If the Twin Towers were NOT brought down by demolition...

[spooked911]

I have a question: how did the central core structures give way so quickly and uniformly?

If possible, could someone describe step by step what happened from when a floor first started collapsing to when the tower starts disintegrating in a violent eruption. And specifically, could someone explain exactly what happens to the core structure in a pancake collapse scenario?

In the case of the south tower, the core was hardly touched-- so how did the core collapse so quickly? Shouldn't the core have been able to support the weight of the building even if part of the outer shell was partially damaged?

In the case of the north tower, the core was probably damaged to some extent, but the hit was almost at the top of the building-- so there was relatively little weight on the damaged core. So what gave rise to the systemic collapse?

I will try to have an open mind about this.

Thanks for your answers.

[philb]

1. Debris didn't look like pancake scenario & huge amt. of fine dust

from concrete, glass, asbestos, etc. in building expelled outward and upward didn't seem to fit pancake theory either

[Rob Conn]

2. The silence is deafening

Don't expect too many responses to this query. The instigators don't have an answer because the buildings were demolished. - R.C.

[Bolo Boffin]

3. The deafening silence of a single hour?

Some of us have lives, you know.

[Bolo Boffin]

4. You are in luck.

The draft of NIST's final report on the WTC towers will be released on June 23. As of right now that's less than 36 hours away.

[spooked911]

5. Does this mean you can't explain what I asked about?

[Bolo Boffin]

7. Well, okay.

I'll do what I can, but what you're asking for will most probably be finally released tomorrow. They will do a much better job than I can do.

Here's the short version, from here:

http://www.nist.gov/public_affairs/releases/wtc_briefing_april0505.htm

The specific factors in the collapse sequences relevant to both towers (the sequences vary in detail for WTC 1 and WTC 2) are:

* Each aircraft severed perimeter columns, damaged interior core columns and knocked off fireproofing from steel as the planes penetrated the buildings. The weight carried by the severed columns was distributed to other columns.
* Subsequently, fires began that were initiated by the aircraft’s jet fuel but were fed for the most part by the building contents and the air supply resulting from breached walls and fire-induced window breakage.
* These fires, in combination with the dislodged fireproofing, were responsible for a chain of events in which the building core weakened and began losing its ability to carry loads.
* The floors weakened and sagged from the fires, pulling inward on the perimeter columns.
* Floor sagging and exposure to high temperatures caused the perimeter columns to bow inward and buckle—a process that spread across the faces of the buildings.
* Collapse then ensued.

The sequences are supported by extensive computer modeling and the evidence held by NIST, including photographs and videos, recovered steel, eyewitness accounts and emergency communication records.

This is the towers (the report on WTC 7 is going to be delayed until later in the year). Nothing is said about uniform destruction of the core. In fact, it's the progressive buckling of the perimeter columns that initiates collapse. Once they buckled, the weight tore the core columns apart, and I doubt that it was a "uniform" process. It happened as it happened.

And the core couldn't support itself without the perimeter columns. That's why they were there. Without the perimeter, the core collapses of its own weight.

[spooked911]

9. Thanks. I agree the early stage of the collapse makes sense

according to this buckling model, if we assume the fire really weakened the columns significantly. What I can't understand is how the initial collapse progressed to the massive volcanic collapse we've all seen. What caused the core structure right below where the buckling occurred to give way evenly and rapidly when it was not affected by the fire?

For instance, the upper 30 stories of the south tower were clearly breaking off as a large chunk-- you can see this part of the building tilt over significantly? Why didn't this section of building continue to fall over and break all the way off? Granted, it would have smashed one side of the building as it fell-- but rather than havng an asymmetrical and partial collapse, the whole section of building below this 30 story section explodes and then the whole building progressively and evenly gives way. This is what I don't understand. The fact is, getting large towers to fall straight down is not a trivial feat. This is why controlled demolitions are used in these situations.

[Kevin Fenton]

6. Opposite way round

Didn't the NIST presentation say there was much more damage to the core in the south tower - 10 columns severed as opposed to 6 (or something like that)?
I thought that's supposed to be why the south tower collapsed first, even though there was less damage to the outer columns and the fires weren't as bad.

[spooked911]

8. Not the presentaiton I saw. They actually don't really know how many core

columns were broken, they can only guess. But what I saw said there were a couple of damaged columns in the south tower and many more in the north-- this makes sense as flight 11 hit full on in the center whereas flight 175 hit on the side and basically missed the core.

[Kevin Fenton]

10. Severed columns

I was talking about this presentation:
http://wtc.nist.gov/NFPA_Presentation_on_WTC.pdf
which was given on 8 June 2005.

Pages 18 - 21 have the column damage diagrams. My interpretation of page 18 (North Tower) is that the 6 red core columns were severed. My interpretation of page 21 (South Tower) is that the 10 red core columns were severed.
I assume the reason the fire in the South Tower is not as hot is because there is less damage to the sprinkler system and the hole was smaller, so less air got in.

