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2 World Trade Center (1971–2001)

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For other uses of "South Tower", see South Tower (disambiguation).
2 World Trade Center
The World Trade Center's South Tower (WTC2), pictured in summer of 2001
Map
Alternative names
  • 2 WTC
  • South Tower
  • WTC 2
  • Building B
  • Building 2
  • Tower B
  • Tower 2
General information
StatusDestroyed
LocationLiberty Street, New York, NY 10048, United States
Construction startedJanuary 1969
Topped-outJuly 19, 1971[1]
Completed1973
OpenedSeptember 1971[1]
InauguratedApril 4, 1973
DestroyedSeptember 11, 2001, 9:59 a.m. Eastern Time Zone[a]
OwnerPort Authority of New York and New Jersey
ManagementSilverstein Properties
Height
Roof1,362 ft (415 m)
Observatory1,377 ft (420 m)[2]
Technical details
Floor count110
Floor area4,759,040 sq ft (442,129 m2)
Lifts/elevators99
Design and construction
Architect(s)
Structural engineerLeslie E. Robertson (Worthington, Skilling, Helle, and Jackson)

The original Two World Trade Center (also known as the South Tower, Tower 2, Building Two, or 2 WTC) was one of the Twin Towers in the original World Trade Center Complex in New York City. The Tower was completed and opened in 1973 at a height of 1,362 feet (415 m) to the roof, distinguishable from its twin, the North Tower (1 World Trade Center), by the absence of a television antenna. On the 107th floor of this building was a popular tourist attraction called "Top of the World Trade Center Observatories," and on the roof was an outdoor observation deck accessible to the public and a disused helipad at the center. The address of this building was 2 World Trade Center, with the WTC complex having its own ZIP code of 10048.

The South Tower was destroyed along with the North Tower in the September 11 attacks. At 9:03 a.m,[b] seventeen minutes after its twin was hit, the South Tower was struck by United Airlines Flight 175. Although it was the second of the two skyscrapers to be hit by a hijacked airliner, it was the first to collapse, at 9:59 a.m.,[c] after burning for 56 minutes. Of the 2,977 victims killed in the attacks, around 1,000 were in the South Tower or on the ground.

The new 2 World Trade Center, which is currently on hold, is planned to have a diagonally-pointed roof, with no observation deck, and no mechanical floors. At the National September 11 Memorial & Museum, the southern pool marks the spot where the South Tower stood.

History

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Development

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In 1961, the Port Authority of New York and New Jersey agreed to build the World Trade Center on the site of the Hudson Terminal in Lower Manhattan, New York City.[9] On September 20, 1962, the Port Authority announced the selection of Minoru Yamasaki as lead architect and Emery Roth & Sons as associate architects.[10] Yamasaki devised the plan to incorporate twin towers. His original plan called for the towers to be 80 stories tall,[11] 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.[12] 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.[11][13]

In March 1965, the Port Authority began acquiring property at the World Trade Center site.[14] Demolition work began on March 21, 1966,[15] and groundbreaking for the construction of the World Trade Center took place on August 5, 1966.[16] In January 1967, the Port Authority awarded $74 million in contracts to various steel suppliers.[17] Construction on the South Tower was under way by January 1969.[18] The topping out ceremony for 2 WTC (the South Tower) occurred on July 19, 1971.[18] The South Tower began accepting tenants in January 1972,[19] and a ribbon cutting ceremony took place on April 4, 1973.[20]

Operation

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In 1981, the Port Authority announced a $45 million plan to install sprinklers throughout the World Trade Center, following a major fire that occurred at the North Tower in 1975.[21]

On February 26, 1993, a Ryder truck filled with 1,500 pounds (680 kg) of explosives (planted by Ramzi Yousef) detonated in the North Tower's underground garage.[22] According to a presiding judge, the conspirators' chief aim at the time of the attack was to destabilize the North Tower and send it crashing into the South Tower, toppling both skyscrapers.[23] Six people were killed and 1,042 others were injured in the attacks.[24][25]

In February 2001, the Port Authority leased the entire World Trade Center complex to Vornado Realty Trust.[26] However, Vornado insisted on last minute changes to the deal,[27] and the next-highest bidder, Silverstein Properties, signed a lease for the complex on July 24, 2001.[28]

September 11 attacks

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United Airlines Flight 175 hits 2 World Trade Center in the September 11 attacks

