Debunked: WTC: Multi-ton steel sections ejected laterally.

[Mick West]

Maybe its a matter of translation... Again: I´m german.
In my understanding, there is a difference between "falling off", "being ejected", "tipping over/away" and "peeling out".
To me it seems impossible to determinate which of those happened to the facade.

What do you think is happening to the section I circled in red, above?

 

[Mick West]

In my understanding, there is a difference between "falling off", "being ejected", "tipping over/away" and "peeling out".

The thread is about the claim that sections were "elected laterally". That means they had an initial horizontal velocity away from the building, as if they were shot out of a cannon.

The general agreement here is that there are no examples known that cannot be explained by a gravity driven collapse. If you'd like to point to one then please try to produce a frame by frame analysis showing the trajectory.

 

[Mick West]

The attached video is made from a sequence of photos, so the timing is not perfect. Howeve,r it does quite clearly show a large section lean out to the side. It's the one on the upper right that momentarily brightens as it falls into the sunlight.

I've attached the file so you can analyze it better. Also on YouTube


Source: https://www.youtube.com/watch?v=oqxveCGOGKQ

 

[Oystein]

Maybe its a matter of translation... Again: I´m german.
In my understanding, there is a difference between "falling off", "being ejected", "tipping over/away" and "peeling out".
To me it seems impossible to determinate which of those happened to the facade.

I am German, too.
You askked for evidence of exterior columns "peeling out" - which is the same, in my understanding as "tipping over/away", but different from "falling off" or "being ejected".

This thread is about "Multi-ton steel sections ejected laterally", and discussion of wall segments tipping/toppling/peeling outwards in large, connected sheets is on-topic only insofar as this rules out that these same segments were "ejected laterally".

The video I posted shows, among other things, a fairly rigid wall section, many stories high, on the right side of the tower rotating about a pivot that's hidden behind the dust cloud but can be estimated to be near the original perimeter, and thus falling over/tipping/toppling like a tree. Do you see what I mean?

Here, let me help you with screenshots and red circles around the wall segment I am talking about:

 

[deirdre]

unclear discussion about what English words mean to a German ear moved to
https://www.metabunk.org/9-11-ejected-laterally-definition-argument.t9923/

 

[toutdoubt]

There is no evidence that the so called "expulsions" traveled at 80 mph. All the columns which fell away followed the basic law of trajectories. The furthest measured steel from 1wtc was at the Winter Garden across West Street. It's max horizontal velocity... toppling from the 80th floor or so was about 35 mph.

What appears to be material flying upwards is mostly material left behind as the "bottom fell out" and the building collapsed down.

In order to explain what happened you need accurate observations and knowledge of mechanics. Otherwise you are dealing with garbage in garbage out.
View attachment 31585

Anyway I can get those small images bigger? the equations etc. Thanks!!

 

[Manooper]

I've come to the same conclusion, that is the pieces are clearly peeling away from the towers, rather than being ejected out. Given the enormous height of the towers, it should be expected that pieces end up hundreds of feet away as the sides fall away.

 

[Jeffrey Orling]

google free fall... the graphics was from the WWW and I don't seem to have the file anymore.

 

[Mick West]

Anyway I can get those small images bigger? the equations etc. Thanks!!

google free fall... the graphics was from the WWW and I don't seem to have the file anymore.

It does not seem to exist anywhere. Perhaps it was clipped from a pdf, or from a private forum.

The diagram in the middle seems to just be a derivation of range (R) from height (h) and eject velocity (Ve) (along with time to fall (t) and impact vertical velocity (Vi). I've roughly recreated it here:

 

[Mick West]

Not only would it not need explosives - worse yet, explosives can't do it without totally obvious supersonic shockwaves from very substantial high explosives charges. I am currently writing up a paper that investigates how much explosives it would take to hurl a wall panel at rest from the nearest WTC wall to the adjacent walls of peripheral buildings (130 Liberty St, WTC 7, WFC3) - or 600 ft, as claimed by AE911T. I have developed math formulas to compute (1) the lateral velocity needed to cross a distance d from a height of h, and then (2) the mass ratio steel:explosives needed to attain that velocity, given the Specific energy of the explosive material. The latter is varied through a range from 1.5 MJ/kg (nano-thermite; or conventional explosives with 30-50% efficieny) to 6.0 MJ/kg (the most energetic high explosives at almost 100% efficiency).
The derivation uses the laws of Conversation of Momentum and of Energy.

