What a Gravity Driven Demolition Looks Like by David Chandler - sottotitolato in italiano

[wildbilln864]

[William Seger]

1. What a paranoia driven cognitive dissonance looks like e.g. David Chandler

Last edited Mon Nov 9, 2015, 02:02 PM - Edit history (1)

Chandler claims that it's been "proved" that "the top section of the north tower of the WTC could not have crushed the lower section of the building." His own "proof" is an analysis which completely ignores dynamic forces, which is a mistake worth about two orders of magnitude. He plots points 0.2 seconds apart from a grainy video, draws a line through them, and declares that his own straight line means the top fell at "constant acceleration," ignoring whatever might be going on between the points. But to make things worse, Chandler claims that the constant acceleration he thinks he measured must be the result of destroying about 90% of the columns. That's an argument which simply demonstrates Chandler's ignorance of structural mechanics and failure modes, in which the resistance would be anything but constant as the top descended, whether it was all the columns or only a few. Chandler has yet to show how any type of collapse, even with magical silent explosives, could possibly produce the constant acceleration he claims. Now, since more careful measurements show that it isn't actually constant, that's a mystery Chandler really needn't solve, but he should at least try if he's going to keep making the same fallacious argument.

Next, Chandler says "the other side of the same coin" is Szamboti's "missing jolt" hypothesis which he claims is another proof because not seeing deceleration "jolts" in videos means there weren't any impacts. That's just a false claim for two reasons: first, small jolts are seen when Szamboti's own data are analyzed properly; and second, if gravity is continuing to accelerate the mass, then impacts don't necessarily produce deceleration. The small jolts that are seen are not of the magnitude Szamboti expected because his first premise is wrong: the top of the building did not fall squarely onto the bottom, allowing all the columns to simultaneously react with their maximum resistance to buckling. The collapse started on one side and progressed horizontally, which produced a tilt and a series of individual failure events spread out over time, with virtually no column-on-column collisions. Examination of the debris shows that most of the destruction was due to ripping the floor structures away from the columns, and with that loss of lateral restraint, most of the columns were pushed aside or buckled and broken at their splices. That required much less force than crushing the columns, which is why it happened first, and in individual failure events where the required force was less than that required to completely counteract the continued gravitational acceleration of the impacting mass, there would be no actual deceleration -- no "jolt" -- just reduced acceleration. Chandler and Szamboti both completely ignore the fact that when they measure the fall of the roof-line, they are really just measuring the averaged effects of thousands of individual failures spread out over time. And, like Chandler, Szamboti does not actually produce any rational controlled demolition hypothesis that actually explains what we see; he just assumes that it's somehow a better explanation.

"To check why this analysis is correct" Chandler then shows a video of a Verinage demolition where the top of a building does indeed fall squarely on the bottom, which explains why the "jolts" are more noticeable. Although it was actually a building with load-bearing walls instead of columns, as Chandler mistakenly assumes, what Verinage demolitions really prove is that if the top of a conventionally designed building falls onto the bottom, there is more than enough gravitational energy to destroy the building, with no need for additional energy from explosives.

As an aside, Chandler then goes on to claim that the Verinage video also shows that the top and bottom sections are destroyed "at the same time" and this "is a clear consequence of Newton's third law, which says that when bodies interact, the forces act equally in both directions." What this really shows is that knowing Newton's laws and applying them correctly in a given situation are two different things, even if you're a high school physics teacher. Chandler completely ignores that the "bodies" that interact in the destruction of the top section are the top interacting with everything below, and the force is due to the mass and momentum of just the top, whereas the destruction of the bottom section involves the interaction of the bottom with everything falling, and the force is due to the mass of the top section plus a debris layer that's increasing as the collapse proceeds. With that understanding, one should not be surprised that in videos of Verinage demolitions where the collapse front can be more clearly seen, the bottom section is in fact destroyed more rapidly than the top. What we really see here is Chandler's "confirmation bias" at work following an analysis model that is simply and obviously wrong. But it gets much worse when Chandler tries to explain why this is supposed to matter: he makes the completely stupid claim that "at most, the top 12 floors might have destroyed an additional 12 floors, but the top section would have been consumed in the process, leaving nothing to crush the rest of the building." In other words, in this physics teacher's world of imaginary physics, the mass and momentum of the debris from those 24 floors would just disappear into an alternate universe because it has somehow been "consumed" by the impacts. Chandler seems to think this ridiculous argument is an additional "proof" against a gravitational collapse, but in fact it raises serious questions about what other kinds of nonsense he might be teaching his students.

