AE911Truth pressures NIST for decision on WTC 7 report

[Crazy Chainsaw]

If I recalled correctly early explanations suggested dropping "pancakes" (floors). The problem with that was it made no sense for all axial supports for the square donut shaped floors to fail simultaneously. So the collapsing floors was "correct"... but they were not pancakes.

The dropping top blocks led to entire floors being shattered and dropping... along with the perimeter panels as a tube. The dynamic loading on the intact floors led to the impacted floor to shatter and drop and this began a runaway process of shattering the floors rapidly all the way down. No pancakes... No columns were crushed... they were bypassed and actually unloaded by the floor collapse. But the columns were dependent on lateral bracing... and that was provided by the floor "system".... beams, girders, trusses and slabs. So the final act was the toppling of the core columns absent bracing and the the peeling and toppling of the perimeter.

Columns would only buckle from being overloaded in a process of load redistribution... when a column fails and it's loads are taken up by adjacent columns. This was the likely process going on in the cores as the fires raged... until the tops dropped, driven by heat from fire warping the frame and lowers the capacity of the steel. Slabs did not have the capacity to resist the mass falling and arrest the collapse. Once started every floor would collapse.

Actually the Greening computer simulation used beam on Beam impacts to sheer the steel on the welds of the beams and the columns by leveraged of center impacts.
It took 1,000,000 foot pounds to shear though a mechanical floor, but at one foot from the weld it only took, 100,000 foot pounds of force, that's equal to 2600 pounds dropped 12 feet.
The objective of the Banzant paper By Banzant, Greening, and David Banes Benson, and Zao was to show it was physically Impossible for the collapse to be arrested by the Mechanical Floors as Claimed by David Chandler and the Physics Community in their Attacks on Banzant, claimed.
I think the paper was miss used intentionally by the 9/11Truth movement.
It was never intended to be an actual simulation of the Collapse, only to show the Collapse was Impossible to stop, so preventing the start of a collapse was the only way to prevent a building from collapsing.

 

[JSanderO]

Mech floors were stronger but surely could not resist the dynamic loads of 30 floors hitting them. Seems intuitive.

 

[ozeco41]

The funny thing is that just recently Tony Szamboti has argued that the columns of the falling portion would exactly hit the columns of the lower intact portions because the massive inertia it had will twist any lateral movement.

Tony Szamboti's confusion goes back a long way. His fundamental problem is that he has never understood the real mechanism of the collapse of the Twin Towers. He is not the only one to make that error. The history of debate as it polarised into the two opposing "sides" of "Truthers" and "Debunkers" was that both sides were equally wrong for many years. Mostly the result of three factors:
1) Most early debates focussed on gross motion - macro measurements of velocities, accelerations and calculations of energies. Very little attention was given to the actual mechanism.
2) Misunderstanding of Bazant & Zhous paper(s) of 2001-2 which presented a legitimate "limit case" argument assuming that the Top Block (a) DROPPED onto the lower tower; (b) with column ends aligned thereby creating the best case for survival/worst case for collapse by "crushing" of columns. i.e. a valid limit case argument.
3) The reality that the collapses occurred in distinct stages. Two main ones (a) an "initiation" stage which resulted in the Top Block starting to descend bodily; Then (b) a rapid "progression" stage to global collapse. The two involved very different mechanisms - the first was complex, the second simple provided it was recognised. Recognition took time. (And that is a diplomatic understatement as longer serving members will recognise. )

T Szamboti took it literally on both points. i.e. "dropped" to "axial aligned impact". Neither was true in the real mechanism of the event. "Debunkers" as they became known gradually realised that it was wrong to assume axial contact. But sadly many still hang on to the false presumption of "dropping to impact".

BTW a comprehensive explanation is probably best described as four stages but I won't persist with the off-topic drift. We probably need a new review and consolidation thread to keep the history in one place - it is scattered across multiple threads.

Funny because he is more or less giving the game away here. The massive inertia the falling part resisting lateral movement does imply that a more or less symmetrical fall is to be expected.