[spooked911]

11. Okay-- thanks for that. The NIST powerpoint presentation from last year

showed more columns affected in the North tower. So they changed it-- probably to help explain why the south tower came down first.

[Kevin Fenton]

12. My impression

is very much that they built a computer model and fed various numbers into it until the towers came down at exactly the right time. If they said, "OK, we've built this computer model and it's not 100% accurate - the South Tower falls five minutes later and the North Tower falls five minutes earlier" - then I would find that more credible than if the model shows why the towers fall down exactly when they do.

[spooked911]

13. Good point. You do have to wonder how much they finessed their

model to come out the right way-- and it's not like they show you all their calculations.

[Christophera]

14. Instant Molecular Disintegration Buckling

Remarkably the central core structures collapsed of their own weight torn apart by the falling perimeter columns then molecuarly disintegrated, never to be seen again.

Devastating Muslim technology, defying the laws of physics and destined to take mankind into outer space.

[philb]

17. Is anyone really suggesting this was caused by pancake effect??

http://911research.wtc7.net/talks/towers/mushrooming.html

Its pretty obvious there is some type of huge explosive force when the towers started to explode and disintegrate- I don't think you could call that a collapse.

[Christophera]

18. Photos Don't Show Multiple Core Columns = Does Not Compute.

Posted by philb

Its pretty obvious there is some type of huge explosive force when the towers started to explode and disintegrate- I don't think you could call that a collapset

The above has ALWAYS been my position from the first second on 9-11-01 watching live, the towers falling.

spooked911

If the Twin Towers were NOT brought down by demolition...
I have a question: how did the central core structures give way so quickly and uniformly?

The buckling causes 1300 foot long super strong pieces of steel, pieces of steel that have to topple and fall outwards from the footprint. Where are they? There were 47 and supposedly a number were severed, well, what happened to the rest of these things. They were huge, supposedly bigger than this spire formed by an interior box column as can be seen by the floor beams connected to it, It is outside the core.



The pancake thing. OMG, don't make me try and discuss that. Absolutely ludicrious to imagine 14 x 14 inch box columns spaced on 22 inch centers buckling with floor loads one after another. The floors couldn't support enough weight to do that. I can't imagine one floor doing that. It is pure fiction that floor after floor of light trussed steel panels W/lightweight concrete could shear clete hangers for beams AND buckle steel walls. eagers theory points to the shearing clips, others to buckling walls The 1x3 foot "I" beams had clips on the top and bottom flanges but the entire web of the beam was 100% welded to the spandrel plates connecting the box columns.

The notion of pancaking is fully belied by the type wreakage left at ground zero.

[Old and In the Way]

15. I've never understood this point either.

From what I can see in the construction of the WTC, the core was fixed to the bedrock up through all 105 floors. As each floor was build, the core was poured around a steel box frame and then each floor was poured and attached to the core. It would make sense that the design would address deconstruction...at some point they'd want to drop one floor on the next in a controlled manner. Seems the core would be the guide for the floors to drop, one on top of the other. What forces were created to take the core down at the same rate as each floor? I can understand the mass of the floors would create momentum as more and more floors collapse, making the next floor's ability to withstand that accummulated mass shorter in duration.

But that's not what I see in the collapse.

(1) Core collapses at the same rate as the floors.
(2) The rate of collapse is reasonably constant from the beginning to the end of the event.
(3) Why wouldn't the collapse rate be slower at the beginning than at the end? I think the whole event time is somewhere around 18 seconds. The theoretical fastest time the top of each building could hit the ground without factoring any resistance is something like 10 seconds...so that leaves 8 seconds/105 floors....an average of .07 seconds of endurance time before each floor gives way. If we can assume that the mass droping on the 1st floor would withstand for, say, at least 2 seconds before failing, then the rate should get progressive faster as more mass is applied to the next floor in the collapse sequence. But that would seem to mean that the entire event time should have been 2-3x longer than it really took.

That's why I find those seismic spikes so suspicious (the huge one, then 5 or six more immediately following)....if you blew the core pilings, there'd be nothing to support the core's standing. Then if you had charges in the core timed to go sequentially as the event started, every 15 floors or so...you'd end up with nothing but rubble when the smoke cleared.

[Old and In the Way]

16. It would be interesting to know what the plan for deconstruction was.

How would they deconstruct the WTC's when they reached end-of-life? Certainly, a lot of care would be needed to do it with minimal environmental damage. Here's how I would envision it:

Drop the top floor and push the debris down the elevtor shafts, deconstruct the core and the debris down the elevator shaft. Cut up and drop the aluminum perimeter walls/steel carriers down the elevator core.....proceed to the next floor and repeat.