The result is that you'd need at leat 3 kg of explosives per ton of steel (e.g. for the Bankers Trust building, only 80 m away, requiring a lateral velocity of just 22.5 mph), but easily exceeding 12 kg/ton (600 ft distance from WTC1 fire zone to the ground). This would result in average gas velocities of 1720 to 3000 m/s - many times the speed of sound in air, i.e. shockwaves. For wall panels weighing several tons, we'd soon approach realistic charge sizes of 50 to 100 kg, perhaps more - and they claim such huge blasts occurred multiple times. That's simply unreal.

Did you ever write this paper? I was thinking this topic might make a good explainer video.

 

[Oystein]

I never completely finished it, but the model and calculations are pretty much done. I just created the attached PDF file from a LibreOffice Writer (.odt) file I had last saved on 2016/Oct/16 [Edited to add: 2017, not 2016].

 

[Todd Cee]

I never completely finished it, but the model and calculations are pretty much done. I just created the attached PDF file from a LibreOffice Writer (.odt) file I had last saved on 2016/Oct/16.

very impressive ... this should be finalized and submitted for peer review ...

 

[Jeffrey Orling]

Do Oy's calc take into consideration that the explosions would also have break the connections of the panels to the adjacent ones and the slabs.... or does it assume the steel panels, members were simply free standing?

 

[Oystein]

Do Oy's calc take into consideration that the explosions would also have break the connections of the panels to the adjacent ones and the slabs.... or does it assume the steel panels, members were simply free standing?

No. I merely compute how much of an explosive would be required to propel a piece of steel of mass m to a velocity v. No losses / additional explosives to deform, break, spin or heat material considered.

 

[Jeffrey Orling]

No. I merely compute how much of an explosive would be required to propel a piece of steel of mass m to a velocity v. No losses / additional explosives to deform, break, spin or heat material considered.

Breaking the connections would require a lot of forces as well... no?
Where would the explosive(s) be placed to propel a relatively intact steel beam, column or facade panel out of or off the building?

 

[Oystein]

Breaking the connections would require a lot of forces as well... no?
Where would the explosive(s) be placed to propel a relatively intact steel beam, column or facade panel out of or off the building?

That would of course very much depend on your CD scheme - and I am not aware that any Truther has advanced a proposal or theory detailing placement and size of explosive charges. I am not going to do their work for them and come up with speculation to calculate the effect on panel expulsion.

Just some musings:

1. We know that taking out the floors would be an efficient way to start collapse: Say, attack all the truss seats of 3 consecutive floors at once, or perhaps timed that all three floors hit the one below at about the same time, that should guarantee pancaking goes all the way down, total collapse ensues. But that would require only relatively small charges. Though I would not dare to speculate on a number we are very certainly talking about far less than 1 pound per charge. How many truss seats are there per wall panel? 9? Or double that, 18? Eitherway, as even the lightest panels weighed multiple tons, and my white paper shows that more than 9 pounds of explosives are needed per ton of hurled mass just to hurl, rigging the floor trusses would not include enough to do such hurling. Oh and anyway, rigging just the floor trusses would not cut panels loose from the next panel, they would not be pushed out by the explosions at all
2. If you rig the columns - whether at their slices (which would be the most efficient, if you can get to the bolts) or anywhere in between - to cut them apart, then ipso facto the explosions will occur at the extreme ends of the columns/panels, and so unless you have equal sized charged on both ends explosing at the exact same time, any kinetic energy imparted on the wall panel will have a large rotational (angular) component, which will subtract substantially from the lateral velocity, which is the only velocity of interest here. My white paper assumes that the explosives are placed evenly around the Center of Mass of the panel AND does not destroy the panel there. Of course such a placement maximizes the lateral velocity while making no sense, at all, even negative sense, as cutting charges. Besides, Truther, as best as I can determine, would theorize that charges were fired in a timed sequence that mimicks the "nearly freefall" descent of the top, in other words, they'd not fire charges on either end of 3-floor panel at the exact same moment, but as much as 300 milliseconds apart. For a panel that's supposed to travel 48 mph laterally (to take one of the lowest numbers consistent with Truther claims), which is 21.4 m/s, the top of the panel would already have travelled laterally more than 20 feet by the time its bottom gets cut from the panel below. Which makes zero sense of course.
3. So the "best" idea that I think Truthers could come up with would be a reference to "kicker charges". They may have heard of this demolition technique where you have two separate charges per location: One cutting charge that severs the column apart, followed in close succession by a kicker charge that laterally moves the end of one or both parts of the column laterally such that the top end no longer stands on the bottom end and instead falls through thin air. A Truther might hypothesize that they used kicker charges to move entire panels laterally - but shooting them out at 48 mph would be overkill.

