Friday, September 23, 2011

Impression after Reading NOVA Transcript "Why the Towers Fell" April 30, 2002

"Why the Towers Fell"

My friend on Newsvine told me I need help because I'm a 911 truth seeker. I had provided a link to 911 review, which he said had been debunked. So I asked him for more information. He sent me to NOVA. So I read the transcript. Most of the "facts" are presented by the narrator. The experts are ambiguous. It just looks like another Op-Ed piece.

They (NOVA) didn't put a lot of effort into introducing the players in the interviews. So I decided to help them out a little.
MATTHYS LEVY (Author, Why Buildings Fall Down) -- Matthys Levy is an author, for certain, but so much more.
W. GENE CORLEY (Structural Engineer) -- From Wiki: "served as the lead investigator on the FEMA World Trade Center Building Performance Study, following the September 11, 2001 attacks"
JAKE PAULS (Building Safety Analyst) -- Has a great website, but I'm not sure what he had to do with the official investigation.
LESLIE ROBERTSON (Engineer, World Trade Center) -- Speaks for itself.
CHARLES THORNTON (Structural Engineer) -- I don't know. This site may belong to him.
JONATHAN BARNETT (Professor, Fire Protection Engineering) -- PROFESSOR OF FIRE PROTECTION ENGINEERING AT WORCESTER POLYTECHNIC INSTITUTE

Then I divided the facts into statements by the narrator and the experts as follows.
The narrator makes authoritative statements:


NARRATOR: These pictures show that the South Tower fell away from the impact wall and toward the side where the fire had concentrated. To the team, this suggested a particular mechanism for the collapse, which the video helped confirm.The plane slammed along the eastern wall, starting a fierce fire in the northeast corner and severely damaging many of the steel columns in this area. The heat of the fire would have softened both the floor trusses and the outer columns they were attached to. When the steel became weak, the trusses would have collapsed. And without the trusses to keep them rigidly in place, the columns would have bent outward and then failed.
NARRATOR: The team now believes the North Tower collapsed in a different manner than the South. The main clue lies in what happened to the TV antenna, which rested directly on top of the core.



NARRATOR: The reason the core failed first in the North Tower can be explained by the way it was hit. The 767 had smashed through the outer wall and impacted the inner core directly, damaging or destroying essential load-bearing columns and their fire protection.In this scenario, the fire would have softened the already weakened core columns to the point where they could no longer carry weight from above. When these columns finally failed they immediately precipitated another progressive collapse.Knowing how the towers collapsed does not fully explain what specific components failed. For that, the investigators needed to examine the remains of the buildings.
NARRATOR: The plane sliced into the South Tower at an angle to the right. Unlike in the North Tower, the core was not hit dead on. But in one crucial respect the South Tower was hit in a far more damaging way than the North. It had been struck far lower down which meant the wounded section was having to bear a far heavier load.


NARRATOR: Although the path of the impact did not compromise the core as severely as in the North Tower, here the plane acted like a snowplow, pushing office contents and debris into the northeast corner and starting a raging fire at that spot.



NARRATOR: Clark and Praimnath were two of only eighteen people to escape the towers from the impact zones or above.
Less than a quarter of an hour after it had been hit, all the conditions for the collapse of the South Tower were in place. The huge weight of the top third of the building was bearing down on the weakening structure. Analysis of the steel from this part of the building reveals that the fire here reached 2000 degrees Fahrenheit, a temperature that would definitely have caused the steel to buckle.
Inside, the fire was weakening the floor trusses. Some were starting to soften and sag, pulling on their bolted connections to the columns.
NARRATOR: As they searched the visual record for the precise moment and trigger for the South Tower collapse, engineers Gene Corley and Bill Baker found crucial evidence in video shot by a nearby firm of architects. It reveals that much of the central core remained momentarily intact when the outer walls fell.
If the core remained standing, something else must have triggered the collapse.
NARRATOR: These pictures show that the South Tower fell away from the impact wall and toward the side where the fire had concentrated. To the team, this suggested a particular mechanism for the collapse, which the video helped confirm.
The plane slammed along the eastern wall, starting a fierce fire in the northeast corner and severely damaging many of the steel columns in this area. The heat of the fire would have softened both the floor trusses and the outer columns they were attached to. When the steel became weak, the trusses would have collapsed. And without the trusses to keep them rigidly in place, the columns would have bent outward and then failed.
NARRATOR: This footage shows the process in action. A line of columns in the outer skeleton snaps. The top of the building then lurches outwards and falls. As it does so, it dislodges many more floor trusses. Once the trusses fail, the floors they were holding cascade down with a force too great to be withstood. The result is what's called a "progressive collapse," as each floor pancakes down onto the one below.



NARRATOR: The reason the core failed first in the North Tower can be explained by the way it was hit. The 767 had smashed through the outer wall and impacted the inner core directly, damaging or destroying essential load-bearing columns and their fire protection.
In this scenario, the fire would have softened the already weakened core columns to the point where they could no longer carry weight from above. When these columns finally failed they immediately precipitated another progressive collapse.
Knowing how the towers collapsed does not fully explain what specific components failed. For that, the investigators needed to examine the remains of the buildings.
NARRATOR: From the evidence found at the steel yards, and from computer modeling of applied forces, the team now believes the truss connections probably did fail from the force of the impact, the heat of the fire, or both. But the study concludes that there was a more fundamental reason for the overall collapse.