The whole process of the "initiation stage" has been extensively discussed - several key aspects seeing "arse about" interpretations resulting from failure to define the "real mechanism". For example debate of whether "tilt" of either top block would prevent axial impact between column ends of the "dropping" top block. Sequence error - tilt resulted from columns already failed. Another interesting topic for discussion to refresh understanding.

 

[JSanderO]

Excellent summary Ozzie... People wanted a simple explanation and believed it existed... so we got things like "pancake collapse".

What I believe was a missed opportunity was a discussion of "progression" of failures... and the notion of runaway failures in complex systems.... in this case a building's structure. And this required drilling into what was going on in the so called "initiation phase". It is trivial engineering... or settled engineering what happens to materials subject to loads exceeding their capacity to support these loads... This explains the collapse stage.

It's far more complex or mysterious for the average person to understand how some static turned to a collapse and become a pile of disorganized debris. How did the things which were carrying loads no longer carry them. How do structures and their elements support loads? How much over design to structures have?

People can understand when the columns are blown up... a building will collapse... And this is the non critical thinking which is AE's CD theory.

It's not a crisis of imagination... but one of thinking and knowledge.

 

[bknight]

Excellent summary Ozzie... People wanted a simple explanation and believed it existed... so we got things like "pancake collapse".

What I believe was a missed opportunity was a discussion of "progression" of failures... and the notion of runaway failures in complex systems.... in this case a building's structure. And this required drilling into what was going on in the so called "initiation phase". It is trivial engineering... or settled engineering what happens to materials subject to loads exceeding their capacity to support these loads... This explains the collapse stage.

It's far more complex or mysterious for the average person to understand how some static turned to a collapse and become a pile of disorganized debris. How did the things which were carrying loads no longer carry them. How do structures and their elements support loads? How much over design to structures have?

People can understand when the columns are blown up... a building will collapse... And this is the non critical thinking which is AE's CD theory.

It's not a crisis of imagination... but one of thinking and knowledge.

While that may have been the case for many, but the first I heard of pancake collapse was from descriptions of the salvage crews describing the floor pancaked onto one another.

 

[Cosmic Yak]

So has NIST crumbled from all this pressure from AE911T yet?

 

[Crazy Chainsaw]

While that may have been the case for many, but the first I heard of pancake collapse was from descriptions of the salvage crews describing the floor pancaked onto one another.

Actually it was a fire fighter who first described the floors falling like a stack of Pancakes BOOM Boom Boom.

 

[JSanderO]

pancakes don't go boom boom boom.
The term was used.. I believe by PBS or authority figure trying to explain/describe the collapse... floors became pancakes and volia dropped as entire floors. Mostly rubbish but easy to conceptualize.
Whole floor slab collapse only makes sense if there was a large enough impulse spread over most of the floor area simultaneously... And that did kinda happen in the ROOSD collapse... but it's unlikely the impulse was uniform and simultaneous over each entire floor. Chaos made it hard to distinguish impact of the ROOSD mass... and 90 or so floors collapse at the rate of .1 second per floor. Sounded continuous. It was a vertical avalanche of floor MASS(es) not separate floors.

 

[bknight]

Actually it was a fire fighter who first described the floors falling like a stack of Pancakes BOOM Boom Boom.

Read the words that I typed not what you think

but the first I heard of pancake collapse was from descriptions of the salvage crews describing the floor pancaked onto one another.

 

[JSanderO]

stacked one on top of another might be referred to as pancakes... I recall the term being used in a Nat Geo PBS presentation explaining what happened and it was a verb... what the floors did... they pancaked. Not

 

[ozeco41]

So has NIST crumbled from all this pressure from AE911T yet?

No. I've been watching for years with my cynic's hat on.

I think AE911 is inadvertently playing right into the hands of the politicians.

9/11 involved some big technical claims led by "CD at WTC". All since proved wrong. And there were - still are - lots of "political" questions not answered.

Guess where politicians DON'T want attention >> on politics >> on where they went wrong. (And I suggest there is a lot of "both sides" sympathy for that view.)

Keeping the focus on false technical claims led by CD at WTC AE911 has almost single-handedly deflected serious debate from the political issues. And they are still chasing technical claims such as CD at WTC which, long term, will go nowhere because it is wrong.