At 9:03 a.m. EDT on September 11, 2001, five terrorists crashed United Airlines Flight 175 into the southern face of the South Tower.[29][30] Three buildings in the World Trade Center complex, including 2 WTC, collapsed due to fire-induced structural failure.[31] The light construction and hollow nature of the structures allowed the jet fuel to penetrate far inside the towers, igniting many large fires simultaneously over a wide area of the impacted floors. The fuel from the planes burned at most for a few minutes, but the contents of the buildings burned over the next hour to hour and a half.[32]

The fires might not have been as centrally positioned, nor as intense, had traditionally heavy high-rise construction been standing in the way of the aircraft. Debris and fuel would likely have remained mostly outside the buildings or concentrated in more peripheral areas away from the building cores, which would then not have become unique failure points. In this scenario, the towers might have stood far longer, perhaps indefinitely.[33][34] The fires were hot enough to weaken the columns and cause floors to sag, pulling perimeter columns inward and reducing their ability to support the mass of the building above.[35] The South Tower collapsed at 9:59 a.m. after burning for 56 minutes in the fire caused by the impact of United Airlines Flight 175 and the explosion of its fuel.[31]

Architecture

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Minoru Yamasaki was the lead architect for the tower, and Emery Roth & Sons were the associate architects.[10] During the World Trade Center's construction, the structural engineers ended up following draft versions of New York City's 1968 building codes, which incorporated "advanced techniques" in building design.[36] The Twin Towers used a tube-frame design, which required 40 percent less structural steel than conventional building designs.[37] The structures were inspired by the architectural ethic of Le Corbusier and was the seminal expression of Yamasaki's gothic modernist tendencies.[38] Yamasaki was also inspired by Islamic architecture, elements of which he incorporated in the buildings' design, having previously designed Saudi Arabia's Dhahran International Airport with the Saudi Binladin Group.[39][40]

When completed in 1973, the South Tower became the second tallest building in the world at 1,362 feet (415 m), behind the North Tower. Its rooftop observation deck was 1,362 ft (415 m) high and its indoor observation deck was 1,310 ft (400 m) high.[41] Each tower stood over 1,350 feet (410 m) high, and occupied about 1 acre (4,000 m2) of the total 16 acres (65,000 m2) of the site's land.[42]

Facade

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The Twin Towers' facades were made of high-strength, load-bearing perimeter steel columns which acted as Vierendeel trusses.[43][44] Although the columns themselves were lightweight, they were spaced closely together, forming a strong, rigid wall structure.[45][46] There were 59 perimeter columns, narrowly spaced, on each side of the building.[47][44] In all, the perimeter walls measured 210 feet (64 m) long on each side, and the corners were beveled..[48][46] The perimeter structure was constructed of prefabricated modular pieces connected by spandrel plates.[46] From the 7th floor to the ground level, and down to the foundation, the columns were spaced 10 feet (3.0 m) apart to accommodate doorways.[49][44] All columns were placed on bedrock 65–85 feet (20–26 m) below the surface.[50]

Structural features

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Further information: Construction of the World Trade Center § Design of the towers

The building's core 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.[51] The South Tower's structural core was oriented with the long axis north to south.[52] The core columns supported about half the towers' weight.[52] All elevators were located in the core. Each building had three stairwells, also in the core, except on the mechanical floors.[47] The large, column-free space between the perimeter and core was bridged by prefabricated floor trusses, which connected to the perimeter columns.[53]

Hat trusses (or "outrigger truss") located from the 107th floor to the top of the North and South towers were designed to support a tall communication antenna on top of each building.[53] The South Tower never had an antenna fitted.[54] 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.[55] In designing the World Trade Center, Leslie Robertson considered the scenario of the impact of a jet airliner crashing into the building.[56] The National Institute of Standards and Technology (NIST) found a three-page white paper that mentioned another aircraft impact analysis, involving impact of a jet at 600 mph (970 km/h), was indeed considered, but NIST could not locate the documentary evidence of the aircraft impact analysis.[57]

Sprayed-fire resistant materials (SFRMs), gypsum wallboard, and vermiculite were used to provide fireproofing to the interiors.[47] More fireproofing was added after a fire in February 1975,[58] but after the 1993 bombing, inspections found fireproofing to be deficient.[59] The 1968 New York City building codes did not require sprinklers for high-rise buildings, except for underground spaces,[60] but the entire complex was retrofitted by 2001.[61]

Tenants

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Note: Floor numbers in  red  are part of United Airlines Flight 175's impact area during the September 11 attacks, with floors above this zone marked in  dark gray .

