7 World Trade Center

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7 World Trade Center
7 World Trade Center.jpg
The new 7 World Trade Center from the southeast (2008)
General information
StatusComplete
TypeOffice
Location250 Greenwich Street
Manhattan, New York 10006, United States
Coordinates 40°42′48″N74°00′43″W / 40.7133°N 74.0120°W / 40.7133; -74.0120 Coordinates: 40°42′48″N74°00′43″W / 40.7133°N 74.0120°W / 40.7133; -74.0120
Construction startedMay 7, 2002 [1]
Completed2006
OpenedMay 23, 2006
Height
Architectural743 ft (226 m) [2]
Roof741 ft (226 m) [3]
Top floor679 ft (207 m) [2]
Technical details
Floor count52 [3] [4]
Floor area1,681,118 sq ft (156,181 m2) [2]
Lifts/elevators29 [2]
Design and construction
Architect David Childs (SOM) [2]
Developer Silverstein Properties [2] [4]
Structural engineer WSP Cantor Seinuk [2]
Website
7 World Trade Center, wtc.com
References
[2]

7 World Trade Center (7 WTC) refers to two buildings that have existed at the same location within the World Trade Center site in Lower Manhattan, New York City. The original structure, part of the original World Trade Center, was completed in 1987 and was destroyed in the September 11 attacks in 2001. The current structure opened in May 2006. Both buildings were developed by Larry Silverstein, who holds a ground lease for the site from the Port Authority of New York and New Jersey.

World Trade Center site Grounds of the World Trade Center in New York City

The World Trade Center site, formerly referred to as "Ground Zero" or "the Pile" immediately after the September 11 attacks, is a 14.6-acre (5.9 ha) area in Lower Manhattan in New York City. The site is bounded by Vesey Street to the north, the West Side Highway to the west, Liberty Street to the south, and Church Street to the east. The Port Authority owns the site's land. The previous World Trade Center complex stood on the site until it was destroyed in the September 11 attacks.

Lower Manhattan Central business district in New York, United States

Lower Manhattan, also known as Downtown Manhattan or Downtown New York, is the southernmost part of Manhattan, the central borough for business, culture, and government in the City of New York, which itself originated at the southern tip of Manhattan Island in 1624, at a point which now constitutes the present-day Financial District. The population of the Financial District alone has grown to an estimated 61,000 residents as of 2018, up from 43,000 as of 2014, which in turn was nearly double the 23,000 recorded at the 2000 Census.

New York City Largest city in the United States

The City of New York, usually called either New York City (NYC) or simply New York (NY), is the most populous city in the United States. With an estimated 2018 population of 8,398,748 distributed over a land area of about 302.6 square miles (784 km2), New York is also the most densely populated major city in the United States. Located at the southern tip of the state of New York, the city is the center of the New York metropolitan area, the largest metropolitan area in the world by urban landmass and one of the world's most populous megacities, with an estimated 19,979,477 people in its 2018 Metropolitan Statistical Area and 22,679,948 residents in its Combined Statistical Area. A global power city, New York City has been described as the cultural, financial, and media capital of the world, and exerts a significant impact upon commerce, entertainment, research, technology, education, politics, tourism, art, fashion, and sports. The city's fast pace has inspired the term New York minute. Home to the headquarters of the United Nations, New York is an important center for international diplomacy.

Contents

The original 7 World Trade Center was 47 stories tall, clad in red masonry, and occupied a trapezoidal footprint. An elevated walkway connected the building to the World Trade Center plaza. The building was situated above a Consolidated Edison power substation, which imposed unique structural design constraints. When the building opened in 1987, Silverstein had difficulties attracting tenants. Salomon Brothers signed a long-term lease in 1988 and became the main tenants of 7 WTC.

Trapezoid Convex quadrilateral with at least one pair of parallel sides

In Euclidean geometry, a convex quadrilateral with at least one pair of parallel sides is referred to as a trapezoid in American and Canadian English but as a trapezium in English outside North America. The parallel sides are called the bases of the trapezoid and the other two sides are called the legs or the lateral sides. A scalene trapezoid is a trapezoid with no sides of equal measure, in contrast to the special cases below.

Consolidated Edison energy company in the United States

Consolidated Edison, Inc., commonly known as Con Edison or Con Ed, is one of the largest investor-owned energy companies in the United States, with approximately $12 billion in annual revenues as of 2017, and over $48 billion in assets. The company provides a wide range of energy-related products and services to its customers through its subsidiaries:

Salomon Brothers was an American investment bank founded in 1910 by Arthur, Herbert and Percy Salomon and a clerk named Ben Levy, remaining a partnership until the early 1980s. It was acquired by the commodity trading firm Phibro Corporation and became Salomon Inc. Eventually, Salomon (NYSE:SB) was acquired by Travelers Group in 1998; and, following the latter's merger with Citicorp that same year, Salomon became part of Citigroup. Although the Salomon name carried on as Salomon Smith Barney, which were the investment banking operations of Citigroup, the name was abandoned in October 2003 after a series of financial scandals that tarnished the bank's reputation.