Hope that helps

 

[Joe Hill]

What are these bumps in relation to the above picture?


View attachment 17011

They look like torn spandrels from the North Tower perimeter wall.

 

[Joe Hill]

except that these particular "red things" are, IMO, not the "gash makers". They seem to fall too far to the east.

"They" are the "gash makers". Actually, one large piece of wall made the gash. That particular spire is distinct. It appears out of the dust higher and later than all the other pieces, travelling near horizontal. It's easy to identify that spire from north views, and it is clear it lined up with column 20.

Well, let´s use your clip for the moment. I zoomed in and split the screen into 3 areas:

would
I think what we see is like a dozen (but at least 5) core columns in three different bundles.

If you look close, you see large panels falling, with only the leading edge showing due to the dust. If you watch the dust around them, you can make out the larger shape falling as one unit.
Equally as important as studying video of collapse in identifying the falling structural members, is studying other evidence, after which you will find:
1. The entry hole at the top of Building 7 at column 20 is about 40 feet wide, and about as deep into Building 7 footprint. How would a core column(s) make such a hole?
2. Video shows the large standing core section falling east and west. The core was split north/south, and the east half fell east while the west half fell west. None can be seen falling north.
3. Aerial photos of the site show core columns spread out south, east, and west of the NT footprint. There are no signs of core columns north of the footprint. North of the footprint, debris is predominately NT perimeter wall panels. There are a few single columns north, but they are not the same length as NT core columns observed elsewhere. They more likely are columns from Building 6.
There simply is no evidence that the NT core fell north, and the entry hole damage in Building 7 does not match potential damage from core columns; it does match potential damage from perimeter wall panels.

 

[Joe Hill]

They look like torn spandrels from the North Tower perimeter wall.

For the record, upon closer inspection, they are too large to be torn ends of spandrel plates. It is more likely they are the ends of 3 to 4 still joined perimeter panels, which comports with the size of the hole created at the top of Building 7.

 

[econ41]

...
However- you say the floors are collapsing one on top another all the way down.
Those floors are stung between the inner and outer columns. Those floors sit beside the core not on top of it.
The only things those floors will crush is those floors- they can't get at the core.
How are you destroying the core with falling floors?

cptn_fantastic - your discussion with johnnyH is way off topic as I noted in my previous post.

And you are repeating many questions which I have already offered to respond to or explain....in an appropriate thread.

However I see that you ignore my post and my offer to assist. So I will cease commenting on the off topic material.

 

[cptn_fantastic]

The only thing thst can reduce the (vertical or horizontal) velocity of such a ball is air resistance (drag). Air resistance won't kill the horizontal velocity of a steel ball until the ball has travelled a few hundred metres--assuming the ball doesn't hit the ground first.

So yes, the time of fall and hence the original height will influence the horizontal distance travelled before the ball hits the ground.

If the height is sufficient for both balls to run out of horizontal momentum prior to colliding with the ground, both balls travel equidistant from the building.
A thrown ball, whether made of rubber or steel, will land the same distance from the building whether thrown from the 110th floor or the 100th.

 

[Mick West]

cpth_fantatic's misunderstanding of physics and related discussion moved to: https://www.metabunk.org/cptn_fantastics-physics-lessons.t10908/

 

[Mick West]

@Christopher 7, if you were to pick ONE piece of debris that you think was most obviously propelled by explosives, which would you pick? Maybe we can work together to figure out how it got there?

 

[Christopher 7]

The general agreement here is that there are no examples known that cannot be explained by a gravity driven collapse. If you'd like to point to one then please try to produce a frame by frame analysis showing the trajectory.

David Chandler did that.

Source: https://www.youtube.com/watch?v=eHnLlwqiu0A

1:42 "First I looked at the westward moving projectile from the north tower that I had crudely measured on the television screen two years ago.

