The 9/11 Forum

Hi all, sorry not been on in ages!

I was wondering if anyone could help address these points raised in another forum:

''All I am trying to say is that given a natural collapse scenario, the top section would have been destroyed at the same rate as the lower section, or even faster because the members become stronger lower in the building. The hypothetical pile driver would be consumed in the process. See What a Gravity-Driven Demolition Looks Like

However, what we actually witness is the top section being destroyed even faster. It is half gone by the time the lower section starts descending.''

Yes with the 12 foot drop the top section experiences, its not going to be able to be arrested.

''Your claim is not based on any analysis other than your intuition. In fact this has been computed competently by others, and even if it stayed intact, its motion would be arrested. See NIST and Dr. Bazant - Simultaneous Failure in the Journal of 9/11 Studies.''

I see nothing unusual about air being forced out of different areas on their respective floors. The towers were around 95% air remember.

''Squibs occur many floors below the collapse front where floors are not collapsing. If floors were collapsing to account for isolated squibs the problem would be where did all the rest of the air go? The typical squibs do not have the volume flow to account for it all. Furthermore, in the squibs we are seeing material other than air blown out. What is causing this to happen far below the collapse front? We are clearly looking at a different phenomenon that can best be accounted for by explosives.''

I would really appreciate any thoughts on this.

SImple: the lower section participates in its own destruction. It's not "block versus block"; as lower floors are hit by the upper section they join that pile driver and assist in the pounding of floors below. Moreover: the upper section telescopes into the lower section, and gets funneled downward by the perimeter, which peels off after the crush front has already passed by. You won't see that "block" hammering from your (camera based) vantage point. You're seeing rubble thrusting down through a chute (the perimeter).

As for those squibs: apart from the terminology being erroneous (ask OneWhiteEye), I personally believe they were caused by debris pushed through HVAC shafts not visible in the original architectural drawings. However, others, such as OWE iirc, have postulated naturally occurring vent paths along corridors. Kevin Ryan's "overpressure" analysis at J.O.N.E.S. is correct, afaict, but ignores these possibilities. The first time I thought I had "cracked" the puzzle was when I saw an Achimspok video where I saw a so-called "squib" 's horizontal velocity increase linearly with the upper section's vertical velocity.

I wish I had the time to be more elaborate here, but I don't, and I feel lazy too.

At the very least: let go of that artificial separation/split between upper and lower. It's useful for Bazant's bounding case but not as a deterministic reflection of what actually happened. Lower iteratively becomes the new upper as the building collapse progresses.

No, I appreciate your reply thanks. I agree that the two sections should not be considered as blocks, and it makes more sense now about the 'squibs'.

The *squib* ejections appear to be the artifact of material falling at close to free fall... with little to no resistance INSIDE the tower. Ha? This is conceptually possible if there are vertical pathways for materials to fall. There were - elevator and mechanical shafts.

The concept being that the destroyed material above these shafts... which need not be continuous the entire height.. but continuous over many stories such the shaft functioned as a frictionless duct/channel for descending material. The rest of the material seen ejected at the crush front had to over come the resistance of each floor.. so it had to be slower than FF acceleration and appears to be moving down through the tower at 65mph.

The theory about why it shoots out horizontally is that the shafts had terminations... such as elevator pits which forced the downward falling debris to be forced out of the shaft in a path of least resistance, perhaps directed by corridors within the core.

This sounds a reasonable theory to me, do you think there would also be lots of air, being forced down the buildings shafts at great speed, increasing the velocity of the debris being ejected?

One response someone made was:

The core structure is thoroughly cross braced. Destroying the core is part of the problem NIST couldn't answer, so they went to the solid block model and claimed a pile driver. (As you recall, my use of the pile driver model was in order to show its flaws.) If the columns misaligned and speared past one another, the cross bracing would be torn apart, both in the top section and lower section of the building, and you would have just loose rubble falling, which would not be able to crush the lower core section. Therefore 12 top floors would be expected to survive no more than the destruction of 12 lower floors.

The core was not crossed braced except below the plaza level

The towers were a moment frame with rigid connections and used the pre assembled panels which formed a membrane like vierendeel truss for stiffness. A typical approach is to use diagonal members which create triangles which cannot distort as a rectangle can become a parallelogram. A vierendeel truss simply makes the 90° joints so rigid that the frame can't deform under expected loads.