Floor # Companies Business
R Outdoor Observatory Tourism
109 Mechanical floor
108 Mechanical floor
107 Showtime Pictures, Top of the World Trade Center Observatories (Indoor Observatory), Sbarro Street Station, Nathan's Famous Hot Dogs, Manhattan Magic, Kodak Business services, Tourism, Food, Entertainment
106 Atlantic Bank of New York Banks/Financial
105 AON Corporation Insurance
104 AON Corporation, Sandler O'Neill and Partners Insurance, Investment
103 AON Corporation Insurance
102 AON Corporation Insurance
101 AON Corporation Insurance
100 AON Corporation Insurance
99 AON Corporation Insurance
98 AON Corporation Insurance
97 Fiduciary Trust Company International Banks/Financial
96 Fiduciary Trust Company International Banks/Financial
95 Fiduciary Trust Company International Banks/Financial
94 Fiduciary Trust Company International Banks/Financial
93 AON Corporation, Regus Business Centers Insurance, Co-working
92 AON Corporation Insurance
91 Gibbs & Hill, Raytheon Company, Washington Group International Engineers, Manufacturing
90 Fiduciary Trust Company International Banks/Financial
89 Keefe, Bruyette & Woods Investment
88 Keefe, Bruyette & Woods Investment
87 New York State Department of Taxation and Finance, Corporation Service Company Government, Financial
86 New York State Department of Taxation and Finance Government
85 Harris Beach & Wilcox Attorneys
84 Euro Brokers Financial
83 IQ Financial Systems, Chuo Mitsui Trust & Banking Financial
82 Fuji Bank Banks/Financial
81 Fuji Bank Banks/Financial
80 Fuji Bank Banks/Financial
79 Fuji Bank Banks/Financial
78 Skylobby, First Commercial Bank, Baseline Financial Services Banks/Financial, Financial
77 Baseline Financial Services Financial
76 Mechanical floor
75 Mechanical floor
74 Morgan Stanley Investment
73 Morgan Stanley Investment
72 Morgan Stanley Investment
71 Morgan Stanley Investment
70 Morgan Stanley Investment
69 Morgan Stanley Investment
68 Morgan Stanley Investment
67 Morgan Stanley Investment
66 Morgan Stanley Investment
65 Morgan Stanley Investment
64 Morgan Stanley Investment
63 Morgan Stanley Investment
62 Morgan Stanley, Demeter Management Corporation Investment, Not available
61 Morgan Stanley Investment
60 Morgan Stanley Investment
59 Morgan Stanley Investment
58 Bridge Information Systems Financial Information Provider
57 Hold Brothers[62] Financial
56 Morgan Stanley Investment
55 Guy Carpenter, Garban Intercapital, Harlows Reinsurance, Investment, Not available
54 Guy Carpenter Reinsurance
53 Guy Carpenter Reinsurance
52 Guy Carpenter Reinsurance
51 Guy Carpenter Reinsurance
50 Guy Carpenter Reinsurance
49 Guy Carpenter, Seabury & Smith Reinsurance, Insurance
48 Fireman's Fund Insurance Company, Guy Carpenter Insurance, Reinsurance
47 Guy Carpenter Reinsurance
46 Morgan Stanley Investment
45 Morgan Stanley Investment
44 Skylobby, Morgan Stanley Investment
43 Morgan Stanley Investment
42 Mechanical floor
41 Mechanical floor
40 Sitailong International USA, Thacher Proffitt & Wood, LLP Not available, Attorneys