This time I got a reliable value of 25 meters per second which translates to about 56 miles per hour."

1:59 "On a video of the south tower, I noticed a large elongated object moving like a javelin above the main debris cloud. On the original video where I saw this object, the camera was zooming the whole time which made the measurement difficult."
2:14 "I recently found another video which shows the same projectile but taken with a stationary camera.

Result, 20 meters per second, 45 miles per hour."

2:26 "Another high speed projectile was launched northward from the north tower late in the collapse toward building 7.

2:53 "I used the stabilized video to do the measurements and got good uniform results; 35 meters per second or 78 miles per hour."

 

[Oystein]

1, 2 and 3 are correct.
There is no way to know if the ejection of framework sections laterally at speeds up to 70 mph was undesired. I don't think the perpetrators cared. They were relying on shock and awe.

But earlier you said, and that is what I responded to:

"They were designed to look like a gravity collapse."

This claim implies
a) That you know, partially at least, the intention of the hypothesized perpetrators: That they intended for the collapse "to look like a gravity collapse".
b) Something in the look, "design" of the collapses is different from what it would be if these were "normal" or "undesigned" controlled demolitions and instead more like what one would expect from "a gravity collapse".

So what is this difference in "look" between an "undesigned" controlled demolition and a "gravity collapse" that you spot in the WTC collapses and assign to "design"?

Or, if you have no answer to this, what observed properties of the collapses lead you to believe that "they were designed to look like a gravity collapse"?
In particular, is the alleged "ejection" of "multi-ton" pieces part of the reason that you think the "collapses were designed to look like a gravity collapse"?

The ejections were a result of massive explosions. It would be impossible for something falling down to tear loose and eject multi-ton sections of framework sideways at 70 mph. And to suggest that it was a gimmick is silly.

So "designed to look like a gravity collapse" is contradicted, not supported, by such "ejections"?

I think your claims are a confusing mess. You imply you know the intentions of the hypothetical perpetrators, then you deny it. You bring up ejections in the context of "looking like a gravity collapse", then deny that looks like a "gravity driven" collapse.

Now let us repeat the excercise that got us into this mess. Here is Bruno D.'s question, and your evasive and confusinf answer, and I wish you could give us a straight answer this time:

1 - Can you provide a single video from any controlled demolitions around the world showing multi-ton framing sections being ejected laterally at speeds up to 70mph?

Of course not. The Trade Towers were not normal demolitions. They were designed to look like a gravity collapse.

Alright, Christopher 7: Can you provide a single video from any controlled demolitions around the world showing multi-ton framing sections being ejected laterally at speeds up to 70mph? And if not, why not? As such ejections are, in your opinion, NOT typical for "gravity collapses", the explanation "They were designed to look like a gravity collapse" just doesn't cut it - it makes zero sense.

Why do "normal" explosive demolitions not eject laterally multi-ton framing sections? Why do you think this happened at the WTC?
And keep in mind the overall context - that the fact these were "explosive demolitions" is "obvious", and that, supposedly, such lateral ejections are part of what makes this "obvious", despite such lateral ejections not actually ever happening at actual explosive demolitions.

 

[Christopher 7]

@Christopher 7, if you were to pick ONE piece of debris that you think was most obviously propelled by explosives, which would you pick? Maybe we can work together to figure out how it got there?

I would not try to pick one piece. Chandler provides three examples. However, we can start with the first example of a framing section being ejected at 56 mph.

Source: https://www.youtube.com/watch?v=eHnLlwqiu0A

1:42 "First I looked at the westward moving projectile from the north tower that I had crudely measured on the television screen two years ago.

This time I got a reliable value of 25 meters per second which translates to about 56 miles per hour."

 

[Gamolon]

I would not try to pick one piece. Chandler provides three examples. However, we can start with the first example of a framing section being ejected at 56 mph.

In the image below, where do you think the framing in question was located on the tower prior to being ejected?

 

[Mick West]

(if you click on the above image, you can pause it and go frame-by-frame with the arrow keys. Also see the more HD version at https://www.metabunk.org/data/video/40/40992-713aff47ca21c7ce68006eb4dd4eb18d.mp4 )

Conservatively, it would have started at the frame below. The collapse wave had already passed it by, and essentially it was the top of a VERY large region of the wall that pivoted away.

