Use of Scale Model or Full Sized models for investigating 9/11 collapses

Who said anything about a CD?

I cannot understand your continuing point, then?

....because....over the years I have seen you "question" the collapses of the WTC 1 & 2. AND just in this thread, "question" the last 13 years of engineering graduates who pay around $100,000 for their degrees.

So....this thread is ABOUT the modelling of the collapses of THREE buildings, on 11 September, 2001. MANY very prominent explanations have been put forward, over the last 13 years. NONE (that are viable) involve controlled demolition (which is a provenance ONLY of those in the so-called "truther movement").

So, what is left? Logically? This is not meant as a 'rhetorical' question. It is about LOGIC, and science.
 
When does anyone ever specify the number of connections around the inner and outer edges of the floors?

They aren't even interested in accurate data on the distribution of steel down the towers. Like two flat sticks can represent a floor that went all around a core connected by beams constructed differently from the trusses that supported the main floor.

psik

Ironic that you would call into question the precision by which a model represents the WTC towers.

Lateral support and floor to column connection in your model are indestructible. You essentially have indestructible connections due to the dowel which never allows misalgnment
 
When does anyone ever specify the number of connections around the inner and outer edges of the floors?

I think these specifics can be found, with proper search criteria.

THEN these can be included into the models of the collapse scenarios. Seems rather obvious, if indeed not "easy" for a model to accomplish. BUT, that is up to those who are clever....
 
Ironic that you would call into question the precision by which a model represents the WTC towers.

Lateral support and floor to column connection in your model are indestructible. You essentially have indestructible connections due to the dowel which never allows misalgnment

Now that is funny!

There was HUGE misalignment when the top of the south tower tilted 25 degrees, but the collapse advocates do not have to explain why it did not fall down the side. We do not even hear discussion of the location of the centers of mass or rotation of the tilted top portion.

Just leave out information and you don't have to explain simple physics.

Since my model is so narrow relative to its height, the top would almost have to fall down the side.

psik
 
Since my model is so narrow relative to its height, the top would almost have to fall down the side.

That's not really why though, it's because of the construction and relative strength of materials. The towers essentially crumbled, because of scale. It don't think you can really simulate that at the scale of your model.
 
That's not really why though, it's because of the construction and relative strength of materials. The towers essentially crumbled, because of scale. It don't think you can really simulate that at the scale of your model.

The paper loops are so weak it is impossible to make the stack stand 33 levels tall. I have tried it. It falls over at about 20 levels.

If the towers "crumbled" then why shouldn't it be easy to make a model that duplicates the phenomenon and why won't official sources provide complete data? Why is it that sources from before 9/11 say there were 425,000 cubic yards of concrete but since then we can't determine where that much concrete was inside the towers? We don't even know all of the different weights of perimeter panels and quantities of each.

Very Scientific!

psik
 
Ironic that you would call into question the precision by which a model represents the WTC towers.

Lateral support and floor to column connection in your model are indestructible. You essentially have indestructible connections due to the dowel which never allows misalgnment

My model does not have any FLOORS! The washers are just mass that must be supported. My model is not an attempt to be to scale it is a physics demonstration.

How does anyone explain why the top of the south tower did not fall down the side and bring up the center of mass? People just BELIEVE in the 9/11 Religion without doing the physics. 13 years and "experts" do not even discuss the distribution of mass in skyscrapers even though 50 buildings over 1000 feet tall have been constructed since 9/11.

psik
 
My model does not have any FLOORS! The washers are just mass that must be supported.
:confused::p
What do you think office floorspace is?
How does anyone explain why the top of the south tower did not fall down the side
What would shove it to the side?
bring up the center of mass?
What the H would that affect in terms of collapse sequence?
People just BELIEVE in the 9/11Religion without doing the physics. 13 years and "experts" do not even discuss the distribution of mass in skyscrapers even though 50 buildings over 1000 feet tall have been constructed since 9/11.
13 years and such questions are irrelevant or make no sense to, the majority of the world's experts. This to you means?????? A cover up of enormous magnitude or ineptitude in an entire profession???
To me it illustrates that the questions are irrelevant or meaningless.
 
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If the towers "crumbled" then why shouldn't it be easy to make a model that duplicates the phenomenon

Because of scale. The towers were very big. Models are very small. Some of the physics is going to scale very badly. You can demonstrate aspects of the principal of collapse, but it would be impossible to make an exact scale model that duplicates it.