39 Thacher Proffitt & Wood, LLP Attorneys
38 Thacher Proffitt & Wood, LLP Attorneys
37 — —
36 Frenkel and Company Insurance
35 Frenkel and Company Insurance
34 OppenheimerFunds Investment
33 OppenheimerFunds Investment
32 OppenheimerFunds, Commerzbank Capital Markets Investment, Financial
31 OppenheimerFunds Investment
30 New York Stock Exchange, Hartford Steam Boiler Financial, Insurance
29 Weatherly Securities Corporation, New York Stock Exchange Investment, Financial
28 New York Stock Exchange, Inc., Big A Travel Agency, Law Office Of Joseph Bellard, Hua Nan Commercial Bank Ltd. Financial, Transportation, Law Firms, Financial Institutions
27 — —
26 Sun Microsystems Computer services
25 Sun Microsystems Computer services
24 Allstate Insurance Company, China Chamber of Commerce, Globe Tour and Travel, SCOR U.S. Corporation, Sinolion, TD Ameritrade Insurance, Organizations, Travel, Insurance, Not available, Investment
23 SCOR U.S. Corporation, Unistrat Corporation of America Insurance, Consultants
22 Antal International, Mancini Duffy, NYS Retirement System Not available
21 Adecco SA, Career Engine, Mancini Duffy, Matthews & Wright Inc., Taiwan Sugar Corporation Employment agency, Research, Architects, Not available
20 Thacher Proffitt & Wood, LLP, New York Shipping Association Attorneys, Transportation
19 New York Shipping Association, Waterfront Commission of New York Harbor Transportation, Not available
18 AbraCadabra Digital Printing, Alliance Consulting Group, Weiland International Inc. Business Services, Not available
17 New York Institute of Finance Banks/Financial
16 National Development and Research Institute Research
15 Candia Shipping, Orient International(South Korean investment company,later merged with Yuanta Securities) CINDE Costa Rican Investment Board, DigiOrbit Corporation, Millennium Management Resources Inc., Optech Systems Inc., Stallion Commerce Corporation, TD Ameritrade Not available, Investment, Not available, Banks/Financial
14 Charna Chemicals, Paging Network of New York, Patinka International (USA), Union Bank of California Manufacturing, Telecommunication, Business services, Banks/Financial
13 Verizon Communications Telecommunication
12 Verizon Communications Telecommunication
11 Verizon Communications, Candia Shipping Telecommunication, Shipping
10 Verizon Communications Telecommunication
9 Verizon Communications Telecommunication
8 Mechanical floor
7 Mechanical floor
6 — —
5 — —
4 — —
3 — —
2 TKTS Ticket booth
1 Colortek Kodak Imaging Center Business services
L Nichols Foundation Government/Schools
C The Mall at the World Trade Center Retail
B Xerox Document Company, Morgan Stanley, Anthem, NY Chamber of Commerce Manufacturing, Investment, Insurance, Government
NA Continental Insurance Company Insurance
SOURCES: CoStar Group Inc.; Skyscrapers, An Architectural Type of Modern Urbanism; compiled from AP wire reports.
The South Pool of the present-day National September 11 Memorial & Museum, marking the spot upon which the original Two World Trade Center stood.