 

[Mick West]

Here I've taken the piece as it appears near the end of the fall, and traced it back (roughly) to the start. Probably not very accurate, as it would really need to be modeled in 3D. But it gives the basic idea.

 

[Jeffrey Orling]

Here I've taken the piece as it appears near the end of the fall, and traced it back (roughly) to the start. Probably not very accurate, as it would really need to be modeled in 3D. But it gives the basic idea.

This nails it... you don't need 3D.. an aerial photo shows all the facade on the ground from the tower to the WFC and the panel locations correlate to the floor they came from... and there to the velocity they attained.

 

[Mick West]

Plenty of the panels ended up across West Street. The top of this section is probably what did the damage.

 

[Gamolon]

(if you click on the above image, you can pause it and go frame-by-frame with the arrow keys. Also see the more HD version at https://www.metabunk.org/data/video/40/40992-713aff47ca21c7ce68006eb4dd4eb18d.mp4 )

Conservatively, it would have started at the frame below. The collapse wave had already passed it by, and essentially it was the top of a VERY large region of the wall that pivoted away.

View attachment 41671

I'm just trying to understand what evidence/logic Christopher7 is using to support his belief that explosives are the only explanation as to why the multi-ton steel perimeter assemblies reached those descending speeds/trajectories and completely rule out that the descending debris front could have pushed those assemblies out and toppled them over and get the same speeds/trajectories.

 

[Gamolon]

I would not try to pick one piece. Chandler provides three examples. However, we can start with the first example of a framing section being ejected at 56 mph.

Using Mick's image below, I have some questions regarding your belief that explosives were used to eject multi-ton steel assemblies.

1. What was initial ejection speed at the "Start here" point above?
2. If explosives caused said ejection, then how to you explain the multi-ton assembly still in place when the supposed explosive charges are shown going off far below and the detonations have already passed the location of the assembly in question, which has not moved yet?

 

[Gamolon]

I would not try to pick one piece. Chandler provides three examples. However, we can start with the first example of a framing section being ejected at 56 mph.

Look at the image below. If a multi-ton steel assembly was ejected at 56 mph at the time the supposed explosives went at the same level as the ejected assembly, after three seconds, that assembly should be approximately 246 feet from the tower as marked below.

Where is it?

 

[Christopher 7]

(if you click on the above image, you can pause it and go frame-by-frame with the arrow keys. Also see the more HD version at https://www.metabunk.org/data/video/40/40992-713aff47ca21c7ce68006eb4dd4eb18d.mp4 )

Conservatively, it would have started at the frame below. The collapse wave had already passed it by, and essentially it was the top of a VERY large region of the wall that pivoted away.

View attachment 41671

Like Bazant, you have the top part destroying the building below but not being destroyed itself. That is a violation of Newtons third Law: For every action, there is an equal and opposite reaction. In a gravity collapse, the top part of the building would be destroyed at the same rate as the building below.

Furthermore, the "collapse" began on the 98th​ floor.

NCSTAR 1-6 Figure 6-8

The building was descending at 64% of the rate of gravity.

Source: https://www.youtube.com/watch?v=ZjSd9wB55zk

0:32 "On this kind of a graph, a straight line indicates constant acceleration." ...
0:48 "The slope of the graph indicates that the acceleration is 6.31 meters per second squared downward, which is 64% of free fall."

64% of g 32.174 x 0.64 = 20.59 f/s2​

https://www.omnicalculator.com/physics/free-fall

In your video, the "collapse" begins at 1 sec. This frame is 2.5 seconds into the "collapse".
The twin Towers were 110 stories - 1,362 feet high. So the stories were about 12.38' high.
The top part would descend 64' in 2.5 seconds at 64% of the acceleration of gravity.
64/12.38 is about 5 stories.

The top part has already compressed 5 stories as the fire is pushed out of the windows on the 92nd​ floor.

That leaves 14 stories to crush the building below. The upper part would have been destroyed by the time it reached the 78th floor, or sooner if it continued to be destroyed at the same rate as the first 2.5 seconds.

So your depiction of where the internal "collapse" was at the moment the framing section was ejected, is incorrect.

* * * * *
If the object left the building a few stories lower than you depict, it would be where a rapidly expanding debris cloud is, indicating explosive force.

Your video shows the ejected framing section was on the 86th​-88th​ floor.
Would you post the calculations for when and where the framing section left the building please?