On September 11, 2001, the structure was damaged by debris when the nearby North Tower of the World Trade Center collapsed. The debris also ignited fires, which continued to burn throughout the afternoon on lower floors of the building. The building's internal fire suppression system lacked water pressure to fight the fires, and the building collapsed completely at 5:21:10 pm, according to FEMA, [5] :23 while the 2008 NIST study placed the final collapse time at 5:20:52 pm. [6] :19, 21, 50–51 The collapse began when a critical internal column buckled and triggered structural failure throughout, which was first visible from the exterior with the crumbling of a rooftop penthouse structure at 5:20:33 pm. The collapse made the old 7 World Trade Center the first tall building known to have collapsed primarily due to uncontrolled fires, [7] and at the time, the only steel skyscraper in the world to have collapsed due to fire. [8]

Collapse of the World Trade Center collapse of the World Trade Center in New York City on September 11, 2001

New York City's World Trade Center was destroyed during the terrorist attacks of September 11, 2001 after being struck by two hijacked commercial airliners. The North Tower was hit at 8:46 am and collapsed at 10:28 am. The South Tower was hit at 9:03 am and collapsed at 9:59 am. The resulting debris severely damaged or destroyed more than a dozen other adjacent and nearby structures, ultimately leading to the collapse of Seven World Trade Center at 5:21 pm.

Federal Emergency Management Agency United States disaster response agency, part of Department of Homeland Security

The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security, initially created by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Executive Orders on April 1, 1979. The agency's primary purpose is to coordinate the response to a disaster that has occurred in the United States and that overwhelms the resources of local and state authorities. The governor of the state in which the disaster occurs must declare a state of emergency and formally request from the president that FEMA and the federal government respond to the disaster. The only exception to the state's gubernatorial declaration requirement occurs when an emergency or disaster takes place on federal property or to a federal asset—for example, the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, or the Space Shuttle Columbia in the 2003 return-flight disaster.

Construction of the new 7 World Trade Center began in 2002 and was completed in 2006. The building is 52 stories tall (plus one underground floor), making it the 28th-tallest in New York. [2] [3] [4] It is built on a smaller footprint than the original, and is bounded by Greenwich, Vesey, Washington, and Barclay Streets on the east, south, west, and north, respectively. A small park across Greenwich Street occupies space that was part of the original building's footprint. The current building's design emphasizes safety, with a reinforced concrete core, wider stairways, and thicker fireproofing of steel columns. It also incorporates numerous green design features. The building was the first commercial office building in New York City to receive the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED) certification, where it won a gold rating. It was also one of the first projects accepted to be part of the Council's pilot program for Leadership in Energy and Environmental Design – Core and Shell Development (LEED-CS). [9]

Washington Street (Manhattan) Street in Manhattan, New York

Washington Street is a north-south street in the New York City borough of Manhattan. It runs in several distinct pieces, from its northernmost end at 14th Street in the Meatpacking District to its southern end at Battery Place in Battery Park City. Washington Street is, for most of its length, the westernmost street in lower Manhattan other than West Street. The exceptions are a one-block segment in the West Village where Weehawken Street lies between West and Washington Streets, and in Battery Park City).

Reinforced concrete composite building material

Reinforced concrete (RC) (also called reinforced cement concrete or RCC) is a composite material in which concrete's relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel reinforcing bars (rebar) and is usually embedded passively in the concrete before the concrete sets. Reinforcing schemes are generally designed to resist tensile stresses in particular regions of the concrete that might cause unacceptable cracking and/or structural failure. Modern reinforced concrete can contain varied reinforcing materials made of steel, polymers or alternate composite material in conjunction with rebar or not. Reinforced concrete may also be permanently stressed, so as to improve the behaviour of the final structure under working loads. In the United States, the most common methods of doing this are known as pre-tensioning and post-tensioning.

Environmentally sustainable design is the philosophy of designing physical objects, the sustainability of the world is known as sustainable devalopment

Original building (1987–2001)

Design and layout

World Trade Center, New York City - aerial view (March 2001).jpg
Original 7 World Trade Center, the red-tinted building behind and to the left of the Twin Towers (View from southwest)
Wtc7 from wtc observation deck.jpg
The original 7 World Trade Center from the WTC observation deck
Transfer trusses used on the 5-7th floors to redistribute load to the foundation Wtc7 transfer trusses.png
Transfer trusses used on the 5–7th floors to redistribute load to the foundation

The original 7 World Trade Center was a 47-story building, designed by Emery Roth & Sons, with a red granite facade. The building was 610 feet (190 m) tall, with a trapezoidal footprint that was 330 ft (100 m) long and 140 ft (43 m) wide. [10] [11] Tishman Realty & Construction managed construction of the building. [10] The ground-breaking ceremony was hosted on October 2, 1984. [12] The building opened in May 1987, becoming the seventh structure of the World Trade Center. [13]

Emery Roth American architect

Emery Roth was an American architect of Jewish descent who designed many of the definitive New York City hotels and apartment buildings of the 1920s and 1930s, incorporating Beaux-Arts and Art Deco details. His sons continued in the family enterprise, largely expanding the firm under the name Emery Roth & Sons.

