Aqua Tower
Chicago, Illinois
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Case Studies: Mixed Use > Aqua
Tower Concrete Makes Waves in Chicago
 The
Lakeshore East urban development in Chicago has a new iconic tower.
Aqua is a daring new addition to the Chicago skyline. The multi-use
tower will be completed in 2010 with partial occupancy of the lower
levels beginning in 2009. Concrete is utilized in both the structural
support and the tower’s architectural expression.
The tower’s façade features vertical glass with undulating
balconies of reinforced concrete that varies slightly from floor
to floor, creating a rippling, wavelike effect. Overall, the exterior
mimics the natural striated limestone outcroppings and formations
that are plentiful throughout the Great Lakes region. Studio/Gang/Architects
is the consulting architect for the exterior and Loewenberg Architects
is the architect of record. Magnusson Klemencic Associates is the
structural engineer. The three firms combined their efforts to develop
a unique tower that has received international attention.
The 88-story, multi-use high-rise will be home to a hotel, condominiums,
apartments, parking and retail space. Lakeshore East/Magellan Development
Group is the owner of the 2.3 million square foot, 874-foot tall
structure, which has been designed to meet LEED certification. The
typical tower floors are 16,000 square feet and offer spectacular
views of Lake Michigan, the Chicago River and some of Chicago’s
architecture gems.
The contractor is Chicago-based James McHugh
Construction Co., well known as the builder of some of the city’s
landmark structures including Marina City and Trump Tower. McHugh
has constructed eight high-rise structures for Magellan. Prairie
Material Services Inc. is supplying the normalweight concrete with
strengths varying from 5,000 to 12,000 psi. McHugh is self-performing
the concrete work on the project, pouring approximately 100,000
cubic yards of concrete. The project includes 11,000 tons of reinforcing
steel. The 3,000 cubic yard foundation mat utilized a special low-heat
concrete mix.
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| Top of construction with flying slab forms. |
Each floor’s slab shape is unique. The
balconies are cast with a 5,000 psi, air-entrained concrete and
use epoxy-coated rebar. The slab’s rectangular flying forms
extend further outward from the cladding line by more than the maximum
12 foot cantilever balcony. The unique curved slab edges are laid
out using a computerized surveying system to locate the curved slab
closure form angles on the slab forms.
McHugh custom built the concrete forms for the balconies.
The typical slab is 9 inches thick and the balconies
slabs vary in thickness, thickest at the cladding line and thinnest
at the tip of the balcony cantilever. After the shores are removed
the exposed concrete balcony slabs are protected with a white elastomeric
coating. The balconies are cast monolithically with the floor slabs.
This construction sequence allows the curving slabs to be placed
at a rate of one floor every three days using standard formwork
systems.
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| Balcony edge of slab closure form |
Cantilever balconies |
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| Balcony at corner |
Typical slab rebar; Balcony with epoxy rebar in background |
The conventional reinforced concrete core employs a jump form system
while the perimeter reinforced concrete columns and cross walls
are constructed using a stick-built system. Concrete is pumped to
the top of the structure via a Putzmeister pumping system.
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| Core wall jump form system |
Column and cross wall form system |
 The
structure is supported by 305 drilled bell and rock caissons with
diameters ranging from 4 to 10 feet and extending up to 112 feet
below grade. Case Foundation is the foundation contractor and Ground
Engineering Consultants Inc. is the geotechnical consultant.
Aqua is an amazing tower demonstrating how concrete can be creatively
applied to achieve both outstanding architecture and a durable structure.
References:
Chicago Tribune, March 23, 2008 article by Blair Kamin
Concrete Monthly, December 2006
Construction Digest, December 24, 2008 article by Tom Hale
Contact:
Lawrence Novak for additional information.
All photos courtesy Lawrence C. Novak, SE, SECB, LEED AP
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| Owner/Developer:
Lakeshore East/ Magellan Development
Group
Architect of Record: Loewenberg and
Associates
Design Architect: Studio/Gang/Architects
Structural Engineer: Magnusson Klemencic
and Associates
General Contractor: James McHugh Construction
Co.
Concrete Supplier:
Prairie Material Services Inc.
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