You never said if you read this thread. At least the first page. But look at what needed to be done to just test the connection strength on this "scale" model. They had to load it with iron bricks.




And the model is still very large. If you shrink it down smaller, then the weight needed would make it denser than gold - with no free space in the structure.

The material simply don't exist to build a scale mode that's just a few feet high that would crumble like the towers did. All you can do is illustrate various principles.

You model illustrates that if the towers were build from some incredibly strong bendy unbreakable fibrous substance, then they would not have collapsed. It's not much different to Richard Gage's scale model, and I don't imagine you think that demonstrates anything:

 
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Because of scale. The towers were very big. Models are very small. Some of the physics is going to scale very badly. You can demonstrate aspects of the principal of collapse, but it would be impossible to make an exact scale model that duplicates it.

This EXCUSE is nothing but saying YOU can't be wrong.

I admit my model is too small to be conclusive. But if a 50 foot model won't collapse you could say that was too small also.

We know a full model isn't going to be built because it is too expensive. So where is the computer model where complete data is provided?

It is curious how the collapse enthusiasts don't say much about the time of collapse, like it does not have to be explained. Like the intact lower portion would slow down the falling upper portion.

psik
 
I admit my model is too small to be conclusive. But if a 50 foot model won't collapse you could say that was too small also.

We know a full model isn't going to be built because it is too expensive. So where is the computer model where complete data is provided?

Why not just a simplified computer model that demonstrates what you claim your washer model demonstrates, but adjusted for scale? Would that tell you anything?
 
The paper loops are so weak it is impossible to make the stack stand 33 levels tall. I have tried it. It falls over at awbout 20 levels.
You have discovered the issue of slender column instability.
You solved this instability by supplying lateral support in the form of a basically infinitely stiff, full height single central column.
Your floor pans are also kept aligned above the columns and are infinitely strong.
The only mode of failure possible is via column crush buckling. However fracture is not possible.
You employ only perimeter column system of essentially a single exterior tube.
Connections along paper column length (both column section to next upper floor and floor to next upper column) are unfailable due to the constraint supplied by the central column.

You have demonstrated that if a structure is built with essentially infinite lateral support and with un-failable floors and floor mass transfer connection, with a single exterior column tube, then it cannot buckle under the loading conditions you supplied.

If the towers "crumbled" then why shouldn't it be easy to make a model that duplicates the phenomenon
Mick did exactly that in a one dimensional model that fell apart when its "floors" were subject to loading that failed the floor to column connections. He could have mimicked the column section connections as well with a sliver of tape in two sides of the column. However column section splicing was never designed to overcome slender column failure so its a moot point.
ETA: strikes me that Mick could have modeled the floors with saltine crackers and thus allow for floor pan failure as well as possible connection failure. Bit more messy though.

OH! how about Popsicle sticks under saltine cracker floor pans, like relatively brittle concrete over flexible steel trusses. Connection to columns only on the popsicle sticks. Now,,,, how to simulate rebar....?

Why won't official sources provide complete data? Why is it that sources from before 9/11 say there were 425,000 cubic yards of concrete but since then we can't determine where that much concrete was inside the towers? We don't even know all of the different weights of perimeter panels and quantities of each.

Very Scientific!

psik

If you aren't interested in trying to scale a model then you don't need that data.

its odd that you complain about being scientific and asking for precise figures when you admittedly are not being scientific in your modeling. What are you demanding. That we do proper and precise modeling but that you are not required to adhere to the same rules?

No one knew that the breakdown of mass of every component of the towers was going to be of interest to anyone a half century after construction. Total concrete may well have included heavy foundation mix as well as lightweight office floor concrete. It is however fairly easy to estimate at 4 inch thick lightweight concrete and the amount of rebar in them. We could estimate the floor loading but we already have the 29 million pound max load that Keith supplied. Pick a percentage of that. 50% sounds good to me. You know the size of columns, estimate their mass. Precision isn't going to matter unless you are also going to be precise in every other aspect such as bolt and weld failure.

