TWIN TOWERS (WTC)
*********TWIN TOWERS (WTC 1 & 2)**********
Location: New York City
Status: Destroyed September 11, 2001
WTC 1: 1966–1972
WTC 2: 1966–1973
WTC 1: 1,368 ft (417.0 m)
(with antenna 1,727 ft (526.3 m)
WTC 2: 1,362 ft (415.0 m)
Floor count: 110 floors
Floor area: Both had 4,300,000 sq ft (400,000 m2)
Elevators: 99 in each tower.
WTC 1 (North Tower) Collapsed at near free fall @ 10:28am (hit by AA11 @ 8:46) in 11 Seconds (NIST). Burned for 102 minutes. Between the 92nd to 98th floors.
WTC 2 (South Tower) Collapsed at near free fall @ 9:59am (hit by UA175 @ 9:03) in 9 Seconds (NIST). Burned for 56 minutes. Between the 78th to 84th floors.
“The measurements have indicated that Tower one collapsed in about 11 seconds and Tower two collapsed in about 9 seconds…..this is essentially the rate at which free fall would happen.” – Shyam Sunder NIST
WTC Complex: Over 350,000 Tons of steel (FEMA). 96,000 tons of steel in each Tower.
Perimeter Columns: Each tower had 236 Steel perimeter box columns (14 x 14”) spaced 39” apart and joined together with steel spandrels.
Center Core: Total center core size was 87 by 135 feet and contained 47 steel box columns (14 x 35” or 22 x 53”) running from the bedrock to the top of each tower. The lower cores steel was 4″ inches thick and it gradually decreased to 3/4″ at the top.
WTC Facts and Figures
200,000 tons of structural steel
43,600 windows (600,000 sq feet of glass)
5 Million sq ft of sheetrock
6 acres of marble
425,000 cubic yards of concrete or 53,125 cement trucks full of concrete
1,500,000 tons—the weight of the Twin Towers. (Each tower 750,000 tons)
1st floor plans
Ground Zero World Trade Center Twin Towers NY Before 911 Part 1/7
911GATE: WTC Twin Towers Before 9/11
The first step in beginning to analyze and critique the official account of the tower collapses is to understand the way they were built. Each tower was like a giant steel cage made of 236 steel perimeter box columns (35 cm x 35 cm), joined together with steel spandrels at regular intervals. The characteristic vertical lines on the four sides of the towers were simply these steel columns, covered with aluminium. Running up the centre of the towers were 47 even larger steel box columns (36 x 90 cm or 55 x 135 cm), which were cross braced. The steel plate used in the columns was 100 mm thick at the base, and got thinner towards the top, where it had to carry less load.
At each floor, the outer columns were connected to the core columns with steel trusses, bolted to welded steel brackets on the columns (below right). The trusses were covered with corrugated metal sheet, and a layer of concrete was poured on top. Thus each tower was essentially a massive steel structure — steel perimeter, steel core and steel floors — with concrete only serving to distribute the weight on each floor.
Building the World Trade Center and Twin Towers
WTC Tower Structural Design Explained
“Various statements on the structural design and strength of the World Trade Center towers.”
World Trade Center a 3D Visualization – WTC
“The twin towers were the first super tall buildings designed without any masonry.”
“The building had to be tough enough to withstand not just the impact of a plane – and the previous bomb attack in 1993 – but also of the enormous structural pressures created by strong winds.”
“The twin towers, framed in structural steel, had exterior moment frames with 14-in. steel box columns spaced 39 in. on center. The configuration created a complete tube around the building. The central steel core carried gravity loads only. The exterior tube provided all the lateral resistance. Horizontal steel trusses spanned 60 ft from the exterior wall to the core. Concrete on metal deck completed the floor diaphragm.
Each tower contained about 100,000 tons of steel and 4 in. of concrete topping on the 40,000-sq-ft floors, according to Henry H. Deutch, assistant to the chief structural engineer for construction manager Tishman Realty & Construction Co. Inc., New York City, during the construction of the WTC and currently head of HHD Consultants Inc., Osceola County, Fla.”
Engineers versus the eons, or How long will our monuments last?