NOTE: Atlantic Bank of New York had moved out in July 2001, but they were still paying for the rent as of September 2001.

References

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  1. ^ The collapse began at 9:58:59 a.m.; ergo it would not have been fully destroyed until 9:59.
  2. ^ The exact time is disputed. The 9/11 Commission report says 9:03:11,[3][4] NIST reports 9:02:59,[5] some other sources report 9:03:02.[6]
  3. ^ NIST and the 9/11 Commission both state that the collapse began at 9:58:59 a.m.,[7]: 80 [8]: 322  which is rounded to 9:59[7]: 84 [8]: 322  for simplicity. If the Commission's claim that the South Tower was struck at 9:03:11 is to be believed, then it collapsed after 55 minutes and 48 seconds, not 56 minutes.

Citations

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  1. ^ a b "History of the Twin Towers". PANYNJ.gov. 2013. Archived from the original on December 28, 2013. Retrieved September 11, 2015.
  2. ^ Adams, Arthur G. (1996). The Hudson River Guidebook. Fordham University Press. p. 87. ISBN 0-8232-1679-9.
  3. ^ Final Report of the 9/11 Commission on Terrorist Attacks Upon the United States (PDF) (Report). National Commission on Terrorist Attacks Upon the United States. July 22, 2004. pp. 7–8. Archived (PDF) from the original on August 16, 2021. Retrieved August 15, 2021.
  4. ^ Staff Report of the 9/11 Commission on Terrorist Attacks upon the United States (PDF) (Report). National Commission on Terrorist Attacks Upon the United States. September 2005 [August 26, 2004]. p. 24. Archived (PDF) from the original on July 12, 2014. Retrieved August 15, 2021.
  5. ^ Building and Fire Research Laboratory (September 2005). Visual Evidence, Damage Estimates, and Timeline Analysis (PDF). National Institute of Standards and Technology (Report). United States Department of Commerce. p. 27. Archived (PDF) from the original on September 11, 2021. Retrieved August 24, 2021.
  6. ^ "Timeline for United Airlines Flight 175". NPR. June 17, 2004. Archived from the original on August 24, 2021. Retrieved August 24, 2021.
  7. ^ a b National Institute of Standards and Technology (2005). Final Reports from the NIST World Trade Center Disaster Investigation (PDF).
  8. ^ a b 9/11 Final Report of the National Commission (2004). Collapse of WTC2 (PDF).{{cite book}}: CS1 maint: numeric names: authors list (link)
  9. ^ Grutzner, Charles (December 29, 1961). "Port Unit Backs Linking of H&M and Other Lines" (PDF). The New York Times. ISSN 0362-4331.
  10. ^ a b Esterow, Milton (September 21, 1962). "Architect Named for Trade Center" (PDF). The New York Times. ISSN 0362-4331.
  11. ^ a b Huxtable, Ada Louise (January 19, 1964). "A New Era Heralded". The New York Times. ISSN 0362-4331.
  12. ^ Gillespie (1999), p. 49.
  13. ^ NIST NCSTAR 1–1 (2005), p. 7.
  14. ^ Ingraham, Joseph C. (March 29, 1965). "Port Agency Buys Downtown Tract" (PDF). The New York Times. ISSN 0362-4331.
  15. ^ Gillespie (1999), p. 61.
  16. ^ World Trade Center Building Performance Study (2002), p. 1.2.
  17. ^ "Contracts Totaling $74,079,000 Awarded for the Trade Center" (PDF). The New York Times. January 24, 1967. ISSN 0362-4331.
  18. ^ a b "Timeline: World Trade Center chronology". PBS – American Experience. Archived from the original on May 2, 2007. Retrieved May 15, 2007.
  19. ^ NIST NCSTAR 1–1 (2005), p. xxxvi.
  20. ^ Gillespie (1999), p. 134.
  21. ^ Goodwin, Michael (March 13, 1981). "TRADE CENTER TO GET FIRE SPRINKLERS AT $45 MILLION COST". The New York Times. p. 1. Retrieved January 9, 2022.
  22. ^ Reeve, Simon (2002). The new jackals : Ramzi Yousef, Osama Bin Laden and the future of terrorism. Boston: Northeastern University Press. p. 10. ISBN 978-1-55553-509-4.
  23. ^ "Prosecutor: Yousef aimed to topple Trade Center towers". CNN. August 5, 1997. Archived from the original on October 12, 2008. Retrieved November 20, 2008.
  24. ^ Mathews, Tom (March 8, 1993). "A Shaken City's Towering Inferno". Newsweek. Archived from the original on October 30, 2008. Retrieved October 26, 2008.
  25. ^ Barbanel, Josh (February 27, 1993). "Tougher Code May Not Have Helped". The New York Times. ISSN 0362-4331. Retrieved November 20, 2008.
  26. ^ "Brookfield Loses Lease Bid". Toronto Star. February 23, 2001.
  27. ^ Bagli, Charles V. (March 20, 2001). "As Trade Center Talks Stumble, No. 2 Bidder Gets Another Chance". The New York Times. ISSN 0362-4331. Archived from the original on January 19, 2008. Retrieved November 20, 2008.
  28. ^ Smothers, Ronald (July 25, 2001). "Leasing of Trade Center May Help Transit Projects, Pataki Says". The New York Times. ISSN 0362-4331. Archived from the original on May 17, 2008. Retrieved November 20, 2008.