Meanwhile - no debate of the politics. (Sure - belated private class actions against Saudi. But even that is raising less heat than it would 10 or 15 years back.)

From a pollies view - let AE911 keep chasing technical straws till they lose interest, can not afford more or their supporters give up. And, we know their foundation claims are wrong so they will never win substantial claims. So what if we get to the stage that we need to throw then a few scraps. As long as they stay off the political stuff they cannot do much harm

 

[ozeco41]

... the first I heard of pancake collapse was from descriptions of the salvage crews describing the floor pancaked onto one another.

A bit of "historic" perspective:

FEMA did a preliminary report which suggested that "pancaking" was the initiating cause of the Twin Towers collapses. NIST rejected "pancaking" for the initiation stage. (The actual mechanism for the Twin Towers initiation stage was a cascading failure of columns driven by heating and load redistribution.)

The difference between FEMA and NIST has been raised by truthers for mendacious reasons. FEMA was wrong - INITIATION was NOT by pancaking. NIST was right. On that specific point. Initiation stage.

NIST did not explain the progression stage which can be legitimately described as "pancaking", Witnesses reported the rapid "bang...bang...bang...bang..." as sheared off floors fell to impact the next floor down in the progression.


So for some years explanation of the progression stage lacked an "official version" from NIST, We didn't have an official term to describe the mechanism and no general agreement as to what the mechanism was.

It was "dangerous" to use "pancaking" because that would derail debate as truthers revisited the "FEMA and NIST disagreed" nonsense. And the very descriptive acronym "ROOSD" was too contentious for reasons we need not explain yet again.

I prefer to not use "pancaking" because of the association of the term with those old truther claims.

Our colleague - JSanderO - prefers to not use pancaking because the observed process did not see or require every floor slab to fall as a still intact entity. They probably broke and fell in bits. I'm not so fussy - It was pancaking for my purposes.

I need not comment on a couple of other bits of anecdote.

 

[JSanderO]

The collapse phase can be described as pancaking. But a more accurate description is vertical avalanche of floor material on contents... which like an earth or snow avalanche does not arrest. There apparently were sections of slabs relatively intact which "rode" on top of the collapse front and were seen on top of the debris pile.

The problem with the pancake theory relates to initiating a virtual simultaneous failure of most of the slab connections to the belt girder and facade columns.

The problem with the sagging truss initiation theory is that it requires fires of sufficient heat over the entire footprint of the floor slabs heating the trusses almost simultaneously.

As Ozzie wrote the initiation likely was a progressive and runaway failure of the core columns where the fire raged in the plane strike zones. This likely led to a sufficient lateral translation and tilting for the top blocks to fall and as a dynamic load initiated the progressive floor destruction which led to the facade "peel" / tilting away and core columns losing bracing.

There was no column crushing, but there likely was core column buckling in the initiation phase and in the final phase where remaining columns without bracing self buckled from "Euler forces". Columns were unloaded except in the initiation phase during load redistribution.

 

[Crazy Chainsaw]

The collapse phase can be described as pancaking. But a more accurate description is vertical avalanche of floor material on contents... which like an earth or snow avalanche does not arrest. There apparently were sections of slabs relatively intact which "rode" on top of the collapse front and were seen on top of the debris pile.

The problem with the pancake theory relates to initiating a virtual simultaneous failure of most of the slab connections to the belt girder and facade columns.

The problem with the sagging truss initiation theory is that it requires fires of sufficient heat over the entire footprint of the floor slabs heating the trusses almost simultaneously.

As Ozzie wrote the initiation likely was a progressive and runaway failure of the core columns where the fire raged in the plane strike zones. This likely led to a sufficient lateral translation and tilting for the top blocks to fall and as a dynamic load initiated the progressive floor destruction which led to the facade "peel" / tilting away and core columns losing bracing.

There was no column crushing, but there likely was core column buckling in the initiation phase and in the final phase where remaining columns without bracing self buckled from "Euler forces". Columns were unloaded except in the initiation phase during load redistribution.

Problem is there isn't enough heat at the plane crash zone for the fires to have collapsed the buildings there most of the Fuels in that area would have been consumed rapidly, before collapse.

