WORLD TRADE CENTER NEW YORK

NEW YORK CITY , UNITED STATES

The World Trade Center is a complex of buildings

under construction in Lower Manhattan , New York

City , United States, replacing an earlier complex of

seven buildings with the same name on the same

site. The original World Trade Center featured

landmark twin towers, which opened on April 4,

1973, and were destroyed in the September 11

attacks of 2001, along with 7 World Trade Center.

The other buildings in the complex were severely

damaged by the collapse of the twin towers

WTC AREA

The site is being rebuilt with six new

skyscrapers, a memorial to those killed in

the attacks, and a transportation hub. One

world trade center will be the lead building

for the new complex, reaching more than

100 stories at its completion. It is the tallest

building in the United States.

At the time of their completion the "Twin Towers", the

original 1 WTC (417 m), and 2 TWC were the tallest

building in the world. The other buildings in the complex

included the 3 WTC, 4 WTC, 5 WTC, 6 WTC, and 7

WTC. All of these buildings were built between 1975 and

1985, with a construction cost of $400 million

($2,300,000,000 in 2014 dollars).The complex was

located in New York City's Financial District and contained

13,400,000 square feet (1,240,000 m2) of office space.

On the morning of September 11, 2001, Al-Qaeda-

affiliated hijackers flew two Boeing 767 jets into the

complex, one into each tower, in a coordinated act

of terrorism. After burning for 56 minutes, the South

Tower (2) collapsed, followed a half-hour later by the

North Tower (1). The attacks on the World Trade

Center killed 2,753 people.Falling debris from the

towers, combined with fires that the debris initiated

in several surrounding buildings, led to the partial or

complete collapse of all the other buildings in the

complex and caused catastrophic damage to ten

other large structures in the surrounding area

(including the World Financial Center). The process

of cleaning up and recovery at the World Trade Center site took eight months.

Over the following years, plans were created for

the reconstruction of the World Trade Center.

The Lower Manhattan Development

Corporation (LMDC), established in November

2001 to oversee the rebuilding process, organized

competitions to select a site plan and memorial

design. Memory Foundations, designed by Daniel

Libeskind, was selected as the master plan;

however, substantial changes were made to the design.

The first new building at the site was the 7 World Trade Center,

which opened in May 2006. The memorial section of the National

September 11 Memorial & Museum opened on September 11,

2011 and the museum opened in May 2014. Construction of

the One World Trade Center is open in 2013; the 4 World Trade

Center opened on November 13, 2013; the 3 World Trade

Center is under construction and expected to open in 2016, 5

World Trade Center will be developed by the Port Authority of New

York and New Jersey, but, as of February 2014, a schedule was

not confirmed. Two World Trade Center's is still expected to be

completed before 2020.

ORIGINAL BUILDING

Minoru Yamasaki as lead architect has a plan for the towers to be 80 stories tall, but to meet the Port Authority's requirement for 10,000,000 square feet (930,000 m2) of office space, the buildings would each have to be 110 stories tall. A major limiting factor in building height is the issue of elevators; the taller the building, the more elevators are needed to service the building, requiring more space-consuming elevator banks.Yamasaki and the engineers decided to use a new system with two "sky lobbies”

Floor count 1 and 2 WTC: 110 floors

3 WTC: 22 floors

4 and 5 WTC: 9 floors

6 WTC: 8 floors

7 WTC: 47 floors

Construction started 1 WTC: August 1968

2 WTC: January 1969

3 WTC: December 1979

4, 5, and 6 WTC: 1970

7 WTC: 1983Completed

1 WTC: December 23, 1970

2 WTC: July 19, 1971

3 WTC: July 1981

4, 5, and 6 WTC: 1975

7 WTC: May 1987Opening April 4, 1973

The structural engineering firm Worthington, Skilling, Helle

& Jackson worked to implement Yamasaki's design,

developing thetube-frame structural system used in the

twin towers. The tube frame design, using steel core and

perimeter columns protected with sprayed-on fire resistant

material, created a relatively lightweight structure that

would sway more in response to the wind compared to

traditional structures .The tube-frame design, earlier

introduced by Fazlur Khan, was a new approach that

allowed more open floor plans than the traditional design

that distributed columns throughout the interior to support

building loads.

The World Trade Center towers used high-strength, load-

bearing perimeter steel columns called Vierendeel

trusses that were spaced closely together to form a

strong, rigid wall structure, supporting virtually all lateral

loads such as wind loads, and sharing the gravity load

with the core columns.

The core of the towers housed the elevator and utility

shafts, restrooms, three stairwells, and other support

spaces. The core of each tower was a rectangular area

and contained 47 steel columns running from the bedrock

to the top of the tower. The floors used prefabricated floor

trusses ,supported their own weight as well as live loads,

providing stability to the walls and distributing wind loads

among the walls.The floors consisted of 4 inches (10 cm) thick lightweight concrete slabs.

When World Trade Center twin towers were completed,

the total costs had reached $900 million.The ribbon

cutting ceremony was on April 4, 1973

NEW BUILDING

The new complex includes One World Trade

Center (formerly known as the Freedom Tower), 7 World

Trade Center, three other high-rise office buildings, a

museum and memorial, and a transportation hub.

The process of cleanup and recovery continued 24 hours

a day over a period of eight months. On May 30, 2002, a

ceremony was held to officially mark the end of the

cleanup efforts

FLOOR PLAN

PICTURE

1. ancillary building2. plaza level3. sky-lobby4. technical services5. underground car park

13 Load-bearing external wall

17 Core box column20 Floor slab

13. load-bearing external wall14. bar joist 900mm deep15. secondary joist16. horizontal bracing17. core box column

• 21. Floor covering22. In-situ concrete23. Trough decking24. Bar joist25. Electrical services duct26. Air-conditioning duct

32. rock33. concrete base slab34. grillage beams36. external column37. core column

10. open-plan office11. express lifts12. local lifts

33 Concrete base slab

34 Grillage beams

37 Core column

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yamasaki-associates-emery-roth-and-sons/534ee36bc07a80be16000003_ad-

classics-world-trade-center-minoru-yamasaki-associates-emery-roth-

sons_typical_floor_plan-png/

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http://www.Jmhdezhdez.Com/2013/02/one-world-trade-center-new-york-city.Html