There are problems with scaling. Those problems can be overcome by modeling full scale in a computer.
There are problems with precision in physical modeling and these apply to computer modeling as well. (bolt and weld failure stresses, or bracketing a margin of error on various parameters, for instance) but a computer can modify its input data over and over again if new info comes into play for instance. Physical modelling cannot do that, its too cost prohibitive. Computer modelling also creates no waste products requires fewer staff and does not put anyone in physical danger. You don't need a hardhat to do a computer simulation run.
Wow, gets complicated just getting the data estimated. Haven't even tackled the equations that come into play as the initial failure is induced, you calculate breaking points, track large debris and debris trajectory, where that large debris hits other components and how fast.
 
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Why not just a simplified computer model that demonstrates what you claim your washer model demonstrates, but adjusted for scale? Would that tell you anything?
Adjusted for scale? If he wanted to he could sim the model as a 1100 foot dowel with infinite stiffness in all three dimensions (a simplification) , make the floors infinitely stiff as well and therefore only a mass contributor(a simplification) ( a mass he could select at will), and model any fashion of vertical load carrying system he wishes. (ie. how about the floors being 200 feet in diameter and supported by a ring of 8 columns (one every 45 degrees around the central non-load bearing column, makes it simple) of whatever properties he wishes them to have.

He could do it over and over again adjusting anything he wants, including initial dynamic loading on the top floor.


Do I suspect what his reply to this will be ? yes, yes I do.
 
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Mick did exactly that in a one dimensional model that fell apart when its "floors" were subject to loading that failed the floor to column connections. He could have mimicked the column section connections as well with a sliver of tape in two sides of the column.

I did actually try that, but it was getting to be too much work to build the models
 
I did actually try that, but it was getting to be too much work to build the models
Oh I'm great at suggesting others do work.:)

You might notice my latest revisions to my last two posts.

( I am awaiting headquarters to change programming on a local device that in IT's infinite wisdom I am not allowed to access. I get to wait on them so that I can confirm the dang revision operates properly. So I have a few minutes to burn)
 
What was the weight of a perimeter wall panel at the 9th floor? What was the weight of a wall panel at the 109th floor?

psik
No estimate after 13 years? Why no estimate for the difference in 3 inch steel to 1/4 inch steel? Maybe it is time to give up modeling.

Did you want the whole panel, three floors by 10 feet, or what? Is this why you washer model fails to collapse properly?
 
What was the weight of a perimeter wall panel at the 9th floor? What was the weight of a wall panel at the 109th floor?

psik
Why? What do you plan on doing with such data?

Maybe you are questioning why such entities as AE911T don't have that data. Good question. They have a description of the perimeter panels, height, width, thickness of steel. Seems to me that competent engineers wanting to know its mass could use their grade school science and math to calculate it. That is if they were really interested and driven by a desire to do something with the results.
 
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No estimate after 13 years? Why no estimate for the difference in 3 inch steel to 1/4 inch steel? Maybe it is time to give up modeling.

Did you want the whole panel, three floors by 10 feet, or what? Is this why you washer model fails to collapse properly?

You said this:

The mass of the WTC/floor is easy to estimate.

I am trying to see what you know to back that up.

psik
 
I am trying to see what you know to back that up.

How accurate do you need? If you claim to be able to demonstrate that the towers could not collapse based on a experiment with some paper and washers, then surely all you need is a reasonable range?
 
Relevant post from another forum, four years ago:

http://www.rationalskepticism.org/c...y-9-11-thread-part-ii-t6310-2240.html#p611376

Re: The Obligatory 9/11 Thread Part II
#2259 by amused » Dec 05, 2010 6:44 pm

If you want to pretend that you are building models with washers that have any relevance to the actual structure, then at least get the basic physics right. A toy 'model' that mimics the actual layout of the structure would not have anything between the washers. Buildings are mostly air because that's where the people inhabit them. Rather, the washers would be supported only at the edges, thus:
Content from External Source

The red rods should be made of toothpicks glued end to end to mimic the fragility of the columns since they were made of small parts bolted together. Then drop a wad of washers on whatever level so that it breaks the connection between the washer below and the supporting toothpicks. That wad of washers will break loose the first washer it hits, then those will hit the next one down, and so forth. Unless you use epoxy to glue the washers to the toothpicks, the whole thing will come down in a similar fashion to the collapse of the WTC structures. If it doesn't, the edge connections in the 'model' is too strong to accurately model the actual connection.

