7 World Trade Center
From Debunk911myths
7 World Trade Center
7 World Trade Center, located across Vesey Street from the Twin Towers and other World Trade Center buildings, was built in the early-mid 1980s, on top of a two-story Con Edison substation. 7 World Trade Center collapsed at 5:20 pm on September 11, 2001, after suffering extensive damage from fires and falling debris from the collapse of the World Trade Center towers. Soon after September 11, 2001, FEMA initiated a preliminary study into the collapse of the World Trade Center buildings, including 7 World Trade Center. This was followed up by a more extensive investigation by NIST, which is still ongoing.
Construction
- See also: Design and construction
The original Seven World Trade Center was finished in 1987. The original structure had 47 floors and was 570 feet (174 m) tall.[1] Construction began in 1984; in March 1987, the building opened, to become the seventh structure of the World Trade Center. The building was built on top of a Con Edison substation dating from 1967.[2] The substation had a caisson foundation designed to carry the weight of a future building on the site.[2] The final design for 7 World Trade Center was for a building covering a significantly larger footprint than originally planned when the substation was built.[3] Between floors 5 and 7, the building had a system of transfer trusses and girders to transfer load to the smaller-sized foundation.[4] The spray-on fireproofing for structural steel elements was gypsum-based Monokote, which had a 2-hour rating for steel beams, girders and truss, and 3 hour rating for columns.[5]
Each floor had 47,000 square feet (4,366 m²) of rentable office space, which made the building's floor plans considerably larger than most other office buildings in the city.[6] In all, 7 World Trade Center had 1,868,000 square feet (174,000 m²) of office space.[5] The building was clad in red exterior masonry. A pedestrian bridge connected it to the main World Trade Center complex, to the south, across Vesey Street. Emery Roth & Sons[1] designed the building. The lobby of 7 World Trade Center had three murals, by artist Al Held, The Third Circle, Pan North XII, and Vorces VII.[7][8]
Tenants
Salomon Smith Barney was by far the largest tenant in 7 World Trade Center, occupying 1,202,900 sq. ft. (62% of the building) including floors 28 - 45.[9][5] Other major tenants included ITT Hartford Insurance Group (122,590 sq ft), American Express Bank International (106,117 sq ft), Standard Chartered Bank (111,398 sq ft), and the Securities & Exchange Commission (106,117 sq ft). Smaller tenants included the Internal Revenue Service Regional Council (90,430 sq ft), and the U.S. Secret Service (85,343 sq ft). The Department of Defense (DOD) and Central Intelligence Agency (CIA) shared Floor #25 with the IRS.[5] The smallest tenants included the Mayor's Office of Emergency Management, NAIC Securities, Federal Home Loan Bank, First State Management Group, Inc., and Provident Financial Management.[9] Floors 46-47 were mechanical floors, as well as the bottom 6 floors and part of floor #7.[5]
Fires
When the North Tower collapsed, the antenna fell and cut through the façade of Building 7, rupturing fuel lines leading to storage tanks used by New York City's emergency services.[10] Following the collapse of WTC1 (North Tower), fires were observed in 7 World Trade Center on the south side of the building, at floors 6, 7, 8, 10, 11, and 19.[11] Sprinklers were not working, and water pressure (to enable firefighting efforts) was very low, so firefighting was curtailed. Fires continued to burn, unabated throughout the day. At 3:30 pm, darker plumes of smoke were observed coming from 7 World Trade Center, indicative of fire fueled by oil.[11] By 5 pm, large amounts of dark smoke were coming out of the lower floors.[11] These observations indicate that the temperature of the fire was hotter than typical office fires, and the presence of fuel tanks and cut fuel lines in the building are suspected as a factors.[11]
The building's fireproofing (passive fire protection) was the last line of defense, absent working sprinklers and firefighting efforts. The fireproofing is designed to protect building structural elements for a certain, limited amount of time while firefighting is done.[11] Such a building is generally designed to resist heat buildup for three hours.[12]
Dr. Astaneh-Asl, a structural engineer from U.C. Berkeley who was on-site after 9/11 to examine steel, saw a charred horizontal I-beam from 7 World Trade Center, a 47-story skyscraper that collapsed from fire eight hours after the attacks. The beam, so named because its cross-section looks like a capital I, had clearly endured searing temperatures. Parts of the flat top of the I, once five-eighths of an inch thick, had vaporized. Less clear was whether the beam had been charred after the collapse, as it lay in the pile of burning rubble, or whether it had been engulfed in the fire that led to the building's collapse, which would provide a more telling clue. The answer lay in the beam's twisted shape. As weight pushed down, the center portion had buckled outward. "This tells me it buckled while it was attached to the column," not as it fell, Dr. Astaneh-Asl said, adding, "It had burned first, then buckled."[13]
Damage
Damage to 7 World Trade Center from falling debris due to the collapse of the Twin Towers was extensive. Among damage observed was a 10 story gash, from the 8 to 18th floor, on the southwest corner of the building. Around 2 o'clock in the afternoon, firefighters noticed a bulge in the southwest corner of 7 World Trade Center, between the 10 and 13th floors, which was a sign that the building might collapse.[14]
Lieutenant Rudy Weindler of Ladder Company 40
"we saw a fire starting to show at windows in 7 World Trade Center, decided to go in and try and see if there was anybody in the building and/or put out the fires, and we did a search from floor to floor of 7 World Trade Center passing fire on floors 3, 7, 9. The standpipes had no water. We tried to extinguish a few fires with cans. When we got to 11, there was just too much smoke and we decided that, without water, if we went any higher, we'd be on fool's mission.