Given that there is no need for explosives to explain what we really see and also no evidence of explosives, either, there is no real use for any explosive demolition hypothesis, especially one that requires magical silent explosives yet still doesn't really explain what we see. Like the Harrit "nonothermite" paint chips, there is exactly zero chance that either Chandler's or Szamboti's arguments would ever be published in a real peer-reviewed technical journal, because they are abject bullshit. And make no mistake about it: this is as good as it gets with "truther science."

[wildbilln864]

2. Chandler's correct! You are not!

You ignore that as the towers got taller the core columns get smaller. The lower you go in the towers the larger and more robust the steel! Doesn't stop you from making up bullshit long paragraphs though. Chandler is a physicist. You are what again?

[hack89]

3. The floor pans did not get more robust lower in the structure.

only the vertical columns. Just how were those vertical columns suppose to remain standing without the floor pans holding the structure together?

[wildbilln864]

4. show me the specs that prove your claim or else you...

are pulling that assertion from your anus! But even if correct, then the building's collapse's would have slowed at the very least. Those towers were demolished to the ground with no slowing. Structural debris was expelled in all directions all the way around the perimeters the entire way down! Maybe the floor pans would have "pancaked" but the core columns and perimeter columns would have stood after to then perhaps fall sideways.

[hack89]

6. Why would it slow if the falling mass was getting heavier every second?

KE=1/2 (mass X velocity squared). That means the energy applied to demolishing the next floor down grew every second.

Secondly, we know the structure was twisting when the collapse started based on how the spire fell and how the side walls were pulled in. So there were lateral forces on the vertical columns that would have ensured that they did not remain upright.

Here is the floor design:

The floors of the Twin Towers completed the structural system whose main elements were the core structures and the perimeter walls. The floor diaphragms were annular structures that spanned the distance between the core structures and the perimeter walls, providing large expanses of uninterrupted floor space. The cores had their own flooring systems, which were structurally independent of the surrounding floor diaphragms.

The floor diaphragms consisted of lightweight concrete slabs poured onto corrugated steel pans, which were supported by trusses. Primary double trusses were interwoven with transverse secondary trusses -- a fact ignored by the truss failure theory. The primary trusses were 900 mm deep, and spaced on 2.04 m centers

http://911research.wtc7.net/wtc/arch/floors.html

[wildbilln864]

7. much of that "falling mass"

was going over the sides as seen here:

[hack89]

8. So it didn't collapse in its own footprint?

I thought that was one the clues that it was CD.

[wildbilln864]

9. 7 did yes...

the towers were blown apart. You're just confused.
But you didn't address my point.

[hack89]

10. Since the collapse left a towering pile of debris that filled a massive hole in the ground

I would say that all the heavy stuff fell straight down - which is what one would expect gravity to do. Lots of light stuff like ground up concrete and gypsum would create billowing clouds of debris that might confuse some.

[wildbilln864]

11. you'd be wrong...

in your speculation I would say.

[hack89]

12. So you are denying there was a huge pile of debris that fill a huge hole in the ground?

you do know that there are pictures of ground zero?

Tell you what - how about you show me pictures of heavy debris spread over a large area. I don't think you can.

[wildbilln864]

13. so now you are saying...

they fell into their own footprints?
What "huge hole" are you speaking of?
The basement floors? They were underground floors not huge holes.

[hack89]

15. Pretty much. How else would heavy objects fall except straight down?

don't you believe that too?

There were seven basement levels - most of which collapsed, creating a big hole.

[wildbilln864]

21. so how did

seven basement floors collapse creating a big hole? Maybe you mean the basement floors were piled onto and perhaps into by the building's collapse? No hole being created that wasn't already there. But perhaps filling the void where structure and furnishings were not present?

[hack89]

23. Wasn't the basement mainly open space?

so when the building fell on top of those spaces, they collapsed - creating a big hole that was filled with debris from the falling towers.

