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October 4, 2011

9/11: The collapses of the three WTC towers still unexplained

Scott Stockdale

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In The Open Civil Engineering Journal, 2008, 2, 35-40, Steven E. Jones, Frank M. Legge, Kevin R. Ryan, Anthony F. Szamboti, and James R. Gourley, explain why, after a thorough investigation, they've concluded that the National Institute of Standards and Technology (NIST) reports on the destruction of the World Trade Center buildings on 9/11 are false.

On September 11, 2001, the Twin Towers of the World Trade Center (WTC) were hit by airplanes. Total destruction of these high-rises at near free-fall speeds ensued within two hours, and another high-rise, which was not hit by a plane (WTC7), collapsed about seven hours later at 5:20 p.m.

The US Congress laid out the charge specifically to the National Institute of Standards and Technology (NIST) to “Determine why and how WTC1 and WTC2 collapsed following the initial impacts of the aircraft and why and how WTC7 collapsed”. The Federal Emergency Management Agency (FEMA) was acting with a similar motivation in their earlier study of these tragic collapses.

Apparently it is difficult to fully explain the complete and rapid collapse of WTC7 with a fire-based hypothesis alone.  FEMA analyzed the remarkable collapse of WTC building 7, the 47-story skyscraper that, even though it was not hit by a plane, collapsed about seven hours after the second Tower collapse. 

Mr. Ryan said he and his co-authors of the above-mentioned paper, agree that that FEMA's best firebased hypothesis for the collapse of WTC 7 has “only a low probability of occurrence.” Thus the actual cause of the building's collapse remains unknown.

Because both WTC1 and WTC2 were designed to withstand the accidental impact of a Boeing 707, it's not surprising that WTC1 and WTC2 were stable after the aircraft impact, standing for 102 minutes and 56 minutes, respectively.

John Skilling's, a leading structural engineer for the WTC Towers, said he and his people concluded, after analysing the effects of a Boeing 707 hitting a WTC building, that there would be a horrendous fire from the airplane's fuel but the building structure would still be there.

An early FEMA report promoted the “pancake theory” of collapse, whereby the progressive failure of the floor systems in the WTC towers. This theory has been strongly pushed in documentaries such as “Why the Towers Fell” and publications such as Popular Mechanics, but Mr. Ryan and his colleagues point out that NIST said that the “pancake theory” is not scientifically tenable.

In its report NIST asks the question “How could the WTC towers collapse in only 11 seconds (WTC1) and 9 seconds (WTC2) — speeds that approximate that of a ball dropped from similar height in a vacuum (with no air resistance)?”

In Section 6.14.4 of NIST NCSTAR 1, it states that these collapse times show that: “… the structure below the level of collapse initiation offered minimal resistance to the falling building mass at and above the impact zone. The potential energy released by the downward movement of the large building mass far exceeded the capacity of the intact structure below to absorb that energy through energy of deformation. Since the stories below the level of collapse initiation provided little resistance to the tremendous energy released by the falling building mass, the building section above came down essentially in free fall, as seen in videos”

Mr. Ryan and his colleagues said NIST neglects a fundamental law of physics in trying to explain the free fall collapse of each Tower, namely, the Law of Conservation of Momentum.

“This law of physics means that the hundreds of thousands of tons of material in the way must slow the upper part of the building because of its mass, independent of deformation which can only slow the fall even more.”

Many published papers claim that leaving the free-fall speeds unexplained is negligence on the part of NIST. Moreover, many critics of NIST's official  report point out it ignores the possibility of controlled demolitions, which achieve complete building collapses in near free-fall times, by moving the material out of the way using explosives.

While the official explanation claims that fire destroyed the buildings, numerous experts - including fire engineering expert Norman Glover – have said that no building like it [WTC7], a modern, steel-reinforced high-rise, had ever collapsed because of an uncontrolled fire; and engineers have been trying to figure out exactly what happened and whether they should be worried about other buildings like it around the country.

Mr. Glover said: “Almost all large buildings will be the location for a major fire in their useful life. No major high-rise building has ever collapsed from fire… The WTC [itself] was the location for such a fire in 1975; however, the building survived with minor damage and was repaired and returned to service.”

Yet for scientifically unexplained reasons, three such high-rise buildings completely collapsed on 9/11.