 

[bknight]

A bit of "historic" perspective:

FEMA did a preliminary report which suggested that "pancaking" was the initiating cause of the Twin Towers collapses. NIST rejected "pancaking" for the initiation stage. (The actual mechanism for the Twin Towers initiation stage was a cascading failure of columns driven by heating and load redistribution.)

The difference between FEMA and NIST has been raised by truthers for mendacious reasons. FEMA was wrong - INITIATION was NOT by pancaking. NIST was right. On that specific point. Initiation stage.

NIST did not explain the progression stage which can be legitimately described as "pancaking", Witnesses reported the rapid "bang...bang...bang...bang..." as sheared off floors fell to impact the next floor down in the progression.


So for some years explanation of the progression stage lacked an "official version" from NIST, We didn't have an official term to describe the mechanism and no general agreement as to what the mechanism was.

It was "dangerous" to use "pancaking" because that would derail debate as truthers revisited the "FEMA and NIST disagreed" nonsense. And the very descriptive acronym "ROOSD" was too contentious for reasons we need not explain yet again.

I prefer to not use "pancaking" because of the association of the term with those old truther claims.

Our colleague - JSanderO - prefers to not use pancaking because the observed process did not see or require every floor slab to fall as a still intact entity. They probably broke and fell in bits. I'm not so fussy - It was pancaking for my purposes.

I need not comment on a couple of other bits of anecdote.

I was responding to JSanderO's comment that

People wanted a simple explanation and believed it existed

I never have stated that this was a method of initiation or continuance. Agin the first I heard of this term was from salvage operations, please do not characterize my simple sentence as any description of the collapse, just the aftermath of the collapse.

 

[JSanderO]

It is my belief that the fires which burned in the plane crash zones... over heated lateral steel... which led to column misalignment a buckling... reduced axial capacity and loss of support mass above and lateral displacement of the top block.

 

[ozeco41]

The collapse phase can be described as pancaking. ¹
As Ozzie wrote the initiation likely was a progressive and runaway failure of the core columns...²
There was no column crushing,³

We are way off-topic, but, briefly,
1 That is what I said.
2 I referred to columns. Meaning ALL columns. I did not limit my comment to core colums. I'm not hung up on "core columns" somehow being different.
3 Remember we are discussing the INITIATION stage and I wouldn't bet against axial compression overload resulting in ANY form of failure - in the INITIATION stage.

 

[Crazy Chainsaw]

It is my belief that the fires which burned in the plane crash zones... over heated lateral steel... which led to column misalignment a buckling... reduced axial capacity and loss of support mass above and lateral displacement of the top block.

It probably happened higher up than that, because you can see the fires above the impacts zones where air was being sucked in.

 

[ozeco41]

I was responding to JSanderO's comment.

So was I - putting the issue in its historic setting and identifying what was probably the most significant aspect of misunderstanding in the discussion of "pancaking".

I never have stated that this was a method of initiation or continuance. Agin the first I heard of this term was from salvage operations, please do not characterize my simple sentence as any description of the collapse, just the aftermath of the collapse.

I never said you did.
I understood your "first heard" example.
I didn't characterise your comment in any way.

Please reads my comment in the context of the ongoing discussion - which is drifting further off-topic.

 

[pgimeno]

NIST did refer to the collapse progression as pancaking in their report, albeit very marginally. They did that when they described the damage observed in the recovered steel pieces.

The most significant observations were made when the panels were categorized by their as-built elevation within the building, Fig. 6-28. Of the 28 floor truss connectors at or below the impact floors for WTC 1, 93 percent were either missing or bent downwards. Only 37 percent of the 38 floor truss connectors above the impact floors had similar characteristics. Comparable results were found for WTC 2 where 88 percent of the floor truss connectors below the impact floors were bent down or missing, while only 55 percent of the floor truss connectors above this region had such damage characteristics. This occurrence was most likely a result of the overloading of the lower floors ("pancaking" mechanism) during collapse of the building.
​

NCSTAR 1-3, NIST (bolding mine).

 

[beachnut]

...
NIST did not explain the progression stage which can be legitimately described as "pancaking", Witnesses reported the rapid "bang...bang...bang...bang..." as sheared off floors fell to impact the next floor down in the progression.
...