From Smithsonian Magazine, March 1984
“As Robertson, said, “Filling of the basements would be the biggest single danger to the Trade Center.” The reason.is rust. But nothing major happens for several centuries, we’ll return to the rust later.”
Could the World Trade Center have been modified to prevent its collapse?
FLOOR DESIGN LAYOUT
The large open floor space of the WTC
“Each floor of the towers possessed an open unobstructed area of roughly 200 by 200 feet. The pursuit of adaptable and open floor space by the client, and satisfied by the engineer, resulted in a problem for the fire service which was two-fold: the potential incidence of fire on each floor approached an acre in area, virtually impossible to extinguish under normal conditions (typical fire loading and serviceable standpipes and elevators), and the absence of intermediate walls and partitions which would have served as redundancies in the structural system of the frame. Interior walls would have both compartmentalized the floor area to resist the spread of fire and simultaneously provided an alternate load path in the event of floor collapse from above.” [Firehouse]
“The towers were designed as “tube in tube” structures, which provided tenants with open floor plans uninterrupted by columns or walls. Numerous, closely spaced perimeter columns provided much of the strength to the structure, along with gravity load shared with the steel box columns of the core. Above the tenth floor, there were 59 perimeter columns along each face of the building, and there were 47 heavier columns in the core. All of the elevators and stairwells were located in the core, leaving a large column-free space between the perimeter that was bridged by prefabricated floor trusses.”
“With a 700 Pa floor design allowable, each floor should have been able to support approximately 1,300 t beyond its own weight. The total weight of each tower was about 500,000 t.”
“As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell. The floor below (with its 1,300 t design capacity) could not support the roughly 45,000 t of ten floors (or more) above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h.”
Elevators were disaster within disaster
“The World Trade Center had one of the world’s great elevator systems — 198 of the biggest, fastest elevators ever built.”
World Trade Center Elevators
The World Trade Center had two Sky Lobbies in each Tower located on the 44th and the 78th floor.
In 1967, Otis won the contract to design the Elevator system in the WTC.
“To further facilitate traffic at the sky lobby on the 44th and 78th floors escalators will provide two-way service between the floors immediately above and below.”
WTC CORE COLUMNS
Center Core: Total center core size was 87 by 135 feet and contained 47 steel box columns (14 x 35” or 22 x 53”) running from the bedrock to the top of each tower.
The Core Structures
“Each tower was supported by a structural core extending from its bedrock foundation to its roof. The cores were rectangular pillars with numerous large columns and girders, measuring 87 feet by 133 feet. The core structures housed the elevators, stairs, and other services. The cores had their own flooring systems, which were structurally independent of the floor diaphragms that spanned the space between the cores and the perimeter walls. The core structures, like the perimeter wall structures, were 100 percent steel-framed.”
Center Core Column Pics:
Ironworker Column Cuts
Perimeter Columns: Each tower had 236 Steel perimeter box columns (14 x 14”) joined together with steel spandrels.
“The towers’ perimeter walls comprised dense grids of vertical steel columns and horizontal spandrel plates. These, along with the core structures, supported the towers. In addition to supporting gravity loads, the perimeter walls stiffened the Towers against lateral loads, particularly those due to winds. The fact that these structures were on the exterior of the Towers made them particularly efficient at carrying lateral loads. Richard Roth, speaking on behalf of the architectural firm that designed the Towers, described each of the perimeter walls as essentially “a steel beam 209′ deep.” 1 Regardless, it is clear that the core structures were designed to support several times the weight of each tower by themselves.”
Perimeter Column Pic:
DESIGNED TO WITHSTAND BOEING IMPACTS
The World Trade Center Twin Towers Were Designed For Jet Impacts
“The core of the towers housed the elevator and utility shafts, restrooms, three stairwells, and other support spaces. The core of each tower was a rectangular area 87 by 135 feet (27 by 41 m) and contained 47 steel columns running from the bedrock to the top of the tower. The large, column-free space between the perimeter and core was bridged by prefabricated floor trusses. The floors supported their own weight as well as live loads, providing lateral stability to the exterior walls and distributing wind loads among the exterior walls. The floors consisted of 4 inches (10 cm) thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors. The trusses connected to the perimeter at alternate columns and were on 6 foot 8 inch (2.03 m) centers. The top chords of the trusses were bolted to seats welded to the spandrels on the exterior side and a channel welded to the core columns on the interior side. The floors were connected to the perimeter spandrel plates with viscoelastic dampers that helped reduce the amount of sway felt by building occupants.”