Such a toy model would at least come close to depicting the layout of the actual structure, where the floor trusses rested on shelf angles that were supported only at the inside face of the exterior columns and core columns:
Content from External Source


The shelf angles in the blue circles were the only thing holding the floors up, and also held the building together. The angles in the red circles were for lateral support to the floor assembly. [...]
Content from External Source
Removed some stuff at the end for politeness.

[Edit - removed off-topic musing]
 
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How to calculate mass of a hypothetical box column:

Steel has a density of about 490 pounds/cu.ft.

A steel box column 30 feet long and twelve inches per side and 1/2 inch thick steel sides.

Each side is then 30 X 1 X 1/24 = 1.25 cubic feet
Four sides gives us 5 cubic feet which we then see is 2450 pounds worth.

Density of steel listed on the internet actually is between 484 and 502 pounds per cu.ft. so what's the margin of error?

2420 pounds to 2510 pounds. Midpoint would be 2465 pounds, not too far off.

Just for ease of calcs let's says it at the high end, 2500 pounds. If we had 100 of such columns their total mass would be 250,000 pounds. Assume that the floor pan on top is capable of carrying 5 million pounds and was operating at 50% of that. You have 250000 pounds holding up 2500000. What is contributing the most mass?

Now all an interested person need do is look up the description of the columns and multiply factors to their heart's content.
 
There seem to be two separate issues in this thread:

1) Building a model that would demonstrate if progressive collapse of a 110 story tower is possible, or not.
2) Building a model of a WTC tower to demonstrate that the the observed collapse was or was not consistent with what was observed.

I think it makes most sense to address the first issue before moving onto the second.
 
Relevant post from another forum, four years ago:



I ignored that idiotic drivel years ago because there is no way anyone could build it and control the strength of the glued connections with any precision.

I tested the paper loops to see how much of a static load they could handle. A single paper loop collapsed under 12 to 15 washers. That is why I have 11 single loops at the top. I did not just pull the number out of my ass.

Anybody that wants to can build that glued contraption. I am not going to waste my time on it. I never equated the washers with FLOORS. They are just masses being held up by crushable supports. I am not thinking by analogy.

psik
 
They are just masses being held up by crushable supports.

Unlike the WTC towers, where the failure of the floors was not dependent on the columns being "crushed"

Perhaps the toothpick model is too difficult to build, the point is that it more accurately represents the situation than your model, which really tells us nothing about the towers.
 
there is no way anyone could build it and control the strength of the glued connections with any precision.

I tested the paper loops to see how much of a static load they could handle. A single paper loop collapsed under 12 to 15 washers. That is why I have 11 single loops at the top.

Anybody that wants to can build that glued contraption. I am not going to waste my time on it. I never equated the washers with FLOORS. They are just masses being held up by crushable supports. I am not thinking by analogy.

psik

As has been stated already, the floors of a building ARE the mass that supplies the forces that must be transmitted to a structure's columns (plus the mass of the columns themselves). Whether YOU equated them with floors they obviously perform the same task as a floor.

You showed that it is possible to manufacture a set of conditions that would allow a progressing collapse to arrest by including several components that cannot possibly fail.That is irrelevant wrt the WTC tower collapses. You also showed a progressive failure mode that does not have any relevance to the collapse mechanism of the WTC towers.

You cannot think of any way to consider the glued connection strength,, nothing at all?

Ok, how about one first makes 15 single level models and test them each to failure. Then you take the simple average of those 15 results as the failure load. Or, use the minimum failure load in the 15 samples if they do not vary a great deal.
 
Unlike the WTC towers, where the failure of the floors was not dependent on the columns being "crushed"

Perhaps the toothpick model is too difficult to build, the point is that it more accurately represents the situation than your model, which really tells us nothing about the towers.
Psyky modeled a strict column crush mechanism so what the heck, next choice is to model a strict floor/floor connection progression collapse. To that end one could use solid, long dowels as the columns representing essentially infinitely stiff columns with floors, or non-vertical component masses, connected to those columns.
 
As has been stated already, the floors of a building ARE the mass that supplies the forces that must be transmitted to a structure's columns (plus the mass of the columns themselves). Whether YOU equated them with floors they obviously perform the same task as a floor.

So you are saying that the cores and the perimeters columns had no significant mass?