Granite A common type of intrusive, felsic, igneous rock with granular structure

Granite is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Granites can be predominantly white, pink, or gray in color, depending on their mineralogy. The word "granite" comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a holocrystalline rock. Strictly speaking, granite is an igneous rock with between 20% and 60% quartz by volume, and at least 35% of the total feldspar consisting of alkali feldspar, although commonly the term "granite" is used to refer to a wider range of coarse-grained igneous rocks containing quartz and feldspar.

Tishman Realty & Construction Co., Inc. is an American corporation founded in 1898 that owns and develops real estate. The company is known for being the contractor that built the original World Trade Center in New York City. Tishman Construction Corporation, the construction division of the company, was sold to AECOM in 2010.

7 World Trade Center was constructed above a two-story Con Edison substation that had been located on the site since 1967. [14] [12] The substation had a caisson foundation designed to carry the weight of a future building of 25 stories containing 600,000 sq ft (56,000 m2). [15] The final design for 7 World Trade Center was for a much larger building than originally planned when the substation was built. [16] :xxxviii The structural design of 7 World Trade Center therefore included a system of gravity column transfer trusses and girders, located between floors 5 and 7, to transfer loads to the smaller foundation. [6] :5 Existing caissons installed in 1967 were used, along with new ones, to accommodate the building. The 5th floor functioned as a structural diaphragm, providing lateral stability and distribution of loads between the new and old caissons. Above the 7th floor, the building's structure was a typical tube-frame design, with columns in the core and on the perimeter, and lateral loads resisted by perimeter moment frames. [15]

Electrical substation part of an electrical generation, transmission, and/or distribution system

A substation is a part of an electrical generation, transmission, and distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. Between the generating station and consumer, electric power may flow through several substations at different voltage levels. A substation may include transformers to change voltage levels between high transmission voltages and lower distribution voltages, or at the interconnection of two different transmission voltages.

Caisson (engineering) Rigid structure to provide workers with a dry working environment below water level

In geotechnical engineering, a caisson is a watertight retaining structure used, for example, to work on the foundations of a bridge pier, for the construction of a concrete dam, or for the repair of ships. Caissons are constructed in such a way that the water can be pumped out, keeping the work environment dry. When piers are being built using an open caisson, and it is not practical to reach suitable soil, friction pilings may be driven to form a suitable sub-foundation. These piles are connected by a foundation pad upon which the column pier is erected.

Tube (structure) system to resist lateral loads in structural engineering

In structural engineering, the tube is a system where, to resist lateral loads, a building is designed to act like a hollow cylinder, cantilevered perpendicular to the ground. This system was introduced by Fazlur Rahman Khan while at the architectural firm Skidmore, Owings & Merrill (SOM), in their Chicago office. The first example of the tube’s use is the 43-story Khan-designed DeWitt-Chestnut Apartment Building, since renamed Plaza on DeWitt, in Chicago, Illinois, finished in 1966.

A shipping and receiving ramp, which served the entire World Trade Center complex, occupied the eastern quarter of the 7 World Trade Center footprint. The building was open below the 3rd floor, providing space for truck clearance on the shipping ramp. [15] The spray-on fireproofing for structural steel elements was gypsum-based Monokote, which had a two-hour fire rating for steel beams, girders and trusses, and a three-hour rating for columns. [5] :11

Mechanical equipment was installed on floors four through seven, including 12  transformers on the 5th floor. Several emergency generators installed in the building were used by the New York City Office of Emergency Management, Salomon Smith Barney, and other tenants. [5] :13 In order to supply the generators, 24,000 gallons (91,000 L) of diesel fuel were stored below ground level. [17] Diesel fuel distribution components were located at ground level, up to the ninth floor. [18] :35 After the World Trade Center bombings of February 26, 1993, New York City mayor Rudy Giuliani decided to situate the emergency command center and associated fuel tanks at 7 World Trade Center. Although this decision was criticized in light of the events of 9/11, the fuel in the building is today not believed to have contributed to the collapse of the building. [19] [20] :2 The roof of the building included a small west penthouse and a larger east mechanical penthouse. [14]

