World Trade Center

The original **World Trade Center** (**WTC**) was a large complex of seven buildings in the Financial District of Lower Manhattan in New York City. It opened on April 4, 1973, and was destroyed in 2001 during the September 11 attacks. At the time of their completion, the **Twin Towers**—the original 1 World Trade Center (the North Tower) at 1,368 feet (417 m); and 2 World Trade Center (the South Tower) at 1,362 feet (415.1 m)—were the tallest buildings in the world. Other buildings in the complex included the Marriott World Trade Center (3 WTC), 4 WTC, 5 WTC, 6 WTC, and 7 WTC. The complex contained 13,400,000 square feet (1,240,000 m2) of office space.

The core complex was built between 1966 and 1975, at a cost of $400 million (equivalent to $3.56 billion in 2022). The idea was suggested by David Rockefeller to help stimulate urban renewal in Lower Manhattan, and his brother Nelson signed the legislation to build it. The buildings at the complex were designed by Minoru Yamasaki. In 1998, the Port Authority of New York and New Jersey decided to privatize it by leasing the buildings to a private company to manage. It awarded the lease to Silverstein Properties in July 2001. During its existence, the World Trade Center symbolized globalization and the economic power of America. Although its design was initially criticized by New York citizens and professional critics, the Twin Towers became an icon of New York City. It had a major role in popular culture, and according to one estimate was depicted in 472 films. The Twin Towers were also used in Philippe Petit's tightrope-walking performance on August 7, 1974. Following the September 11 attacks, mentions of the complex in various media were altered or deleted, and several dozen "memorial films" were created.

The World Trade Center experienced several major crime and terrorist incidents, including a fire on February 13, 1975; a bombing on February 26, 1993; and a bank robbery on January 14, 1998, as well as the terrorist attacks on September 11, 2001. The latter began after Al-Qaeda-affiliated hijackers flew two Boeing 767 jets into the Twin Towers at 8:46 and 9:03 a.m., respectively. Between 16,400 and 18,000 people were in the Twin Towers when they were struck. The fires from the impacts were intensified by the planes’ burning jet fuel, which along with the initial damage to the buildings’ structural columns, ultimately caused both towers to collapse. The attacks in New York City killed 2,606 people in and within the vicinity of the towers, as well as all 157 on board the two aircraft. 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 WTC complex's buildings including 7 World Trade Center, and caused catastrophic damage to 10 other large structures in the surrounding area.

The cleanup and recovery process at the World Trade Center site took eight months, during which the remains of the other buildings were demolished. On May 30, 2002, the last piece of WTC steel was ceremonially removed. A new World Trade Center complex is being built with six new skyscrapers and several other buildings, many of which are complete. A memorial and museum to those killed in the attacks, a new rapid transit hub, and an elevated park have been opened. The memorial features two square reflecting pools in the center marking where the Twin Towers stood. One World Trade Center, the tallest building in the Western Hemisphere at 1,776 feet (541 m) and the lead building for the new complex, was completed in May 2013 and opened in November 2014.

## Before the World Trade Center

Radio Row in 1936; Cortlandt Street station in background
Lower Manhattan in 1980. The twin towers can be seen in the very background.

### Site

The western portion of the World Trade Center site was originally under the Hudson River. The shoreline was in the vicinity of Greenwich Street, which is closer to the site's eastern border. It was on this shoreline, close to the intersection of Greenwich and the former Dey Street, that Dutch explorer Adriaen Block's ship, *Tyger*, burned to the waterline in November 1613, stranding him and his crew and forcing them to overwinter on the island. They built the first European settlement in Manhattan. The remains of the ship were buried under landfill when the shoreline was extended beginning in 1797 and was discovered during excavation work in 1916. The remains of a second eighteenth-century ship were discovered in 2010 during excavation work at the site. The ship, believed to be a Hudson River sloop, was found just south of where the Twin Towers stood, about 20 feet (6.1 m) below the surface.

Later, the area became New York City's Radio Row, which existed from 1921 to 1966. The neighborhood was a warehouse district in what is now Tribeca and the Financial District. Harry Schneck opened City Radio on Cortlandt Street in 1921, and eventually, the area held several blocks of electronics stores, with Cortlandt Street as its central axis. The used radios, war surplus electronics (e.g., AN/ARC-5 radios), junk, and parts were often piled so high they would spill out onto the street, attracting collectors and scroungers. According to a business writer, it also was the origin of the electronic component distribution business.

### Establishment of the World Trade Center

The idea of establishing a World Trade Center in New York City was first proposed in 1943. The New York State Legislature passed a bill authorizing New York Governor Thomas E. Dewey to begin developing plans for the project, but the plans were put on hold in 1949. During the late 1940s and 1950s, economic growth in New York City was concentrated in Midtown Manhattan. To help stimulate urban renewal in Lower Manhattan, David Rockefeller suggested that the Port Authority build a World Trade Center there.

Plans for the use of eminent domain to remove the shops in Radio Row bounded by Vesey, Church, Liberty, and West Streets began in 1961 when the Port Authority of New York and New Jersey was deciding to build the world's first world trade center. They had two choices: the east side of Lower Manhattan, near the South Street Seaport; or the west side, near the Hudson and Manhattan Railroad (H&M) station, Hudson Terminal. Initial plans, made public in 1961, identified a site along the East River for the World Trade Center. As a bi-state agency, the Port Authority required approval for new projects from the governors of both New York and New Jersey. New Jersey Governor Robert B. Meyner objected to New York getting a $335 million project. Toward the end of 1961, negotiations with outgoing New Jersey Governor Meyner reached a stalemate.

On September 20, 1962, the Port Authority announced the selection of Minoru Yamasaki as lead architect and Emery Roth & Sons as associate architects. Yamasaki devised the plan to incorporate twin towers. His original plan called 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.