There is not a single piece of hard evidence of a floor breaking loose from the core and falling on another floor. That is entirely presumption.

We are told by various sources that the buildings weighed from 400,000 to 500,000 tons. The NIST says the standard floor assembly weighed 750 tons. 750×110 is 82,500 tons.

The NIST says there was 100,000 tons of steel in each tower. If we accept the source claiming 425,000 cubic yards of concrete means more than 300,000 tons of concrete per building.

psik
 
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You said this:

I am trying to see what you know to back that up.

psik
I think it is easy, but I think landing in driving rain at 2000 RVR is easy, and building computers is easy. There is no excuse for not estimating the masses you want to know after 13 years.
If I was obsessed with mass, I would have an estimate before 13 years passed, not complaining about it for years. It is easy as show in the post above.

What I wrote last night watching Bad Teacher...
""What was the plate thickness at floor 9, 3 inches? 109, was it .25 inches? I wonder if 1/2 inch steel would have stopped the aircraft at the shell? I think it might (stop the aircraft)... however, the estimate, you have one right? If not... Next you need to look up the density/mass of steel, then dimensions, etc, and then you have it. The concrete is easier... 4 inch floors, density/mass of concrete. How much help do you need? Try starting with this, and see what you get. I would look up more for you, but I am copying slides with my digital camera and have to trim the walnut trees, and cut down an oak tree... I will help when I can, but it is easy to do, but it takes time and effort, and much more rewarding if you try on your own. My model has the WTC collapsing once a floor is loaded past 30,000,000 pounds, and it can't stop until the ground. My model is simple, and has the collapse time of 12.08 seconds. I can almost do my model in my head, I needed excel for the collapse time.

Do 12 floors in your estimate weigh more than 30,000,000 pounds? You have estimates for floors mass after 13 years.

What did you get? On the mass of a perimeter wall panel? Are you limiting it to one floor, or the whole panel, three floors?

Did you know some of the best ways to start finding information on the WTC structure is from 911 truth sources, especially ones with references to real work. Like this...

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

I think I saw this over 5 years ago, did you find it too? Did it help estimate your needs?

Models for floors, the floors weigh the same (you could use washers), one estimate, the connections remain the same, each floor fails at over 29,000,000 pounds, an easy model. 911 failure mode, a floor is over loaded, fails, the mass moves to the next floor, the floor fails, each impact can be modeled as a momentum transfer, the debris mass moves faster each floor due to g, and the velocity is slowed by each increase in mass as each floor fails and joins the falling debris mass. What would slow the destruction of the core and shell is the fact the shell plate thickness goes from 1/4 inch to 3 or 4 inches at the base, and that changes a lot. Do you model the shell, or core; the floor connections are the constant, and floors would fail to the bottom, if the load exceeds 29,000,000 pounds, and a moving debris pile would not have to be that much mass to break a floor from the core and shell.

Once started I can't see how you can stop lower floors from seeing loads in excess of their load limits; is this why your model fails, a floor still fails at the same weight all the way down (maintenance floors can hold more right... )
The big problem might be, understanding the shell and the core can hold all 110 floors, plus more, they have no problem holding up the WTC, but the floors can't hold more debris than 11 or 12 floors, then it fails. Understanding the WTC has to have the floors holding the core to the shell as a system; this is how the WTC was built, a floor at a time, it was a system which made it the strongest building around; anything which separates the floors from the shell or the core would destroy the WTC system.

If you have not estimated the WTC masses of interest after 13 years, NIST has some stuff you could use too, but you have to dig through NIST. Or libraries, after 13 years I think a good estimate could be made. Yes, I would say going to the moon and back is hard, but estimating the WTC masses is easy, it is all relative...

Someone has all the floor plans, blue prints...

In your model, what can a floor (the washer) hold in weight? How many washers/floors can your washer model hold. The WTC the magic number is 11 or 12, then the washer/floor fails. Thus a proper washer model would collapse to the ground. ""
Wow, don't post watching Bad Teacher... Good luck with your estimates

If you model washer floor can hold more than 12 washers, it does not model the WTC.

It easy to estimate stuff, you do the research, and then calculate. Post 425 gives some clues. Do you think easy means 10 seconds, or what? You might need to spend a semester working on it, or a week, but there is no excuse for complaining about the mass when you can estimate it with knowledge.