Each floor had 47,000 sq ft (4,400 m2) of rentable office space, which made the building's floor plans considerably larger than most office buildings in the City. [21] In all, 7 World Trade Center had 1,868,000 sq ft (173,500 m2) of office space. [5] :1 Two pedestrian bridges connected the main World Trade Center complex, across Vesey Street, to the third floor of 7 World Trade Center. The lobby of 7 World Trade Center held three murals by artist Al Held: The Third Circle, Pan North XII, and Vorces VII. [22]

Tenants

The position of building 7 in relation to the other WTC buildings before September 11, 2001 WTC Building Arrangement and Site Plan (building 7 highlighted).jpg
The position of building 7 in relation to the other WTC buildings before September 11, 2001

In June 1986, before construction was completed, developer Larry Silverstein signed Drexel Burnham Lambert as a tenant to lease the entire 7 World Trade Center building for $3 billion over a term of 30 years. [23] In December 1986, after the Boesky insider-trading scandal, Drexel Burnham Lambert canceled the lease, leaving Silverstein to find other tenants. [24] Spicer & Oppenheim agreed to lease 14 percent of the space, but for more than a year, as Black Monday and other factors adversely affected the Lower Manhattan real estate market, Silverstein was unable to find tenants for the remaining space. By April 1988, he had lowered the rent and made other concessions. [25]

In November 1988, Salomon Brothers withdrew from plans to build a large new complex at Columbus Circle in Midtown, and agreed to a 20-year lease for the top 19 floors of 7 World Trade Center. [26] The building was extensively renovated in 1989 to accommodate the needs of Salomon Brothers. This led to the alternative naming of the building as the Salomon Brothers building. [27] Most of three existing floors were removed as tenants continued to occupy other floors, and more than 350 tons (U.S.) of steel were added to construct three double-height trading floors. Nine diesel generators were installed on the 5th floor as part of a backup power station. "Essentially, Salomon is constructing a building within a building – and it's an occupied building, which complicates the situation", said a district manager of Silverstein Properties. The unusual task was possible, said Larry Silverstein, because it was designed to allow for "entire portions of floors to be removed without affecting the building's structural integrity, on the assumption that someone might need double-height floors." [27]

At the time of the September 11, 2001, attacks, Salomon Smith Barney was by far the largest tenant in 7 World Trade Center, occupying 1,202,900 sq ft (111,750 m2) (64 percent of the building) which included floors 28–45. [5] :2 [28] Other major tenants included ITT Hartford Insurance Group (122,590 sq ft/11,400 m2), American Express Bank International (106,117 sq ft/9,900 m2), Standard Chartered Bank (111,398 sq ft/10,350 m2), and the Securities and Exchange Commission (106,117 sq ft/9,850 m2). [28] Smaller tenants included the Internal Revenue Service Regional Council (90,430 sq ft/8,400 m2) and the United States Secret Service (85,343 sq ft/7,900 m2). [28] The smallest tenants included the New York City Office of Emergency Management, [29] National Association of Insurance Commissioners, Federal Home Loan Bank, First State Management Group Inc., Provident Financial Management, and the Immigration and Naturalization Service. [28] The Department of Defense (DOD) and Central Intelligence Agency (CIA) shared the 25th floor with the IRS. [5] :2 (The clandestine CIA office was revealed only after the 9/11 attacks.) [30] Floors 46–47 were mechanical floors, as were the bottom six floors and part of the seventh floor. [5] :2 [30]

9/11 and collapse

7 World Trade Center on fire after the collapse of the Twin Towers on 9/11 Wtc7onfire.jpg
7 World Trade Center on fire after the collapse of the Twin Towers on 9/11

Collapse

As the North Tower collapsed on September 11, 2001, heavy debris hit 7 World Trade Center, damaging the south face of the building [31] :18 (PDF p. 22) and starting fires that continued to burn throughout the afternoon. [6] :16, 18 The collapse also caused damage to the southwest corner between floors 7 and 17 and on the south face between Floor 44 and the roof; other possible structural damage included a large vertical gash near the center of the south face between Floors 24 and 41. [6] :17 The building was equipped with a sprinkler system, but had many single-point vulnerabilities for failure: the sprinkler system required manual initiation of the electrical fire pumps, rather than being a fully automatic system; the floor-level controls had a single connection to the sprinkler water riser, and the sprinkler system required some power for the fire pump to deliver water. [32] :11 Additionally, water pressure was low, with little or no water to feed sprinklers. [33] :23–30