Yamasaki's design for the World Trade Center, unveiled to the public on January 18, 1964, called for a square plan approximately 208 feet (63 m) in dimension on each side. The buildings were designed with narrow office windows 18 inches (46 cm) wide, which reflected Yamasaki's fear of heights as well as his desire to make building occupants feel secure. His design included building facades clad in aluminum-alloy. The World Trade Center was one of the most striking American implementations of the architectural ethic of Le Corbusier and was the seminal expression of Yamasaki's gothic modernist tendencies. He was also inspired by Islamic architecture, elements of which he incorporated in the building's design, having previously designed Saudi Arabia's Dhahran International Airport with the Saudi Binladin Group.
A typical floor layout and elevator arrangement of the WTC towers
Schematic of the prefabricated composite floor truss system used in the construction of the towers

A major limiting factor in building height is the issue of elevators; the taller the building, the more elevators are needed to service it, requiring more space-consuming elevator banks. Yamasaki and the engineers decided to use a new system with two "sky lobbies"—floors where people could switch from a large-capacity express elevator to a local elevator that goes to each floor in a section. This system, inspired by the local-express train operation used in New York City's subway system, allowed the design to stack local elevators within the same elevator shaft. Located on the 44th and 78th floors of each tower, the sky lobbies enabled the elevators to be used efficiently. This increased the amount of usable space on each floor from 62 to 75 percent by reducing the number of elevator shafts. Altogether, the World Trade Center had 95 express and local elevators.

The structural engineering firm Worthington, Skilling, Helle & Jackson worked to implement Yamasaki's design, developing the framed-tube structural system used in the twin towers. The Port Authority's Engineering Department served as foundation engineers, Joseph R. Loring & Associates as electrical engineers, and Jaros, Baum & Bolles (JB&B) as mechanical engineers. Tishman Realty & Construction Company was the general contractor on the World Trade Center project. Guy F. Tozzoli, director of the World Trade Department at the Port Authority, and Rino M. Monti, the Port Authority's Chief Engineer, oversaw the project. As an interstate agency, the Port Authority was not subject to the local laws and regulations of the City of New York, including building codes. Nonetheless, the World Trade Center's structural engineers ended up following draft versions of New York City's new 1968 building codes.
The exterior frame of the Twin Towers, 1979
The framed-tube design, introduced in the 1960s by Bangladeshi-American structural engineer Fazlur Rahman 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. Each of the World Trade Center towers had 236 high-strength, load-bearing perimeter steel columns which acted as Vierendeel trusses. The perimeter columns 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 perimeter structure containing 59 columns per side was constructed with extensive use of prefabricated modular pieces, each consisting of three columns, three stories tall, connected by spandrel plates. The spandrel plates were welded to the columns to create the modular pieces off-site at the fabrication shop. Adjacent modules were bolted together with the splices occurring at mid-span of the columns and spandrels. The spandrel plates were located at each floor, transmitting shear stress between columns, allowing them to work together in resisting lateral loads. The joints between modules were staggered vertically so that the column splices between adjacent modules were not on the same floor. Below the 7th floor to the foundation, there were fewer, wider-spaced perimeter columns to accommodate doorways.

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 87 by 135 feet (27 by 41 m) and contained 47 steel columns running from the bedrock to the top of the tower. The large, column-free space between the perimeter and core was bridged by prefabricated floor trusses. The floors supported their own weight as well as live loads, providing lateral stability to the exterior walls and distributing wind loads among the exterior walls. The floors consisted of 4-inch (10 cm) thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors. The trusses connected to the perimeter at alternate columns and were on 6 foot 8 inch (2.03 m) centers. The top chords of the trusses were bolted to seats welded to the spandrels on the exterior side and a channel welded to the core columns on the interior side. The floors were connected to the perimeter spandrel plates with viscoelastic dampers that helped reduce the amount of sway felt by building occupants.
Twin Tower framed tube structure
Hat trusses (or "outrigger trusses") located from the 107th floor to the top of the buildings were designed to support a tall communication antenna on top of each building. Only 1 WTC (north tower) actually had a spire antenna fitted, which was added in May 1979. The truss system consisted of six trusses along the long axis of the core and four along the short axis. This truss system allowed some load redistribution between the perimeter and core columns and supported the transmission tower.

The framed-tube 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, such as the Empire State Building that has thick, heavy masonry for fireproofing of steel structural elements. During the design process, wind tunnel tests were done to establish design wind pressures that the World Trade Center towers could be subjected to and structural response to those forces. Experiments also were done to evaluate how much sway occupants could comfortably tolerate; however, many subjects experienced dizziness and other ill effects. One of the chief engineers Leslie Robertson worked with Canadian engineer Alan G. Davenport to develop viscoelastic dampers to absorb some of the sways. These viscoelastic dampers, used throughout the structures at the joints between floor trusses and perimeter columns along with some other structural modifications, reduced the building sway to an acceptable level.

## Facts

* on 1973 the doors opened but the date is unknown.
* on feburay 1993 a car bomb was blown up in the parking garage, and the attack was supports to **Tummble the tower** and falll making the other fall as well but it failed (with was a good thing).
* a few months after 1993 the police hellacopter flying from nyc past the world trade center still standing
* on the plaza and mall plays music, you can find them on youtube
* she's always a women was playing on the plaza on 9/11

## Gallery (google only)

the startingcompletedPlazaPlazaPlazathe day of 1993from the streets
## The Day of 9/11

Morning Of 9/11After The first Plane HitSecond Planeboth towers on fireboth towers BurningSouth Tower Collaspesafter the South Tower Collaspesafter the North Tower collapsesSmoke after both towers has collapedAftermath