So we left 7 World Trade Center, back down to the street, where I ran into Chief Coloe from the 1st Division, Captain Varriale, Engine 24, and Captain Varriale told Chief Coloe and myself that 7 World Trade Center was badly damaged on the south side and definitely in danger of collapse. Chief Coloe said we were going to evacuate the collapse zone around 7 World Trade Center, which we did."
Captain Robert Sohmer Ladder 85
"As the day went on they started worrying about 7 World Trade Center collapsing and they ordered an evacuation from that area so at that time, we left the area with the other companies, went back to the command post on Broadway, where we were instructed, they were looking for companies to go to the west side to operate on the bridges, to cut members out that they had confirmed were pinned and trapped under the bridges on the west side.
A Battalion Chief was assigned to us. We took our apparatus to West Street to the north bridge, on that side over there, where we began to operate. We had identified different members who were deceased and trapped in rigs. We were about to proceed our operation there and this was in the afternoon, I would say approximately maybe 2:00 roughly, where we started to operate and then they asked us to fall back again due to the potential of 7 World Trade Center collapsing."
He was operating between 4 and 5 World Trade Center, when "They made us evacuate due to the fear of 7 coming down."
Collapse
NIST's interim report on 7 World Trade Center displays photographs of the southwest façade of the building that show it to have significant damage. The report also highlights a 10-story gash in the center of the south façade, toward the bottom, extending approximately a quarter of the way into the interior.[15][2] A unique aspect of the design of 7 World Trade Center was that each outer structural column was responsible for supporting 2,000 sq ft (186 m²) of floor space, suggesting that the simultaneous removal of a number of columns severely compromised the structure's integrity.[16] Consistent with this theory, news footage shows cracking and bowing of the building's east wall immediately before the collapse, which began at the penthouse floors.[2] In video of the collapse, taken from the north by CBS News and other news media, the first visible sign of collapse is movement in the east penthouse 8.2 seconds before the north wall began to collapse, which took at least another 7 seconds.[2][17]
A progress report was released in June 2004, outlining NIST's working hypothesis.[18][2] The hypothesis, which was reiterated in a June 2007 status update, is that an initial failure in a critical column occurred below the 13th floor, caused by damage from fire and/or debris induced structural damage of a critical column, from the collapse of the two main towers. The collapse progressed vertically up to the east mechanical penthouse. The interior structure was unable to handle the redistributed load, resulting in horizontal progression of the failure across lower floors, particularly the 5th to 7th floors. This resulted in "a disproportionate collapse of the entire structure."[19]
Controlled demolition?
Claim
Controlled demolition was used to bring about the collapse of 7 World Trade Center on the afternoon of September 11, 2001.
Vincent Dunn, a retired deputy FDNY fire chief and author of the textbook, The Collapse of Burning Buildings, spoke with Popular Mechanics and explained the how the unique design of 7 World Trade Center, which was built on top of a Con Ed substation, made it extra vulnerable to the stresses imposed by the falling debris and fires on 9/11.
- "Instead of the vertical beams terminating in the foundation, many of them terminate in these broad, horizontal trusses that span the width of the building. Because the building was basically hollow from the sixth floor down. It was built over this big Con Ed substation. So those trusses carry these enormous loads far, far higher than we would see in a typical skyscraper. The combination of the falling debris - which greatly stressed the structure - raised the strain on these trusses. And then these fires that were fed in one case by a pressurized diesel fuel line, that raged for seven hours - and the current thinking of the engineers who investigated is more than enough to explain the collapse of the building. And in fact when those trusses failed, what you would've seen was exactly what we did see, which is the building almost collapsing from the inside first."[20]
Pull it
Claim
This claim was bolstered by a comment made by Larry Silverstein on a PBS documentary, America Rebuilds, where he uttered the phrase "pull it". Conspiracy theorists claim that this is slang term used in building implosions, and that with those words, Silverstein was authorizing the demoltion of WTC 7.