  29. ^ "Flight Path Study – American Airlines Flight 11" (PDF). National Transportation Safety Board. February 19, 2002. Archived (PDF) from the original on February 14, 2007. Retrieved April 24, 2014.
  30. ^ "Flight Path Study – United Airlines Flight 175" (PDF). National Transportation Safety Board. February 19, 2002. Archived (PDF) from the original on June 17, 2014. Retrieved April 24, 2014.
  31. ^ a b Miller, Bill (May 1, 2002). "Skyscraper Protection Might Not Be Feasible, Federal Engineers Say". Orlando Sentinel. Archived from the original on December 3, 2013. Retrieved November 24, 2013.
  32. ^ Field, Andy (2004). "A Look Inside a Radical New Theory of the WTC Collapse". Fire/Rescue News. Archived from the original on June 19, 2006. Retrieved July 28, 2006.
  33. ^ Gross, John L.; Therese P. McAllister (2004). "Structural Fire Response and Probable Collapse Sequence of the World Trade Center Towers" (PDF). Federal Building and Fire Safety Investigation of the World Trade Center Disaster NIST NCSTAR 1–6. National Institute of Standards and Technology. Archived (PDF) from the original on July 28, 2011. Retrieved November 24, 2010.
  34. ^ Wilkinson, Tim (2006). "World Trade Center – Some Engineering Aspects". Archived from the original on March 6, 2012. Retrieved July 28, 2006.
  35. ^ National Construction Safety Team (September 2005). "Executive Summary". Final Report on the Collapse of the World Trade Center Towers (PDF). NIST. Archived (PDF) from the original on May 27, 2008. Retrieved April 24, 2014.
  36. ^ NIST NCSTAR 1–1 (2005), p. xxxviii.
  37. ^ American Iron and Steel Institute (1964). "The World Trade Center – New York City". Contemporary Steel Design. 1 (4). American Iron and Steel Institute.
  38. ^ Darton (1999), pp. 32–34.
  39. ^ Grudin, Robert (April 20, 2010). Design And Truth. Yale University Press. p. 39. ISBN 978-0-300-16203-5. Archived from the original on May 27, 2016. Retrieved April 18, 2019.
  40. ^ Kerr, Laurie (December 28, 2001). "Bin Laden's special complaint with the World Trade Center". Slate Magazine. Archived from the original on September 19, 2015. Retrieved October 12, 2015.
  41. ^ McDowell, Edwin (April 11, 1997). "At Trade Center Deck, Views Are Lofty, as Are the Prices". The New York Times. ISSN 0362-4331. Archived from the original on April 10, 2008. Retrieved November 21, 2008.
  42. ^ "1973: World Trade Center Is Dynamic Duo of Height". Engineering News-Record. August 16, 1999. Archived from the original on June 11, 2002.
  43. ^ William Baker; Johnathan Barnett; Christopher Marrion; Ronald Hamburger; James Milke; Harold Nelson (September 1, 2002). "Chapter 2. WTC 1 and WTC 2". World Trade Center Building Performance Study. FEMA. p. 33. ... the loads initially carried by the damaged exterior columns were transferred by Vierendeel truss action to the remaining exterior columns immediately adjacent to the impact area.
  44. ^ a b c NIST NCSTAR 1 (2005), p. 6.
  45. ^ Goldberger (2004), p. 26.
  46. ^ a b c NIST NCSTAR 1 (2005), pp. 5–6.
  47. ^ a b c NIST NCSTAR 1–1 (2005), p. 8.
  48. ^ NIST NCSTAR 1–1 (2005), p. 9.
  49. ^ NIST NCSTAR 1–1 (2005), p. 10.
  50. ^ Tamaro, George J. (Spring 2002). "World Trade Center "Bathtub": From Genesis to Armageddon". Bridges. 32 (1). Archived from the original on September 30, 2007.
  51. ^ NIST NCSTAR 1 (2005), p. 8.
  52. ^ a b Zarghamee, Mehdi S.; Kitane, Y.; Erbay, Omer O.; McAllister, Therese P.; Gross, John L. (December 1, 2005). "Global Structural Analysis of the Response of the World Trade Center Towers to Impact Damage and Fire. Federal Building and Fire Safety Investigation of the World Trade Center Disaster (NIST NCSTAR 1-6D)". NIST: 285.
  53. ^ a b NIST NCSTAR 1 (2005), p. 10.
  54. ^ "New York: A Documentary Film – The Center of the World (Construction Footage)". Port Authority / PBS. Archived from the original on April 1, 2007. Retrieved May 16, 2007.
  55. ^ Glanz & Lipton (2003), p. 138.
  56. ^ Robertson, Leslie E. (2002). "Reflections on the World Trade Center". The Bridge Volume 32, Number 1. National Academy of Engineering. Retrieved July 28, 2006.
  57. ^ Sadek, Fahim. Baseline Structural Performance and Aircraft Impact Damage Analysis of the World Trade Center Towers(NCSTAR 1–2 appendix A). NIST 2005. pp. 305–307.
  58. ^ Hamburger, Ronald; et al. "World Trade Center Building Performance Study" (PDF). Federal Emergency Management Agency. Retrieved July 27, 2006.
  59. ^ NIST NCSTAR 1–6 (2005), p. lxxi. NIST lists upgraded floors as 92–100 and 102 plus 8 unspecified floors.
  60. ^ NIST NCSTAR 1–1 (2005), p. 162.
  61. ^ NIST NCSTAR 1–4 (2005), p. 14.
  62. ^ "Hold Brothers Commemorates the 16th Anniversary of their WTC Tenantship". prweb. Retrieved January 30, 2018.

Sources

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