But the progression did partly progress to Pancaking... and NIST did cover this emeded in the countless pages, somewhere...

And clearly explains Pancaking in FACTS, and other areas of NIST, if one is into details, math (material science, engineering), etc, etc, etc ...

Consider a typical floor immediately below the level of collapse initiation and conservatively assume that the floor is still supported on all columns (i.e., the columns below the intact floor did not buckle or peel off due to the failure of the columns above). Consider further the truss seat connections between the primary floor trusses and the exterior wall columns or core columns. The individual connection capacities ranged from 94,000 pounds to 395,000 pounds, with a total vertical load capacity for the connections on a typical floor of 29,000,000 pounds (see Section 5.2.4 of NIST NCSTAR 1-6C).

Math exposes, in part the progression of collapse is... Pancaking, a floor fails instantly when overloaded past ~29,000,000 pounds. (how did NIST figure this out...)

 

[ozeco41]

A bit of "historic" perspective:

NIST did not explain the progression stage which can be legitimately described as "pancaking",

But the progression did partly progress to Pancaking... and NIST did cover this emeded in the countless pages, somewhere...

That is what I said. (1) NIST did not explain the "progression stage - merely asserting "global collapse was inevitable" or words to that effect. And (2) "can be legitimately described as pancaking.."

And the NIST comment you linked with this also agrees with what I said:

And clearly explains Pancaking in FACTS, and other areas of NIST, if one is into details, math (material science, engineering), etc, etc, etc ...

NIST says this which is a clearly referring to initiation:

NIST's findings do not support the "pancake theory" of collapse, which is premised on a progressive failure of the floor systems in the WTC towers (the composite floor system—that connected the core columns and the perimeter columns—consisted of a grid of steel "trusses" integrated with a concrete slab; see diagram). Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.

.. which agrees with what I said: " NIST rejected "pancaking" for the initiation stage."

 

[Crazy Chainsaw]

That is what I said. (1) NIST did not explain the "progression stage - merely asserting "global collapse was inevitable" or words to that effect. And (2) "can be legitimately described as pancaking.."

And the NIST comment you linked with this also agrees with what I said:
NIST says this which is a clearly referring to initiation:

.. which agrees with what I said: " NIST rejected "pancaking" for the initiation stage."

That's because pancaking occurs only after the Initial structural failures a phenomenon lost on the Truth movement, the Initial stage progresses into gravitationally driven Pancaking, as momentum builds in the collapse at a progressive rate.

 

[JSanderO]

I don't thinking pancaking is a good description even in the collapse phase. I've noted this many times over the years.

Once the ROOSD mass "formed"... a mass which could not be supported by a typical WTC floor slab... that slab "shattered" and "collapsed". It's likely that this was a local phenomena... not actually occurring over / throughout the entire floor at the same instant. But it was almost simultaneous. Over a short period of time the collapse formed a "front"... a mass of many floors which rapidly drove down to the ground taking out each floor as it went. The "front" quickly encompassed the entire footprint. The mass grew with each floor it destroyed. The collapse quickly reached a "terminal velocity" of about 10 floor per second... over 60 mph.
A pancake in my thinking is the collapse of an individual floor... because it loses its supports at the columns (and belt girder)... not a overall crushing of the floor.

If a roof collapses from a snow load.... is it called a pancake collapse?

Sure the floors were destroyed one at a time top to bottom people like thinking of the floors as pancakes.

The defining characteristic of a pancake collapse is a "stack" of reasonably intact floor slabs. This was NOT the case at the WTC. There were some intact slab sections on the top of the pile.... but not inside or at the bottom IIRC.

 

[Crazy Chainsaw]

I don't thinking pancaking is a good description even in the collapse phase. I've noted this many times over the years.

Once the ROOSD mass "formed"... a mass which could not be supported by a typical WTC floor slab... that slab "shattered" and "collapsed". It's likely that this was a local phenomena... not actually occurring over / throughout the entire floor at the same instant. But it was almost simultaneous. Over a short period of time the collapse formed a "front"... a mass of many floors which rapidly drove down to the ground taking out each floor as it went. The "front" quickly encompassed the entire footprint. The mass grew with each floor it destroyed. The collapse quickly reached a "terminal velocity" of about 10 floor per second... over 60 mph.
A pancake in my thinking is the collapse of an individual floor... because it loses its supports at the columns (and belt girder)... not a overall crushing of the floor.