Fact
Controlled demolition experts reject the notion that "pull it" is a term used in building implosions.
The only context that "pull" has been used in building demolition is for small buildings (a few stories tall), where construction crews attach long cables to pre-weaken a structure and literally pull it down with bulldozers and other equipment.
"Pull" is also used by firefighters in reference to "pulling firefighters out of a building", because the situation is too dangerous. It is in this context that Silverstein used the term "pull it".
His spokesperson, Dara McQuillan, said that by "it", Silverstein was referring to the contigent of firefighters in WTC 7.
Firefighters
FDNY interviews available on the New York Times website also shed light on the use of "pull" in firefighting on 9/11, and help address the question of whether firefighters were in WTC 7 in the afternoon.
FDNY Captain Ray Goldback:
- "I'm going to guess it was after 3:00...we walked all the way back down to Vesey Street. There was a big discussion going on at that point about pulling all of our units out of 7 World Trade Center. Chief Nigro didn't feel it was worth taking the slightest chance of somebody else getting injured. So at that point we made a decision to take all of our units out of 7 World Trade Center because there was a potential for collapse." [1]
Firefighter Richard Banaciski was in the Verizon Building, adjacent to WTC7.
- "Finally they pulled us out. They said all right, get out of that building because that 7, they were really worried about. They pulled us out of there and then they regrouped everybody on Vesey Street." [2]
Deputy Chief Peter Hayden:
- "By now, this is going on into the afternoon, and we were concerned about additional collapse, not only of the Marriott, because there was a good portion of the Marriott still standing, but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse. You actually could see there was a visible bulge, it ran up about three floors. It came down about 5 o'clock in the afternoon, but by about 2 o'clock in the afternoon we realized this thing was going to collapse."
- "Firehouse: Was there heavy fire in there right away?"
- "Hayden: No, not right away, and that's probably why it stood for so long because it took a while for that fire to develop. It was a heavy body of fire in there and then we didn't make any attempt to fight it. That was just one of those wars we were just going to lose. We were concerned about the collapse of a 47-story building there. We were worried about additional collapse there of what was remaining standing of the towers and the Marriott, so we started pulling the people back after a couple of hours of surface removal and searches along the surface of the debris. We started to pull guys back because we were concerned for their safety." [3]
Command and control
The most important operational decision to be made that afternoon was the collapse had damaged 7 World Trade Center, which is about a 50 story building, at Vesey between West Broadway and Washington Street. It had very heavy fire on many floors and I ordered the evacuation of an area sufficient around to protect our members, so we had to give up some rescue operations that were going on at the time and back the people away far enough so that if 7 World Trade did collapse, we wouldn't lose any more people. — Chief Daniel Nigro [4]
Free fall?
Fact
The collapse did not occur at free fall speed. It took 16 seconds, with the east mechanical penthouse beginning to collapse 8.2 seconds before any more obvious signs of total collapse (as seen on videos).
- How fast did WTC7 fall - video
For comparison to see what an actual controlled demolition is like, here is a video of one that took place in June 2006, with the demolition of the Tencza apartments in Arlington, Virginia - See video
BBC reported collapse of WTC7 early
Fact
- Part of the conspiracy? - BBC
- Part of the conspiracy? (2) - BBC
No steel was recovered from WTC7
Fact
Members of the FEMA/ASCE Building Performance Study Team and others including members of the Structural Engineers Association of New York (SEAoNY), Dr. J. Gross, a structural engineer at NIST, and Professor A. Astaneh-Asl of the University of California, Berkeley had access to the recovery yards where debris, including the steel, was taken during the cleanup effort.
There were four major sites where debris from the WTC buildings was shipped during the clean-up effort and these teams looked for debris were:
- Hugo Neu Schnitzer, Inc., Fresh Kills Landfill in Staten Island, New Jersey;
- Hugo Neu Schnitzer East, Inc., Claremont Terminal in Jersey City, New Jersey;
- Metal Management, Inc., in Newark, New Jersey; and
- Blanford and Co. in Keasbey, New Jersey.
Specific pieces of debris they were searching for included badly burned pieces from WTC 7, and connections from WTC 1, 2, and 7 (e.g., seat connections, single-shear plates, and column splices). They were unable to unambiguously identified any pieces as being from WTC 7.