NIST stated that: “The initial jet fuel fires themselves lasted at most a few minutes,” and it added that at any given location the duration of (air, not steel) temperatures near 1000 degrees Celsius was about 15 to 20 minutes. The rest of the time, the calculated temperatures were near 500 degrees Celsius or below.

Mr. Ryan and his colleagues ask how, if the fires were brief and patchy, could both towers experience sudden-onset failure of structural steel  over a broad area in each tower; and how could the collapses of all three WTC high-rises have been so symmetrical and complete?

Moreover, in no instance did NIST report that steel in the WTC towers melted due to the fires. The melting point of steel is about 1,500 degrees Celsius (2,800 degrees Fahrenheit). Normal building fires and hydrocarbon (e.g., jet fuel) fires generate temperatures up to about 1,100 degrees Celsius (2,000 degrees Fahrenheit).

Professor Thomas Eagar said the fire is the most misunderstood part of WTC collapse, not doubt in no small part because of the deliberately misleading information that was and is being put out about it.

“Even today, the media report (and many scientists believe) that the steel melted. It is argued that the jet fuel burns very hot, especially with so much fuel present. This is not true.... The temperature of the fire at the WTC was not unusual, and it was most definitely not capable of melting steel,” Professor Eagar said.

Of course, NIST then may have trouble explaining the molten material flowing out of the South Tower just before its collapse.

In what is a clear violation of investigative procedures, it is estimated that roughly 0.25 percent to 0.5 percent of the 200,000 tons of steel used in the construction of the two towers was recovered, while the lack of WTC7 steel precludes tests on actual material from the structure.

Mr. Ryan said that not only was the steel not examined, it was disposed of, preventing future examination.

“For more than three months, structural steel from the World Trade Center has been and continues to be cut up and sold for scrap. Crucial evidence that could answer many questions about high-rise building design practices and performance under fire conditions is on the slow boat to China, perhaps never to be seen again in America until you buy your next car.”

He added that hopefully we can agree that the destruction of 99 per cent of the steel – evidence from a crime scene – was suspicious and, probably illegal.

Meanwhile, FEMA (based on work by Worchester Polytechnic Institute Investigative team) found “evidence of severe high temperature corrosion attack on the steel, including oxidation and sulfidation with subsequent intergranular melting,” which it deemed to be very unusual, as there is no clear explanation for the source of the sulfur.

WPI researchers called for a detailed study of this high temperature oxidation and sulfidation, but yet this was ignored by NIST.

Meanwhile, an article in the journal New Civil Engineer states:

“World Trade Center disaster investigators [at NIST] are refusing to show computer visualisations  of the collapse of the Twin Towers despite calls from leading structural and fire engineers, NCE has learned. Visualisations of collapse mechanisms are routinely used to validate the type of finite element analysis model used by the [NIST] investigators. …A leading US structural engineer said NIST had obviously devoted enormous resources to the development of the impact and fire models.”

Due to the many errors and omissions they found in the NIST report about the collapse of the WTC buildings, Mr. Ryan sent a letter to NIST asking for corrections and explanations for its conclusions. NIST replied with remarkable candor.  Its letter stated: “This letter is in response to your April 12, 2007 request for correction...we are unable to provide a full explanation for the total collapse. “

And this was after NIST had published some 10,000 pages on the collapse the WTC towers.

Mr. Ryan also questions why NIST didn't test the evidence of the WTC towers for explosive or thermite residues, when probing for residues from pyrotechnic materials including thermite in particular, is specified in fire and explosion investigations by the NFPA 921 code:

“Unusual residues might remain from the initial fuel. Those residues could arise from thermite, magnesium, or other pyrotechnic materials.”

Mr. Ryan said he and his colleagues may be able to help out here because they have looked at residues  from the WTC, using state-of-the-art analytical methods  - especially in the toxic dust that was produce as the buildings fell, killing thousands of people – and he said  the evidence for thermite is mounting.

After outlining numerous discrepancies and unexplained events in NIST's report, Mr. Ryan wrote to NIST and said his investigative team would like to build from this foundation and correspond with the NIST investigation team.

“We are offering to discuss these matters in a civil manner as a matter of scientific and engineering courtesy and civic duty. The lives of thousands of people may very well depend on it.”

To date there has been no evidence of a reply.

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