As they move around the floors, occupants encounter a series of small openings that chan- nel light into the interiors.
The spiraling geometry
was developed by
subtracting a quadrant
of a typical filleted
square floor plan and
the subtracted portion
at each higher level.
Technologies Corporation, of Irvine, California. To further protect the pile reinforcement, the
clear cover requirements set
forth in the American Concrete
Institute standard 318M (
Building Code Requirements for Structural Concrete) were increased to
100 mm. After careful consideration, the corrosion-resistant
reinforcement was ultimately
removed from the project and
replaced with an engineered cathodic protection system as a contractor substitution.
The raft foundation was poured in 15 separate pours over
a period of four months because of limits on the plant’s batch
capabilities. This segmented approach to the raft pour was
beneficial in limiting the peak concrete curing temperature
because the insulation prevented damaging temperature differentials near the concrete surface. Concrete curing temperatures were further minimized by using a concrete mix with a
high content (by volume) of fly ash.
THE LATERAL SYSTEM for resisting the control- ling wind and gravity load combinations consists of a cast-in-place reinforced-concrete shear wall
core supplemented by a perimeter moment-resisting frame.
The shear wall core was designed with thicker walls on the
perimeter of the core, optimizing the placement of material to maximize the resistance of the core to the gravity-load-induced torsion. The flared walls that connect back to
the core also are part of the lateral-force-resisting system.
Since the shear wall core would
be resisting the majority of the
wind-induced forces, it was determined that the most efficient
approach to the seismic design
of the tower would be to designate only the reinforced-concrete
shear walls as the seismic-force-resisting system. This made it
possible for a full seismic design
of the tower to be executed without having to use more material
anywhere in the structure. The
reinforced-concrete shear walls in the Al Hamra tower range
in thickness from 1,200 to 300 mm and in cube compressive
strength from 50 to 80 MPa. The moment-resisting frame
beams are typically 800 mm wide by 600 mm deep and are
poured with the floor framing using concrete with a cube
compressive strength of 40 MPa.
The shear walls on the south facade were engineered to
incorporate complex, unsymmetrical cuts that were placed
to control heat gain and light within interior spaces. Custom
reinforcing solutions were incorporated around each opening with specific geometry defined. As they move around the
floors, occupants encounter a series of small openings, and
from the elevator lobby they can look directly outward to the
city and the desert beyond. Along the interior of the south
wall, light enters the space through openings in the wall.
By using a 160 mm slab spanning between beams placed
6.0 m on center, only slightly more material was used than
would have been the case with a thin slab spanning 3.0 m
on center, but a greater proportion of the materials used
© SKIDMORE, OWINGS & MERRILL, LLP
 Civil Engineering SEPTEMBER 2012