If a roof collapses from a snow load.... is it called a pancake collapse?

Sure the floors were destroyed one at a time top to bottom people like thinking of the floors as pancakes.

The defining characteristic of a pancake collapse is a "stack" of reasonably intact floor slabs. This was NOT the case at the WTC. There were some intact slab sections on the top of the pile.... but not inside or at the bottom IIRC.

Pancaking does not require a stack, it only requires rapidly increasing Gravity Driven floor failures. Those floors can be destroyed, in the process or as you said form a stack if the energy in the collapse is low, and the floors are strong enough to survive the collapse.

 

[JSanderO]

if you look up the definition pancaking DOES requiring a stack.

 

[Oystein]

if you look up the definition pancaking DOES requiring a stack.

Since you must have looked it up, why don't you post a link
or citation and thus support your claim with evidence?

 

[JSanderO]

https://www.microblife.in/what-is-a-pancake-collapse/

"What Is A Pancake Collapse?
According to structural engineers a “pancake collapse” is named for the way collapsing floors land and stack as they fall. … The damage is usually found in a building’s lower floors or foundation which triggers the top floors to collapse vertically into the floors below.Jul 6 2021"

 

[Crazy Chainsaw]

https://www.microblife.in/what-is-a-pancake-collapse/

"What Is A Pancake Collapse?
According to structural engineers a “pancake collapse” is named for the way collapsing floors land and stack as they fall. … The damage is usually found in a building’s lower floors or foundation which triggers the top floors to collapse vertically into the floors below.Jul 6 2021"

No where in that link does it say floors have to be stacked for the collapse to be considered a result of pancaking.

 

[JSanderO]

google it then... a defining characteristic of a pancake collapse is a "stack of floor (slabs)".

"What Is A Pancake Collapse?
According to structural engineers, a “pancake collapse” is named for the way collapsing floors land and stack as they fall. … The damage is usually found in a building’s lower floors or foundation, which triggers the top floors to collapse vertically into the floors below.Jul 6, 202"

 

[Oystein]

https://www.microblife.in/what-is-a-pancake-collapse/

"What Is A Pancake Collapse?
According to structural engineers a “pancake collapse” is named for the way collapsing floors land and stack as they fall. … The damage is usually found in a building’s lower floors or foundation which triggers the top floors to collapse vertically into the floors below.Jul 6 2021"

Seriously?
microblife.in?

microblife.in answers questions such as "What Is Kinesthetic Intelligence?" or "What Kind Of Communist Are You?".

Is that your go-to source for education on engineering topics?

"According to structural engineers" - well, whom? Is that taken from a textbook - which one? Or did the anonymous author of this microblife article ("Admin") follow some discussion on reddit where participants pretended to be engineers, and that's his take-away?

You ask Chainsaw to "google it then" - the evasive non-answer we get so damned often from Truthers.

The thing is: "pancaking" is not a technical term with a defined meaning, I am sure. It is an ad-hoc conceptualization of broad characteristics of a vague class of occurrences.

And I disagree that the key characteristic involves ending up with a "stack". I am pretty convinced the key characteristic is that the main failure mode in collapse progression is the successive shearing of horizontal sub-assemblies (generally "floors") due to overloading, as opposed to failure of vertical elements.

But I have no source for that, either, and it's my personal, non-expert take. I could probably "find" something on Quora if I try hard...


(I checked out "Ronan Point" on Wikipedia, which is perhaps the classic example of a pancake-style collapse - and the term "pancake" appears nowhere there nor in the linked references, so far as I can open them. Also, the English Wiki article on "Progressive collapse" - "Pancake collapse" redirects there - mentions "pancake only in connection with either the twin towers and NIST, or the Plasco in Teheran. So that would give us a circular argument if we referred to that. The take-away seems to be that the term is not really established and better avoided if you want to talk about details beyond a mere, rough label)

 

[ozeco41]

...and all this scurrying down the rabbit burrows chasing "pancakes" arose because, when attempting to clarify a bit of possibly forgotten history, I said: "can be legitimately described as pancaking.."

