Trump World Tower
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 When
completed this year, the Trump World Tower will be one of the tallest
residential buildings in the world, and the tallest in New York
City. The 90-story, 900-ft (274-m) tower is located at 1st Avenue
and 48th Street overlooking the United Nations complex and the East
River. The United Engineering Center formerly occupied this site.
In addition
to locale and height, there are other noteworthy aspects of this
project, one of which is the lateral force resisting system that
provides an efficient response to the lateral loads while accommodating
greater flexibility in the architectural design.
Structural
Framing System
With overall
plan dimensions of 145 ft by 78 ft (44.2 m by 23.8 m), the main
tower can easily be classified as slender. Due to architectural
requirements, the columns do not follow a regular grid. The longest
span is 24 ft (7.3 m); thus, a conventionally reinforced 8-in. (200-mm)
thick flat plate was chosen for the floor system. The column sizes
are also dictated by architectural requirements with typical perimeter
columns varying from 42 in. by 28 in. (1,070 mm by 710 mm) at the
base of the tower to 36 in. by 16 in. (915 mm by 400 mm) at the
top. The lateral force resisting system is described below. Columns
are supported by spread footings and shear walls are supported by
strip footings, all founded on Manhattan rock.
Lateral Force
Resisting System
The lateral
force resisting system consists of shear walls and frames interacting
for the full height of the building with a perimeter concrete "belt"
at mid-height and a perimeter concrete "hat" at the top.
The belt and hat are full-story concrete walls that form a tube
around the perimeter of the tower. Providing not only an efficient
means of resisting the lateral forces, the belt and hat allow greater
architectural flexibility and create a more functional building
overall. The shear walls vary in thickness from 30 in. (760 mm)
at the base to 12 in. (305 mm) at the top. Further efficiencies
were achieved through the use of high strength concrete in both
the belt and walls.
Lateral Forces
Wind forces
determined from wind tunnel testing govern the lateral design. These
forces are greater than those mandated by the New York City Building
Code.
Concrete
Specifications
Normal
weight concrete was used throughout this project. Concrete with
a compressive strength of 4,000 psi (25 MPa) was originally specified
for the floor slabs. However, due to the higher concrete strengths
of the columns, two different concrete mixes would be required in
the floor slab. Thus, the contractor elected to use 7,000 psi (45
MPa) concrete for the slabs in order to avoid integrating the two
different concrete strengths around the columns at most of the floors.
The compressive strength of the columns and walls is 12,000 psi
(80 MPa) in the lower 20 stories and transitions to 5,000 psi (35
MPa) at the top of the tower.
Concrete
versus Steel Framing
In the preliminary design stages, structural steel was considered
very briefly. Concrete framing was chosen for the following reasons:
· Better
overall response to wind
· Reduced floor-to-floor height (floor heights vary from
10 ft-8 in. (3.3 m) to 12 ft-8 in. (3.9 m), with a 16 ft-8 in.
(5.1 m) height at the penthouse)
· Elimination of ceiling finishes
· Better soundproofing
· Construction schedule
Credits
Developer: The Trump Organization
Architect: Costas Kondylis & Associates, P.C.
Structural Engineer: Ysrael A. Seinuk, P.C.
General Contractor: Daewoo/Lehrer McGovern Bovis, Inc.
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