And finally:
You have not shown how a gravity collapse could eject a section of framework laterally at 56 mph.

* * * * *
You suggest that it was a large framing section that pealed away from the building. That is incorrect. It was not part of a large framing section as can be seen in this photo:

 

[econ41]

Like Bazant, you have the top part destroying the building below but not being destroyed itself.

That is one of the four fatal errors of the Bazant & Verdure 2007 "crush down/crush up" ["CD/CU"] hypothesis. It is NOT valid for WTC Twin Towers on 9/11. I've made that claim many times - never got a serious response. A bit of flack from some Bazantophiles who are scared of committing lèse-majesté.

That is a violation of Newtons third Law: For every action, there is an equal and opposite reaction. In a gravity collapse,

"violation of Newton's 3rd" isn't the reason and it is a bit more complicated.

the top part of the building would be destroyed at the same rate as the building below.

For the Twin Towers on 9/11 it was - concurrent destruction of Top Block and the equivalent levels of the top of the Lower Tower. That is one of the fatal errors with CD/CU applied to WTC.

 

[Jeffrey Orling]

Like Bazant, you have the top part destroying the building below but not being destroyed itself. That is a violation of Newtons third Law: For every action, there is an equal and opposite reaction. In a gravity collapse, the top part of the building would be destroyed at the same rate as the building below.

Furthermore, the "collapse" began on the 98th​ floor.

View attachment 41681
NCSTAR 1-6 Figure 6-8

The building was descending at 64% of the rate of gravity.

Source: https://www.youtube.com/watch?v=ZjSd9wB55zk

0:32 "On this kind of a graph, a straight line indicates constant acceleration." ...
0:48 "The slope of the graph indicates that the acceleration is 6.31 meters per second squared downward, which is 64% of free fall."

64% of g 32.174 x 0.64 = 20.59 f/s2​

View attachment 41686
https://www.omnicalculator.com/physics/free-fall

In your video, the "collapse" begins at 1 sec. This frame is 2.5 seconds into the "collapse".
The twin Towers were 110 stories - 1,362 feet high. So the stories were about 12.38' high.
The top part would descend 64' in 2.5 seconds at 64% of the acceleration of gravity.
64/12.38 is about 5 stories.

View attachment 41684

The top part has already compressed 5 stories as the fire is pushed out of the windows on the 92nd​ floor.

That leaves 14 stories to crush the building below. The upper part would have been destroyed by the time it reached the 78th floor, or sooner if it continued to be destroyed at the same rate as the first 2.5 seconds.

So your depiction of where the internal "collapse" was at the moment the framing section was ejected, is incorrect.

View attachment 41687
* * * * *
If the object left the building a few stories lower than you depict, it would be where a rapidly expanding debris cloud is, indicating explosive force.

Your video shows the ejected framing section was on the 86th​-88th​ floor.
Would you post the calculations for when and where the framing section left the building please?

And finally:
You have not shown how a gravity collapse could eject a section of framework laterally at 56 mph.

* * * * *
You suggest that it was a large framing section that pealed away from the building. That is incorrect. It was not part of a large framing section as can be seen in this photo:

View attachment 41685

Your understanding of what was happening in the towers is incorrect. Briefly, it appears that the "interior" of the top section above the plane strike had lost its structural integrity and the materials of the top collapsed down and onto the intact and undamaged structure below impact the uppermost undamaged floor. which was incapable of support the newly acquired loads on the floors. The facade steel was largely unaffected as the collapse of the top began as was most of the core columns. The mass of floor debris, super imposed dead load such as MEP equipment, plus the super imposed dead loads... furniture and occupants "rained down" and began a runaway collapse of each floor from top to bottom INSIDE the confines of the perimeter steel The structural steel supporting axial loads required the support of lateral bracing which was destroyed by the above mentioned collapse and this led to instability and eventual "self destruction of the interior columns and the facade... largely from what is known as Euler buckling.

 

[Mick West]

Like Bazant, you have the top part destroying the building below but not being destroyed itself.

No, I don't. I'm sure there was plenty of destruction all parts. But the top part of the building does not need to be an intact framework in order to contribute to the collapse. Sorry if my animation is a bit simple.

Shortly after the top falls a short way (i.e. one floor), then the BOTTOM part of the building is also contributing to destroying the remaining intact structure.