.. and I even foreshadowed JSanderO's preferred definition in my failed attempt to minimise sidetracks.

So I'll stick with "can be legitimately described as..." if nobody wants to discuss the topic.

And, on the topic, I still maintain that AE911 is playing the game that a cynical politician would want them to play. It isn't going anywhere.

 

[JSanderO]

Oy makes a good point that the connections of the floor plates must fail to release the floor (pancake?) which drops.... and what seems to have happened at the WTC is that this process went runaway because no floor was able to resist the falling mass. It should be noted that the falling mass could also "destroys/shatters" the floor it falls on... (likely what happened at the ETC) and that floor did not remain "structurally" integrated such that the overloading caused the connections to the columns to fail (shear).
I believe there is evidence of some bent over beam / truss seats indicating a large downward impulse at the connections. I don't know if this was true for all truss seats. But we do know that MOST of the slabs were crushed, pulverized and destroyed but the progressive runaway floor collapses... and there were few "intact" slabs when the dust settled. (someone ate the pancakes?) Perhaps the sections of slabs road on top of the collapse debris mass? But for sure there were no whole pancakes.... and at best only pieces of pancakes.... and no "stacking" of floor slabs when the dust settled.

I did a google search for stacked floors from a collapse and saw only a few pics showing sections of intact slabs. My conclusion is slabs don't survive intact enough to form a stack.


I found this buried in a definition of pancake:

"2. To fall flat to the ground with great force, especially to collapse in such a way that higher floors or structures fall directly on the ones beneath."

of this:

"The act of running towards someone smaller than you, thrusting your full body weight onto them, and causing them to be lying flat on the ground with you laying flat on top of them after impact. Your bodies create the illusion of a short stack."

 

[Crazy Chainsaw]

Oy makes a good point that the connections of the floor plates must fail to release the floor (pancake?) which drops.... and what seems to have happened at the WTC is that this process went runaway because no floor was able to resist the falling mass. It should be noted that the falling mass could also "destroys/shatters" the floor it falls on... (likely what happened at the ETC) and that floor did not remain "structurally" integrated such that the overloading caused the connections to the columns to fail (shear).
I believe there is evidence of some bent over beam / truss seats indicating a large downward impulse at the connections. I don't know if this was true for all truss seats. But we do know that MOST of the slabs were crushed, pulverized and destroyed but the progressive runaway floor collapses... and there were few "intact" slabs when the dust settled. (someone ate the pancakes?) Perhaps the sections of slabs road on top of the collapse debris mass? But for sure there were no whole pancakes.... and at best only pieces of pancakes.... and no "stacking" of floor slabs when the dust settled.

I did a google search for stacked floors from a collapse and saw only a few pics showing sections of intact slabs. My conclusion is slabs don't survive intact enough to form a stack.


I found this buried in a definition of pancake:

"2. To fall flat to the ground with great force, especially to collapse in such a way that higher floors or structures fall directly on the ones beneath."

of this:

"The act of running towards someone smaller than you, thrusting your full body weight onto them, and causing them to be lying flat on the ground with you laying flat on top of them after impact. Your bodies create the illusion of a short stack."

Pancaking describes the Mechanism that destroyed the floors through overwhelming load is a short duration of time, the floors in the World Trade Center were not strong enough to survive the collapse and stack in a net order Pancaking is a verb in this instance describing an action.
It could also be referred to as a Rain of Overwhelming Momentum Collapse. Which I proposed to be used instead of Pancaking back in 2006 and was laughed at for that proposal. Yet I was the first to figure out Mathmaticly why the collapse, was so fast though the mechanical Floors, off Center strikes using applied leverage reduce the energy needed to sheer connections.
That fact was used by DBB, In his paper with Banzant and Greening.
The paper a Hypothetical simply showed why the collapse was so Rapid and Total.

 

[Robin]

It's seems, as with many terms, 'pancaking' gets used in different ways. In one of the interviews a fire fighter says, of WTC7 "Relax, it is pancaking, just stay in the car", obviously meaning that it is falling straight down and that they don't need to try to move away

I have watched the WTC 1 and 2 collapses so many times now (as I am sure everyone else here has) and I doubt there is a name for what it does.