After the North Tower collapsed, some firefighters entered 7 World Trade Center to search the building. They attempted to extinguish small pockets of fire, but low water pressure hindered their efforts. [34] Over the course of the day, fires burned out of control on several floors of 7 World Trade Center, the flames visible on the east side of the building. [35] During the afternoon, the fire was also seen on floors 6–10, 13–14, 19–22, and 29–30. [31] :24 (PDF p. 28) In particular, the fires on floors 7 through 9 and 11 through 13 continued to burn out of control during the afternoon. [7] At approximately 2:00 pm, firefighters noticed a bulge in the southwest corner of 7 World Trade Center between the 10th and 13th floors, a sign that the building was unstable and might collapse. [36] During the afternoon, firefighters also heard creaking sounds coming from the building. [37] Around 3:30 pm, FDNY Chief Daniel A. Nigro decided to halt rescue operations, surface removal, and searches along the surface of the debris near 7 World Trade Center and evacuate the area due to concerns for the safety of personnel. [38] The fire expanded the girders of the building, causing some to lose their structural integrity. This led column number 79, a critical column supporting a large part of the 13th floor, to buckle, causing the floors above it to collapse to the fifth floor; however, this could not be seen from outside the building. The structure also developed cracks in the facade just before the entire building started to fall. [6] :21 [39] According to FEMA, this collapse started at 5:20:33 pm EDT when the east mechanical penthouse started crumbling. [5] :23 [40] Differing times are given as to what time the building completely collapsed: [40] at 5:21:10 pm EDT according to FEMA, [5] :23 and at 5:20:52 pm EDT according to NIST. [6] :19, 21, 50–51 There were no casualties associated with the collapse. [39] NIST found no evidence to support conspiracy theories such as the collapse being the result of explosives; it found that a combination of factors including physical damage, fire, and the building's unusual construction set off a chain-reaction collapse. [41]

Reports

Schematic view of collapse progression, with structural failure initiating on lower floors, on the east side of the building and vertical progression up to the east mechanical penthouse Wtc7 collapse progression.png
Schematic view of collapse progression, with structural failure initiating on lower floors, on the east side of the building and vertical progression up to the east mechanical penthouse

In May 2002, the Federal Emergency Management Agency (FEMA) issued a report on the collapse based on a preliminary investigation conducted jointly with the Structural Engineering Institute of the American Society of Civil Engineers under the leadership of Dr. W. Gene Corley, P.E. FEMA made preliminary findings that the collapse was not primarily caused by actual impact damage from the collapse of 1 WTC and 2 WTC but by fires on multiple stories ignited by debris from the other two towers that continued burning unabated due to lack of water for sprinklers or manual firefighting. The report did not reach conclusions about the cause of the collapse and called for further investigation. [20] :3

Subsequently, the National Institute of Standards and Technology (NIST) was authorized to lead an investigation into the structural failure and collapse of the World Trade Center Twin Towers and 7 World Trade Center. [7] The investigation, led by Dr S. Shyam Sunder, drew upon in-house technical expertise as well as the knowledge of several outside private institutions, including the Structural Engineering Institute of the American Society of Civil Engineers (SEI/ASCE); the Society of Fire Protection Engineers (SFPE); the National Fire Protection Association (NFPA); the American Institute of Steel Construction (AISC); the Council on Tall Buildings and Urban Habitat (CTBUH); and the Structural Engineers Association of New York (SEAoNY). [42]

Few photos and video clips exist that show the damage sustained to the south face of 7 World Trade Center on 9/11. An ABC News helicopter captured footage of the south face of 7 World Trade Center, including a glimpse of a gash, extending approximately 10 stories. Abcnews-wtc7damage.jpg
Few photos and video clips exist that show the damage sustained to the south face of 7 World Trade Center on 9/11. An ABC News helicopter captured footage of the south face of 7 World Trade Center, including a glimpse of a gash, extending approximately 10 stories.

The bulk of the investigation of 7 World Trade Center was delayed until after reports were completed on the Twin Towers. [7] In the meantime, NIST provided a preliminary report about 7 WTC in June 2004, and thereafter released occasional updates on the investigation. [31] According to NIST, the investigation of 7 World Trade Center was delayed for a number of reasons, including that NIST staff who had been working on 7 World Trade Center were assigned full-time from June 2004 to September 2005 to work on the investigation of the collapse of the Twin Towers. [43] In June 2007, Shyam Sunder explained,

We are proceeding as quickly as possible while rigorously testing and evaluating a wide range of scenarios to reach the most definitive conclusion possible. The 7 WTC investigation is in some respects just as challenging, if not more so than the study of the towers. However, the current study does benefit greatly from the significant technological advances achieved and lessons learned from our work on the towers. [44]

BMCC's Fiterman Hall was heavily damaged from the collapse of 7 World Trade Center. Fiterman hall damage.jpg
BMCC's Fiterman Hall was heavily damaged from the collapse of 7 World Trade Center.