Frank DeMartini, World Trade Center 1973-2001 (WTC Construction Manager)
“I believe the building probably could sustain multiple impacts of jetliners because this structure is like the mosquito netting on your screen door, this intense grid, and the jet plane is just a pencil puncturing the screen netting. It really does nothing to the screen netting.”
Leslie Robertson discusses WTC aircraft collisions
“We designed the buildings to take the impact of the Boeing 707 hitting the building at any location.” ~ Leslie Robertson (@2:00)
Leslie Robertson – Chief Engineer – World Trade Center – Twin Towers
“We had designed the project for the impact of the largest airplane of it’s time, 707…..”
“I designed it for a 707 to hit it,” ~ Leslie Robertson
Leslie Robertson – The Man Who built the Twin Towers. (Impact of a Plane (BBC) (2nd video link)
“The WTC towers were in fact the first structures outside of the military and nuclear industries designed to withstand the impact of a jet airplane.”
-Leslie E. Robertson in Reflections on the World Trade Center
National Academy of Engineering, Volume 32, Number 1 – Spring 2002
LESLIE ROBERTSON AND STEVEN JONES DEBATE PT1
Leslie Robertson gets another gig!
“The Boeing 707 was the largest in use when the towers were designed. [Leslie] Robertson conducted a study in late 1964, to calculate the effect of a 707 weighing 263,000 pounds and traveling at 180 mph crashing into one of the towers. [Robertson] concluded that the tower would remain standing. However, no official report of his study has ever surfaced publicly.” (Pages 138-139,366)
Believed to Be Safe, the Towers Proved Vulnerable to Jet Fuel Fire
The engineer who said after the 1993 bombing that the towers could withstand a Boeing 707, Leslie Robertson, was not available for comment yesterday, a partner at his Manhattan firm said.
“We’re going to hold off on speaking to the media,” said the partner, Rick Zottola, at Leslie E. Robertson Associates. “We’d like to reserve our first comments to our national security systems, F.B.I. and so on.”
Profile: Leslie Robertson
“However, O’Sullivan consults “one of the trade center’s original structural engineers, Les Robertson, on whether the towers would collapse because of a bomb or a collision with a slow-moving airplane.” He is told there is “little likelihood of a collapse no matter how the building was attacked.””
Leslie E. Robertson Associates
“We designed the towers to resist the accidental impact of a Boeing 707, perhaps lost in the fog while seeking to land. The impact of the Boeing 767s, commandeered by the terrorists, even though larger and flying much faster, was still unable to bring down the towers. The fire-resistive systems, however, did not and could not have contemplated the subsequent fire fueled by thousands of gallons of jet fuel.”
“… the largest aircraft flying today, at least commercially, the 747 fully loaded is on the order of 300 tons. So if you think about a 300 ton element crashing into a building that’s been designed to carry 13,000 tons, you can see that an aircraft crashing into the World Trade Centre would probably not do anything to the major building, it could effect localized structural elements, could knock out a column, and there could be some damage but as far as a plane knocking a building over, that would not happen.” ~ Charlie Thornton 1988
John Skilling, Lead Structural Engineer for the WTC,
In The Seattle Times, February 27, 1993.
Twin Towers Engineered To Withstand Jet Collision
“Concerned because of a case where an airplane hit the Empire State Building, Skilling’s people did an analysis that showed the towers would withstand the impact of a Boeing 707.
“Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed,” he said. “The building structure would still be there.””
“Although Skilling is not an explosives expert, he says there are people who do know enough about building demolition to bring a structure like the Trade Center down.
“I would imagine that if you took the top expert in that type of work and gave him the assignment of bringing these buildings down with explosives, I would bet that he could do it.”
“The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707 – DC 8) traveling at 600 miles per hour [about its maximum speed]. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact…. There would be a horrendous fire [but] the building structure would still be there.”