Structural steel elements were also collected and held by the Port Authority of New York and New Jersey (PANYNJ) in Hanger 17 located at John F. Kennedy (JFK) International Airport. The main goal of the PANYNJ project was to decontaminate and preserve the steel, as well as other WTC artifacts, for future exhibits and memorials.
At Fresh Kills and the other sites, they were unable to identify with 100% certainty any pieces as being from WTC 7, and not from the twin towers. But, they had the opportunity to look and did collect samples for the twin towers. With any pieces found from WTC 7, NIST also needed to to know where in the structure the piece was located. Pieces from the twin towers were marked with identification codes to help determine the location, but that may not have been the case in WTC7. A piece of A36 steel from WTC 7 was recovered and analyzed by J.R. Barnett, R.R. Biederman, and R.D. Sisson, Jr., though they could not determine the exact location of this beam. [5]
Although no steel was recovered from WTC7 to allow NIST to conduct tests on actual material from the structure, WTC 7 was constructed of three grades of conventional steel (36 ksi, 42 ksi, and 50 ksi). Literature values can be used to estimate properties of these standard types of steel.
NIST also worked from structural design drawings and standard practice for the mid 1980’s, interviewed building designers, and reviewed available photographs of building during renovations.
- Steel Inventory and Identification
- An Initial Microstructural Analysis of A36 Steel from WTC Building 7
Damage to 7 World Trade Center
Other images
See also
References
- ↑ 1.0 1.1 Seven World Trade Center (pre-9/11). Emporis.com.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Interim Report on WTC7. National Institute of Standards and Technology (June 2004).
- ↑ Lew, H.S., et al (September 2005). "NIST NCSTAR 1-1: Design, Construction, and Maintenance of Structural and Life Safety Systems", Final Reports of the Federal Building and Fire Investigation of the World Trade Center Disaster. NIST, p. xxxvii.
- ↑ Interim Report on WTC7 p. L-3. National Institute of Standards and Technology (June 2004).
- ↑ 5.0 5.1 5.2 5.3 5.4 WTC7 (Chapter 5), pdf. FEMA.
- ↑ Horsley, Carter B.. "Lower Manhattan Luring Office Developers", The New York Times, October 25, 1981.
- ↑ Al Held. National Gallery of Australia.
- ↑ Plagens, Peter. "Is Bigger Necessarily Better?", Newsweek, April 17, 1989.
- ↑ 9.0 9.1 7 World Trade Center tenants, CNN
- ↑ Ground Zero's Silverstein Expects Brokerage Tenants, Bloomberg News
- ↑ 11.0 11.1 11.2 11.3 11.4 http://irc.nrc-cnrc.gc.ca/pubs/fulltext/prac/nrcc44753/nrcc44753.pdf
- ↑ Glanz, James, Towers Believed to Be Safe Proved Vulnerable to an Intense Jet Fuel Fire, Experts Say. The New York Times. September 12, 2001
- ↑ Chang, Kenneth. "Scarred Steel Holds Clues, And Remedies", The New York Times, October 2, 2001.
- ↑ WTC: This Is Their Story, Interview with Chief Peter Hayden. Firehouse.com (September 9, 2002).
- ↑ "Debunking the 9/11 Myths: Special Report", Popular Mechanics, March 2005.
- ↑ NIST Response to the World Trade Center Disaster (Part IIC - WTC 7 Collapse) (pdf). NIST (April 5, 2005). Retrieved on 2007-08-23.
- ↑ CBS News. (2001, September 11). CBS Sept. 11, 2001 4:51 pm - 5:33 pm (September 11, 2001) [Television]. WUSA, CBS 9, Washington, D.C..
- ↑ Key Findings of NIST’s June 2004 Progress Report on the Federal Building and Fire Safety Investigation of the World Trade Center Disaster. Fact sheets from NIST. National Institute of Standards and Technology (2004). Retrieved on 2006-07-28.
- ↑ National Institute of Standards and Technology (June 29, 2007). NIST Status Update on World Trade Center 7 Investigation. Press release.
- ↑ 'Popular Mechanics' Tackles Sept. 11 Conspiracy Theories National Public Radio (NPR) September 7, 2006
Other references
- FEMA - World Trade Center Building Performance Study - WTC7
- Interim Report on WTC 7, NIST
- Photographs and video - by Steve Spak
- WTC 7 (Engineering Disasters) - video
- Salvarinas, John J. 1986. Seven World Trade Center, New York, Fabrication and Construction Aspects, Proceedings of the 1986 Canadian Structural Engineering Conference, Vancouver, Canadian Steel Construction Council, Ontario. February 24-25.
- Gilsanz, Ramon and Willa Ng (November 2007) Single Point of Failure, Structure Magazine.