In November 2008, NIST released its final report on the causes of the collapse of 7 World Trade Center. [6] This followed NIST's August 21, 2008, draft report which included a period for public comments, [7] and was followed in 2012 by a peer-reviewed summary in the Journal of Structural Engineering . [45] In its investigation, NIST utilized ANSYS to model events leading up to collapse initiation and LS-DYNA models to simulate the global response to the initiating events. [46] :6–7 NIST determined that diesel fuel did not play an important role, nor did the structural damage from the collapse of the Twin Towers or the transfer elements (trusses, girders, and cantilever overhangs). The lack of water to fight the fire was an important factor. The fires burned out of control during the afternoon, causing floor beams near column 79 to expand and push a key girder off its seat, triggering the floors to fail around column 79 on Floors 8 to 14. With a loss of lateral support across nine floors, column 79 buckled – pulling the east penthouse and nearby columns down with it. With the buckling of these critical columns, the collapse then progressed east-to-west across the core, ultimately overloading the perimeter support, which buckled between Floors 7 and 17, causing the remaining portion of the building above to fall down as a single unit. The fires, which were fueled by office contents and burned for 7 hours, along with the lack of water, were the key reasons for the collapse. [6] :21–22 Incidentally, this made the old 7 WTC the only steel skyscraper at the time to have collapsed from fire. [8]

When 7 WTC collapsed, debris caused substantial damage and contamination to the Borough of Manhattan Community College's Fiterman Hall building, located adjacent at 30 West Broadway, to the extent that the building was not salvageable. [47] A revised plan called for demolition in 2009 and completion of the new Fiterman Hall in 2012, at a cost of $325 million. [48] The adjacent Verizon Building, an art deco building constructed in 1926, had extensive damage to its east facade from the collapse of 7 World Trade Center, though it was able to be restored at a cost of US$1.4 billion. [49]

Aerial view of WTC remains and neighboring buildings after 9/11, with the original footprints of the Twin Towers and 7 WTC outlined WTC Area With Building Numbers 50dpi contrast.jpg
Aerial view of WTC remains and neighboring buildings after 9/11, with the original footprints of the Twin Towers and 7 WTC outlined

Files relating to numerous federal investigations had been housed in 7 World Trade Center. The Equal Employment Opportunity Commission estimated over 10,000 of its cases were affected. [50] Investigative files in the Secret Service's largest field office were lost, with one Secret Service agent saying, "All the evidence that we stored at 7 World Trade, in all our cases, went down with the building." [51] Copies of emails in connection with the WorldCom scandal that were later requested by the SEC from Salomon Brothers, a subsidiary of Citigroup housed in the building, were also destroyed. [52]

The NIST report found no evidence supporting the conspiracy theories that 7 World Trade Center was brought down by controlled demolition. Specifically, the window breakage pattern and blast sounds that would have resulted from the use of explosives were not observed. [6] :26–28 The suggestion that an incendiary material such as thermite was used instead of explosives was considered unlikely by NIST because of observations of the fire and the building's structural response to the fire, and because it is unlikely the necessary quantity of material could have been planted without discovery. [7] Based on its investigation, NIST reiterated several recommendations it had made in its earlier report on the collapse of the Twin Towers. [6] :63–73 It urged immediate action on a further recommendation: that fire resistance should be evaluated under the assumption that sprinklers are unavailable; [6] :65–66 and that the effects of thermal expansion on floor support systems be considered. [6] :65, 69 Recognizing that current building codes are drawn to prevent loss of life rather than building collapse, the main point of NIST's recommendations was that buildings should not collapse from fire even if sprinklers are unavailable. [6] :63–73

New building

Preliminary site plans for the World Trade Center rebuild WTC Building Arrangement in preliminary site plan.svg
Preliminary site plans for the World Trade Center rebuild
The new 7 World Trade Center from the ground Wtc7-lookingup.jpg
The new 7 World Trade Center from the ground

The new 7 World Trade Center has 52 stories and is 741 ft (226 m) tall. [53] The building has 42 floors of leasable space, starting at the 11th floor, and a total of 1,700,000 sq ft (160,000 m2) of office space. [54] The first ten floors house an electrical substation which provides power to much of Lower Manhattan. The office tower has a narrower footprint at ground level than did its predecessor, so the course of Greenwich Street could be restored to reunite TriBeCa and the Financial District. The original building, on the other hand, had bordered West Broadway on the east, necessitating the destruction of Greenwich Street between Barclay Street and the northern border of the World Trade Center superblock. [55]