NIST didn't answer much of the structural issues because they were hiding the true nature of the collapse which has nothing to do with the core... The collapse of the core at the plane strike zone enabled the collapse of the floors below leaving all columns below the crash zone UNCRUSHED.... they fell and broke apart from Euler buckling and LATERAL forces associated with the floor collapse. The facade panels parted by ripping their bolted and some cased welded connections.

There was no diagonal bracing in the twins core except in the hat truss (naturally) and below the plaza level.

Thanks when you say NIST were hiding the tru nature of the collapse what does that mean>? I know they were tasked with the collapse initiation but that's all.

Ill,
We act with intention behind our actions (and words)... NIST was tasked to explain the collapses... admittedly hard to believe at first glance... how could such massive structures collapse like that.. especially if they survived the impacts of the planes?

So they had to explain what happened to a waiting public. And of course it would be a *scientific and engineering based* explanation... technical.

We don't know what their investigation revealed. But some of us... who post at this forum came up with a sound technical explanation... as compared with the one NIST produced which is clearly not based on the observations data or the engineering features of the towers and engineering principles in general.

How did that happen? We don't know. I suspect...with no basis other than their dumb explanation AND the fact that they DID /DO have the technical expertise to get it right... that they had some agenda to *get it wrong*. They had far more data and test samples than those on this forum have/had.

My suspicion as stated in other threads... is that they discovered that both the twins and B7 had collapsed because of structural design (decisions) which I will call errors/incompetence and these decisions would make those who took them responsible for criminal negligence leading to the wrongful death of thousands.

While it certainly COULD be true that a hijacked plane slamming into the twins could set off a "chain reaction" of events... a cascading series of failures... or even a few well placed devices in the core... once the cores failed at the plane strike zone.. the towers were toast... they came down like a house of cards.

NIST probably realized the flaws and that structures such as the Sears Tower, the Empire State Building and other traditional steel frames would NOT collapse like a house of cards decided to conceal this finding/fact and so they came up with a truss failure from EXTREME fires. It seems to have been a CORE failure leading to the ROOSD floor collapse... It's the ROOSD that is what they don't want to reveal... and they don't even discuss the global collapse mechanism because that's where the design flaws were... among other decisions... like the type of FP on the core columns etc.

The NIST reports provided cover for the engineers, architects, developers etc. who enabled the open floor concept in an extremely tall building.

That's my hunch.

So basically you're saying NIST's findings were predetermined to protect those who (badly?)designed the structures? I think that for example the inward bowing of the perimeter columns was an observation they saw and used in their report.

Ill,
They can't fabricate the entire event... this is not quite through the looking glass. They, as they did in B7 make up some story which includes some correct observations, engineering and the actual structure... but they also omit stuff, distort or omit observations.

You could probably fail a structure starting from an single column failure with enough heat inputs in the structure to weaken it. But with B7 it didn't relate to reality.

Same thing with CD... it fits some observations, ignores others and misreads many and dismisses physics and engineering such a Euler...to come to the CD explanation. Junk science essentially will return any result and fool many.

One question I always find a good one is, how can building 7 fall at free fall for 8 stories? Its a tough one right?

The answer is not simple. But first I challenge you to prove that the entire building fell at free fall. To be honest you are seeing a video and can't see past the facade... You can't see anything below something like the 23rd floor and there are only a few camera angles at that.

What we do see falling at FF had nothing below to resist its descent. Perhaps the entire lower 8 stories folded inward... the sub station was rather empty structurally.. and so if it did and pulled the curtain wall with it .. the curtain wall from flr 8 would have nothing above it... ergo it could show FF descent.

There is reason to believe that something like the above may have happened... the core above flr 8 dropped through the sub station and the region around would then likely be pulled in after it.. none of this seen by the video cameras.

How does that sound?

Illuminist14 wrote:One question I always find a good one is, how can building 7 fall at free fall for 8 stories?

It didn't.. Both Chandler AND NIST's measurements are inadequate. A video camera is not a scientific measurement apparatus. Other measurements exist and have been published on this forum which show a very different acceleration profile, which even exceeds g and has different implications. (However, even that has now been challenged again... and so on and so forth)

It is possible that WTC 7 was deliberately demolished with explosives, yes. But the argument you are putting here is based on a faulty premise from AE911Truth and NIST. (8 stories of gravitational acceleration)