Trade Center architect discusses buildings (Aaron Swirski)
“The criterion was that if a plane hits, it would go right through it. And nobody could foresee something like that. The tower was protected in such a way that the damage would be limited to one story, but it wouldn’t travel to the other stories.”
“I imagine, when I saw the pictures of the implosion of the building, it looks like the fuel must have leaked right to the core of the building, and from there it was the massive explosion that caused the building to collapse.”
Aaron Swirski, architect, says WTC floors designed to self-seal in case of emergency.
“HARRIS: As a member of the team, and having such insight to how this building was constructed, could you believe that a plane could bring these buildings down?
SWIRSKY: No, as a matter of fact, one of the rationales of the structure of the building was that it would be built as a pipe. And that proved itself to work during the explosion of 1993, when a hole was brought into the building, and it survived. But somehow, nobody could foresee anything like (Sept. 11th incident).
Also, at that time, the planes were not like these types of planes that we have now. I think the biggest plane was a 100-passenger plane, something like that, and the fuel capacity of those planes was not like they are today.
The criterion was that if a plane hits, it would go right through it. And nobody could foresee something like that. The tower was protected.”
Shyam Sunder (NIST)
”I’m going to touch on a number of aspects of our investigation which I think it’s worth for the public to know at this point in time. First of all the issue with regard to the safety of the towers in an aircraft collision. Buildings are not designed to withstand the impacts of fuel laden commercial airliners. However, in the case of the World Trade Center, it was a consideration. The structural safety of the towers in an aircraft collision was considered in the original design. We have some documents from 1964 that suggest that. The impact scenario that was considered is a Boeing 707 traveling at 600 miles an hour. There’s another document a month later that considers an aircraft impact at the 80th floor of one of the towers. When you put those two together, the events of September 11th look strikingly similar. The analysis that was reported from that time indicated that such collision would result in only local damage which could not cause collapse or substantial damage to the buildings.”
-Dr. Shyam Sunder of NIST,
Transcript of NIST Public Meeting NYC February 12, 2004 pg 4
”Earlier statements by Port Authority officials and outside engineers involved in designing the buildings suggested that the designers considered an accidental crash only by slower aircraft, moving at less than 200 miles per hour. The newly disclosed documents, from the 1960’s, show that the Port Authority considered aircraft moving at 600 m.p.h., slightly faster and therefore more destructive than the ones that did hit the towers, Dr. Sunder said.”
“WTC 2 displayed significant reserve capacity, as evidenced by a post-impact rooftop sway that was more than one-third of that under the hurricane force winds for which the building was designed. The oscillation period of this swaying was nearly equal to that calculated for the undamaged structure. ”
– NIST NCSTAR 1, WTC Final Report (p. 182)
”In July of 1971, the American Society of Civil Engineers (ASCE) presented a national award judging the WTC Towers to be “the engineering project that demonstrates the greatest engineering skills and represents the greatest contribution to engineering progress and mankind.”
Twin Towers’ Designers Anticipated Jet Impacts Like September 11th’s
“A white paper released on February 3, 1964 states that the Towers could have withstood impacts of jetliners travelling 600 mph — a speed greater than the impact speed of either jetliner used on 9/11/01.
The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at 600 miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact.”
** Appendix A, NISTNCSTAR1-2, April 26, 2006 update.
1, 2 World Trade Center Report Challenged
Aircraft collision ‘would not cause collapse or substantial damage’, NIST does not support ‘pancake theory’
Debunking 9/11 Debunking: On WTC’s Design to Withstand 707 Impact
“These Buildings Were Designed To Come Straight Down If Anything Happened”
“I attended the skyscraper safety hearings for the 9/11 Commission, and I understood that these buildings were designed to come straight down if anything happened, rather than causing greater damage by toppling over in one piece” – Allison Crowther (Family member)
NOTES: Ask any Architect if they have ever designed a steel framed high rise to implode on itself? Is Allison Crowther an expert on steel framed structures?
WTC Tower Structural Design Explained (@5:00)
Debunkers will argue that the Towers were not designed to take the impact of a 767 but a “much” smaller 707. Here are Boeing Specifications for comparison:
The Boeing 767 is only 10′ wider and 6′ longer. The 767 holds roughly the same amount of fuel and weights 60,000 lbs more than the Boeing 707. One point debunkers fail to mention is that a 707 can fly 70 mph faster.