Design

David Childs of Skidmore, Owings and Merrill worked in conjunction with glass artist and designer James Carpenter to create a design that uses ultra-clear, low-iron glass to provide reflectivity and light, with stainless-steel spandrels behind the glass to help reflect sunlight. [56] Stainless steel used in the building façade is molybdenum-containing Type 316, which provides improved resistance to corrosion. [57] To enclose the power substation and improve its aesthetics, the base of the building has a curtain wall with stainless steel louvers that provide ventilation for the machinery. [58] During the day, the curtain wall reflects light, while at night it is illuminated with blue LED lights. [59] The curtain wall around the lobby uses heavily laminated, heat-strengthened glass that meets high standards for blast resistance. [60] At night, a large cube of light above the lobby also emanates blue light, while during the day it provides white light to the lobby, and at dusk it transitions to violet and back to blue. [61] Inside the main lobby, artist Jenny Holzer created a large light installation with glowing text moving across wide plastic panels. [56] The entire wall, which is 65 ft (20 m) wide and 14 ft (4.3 m) tall, changes color according to the time of day. Holzer worked with Klara Silverstein, the wife of Larry Silverstein, to select poetry for the art installation. The wall is structurally fortified as a security measure. [62]

The building is being promoted as the safest skyscraper in the U.S. [63] According to Silverstein Properties, the owner of the building, it "incorporate[s] a host of life-safety enhancements that will become the prototype for new high-rise construction." [64] The building has 2-foot-thick (0.61 m) reinforced-concrete and fireproofed elevator and stairway access shafts. The original building used only drywall to line these shafts. [65] The stairways are wider than in the original building to permit faster egress. [65]

7 World Trade Center is equipped with Otis destination elevators. [66] After pressing a destination floor number on a lobby keypad, passengers are grouped and directed to specific elevators that will stop at the selected floor (there are no buttons to press inside the elevators). This system is designed to reduce elevator waiting and travel times. The elevator system is integrated with the lobby turnstile and card reader system that identifies the floor on which a person works as he or she enters and can automatically call the elevator for that floor. [67]

Nearly 30 percent of structural steel used in the building consists of recycled steel. [68] Rainwater is collected and used for irrigation of the park and to cool the building. [56] Along with other sustainable design features, the building is designed to allow in plenty of natural light, power is metered to tenants to encourage them to conserve energy, the heating steam is reused to generate some power for the building, and recycled materials are used for insulation and interior materials. [69]

Construction

7 World Trade Center construction in October 2004 Construction 7wtc.jpg
7 World Trade Center construction in October 2004

The construction phase of the new 7 World Trade Center began on May 7, 2002, with the installation of a fence around the construction site. [1] Tishman Construction Corporation of New York began work at the new 7 World Trade Center in 2002, soon after the site was cleared of debris. Restoring the Con Ed electrical substation was an urgent priority to meet power demands of Lower Manhattan. [55] Because 7 World Trade Center is separate from the main 16-acre (6.5 ha) World Trade Center site, Larry Silverstein required approval from only the Port Authority, and rebuilding was able to proceed quickly. [70] Building Seven was not included in the original World Trade Center master plan by Daniel Libeskind, but was designed by Skidmore, Owings & Merrill under the leadership of David Childs, who largely redesigned One World Trade Center.

Once construction of the power substation was completed in October 2003, work proceeded on building the office tower. An unusual approach was used in constructing the building; erecting the steel frame before adding the concrete core. This approach allowed the construction schedule to be shortened by a few months. [71] Construction was completed in 2006 at a cost of $700 million. [56] Though Silverstein received $861 million from insurance on the old building, he owed more than $400 million on its mortgage. [72] Costs to rebuild were covered by $475 million in Liberty Bonds, which provide tax-exempt financing to help stimulate rebuilding in Lower Manhattan and insurance money that remained after other expenses. [73]

A 15,000 sq ft (1,400 m2) triangular park was created between the extended Greenwich Street and West Broadway by David Childs with Ken Smith and his colleague, Annie Weinmayr, of Ken Smith Landscape Architect. The park comprises an open central plaza with a fountain and flanking groves of sweetgum trees and boxwood shrubs. [74] At the center of the fountain, sculptor Jeff Koons created Balloon Flower (Red), whose mirror-polished stainless steel represents a twisted balloon in the shape of a flower. [75]

Opening

The building was officially opened at noon on May 23, 2006, with a free concert featuring Suzanne Vega, Citizen Cope, Bill Ware Vibes, Brazilian Girls, Ollabelle, Pharaoh's Daughter, Ronan Tynan (of the Irish Tenors), and special guest Lou Reed. [76] [77] Prior to opening, in March 2006, the new 7 World Trade Center frontage and lobby were used in scenes for the movie Perfect Stranger with Halle Berry and Bruce Willis. [78]

Since the building opened, several unleased upper floors have been used for events such as charity lunches, fashion shows, and black-tie galas. Silverstein Properties allowed space in the new building to be used for these events as a means to draw people to see the building. [79] From September 8 to October 7, 2006, the work of photographer Jonathan Hyman was displayed in "An American Landscape", a free exhibit hosted by the World Trade Center Memorial Foundation at 7 World Trade Center. The photographs captured the response of people in New York City and across the United States after the September 11, 2001, attacks. The exhibit took place on the 45th floor while space remained available for lease. [80]