Bazant's calculations are a mathematical abstraction and don't reflect what actually happened, which is why NIST dismissed them, other than as "a simplified approximate analysis"

NCSTAR 1-6, page 323 (pdf page 405)
https://www.metabunk.org/f/files/NCSTAR 1-6 UNLOCKED.pdf

With the exception of the Weidlinger-led study, the analyses for the other collapse hypotheses presented here ignored impact damage, assumed time-temperature curves for structural subsystems (i.e. floor trusses and exterior columns), and conducted analyses of components or subsystems but did not conduct global analyses of the entire structure (i.e., core, floors, exterior walls, and hat truss) that considered all of the load redistribution paths as local members and subsystems were thermally weakened over time. The Weidlinger study included impact damage and assumed time-temperature curves for structural subsystems for their global analyses of each tower.
Northwestern University

The study performed by Northwestern University (Bazant 2002) was a simplified approximate analysis of the overall collapse of the WTC towers which addressed the question of why a total collapse occurred. The analysis addressed the results of prolonged heating which would have caused the columns of a single floor to lose their load carrying capacity and initiated the collapse of the building. The analysis assumed loss of thermal insulation during impact, uniform temperatures of 800 °C for a uniform column size and load across a single floor, and creep buckling and loss of load carrying capacity in over half of the columns. The analysis included evaluation of the dynamic amplification of the loads and the ability of the columns in the lower floors to dissipate the kinetic energy of the falling upper building mass through formation of plastic hinge mechanisms. The analysis found that the ratio of the kinetic energy of the upper building section dropping one floor to the deformation energy of plastic hinge rotation in the lower building columns was approximately a factor of eight.
The study by Northwestern did not address the details of impact damage, fire dynamics, or structural response of the towers. Rather, a generalized condition was assumed of heated columns, and the question of why there was total collapse was addressed. NIST agrees with the assessment of the tower's required structural capacity to absorb the released energy of the upper building section as it began to fall as an approximate lower bound. The likelihood of the falling building section aligning vertically with the columns below was small, given the observed tilting, so that the required capacity would be greater if interaction with the floors was also considered, as pointed out in the study.

(emphasis mine)

AE911 (and you) continuing to ignore this at this point is inexplicable.

 

[Christopher 7]

Like Bazant, you have the top part destroying the building below but not being destroyed itself.

No, I don't.

Yes you do. You show the top part moving down unchanged, to the point where you say "But internal collapse wave is here" with an arrow pointing to the yellow line representing the bottom of the upper section.

I'm sure there was plenty of destruction all parts.

That's not what your video shows. It has the top part descending without decreasing in size.

But the top part of the building does not need to be an intact framework in order to contribute to the collapse.

True, but there is no evidence that the collapse would continue all the way to the ground. There is, however, a peer reviewed paper that shows it didn't.

Some Misunderstandings Related to WTC Collapse Analysis
Reprinted from International Journal of Protective Structures
Volume 4 · Number 2 · June 2013
[BROKEN LINK]

Bazant's calculations are a mathematical abstraction and don't reflect what actually happened, which is why NIST dismissed them, other than as "a simplified approximate analysis"

NIST did not dismiss Bazant's analysis. They used Bazant's analysis to explain the total collapse because NIST did not.

The study by Northwestern did not address the details of impact damage, fire dynamics, or structural response of the towers. Rather, a generalized condition was assumed of heated columns, and the question of why there was total collapse was addressed. NCSTAR 1-6 p. 323 [PDF p. 405]

NIST reply to stj911truth
Page 4
We are unable to provide a full explanation of the total collapse.
NIST has stated that it did not analyze the collapse of the towers.
NIST's analysis was carried to the point of collapse initiation.
http://journalof911studies.com/volume/2007/NISTresponseToRequestForCorrectionGourleyEtal2.pdf[/

* * * * *
You did not respond to these three points. Please do so.

Your video shows the ejected framing section was on the 86th-88th floor.
Would you post the calculations for when and where the framing section left the building please?

You have not shown how a gravity collapse could eject a section of framework laterally at 56 mph.

You suggest that it was a large framing section that pealed away from the building. That is incorrect. It was not part of a large framing section as can be seen in this photo:

 

[Mick West]

It was not part of a large framing section as can be seen in this photo:

You can't find a better photo? Really?