buildings_trump2When 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-feet 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-by-78-feet, 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 feet; thus, a conventionally reinforced 8-inch 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-by-28-inches at the base of the tower to 36-by-16-inches 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 inches at the base to 12 inches 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 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 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  in the lower 20 stories and transitions to 5,000 psi 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 feet 8 inches to 12 feet 8 inches, with a 16 feet 8 inches height at the penthouse
  • Elimination of ceiling finishes
  • Better soundproofing
  • Construction schedule

Credits 

Developer:

The Trump Organization

Architect:
Costas Kondylis & Associates, P.C., New York, New York

Structural Engineer:
Ysrael A. Seinuk, P.C., New York, New York

General Contractor:
Daewoo/Lehrer McGovern Bovis, Inc., New York, New York

Year:
2001