Comments from the experts:

MATTHYS LEVY: It was very much like a controlled demolition when you look at it, because the building essentially fell almost vertically down, as if someone had deliberately set a blast to take place to cause the building to fall vertically downward.

GENE CORLEY: I have looked at now two major terrorist attacks, and I never want to look at another one in the future. I want the findings that we have obtained from these studies to be used to develop buildings that will provide more safety for those who are in those buildings.

LESLIE ROBERTSON: It was really a young person's project. It took a huge amount of energy. Did a lot of things that I don't think an older engineer would have bothered to do, because he would have had confidence in the work that he'd done in the past. And I was charging down a different highway.


LESLIE ROBERTSON: We had designed the project for the impact of the largest airplane of its time, the Boeing 707, that is, to take this jet airplane, run it into the building, destroy a lot of structure and still have it stand up.



LESLIE ROBERTSON: With the 707, to the best of my knowledge, the fuel load was not considered in the design. Indeed, I don't know how it could have been considered.
CHARLES THORNTON: They didn't have the mathematical models in the computers to model a fire as a result of the fuel in a 707. I was asked in 1986 what would happen if a plane flew into the Trade Center. And I said it would not knock the building down from the pure physics of the mass hitting the building. But we...none of us really focused on that kind of a fuel fire.

MATTHYS LEVY (Author, Why Buildings Fall Down): As the steel began to soften and melt, the interior core columns began to give. Then you had this sequential failure that took place where it all pancaked—one after the other.


CHARLES THORNTON: They had two 5/8-inch bolts at one end of the truss and two 3/4-inch bolts at the other end, which is perfectly fine to take vertical load and perfectly fine to take shear loads, but once the floor elements start to sag during a fire...okay...they start exerting tension forces because it becomes a catenary, like a clothesline, and those two little bolts just couldn't handle it.


LESLIE ROBERTSON: I think the structures were stalwart, but they were not that stalwart. There was no fire suppression system that could even begin to deal with that event. Nothing. Nothing. So I didn't know whether they would fall or not fall.


CHARLES THORNTON: As you start to lose the lateral support due to the floors, the exterior just crumples like a piece of paper. Or if you took a sheet of cardboard and you put some weight on it and you take out the lateral supports it will just bow right out.

GENE CORLEY: Looking at the films of the North Tower, it appears that the antenna starts down just a little bit before the exterior of the building. That suggests the core went first.


CHARLES THORNTON: Had the floor system been a more robust floor system with much stronger connections between the exterior and the inside, I think the buildings probably would have lasted longer. Would they ultimately have collapsed? Maybe not.


GENE CORLEY: We found that the types of fireproofing that were used were damaged by the aircraft hitting them. If the fire resistance of the building was increased so that the material in there could burn out before a collapse occurred, then you could come back in quickly afterwards, stabilize the building and save it from collapse.


JONATHAN BARNETT: We have a long history of successful steel construction in this country and, in fact, the world. And one of the great successes is that under normal fire conditions we don't have building collapse. In fact, until 9/11, I was unaware of any protected steel structure that had collapsed anywhere in the world from just a fire.


GENE CORLEY: It was the combination of the impact load doing great damage to the building, followed by the fire, that caused collapse. We need to look for types of fireproofing that can take the impact and can stand up to the impact and stick to the steel after the impact.


I place the authoritative comments from the experts here to separate the opinions from the facts:


CHARLES THORNTON: They had two 5/8-inch bolts at one end of the truss and two 3/4-inch bolts at the other end, which is perfectly fine to take vertical load and perfectly fine to take shear loads, but once the floor elements start to sag during a fire...okay...they start exerting tension forces because it becomes a catenary, like a clothesline, and those two little bolts just couldn't handle it.
MATTHYS LEVY (Author, Why Buildings Fall Down): As the steel began to soften and melt, the interior core columns began to give. Then you had this sequential failure that took place where it all pancaked—one after the other.


Other than the authority of the Narrator, I have two facts from the experts, Charles Thornton and Matthys Levy. Now to the NIST report.


I think this is the final report.


An October 25, 2002 Report "of interest" (not a suspect)

In this report, the study concludes it was not a failure of the trusses, but a failure of the columns in both towers.
The report exonerates the floor trusses for the collapses. "Failure of the floors...was shown not to have had any significant role in the initiation of the collapses," it says. Studies by Hughes Associates and ARUPFire led the team to conclude that tower floors survived the initial impact of the planes, suffering only localized damage. On the basis of a review of smoke plumes and fire spread, for each tower, the engineers concluded that the fires did not lead to the collapses of the floors affected before the towers fell. Additionally, the engineers claim that computer modeling shows that the failure of columns alone, independent of the floors explains the collapses.
If I could pull up the NIST report, I might find another explanation. The NIST site is behaving peculiarly, and I'm tired, so I'll save the rest for later. I'm not a 911 truth-denier or conspiracy theorist. I'm a critical thinker. I was disappointed when I caught my dad playing Santa Claus. Wait, that's not true. Mom and Dad gave us lots of cool toys. I guess I became a skeptic, but I liked the toys. So if I had to choose between Santa and no toys, I would choose Santa. Today we have a different set of problems. I don't believe the official story, and reading from different sources, gathering opinions, I see that the answer is still unknown, which is not a theory.

3 comments:

  1. You are truly a disgrace to the human race. You don't have to seek anything...what happened was an attack on America and we had the right to fight back. Just LEAVE IT ALONE!

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  2. That first line kind of rhymes a little.

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  3. This comment has been removed by a blog administrator.

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