of a
maintaining the
structural steel spire
integrity of the initial
with a diagonally
design concept.
braced lateral
The tower’s Y-
system. High-
shaped floor plan not
performance
only has aesthetic
concrete is utilized
and functional
throughout. The
advantages but is
concrete mix was
also ideal for
designed to provide a
providing a high
low-permeability yet
performance,
high-durability
efficient structure.
Structural system description
The tower is composed of three elements arranged
around a central core. As the tower rises from the flat
concrete. Wall and column concrete strengths range
from C80 to C60 cube strength (11.6 kips per square
inch (ksi) to 8.7 ksi cube strength), and contain
portland cement, fly ash, and local aggregates. The
C80 concrete has a specified Young’s Elastic
desert base, setbacks occur at each element in a
Modulus of 43,800 N/mm2 (6,350 ksi) at 90 days.
spiraling pattern, decreasing the cross section of the
Structural analysis
tower as it reaches toward the sky. There are 27
terraces in Burj Khalifa. At the top, the central core
The entire building structure was analyzed for gravity
emerges and is sculpted to form a finishing spire. A
(including P-Delta analysis), the wind, and seismic
Y-shaped floor plan maximizes views of the Persian
loadings utilizing ETABS version 8.4, from Computers
and Structures, Inc. The 3D analysis model consisted