Where are the “RAGING FIRES”?
LET ME KNOW WHEN YOU SEE FIRE – AE911Truth – the flaming inferno is mind control
“While the towers’ support structure ultimately couldn’t withstand the raging fire, it was strong enough to save thousands of people’s lives. Around 99 percent of the people below the impact in each tower were able to evacuate before the buildings collapsed. If the towers hadn’t been built with redundant structural stability, the death toll would have easily been in the tens of thousands.”
NIST does not claim that the 78th floor was a “raging inferno”, for instance. In fact the NIST fire reconstruction report says “there was only light fire activity observed on the 78th floor”, page 109). No surprise: pictures in the same document clearly show this floor was at the base of the fire-affected area.
National Geographic, Chief Orio Palmer (Battalion 7)
“Battalion Seven … Ladder 15, we’ve got two isolated pockets of fire. We should be able to knock it down with two lines. Radio that, 78th floor numerous 10-45 Code Ones.”
EDNA CINTRON aka “Waving lady”
Edna Cintron – WTC victim. Administrative Assistant, Marsh & McLennan, WTC North Tower.
Fire Weakens Steel but not Woman Waving in WTC North Tower
9/11 Woman Waving In The North Tower Hole
Woman Waving From WTC 1 Impact Area
Video of Edna Cintron waving:
Editor’s note: The appearance of Edna Cintron, looking out of the hole in the North Tower caused by the airplane impact, raises doubts about the existence of raging fires at the impact point hot enough to substantially weaken steel, which according to the official account caused the collapse of the Twin Towers. Note also the near absence of smoke and flames. Where’s that steel melting fire? Where are the “RAGING FIRES”?
FIRE AND SAFETY STANDARDS
Are Steel Framed high rises any safer today than they were on 9/11? What safety measures have been taken to improve the quality of our sky scrapers? Steel framed high rises have never collapsed from fire in the history of modern construction before or after 9/11. Yet we were told it happened three times in one day.
The Behaviour of Multi-Storey Steel Framed Buildings in fire
FIRE BEHAVIOR IN WORLD TRADE CENTER 2
EMERGENCY WARNING FOR OFFICE WORKERS (NIST WTC7)
Are Millions of Business People At Risk of Dying In Collapsing Buildings?
High-rises remain vulnerable after 9/11
“More than a year after terrorists destroyed two of the tallest skyscrapers in the world, few physical or structural changes have been made to strengthen tens of thousands of other high-rises in America.”
HOW LONG DID THE FIRES LAST?
“longest-burning structural fire in history”
Why Didn’t Millions of Gallons of Water Put Out the Ground Zero Fires?
“4 million gallons of water were dropped on Ground Zero within the first 10 days after September 11, according to the U.S. Department of Energy’s Lawrence Berkeley National Laboratories:
Approximately three million gallons of water were hosed on site in the fire-fighting efforts, and 1 million gallons fell as rainwater, between 9/11 and 9/21 ….”
Ground Zero’s fires still burning
“Almost 12 weeks after the terrorist atrocity at New York’s World Trade Center, there is at least one fire still burning in the rubble – it is the longest-burning structural fire in history.
Deputy Chief Charles Blaich of the New York City Fire Department would not predict when the last fire might be extinguished. But compared to the situation at the end of September, when aerial thermal images showed the whole of Ground Zero to be a hot spot, conditions today are much safer for the workers clearing the rubble.
This is in part due to the use of a special foaming agent called Pyrocool FEF. On 27 September, the officials ordered 2000 gallons of the liquid, which when added to water produces a slippery, low-viscosity foam.”
How Did the WTC Fires Burn for Months?
WTC Fire Extinguished
“The underground fires that have burned at the World Trade Center site, New York for the past three months have finally been extinguished, Gov. George Pataki said Wednesday.” December 20, 2001
Governor Pataki on Ground Zero
@ 2:00 “and you look and you see and there’s no concrete. There’s Very little concrete. All you see is aluminum and steel. The concrete was pulverized.”
@ 3:10 “You can see the Buildings around it that have been incredibly damaged… but thank god they are structurally sound, they aren’t going to come down.”