Commercial Architecture March 2018 - 18

FEATURE

building design
Placed between the tracks and the river, the tower occupies less
than 25% of its two-acre site. This narrow building footprint allows
more than 75% of the property to be unenclosed outdoor space,
vastly increasing the pedestrian experience on and surrounding the
site. The park and plaza provide more than 1,000 lineal ft. of seating,
multiple assembly/event spaces, and 360 ft. of Riverwalk frontage.
The Riverwalk component addresses a key element in Mayor Rahm
Emanuel's vision for a Chicago that knits together different parts of
the city and provides an aesthetically pleasing connection to boats
and water taxis.
Vertical mullions (fins), emulating the river, undulate along the
building's east and west facades to help activate them with an
ever-changing pattern of light and shadow. The fins also provide solar
shading and minimize cooling loads during summer months, particularly on the building's west elevation. The narrow north and south
faces are divided into three vertical planes that accentuate the slenderness of the tower, with the center plane recessed to create additional corner offices.
LOBBY BLURS BOUNDARIES

How a high-rise building meets the ground can be more important
than how it meets the sky. While the enclosed building occupies 25%
of the site, the all-glass lobby creates a space that seeks to blur the
boundaries between indoor and outdoor spaces.
To make the lobby equally as bold as the building's overall design
and construction, the design uses an 85-ft.-tall glass wall that hangs
from the tip of the transfer truss at level eight. This glass wall showcases 150 Media Stream, a one-of-a-kind cultural landmark in the
form of a 3,000-sq.-ft. digital-art installation. With content directed
by a full-time curator, the piece displays artwork in collaboration
with local and nationally renowned institutions, such as the Chicago
History Museum, the Hyde Park Arts Center, the University of Illinois at Chicago, the School of the Art Institute of Chicago, the University of Chicago, and world-renowned new-media artists.
ABOVE THE LOBBY

For design continuity, the building core is clad with the same granite
on the interior and exterior. All non-structural surfaces are glazed,
and the west wall of the lobby is enclosed with a 90-ft.-high glass wall,
suspended from the structure above and supported by 2 1/2-ft.-deep
glass mullions.
The Chicago River played a significant role in design and construction. The building's curtainwall enclosure references its location
on the river, where the water is sometimes very smooth and highly
reflective and, at other times, provides a wave-like texture. The sysThe lobby, designed to be just as bold as the building's overall design and construction, uses an 85-ft.-tall glass wall that showcases
150 Media Stream, a one-of-a-kind cultural landmark in the form of a 3,000-sq.-ft. digital-art installation.

tem is composed of 8,500 individual units for a total of 540,000 sq.
ft. of glass.
To ensure the building is fully isolated from the noise and vibrations of the nearby Amtrak and commuter trains and the "L" train

COMMERCI A L A RCHI T EC T URE

MARCH 2018

slopes outward at an angle for the first eight stories, then widens

system, 4-ft.-thick concrete core and crash walls were constructed at

to nearly the full width of the site. To accomplish this feat, Clark

the west edge of the parcel. The public areas above the tracks are

Construction Group, Chicago (clarkconstruction.com), designed

supported by roughly 1-ft.-thick concrete slabs and precast concrete

a core-supported structure-a massive central concrete "spine" that

which, in turn, is supported by foundation elements that bear on

holds the elevator core and also transfers the load of the upper floors

bedrock.

down to the foundation. Caissons were drilled more than 110 ft. be-

To meet these acoustic requirements, the team performed com-

low grade and sunk 10 ft. into bedrock to provide a stable foundation.

prehensive acoustical testing of the curtainwall system. The tests, the

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Table of Contents for the Digital Edition of Commercial Architecture March 2018