Trump Tower Chicago is a multi-use building with a
height of 1134 ft. (1362 ft. including the spire) above grade and
is scheduled for completion in 2009. The building is located on
the site of the existing Sun-Times building, which is bounded by
the Chicago River to the south, Rush Street to the east, and Wabash
Street to the west. Designed by Skidmore, Owings & Merrill LLP
(SOM) the 92 story Trump Tower will be the tallest concrete building
in the United States, and the tallest building built in North America
since the completion of Sears Tower in 1974. The 2.6 million square
foot building includes condominium, service apartments, health club,
parking, and retail functions. Two below-grade levels, lower level
1 and 2, are located between the elevations of Upper and Lower Wabash
Street. A third below-grade level, lower level 4, is located below
the elevation of Lower Wabash Street generally within the footprint
of the tower.
The tower superstructure is generally reinforced concrete. New
ground is being broken through a series of high performance concrete
mixes designed by Prairie Material Sales, Inc. and employed by SOM
on the project. It is believed to be the first application of 16,000
psi self-consolidating concrete pumped and placed to an elevation
up to 650’ above grade. The dense limestone ½”
topsize aggregate is supplied from the Material Service Corporation.
The Thornton quarry in northern Illinois has been specified for
the high strength concrete on the project.
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| Trump Tower - View from east |
The building has major setbacks at levels 16, 29 and 51 that correspond
to the top elevations of prominent neighboring buildings, providing
visual continuity with the building’s surroundings. These
buildings include the historic Wrigley Building on the east, Bertrand
Goldberg’s Marina City to the west, and Mies van der Rohe’s
IBM Building located directly across Wabash Avenue. Transfer walls
occur at the setback levels to distribute discontinuous column forces
to other structural elements. A central reinforced concrete core
wall system, with wall webs generally spaced 30 feet on center,
extends from the foundation level to the top of the tower. The core
wall elements are connected by reinforced concrete link beams. The
core wall dimensions in the north-south direction remain constant.
Individual core wall elements terminate at select setback levels
such that the configuration of the core wall system is similar to
that of the building massing.
The major columns are reinforced concrete. Columns along the north
and south faces are spaced at 30 feet on center while the distance
between columns on the east and west faces varies. Interior columns
below level 16 are generally spaced at 30 feet in the east-west
direction and 45 feet in the north-south direction. Interior columns
above level 16 are generally spaced at 30 feet in the east-west
direction and 20 feet in the north-south direction.
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| Construction of upper residential floors |
Floor structures are generally flat plates or flat slabs. Special
thick, heavily reinforced slabs are required at and above the mechanical
levels. Floor slab thicknesses are increased at many levels to limit
acoustic and vibration transmission. Typical residential floors
are 9” thick flat plates spanning up to a maximum of 30’
without perimeter spandrel elements. This construction minimizes
the structural depth of the floor, allowing higher ceiling heights.
Tower columns are typically 2’ by 4’ rectangular sections
at the top of the building and 6’ diameter circular sections
at the base.
The tower lateral load resisting system is made up of the core
wall system, outrigger system, and north/south face exterior columns.
The outrigger system is composed of (a) outrigger walls that connect
the core and exterior columns and (b) perimeter walls connected
to the outrigger walls that engage exterior columns. The transfer
walls referenced above are generally integrated with the outrigger
system.
The tower foundation system consists of reinforced concrete caissons.
A total of 57 rock caissons support the tower. The tower columns
are supported by 33 of these rock caissons up to 8’ in diameter
and stabilized by a series of caisson caps and grade beams. A 10’
thick concrete mat under the core walls transfers their enormous
loads into a grid of the 24 - 10’ diameter drilled shaft rock
caissons that extend about 80’ down where they are socketed
6’ into solid Chicago limestone bedrock. The design team specified
an Osterberg load cell test be performed on one of the first production
rock caissons to verify an increase in allowable bearing pressure
above the Chicago Building Code allowable 200 TSF. The resulting
successful Osterberg load cell test and the subsequent code variance,
allowed the design team to utilize allowable bearing pressures up
to 270 TSF. The increase in allowable bearing pressures, coupled
with the utilization of high strength (10,000 psi) concrete in the
caisson shafts, resulted in significant reduction in rock caisson
quantities for the project.
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| Utililization of rebar terminators |
Because of the magnitude of the applied loads and the scale of
the outrigger elements, the structural engineering design for these
elements was unique and extremely challenging. Large tie forces
are resisted by top and bottom longitudinal reinforcing and vertical
ties. The heavy longitudinal reinforcing steel must pass from the
thicker outrigger through the thinner core wall web to transfer
forces between the columns and core. To reduce congestion, all primary
reinforcing bars in the outrigger levels are U.S. Grade 75 (520
N/mm2 yield strength). Further, in three especially-tight locations,
high strength structural steel plates with welded shear studs are
used in lieu of reinforcing bars to transfer the necessary forces
through the core wall web.
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| Concrete delivery |
A series of high performance concrete mixtures, specified by SOM
and designed by Prairie Material Sales, Inc., are advancing the
state-of-the-art. Concrete strengths of 12,000 psi at 90 days have
been specified for all vertical column and wall elements up to Level
51. Local areas in the outrigger zones, however, require 16,000
psi concrete at 90 days. Because the 16,000 psi concrete is located
in areas with high reinforcement congestion, self-consolidating
concrete (SCC) with a minimum flow table spread of 24” has
been specified. Further, to reduce the heat gain in the massive
elements, the high performance SCC incorporates slag cement, fly
ash, and silica fume as well as portland cement.
Project completion is scheduled for spring of 2009; however, based
upon the phased-occupancy plan, the 339 room Hotel opened January
30, 2008, and the 16th floor restaurant opened February 2008; well
before the topping out of the structure.
Photos by Lawrence Novak, SE
References:
Baker, W.; Korista, S.; Sinn, R.; Pennings, K.; & Rankin, D.,
“Trump International Hotel and Tower,” Concrete
International, July 2006, 28-32. Marketing article, February,
2007.
Baker, W.; Korista, S.; Rankin, D.; Sinn, R., “Specifying
High Performance Concrete for the Trump Chicago,” Proceedings
of the ASCE/SEI Structures Congress 2008.