An avalanche, as someone said earlier, seems to be the most apt term, but really it just fell like it fell.

 

[ozeco41]

It's seems, as with many terms, 'pancaking' gets used in different ways.

Yes.

and I doubt there is a name for what it does.

An avalanche, as someone said earlier, seems to be the most apt term, but really it just fell like it fell.

Why not use a descriptive term. Which aligns with the unique aspects of the WTC design and the main features of the rapid collapse.

The debris material fell down the open office space created by the tube in tube design.

It was a runaway process. Which resulted in global destruction.

So why not "runaway open office space destruction". We could possibly turn it into an acronym for brevity - both brief and specifically relevant to the WTC Twin Towers collapses.

Meanwhile, the thread topic is still " AE911Truth pressures NIST for decision on WTC 7 report." And AE911 is playing the game that a cynical politician would want them to play. It isn't going anywhere.

 

[Petra]

Yes.

Why not use a descriptive term. Which aligns with the unique aspects of the WTC design and the main features of the rapid collapse.

The debris material fell down the open office space created by the tube in tube design.

It was a runaway process. Which resulted in global destruction.

So why not "runaway open office space destruction". We could possibly turn it into an acronym for brevity - both brief and specifically relevant to the WTC Twin Towers collapses.

Meanwhile, the thread topic is still " AE911Truth pressures NIST for decision on WTC 7 report." And AE911 is playing the game that a cynical politician would want them to play. It isn't going anywhere.

For descriptive term how about "banana peel". In this building demolition in China we see floors at large intervals being blown out with gravity doing the work for the sections of building in between the blowouts. Couldn't the twin towers demolitions have been caused by a similar type of demolition but rather than the blowouts occurring at large intervals and very obviously being horizontal blowouts being much more frequent less obvious blowouts - every couple of floors perhaps.
https://youtu.be/jO15CXhsTM4

 

[Cosmic Yak]

For descriptive term how about "banana peel". In this building demolition in China we see floors at large intervals being blown out with gravity doing the work for the sections of building in between the blowouts. Couldn't the twin towers demolitions have been caused by a similar type of demolition but rather than the blowouts occurring at large intervals and very obviously being horizontal blowouts being much more frequent less obvious blowouts - every couple of floors perhaps.
https://youtu.be/jO15CXhsTM4

That demolition looks nothing like the collapse of WTC7- nor does it sound like it. Despite the -presumably intentionally dishonest- attempts by the makers of that video to disguise the sound, you can still tell there are massively loud explosions. Also, would you say that building collapsed into its own footprint? Doesn't look that way to me: looks to me like stuff was blown out a considerable distance by the detonation of the explosives, and showered the surrounding area with large chunks of debris. As a final point, you can see the building twist slightly and lean forwards as it collapses- so it's not symmetrical either.
You still need to show where and when explosive charges were set in WTC7, by whom, and how those charges survived 7 hours of fires around them.
So, no, nothing in that video lends credibility to speculation about CD.

 

[Robin]

For descriptive term how about "banana peel". In this building demolition in China we see floors at large intervals being blown out with gravity doing the work for the sections of building in between the blowouts. Couldn't the twin towers demolitions have been caused by a similar type of demolition but rather than the blowouts occurring at large intervals and very obviously being horizontal blowouts being much more frequent less obvious blowouts - every couple of floors perhaps.
https://youtu.be/jO15CXhsTM4

Why did you pick a video that doesn't look.or sound even remotely like any of the 9/11 collapses?

 

[Oystein]

... Couldn't the twin towers demolitions have been caused ...

No, for the simple reason that there were no twin tower demolitions.

It escapes me why anyone would present a video that's EDITED!!!! with an overlayed electronic dancefloor track. That destroys any pretense at credibility and respectability right at the outset.

How could you fail to notice that in the actual, explosive demolition, stuff was ejected BEFORE the building section above started to come down? Whereas at the twin towers, stuff ejected AFTER the top part started coming down.
Cause precedes effect.

I sense some hopeless desperation in your post, as you try hard to cling to your old, tired, long-debunked fantasies.