[William Seger]

16. Relatively little debris was going over the side

... because the only debris that could go over the side was stuff near the edges of a building that was over 200 feet wide. Watch the video again and think about it: most of the debris couldn't escape because it was trapped under more debris. The amount going over the side would increase as the collapse progressed, but by then it was too late: there was much more than enough mass and momentum in what was left to continue the destruction, and that just got worse as the collapse progressed. Go try to find a real physicist who agrees with "physicist" Chandler that the mass and momentum were "consumed."

[wildbilln864]

22. well that's obvious bullshit!

?resize=600%2C400
A lot of the building went over the sides in all directions and could not have contributed weight to the collapses which still tore all the way down the towers encountering more robust/stronger core and perimeter columns which were previously undamaged.

[hack89]

24. A lot of dust and the external walls

all the interior structural steel plus the contents of the building went straight down.

Unless you have pictures of the core being flung a great distance?

[William Seger]

25. RELATIVELY little debris was going over the side

Yes, when the floors were smashed free from the perimeter spandrels, most of the perimeter column panels and some other debris near the edge would get pushed over the side. But that was a small mass compared to what was left inside, still headed straight down to smash the next floor loose.

[William Seger]

5. We've been through all this before

If you had understood it then, you wouldn't be embarrassing the board by posting new videos of the same repackaged bullshit, and I can't say I'm surprised that you've passed up yet another opportunity to understand it. Chandler is most certainly not a physicist, and you don't need to be a physicist to understand why the arguments he makes are bullshit. LOTS of people understand this, wildbill, and you could be one of them.

[wildbilln864]

14. you are embarrasing the board not I.

And Chandler shows how he comes to his conclusions which you cannot do. Evidently. "We've been through all this before". Well yes and you still don't understand it. It's ok though. Most people have only a rudimentary (if any at all) understanding of physics and engineering also like you.

[William Seger]

17. "And Chandler shows how he comes to his conclusions which you cannot do."

Why do you reply to my posts without reading them?

[wildbilln864]

18. did you do the

caculations using the same tool/program? Or a similar one. So show me how you find errors? Do you even understand how it's used? Try it yourself and show the difference. Put your money where your mouth(fingers) is?

[William Seger]

19. No need to hunt for math errors

... when there are such blatant errors in logic, basic physics, and structural mechanics. Really, you might at least try reading what I wrote so you could at least attempt to explain where you think I went wrong, as I did with Chandler.

[wildbilln864]

20. so you can't. ok. n/t

[William Seger]

26. so you won't. ok. n/t

[wildbilln864]

27. but I did William...

and it's BS.

[wildbilln864]

28. are you asserting there was...

no acceleration? Or that the energy lost to demolish the undamaged larger cored building below would not affect the collapse speed?

[William Seger]

29. No, I'm saying there was no "uniform" resistance to produce "constant" acceleration

... nor would there be even if you blew out some of the columns. That's because the collapse was actually a series of impacts followed by structural failures, followed by the continued gravitational acceleration of the debris down to the next impact. One way to look at it is that the reason the collapse rate was "near freefall" was because mostly the debris WAS in freefall between collisions, after a very a brief descent through the resistance provided by the failing members. Those impacts are the source of the dynamic loading that Chandler's analysis ignores and that Szamboti's analysis overestimates. As I said, what Chandler and Szamboti actually measure is just the AVERAGE of all those individual failure events, and there is no reason to expect a single large "jolt" from them.

[wildbilln864]

30. akin to that ridiculous

sledge hammer meeting Steuben glass nonsense. No! The impacts took energy away from the masses resulting in less energy to destroy the next resisting mass. This would/should slow down the collapses! But it did not which indicates the underlying structures were indeed demolished before impact taking away their resistance. So no reduction in speed and acceleration instead.

[William Seger]

31. You're ignoring gravity

... which is never a good idea. In fact, it's ridiculous. Each collision used up some of the kinetic energy, yes, but it didn't bring the falling mass to a halt, so it didn't absorb all of the kinetic energy. Then, the debris kept falling, which means that even more gravitational potential energy was being converted into kinetic energy as the newly increased mass fell to the next collision. So the falling mass and its momentum and kinetic energy were increasing the whole time. This is basic physics -- you can't turn off gravity -- and if you don't understand it you will never understand the collapse.