I would post the photos I am working on, slides to digital using a DSLR, at 36 mega pixels I can see the grain (I think) on the Ektachrome/Kodachrome slides, but it would not help your estimates, the estimates you want, your estimates. - it is off topic, and something I find easy to do for real. We do those things we find important, and I think estimating the WTC masses you want is easy, I choose to do those things I want to do. I don't have any problems finding enough to estimate what you want, but I will not be doing your work for you. Good luck
 
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So you are saying that the cores and the perimeters columns had no significant mass?
No, I am saying that the most important mass in a structure must be the working space. Are you saying that the length of column between floors weighs more than the floor? You will also notice that I included the mass of the columns as well.
But lets see: say we have a set of columns capable of supporting a total load of X Kg. If the set of columns equals X Kg, it is already at its max load. Now there is no possibility of supporting floors. So max load must be less than the mass of the columns, therefore floor plus live load all times 110 must be less than the difference between max load and mass of columns.
For only the top ten storeys of course the columns only have to support the mass of the structure above that level. Note though that the floor design doesn't change (yeah, yeah except for mech floors which are heavier)

There is not a single piece of hard evidence of a floor breaking loose from the core and falling on another floor. That is entirely presumption.
Is there another more obvious and better proven mechanism? Perhaps you have evidence to support the notion that column crush was the primary mechanism of collapse?

We are told by various sources that the buildings weighed from 400,000 to 500,000 tons. The NIST says the standard floor assembly weighed 750 tons. 750×110 is 82,500 tons
Citation please, I'd like to check the context.

The NIST says there was 100,000 tons of steel in each tower. If we accept the source claiming 425,000 cubic yards of concrete means more than 300,000 tons of concrete per building.

psik

You have concrete at 1410 lbs/cu yd?

lightweight concrete has a density of, upper value, 115 lbs/cu ft according to several online sources.
115 X 27 = 3105 lbs/cu.yd. (there are 3x3x3=27 cu ft in a cu yd)
425,000 cu.yd. X 3105 lb/cu.yd =1,319,625,000 lbs
1319625000/2000 = 659,812.5 tons

Now does any of this volume of concrete belong to the foundation, which would be normal weight or greater and therefore 1.3+ times as dense? Can't very well add foundation mass into calcs in the collapse of above grade structure.

Quick check. IIRC the towers were 200 feet by 200 feet (roughly) and the floor pans were 4 in thick of concrete.
200 X 200 X 0.33 =13,000 cu ft of concrete. At 115 lbs per cu ft that's 1,400,000 lbs (700 tons) per level , 77000 tons for 110 floors. Pretty much on par with what NIST says for a floor assembly.

Ok, I invite, nay, implore, others to check my math here. There's a big difference between 660 million and 77 million tons. I either misplaced a decimal point somewhere, or most of the mass of concrete was in the foundation.
 
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There is not a single piece of hard evidence of a floor breaking loose from the core and falling on another floor. That is entirely presumption.

Psikey, you were previously given photographic evidence of pancaked floors, which by definition means they had become unconnected from the core and perimeter columns:

You did not extend the courtesy of a response, but merely repeated your claim. But more to the point, do I understand you right?
  • You are not interested in proving that the collapses could continue unaided by demolition charges.
  • You are not interested in scaling a physical model.
  • You are upset because neither NIST nor any engineering school has built a physical model for the collapses, nor done a computer simulation.
So you really have no claim, just a kvetch. Since this forum is about evaluating specific claims, I suggest that this entire discussion is not germane to the forum and should be removed to "rambles". You've been at this for a long time. Since, after all these years, you still can't make a specific claim, I would suggest that you are a "model" for the failure of the "Truth Movement".
 
Psikey, you were previously given photographic evidence of pancaked floors, which by definition means they had become unconnected from the core and perimeter columns:

If that looks like floors to you that it your problem.

Do you have a link to the source where the people who actually examined it say something about it?

Like a picture can tell the difference between floor from outside the core from floor slabs from within the core.

psik
 
I think the conceptual representation of "pancaking" floors over-simplifies the reality.

These floor pans would have broken up, during the collapses, as the extreme forces acted upon them. In what are actually a very chaotic way. This would be difficult to model "exactly". But, most can comprehend the principles involved.
 
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