New York Academy of Sciences office (lobby) on the 40th floor Nyas lobby wtc7.jpg
New York Academy of Sciences office (lobby) on the 40th floor

By March 2007, 60 percent of the building had been leased. [81] In September 2006, Moody's signed a 20-year lease to rent 15 floors of 7 World Trade Center. [82] Other tenants that had signed leases in 7 World Trade Center, as of May 2007, included ABN AMRO, [83] Ameriprise Financial Inc., [84] [77] law firm WilmerHale, Darby & Darby P.C., [85] Mansueto Ventures LLC, business publisher of Fast Company and Inc., [86] and the New York Academy of Sciences. [87] [77]

The space occupied by Mansueto Ventures has been designed to use the maximum amount of natural light and has an open floor plan. [88] The space used by the New York Academy of Sciences on the 40th floor, designed by H3 Hardy Collaboration Architecture, works with the parallelogram shape of the building. Keeping with the green design of the building, the NYAS uses recycled materials in many of the office furnishings, has zoned heating and cooling, and lights that detect motion, coming on automatically only when people are present, and adjust according to incoming sunlight. [89]

Silverstein Properties also has offices and the Silver Suites executive office suites [90] in 7 World Trade Center, along with office space used by the architectural and engineering firms working on 1 World Trade Center, 150 Greenwich Street, 175 Greenwich Street, and 200 Greenwich Street. [91] The building became fully leased in September 2011 when MSCI was reported to have leased a 125,000 square feet (11,600 m2) space on the top floor. [92]

See also

Related Research Articles

Larry Silverstein American businessman

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Marriott World Trade Center architectural structure

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One World Trade Center is the main building of the rebuilt World Trade Center complex in Lower Manhattan, New York City. One WTC is the tallest building in the United States, the tallest building in the Western Hemisphere, and the sixth-tallest in the world. The supertall structure has the same name as the North Tower of the original World Trade Center, which was destroyed in the terrorist attacks of September 11, 2001. The new skyscraper stands on the northwest corner of the 16-acre (6.5 ha) World Trade Center site, on the site of the original 6 World Trade Center. The building is bounded by West Street to the west, Vesey Street to the north, Fulton Street to the south, and Washington Street to the east.

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The construction of the first World Trade Center complex in New York City was conceived as an urban renewal project to help revitalize Lower Manhattan spearheaded by David Rockefeller. The project was developed by the Port Authority of New York and New Jersey. The idea for the World Trade Center arose after World War II as a way to supplement existing avenues of international commerce in the United States.

5 World Trade Center Proposed skyscraper in Manhattan, New York

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3 World Trade Center Office skyscraper in Manhattan, New York

3 World Trade Center is a skyscraper constructed as part of the rebuilding of the World Trade Center in Lower Manhattan, New York City. The tower is located on the east side of Greenwich Street, on the eastern side of the World Trade Center site.

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Architects & Engineers for 9/11 Truth (AE911Truth) is an American non-profit organization promoting a controlled demolition conspiracy theory, disputing accepted conclusions around the September 11 attacks, including the 9/11 Commission Report, as well as FEMA's "WTC Building Performance Study" (2002).

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2 World Trade Center is a skyscraper under construction as part of the World Trade Center complex in Manhattan, New York City. It will replace the original 2 World Trade Center, which was completed in 1972, and subsequently destroyed during the September 11 attacks in 2001, and it will occupy the position of the original 5 World Trade Center. The foundation work was completed in 2013.

World Trade Center (1973–2001) Former skyscraper complex in Manhattan, New York

The original World Trade Center was a large complex of seven buildings in the Financial District of Lower Manhattan, New York City, United States. 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, at 1,368 feet (417 m); and 2 World Trade Center, 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, 4 WTC, 5 WTC, 6 WTC, and 7 WTC. The complex contained 13,400,000 square feet (1,240,000 m2) of office space.

World Trade Center (2001–present) Skyscraper complex in Manhattan, New York

The World Trade Center is a mostly completed complex of buildings in Lower Manhattan, New York City, U.S., replacing the original seven buildings on the same site that were destroyed in the September 11 attacks. The site is being rebuilt with up to six new skyscrapers, four of which have been completed; a memorial and museum to those killed in the attacks; the elevated Liberty Park adjacent to the site, containing the St. Nicholas Greek Orthodox Church and Vehicular Security Center; and a transportation hub. The 104-story One World Trade Center, the tallest building in the Western Hemisphere, is the lead building for the new complex.

The National Construction Safety Team Act, signed into law on October 1, 2002 by President George W. Bush, mandated the National Institute of Standards and Technology (NIST) to establish the likely technical cause or causes of the three building failures that occurred on September 11, 2001 at the World Trade Center as a result of a terrorist attack. NIST issued its final report on the collapse of the World Trade Center Twin Towers in September 2005. It issued its final report on 7 World Trade Center in November 2008.

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