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

[OneWhiteEye]

At least two serious issues have been brought up in relation to psikeyhackr's small physical model, scaling and inapplicable failure mode. All the same, it should be possible to build a scaled down physical model which will self-crush given a modest initial defect. While I liken the towers to a house of cards as the nearest everyday category of metastable systems, if the work of Bazant, Seffen and others has any validity, the formulations should allow design for such a structure.

Indeed it could be done, but not as easily as the paper loops and washers on a stick (unless you're more clever than I, which is certainly possible).

The basic criterion for progressive collapse in a simple 1D model like this is that energy expended on crushing supports is less than potential energy lost in the act of crushing. Several years ago I showed psikeyhackr how this characteristic plays out in terms of load displacement diagrams [1] and how a 1D stepwise algebraic model could be used to reproduce his paper loops and washer result [2] given the model data. Finally, I did a physical experiment on paper loops of the given spec to show that they do not satisfy the basic criterion for progressive collapse [3]. That pretty much covers the whys and wherefores of why this model arrests.

Once the basic physics is understood and accepted, it suffices to note that, since it did arrest, it doesn't model the properties of steel columns in axial compression despite being "as weak as possible" statically. It can be argued that it does model the action of so-called "stout" columns which fail via diamond/concertina folding, which could lead to arrest, but the nature of this argument is akin to debating how many angels can dance on the point of a pin. This is the tack in Tony Szamboti's most recent paper but, as I showed elsewhere on this forum, he didn't even know that was the case.

Satisfying the static constaint of stably self-supporting without defect and yet also the dynamic constraint on energy dissipation while crushing supports comes naturally when scaled to the level of the towers. These are superlative structures in which great effort and expense go towards making it sufficiently strong, yet not many times stronger than is necessary. At everyday scales, finding something which preserves those characteristics is difficult. The best suggestion I can offer is very thin glass rods as supports. What a pain to assemble.

[1] http://www.rationalskepticism.org/post649597.html#p649597
[2] http://www.rationalskepticism.org/post636274.html#p636274
[3] http://www.rationalskepticism.org/post796166.html#p796166
------------

Side note on thought experiments: I was bored during a commute the other day when I considered the case of an ideal rigid disk rotating at relativistic speed, and was led to the apparent geometric paradox of the relation circumference not equal to pi times diameter. Admittedly, I did have a class in special relativity so maybe I was just remembering something I already heard, but it hardly matters. Figuring I wasn't the first, I looked and, sure enough, it's the Ehrenfest paradox (https://en.wikipedia.org/wiki/Ehrenfest_paradox). Interesting that it took about four years after SR was published before this was formulated.

From the WP article:

The paradox has been deepened further by Albert Einstein, who showed that since measuring rods aligned along the periphery and moving with it should appear contracted, more would fit around the circumference, which would thus measure greater than 2πR. This indicates that geometry is non-Euclidean for rotating observers, and was important for Einstein's development of general relativity

Thought experiments are wonderful things.

 

[Mick West]

Satisfying the static constaint of stably self-supporting without defect and yet also the dynamic constraint on energy dissipation while crushing supports comes naturally when scaled to the level of the towers. These are superlative structures in which great effort and expense go towards making it sufficiently strong, yet not many times stronger than is necessary. At everyday scales, finding something which preserves those characteristics is difficult.

And at a small enough scale, literally impossible. Once could not model it 1cm high, for example.

An interesting calculation for the student of physic would be the find the limit in the height of the model of the WTC at which and exact scale model (dimensions and materials) would self arrest.

Then the same calculation for a scale model with weight adjusted.

Then the same with a scale model with different materials.

Then the same for any model that demonstrates the basic principle of collapse.

I think a big problem the truthers have is that the principals of the collapse do not scale down very well at all (and the suggested models do not scale up), and so it seem intuitively obvious that it would not collapse, because people are thinking in small scale.

Picture another thought experiment. In the vacuum of space, two equal sized balls of solid iron bang into each other at a speed equal to one ball's diameter per minute. Under any normally conceivable circumstance, the balls would bounce off each other and continue on at a slower speed.

But what if each ball was the size of the Moon? Or Jupiter? Our intuitive expectations do not scale.

 

[WeedWhacker]

Once could not model it 1cm high, for example.

OF course as I suggested, the gravity must then be "scaled".

9.8 M/per/sec/per/sec = ONE Earth 'G'.

I think everyone can "do the math" from here.....

\(EDIT)/...Oh, Mick already added this in....using "Jupiter" for instance. Problem is, Jupiter does NOT have a solid surface.....thus its gravity is variable, based on the distance from its center....but, this is not relevant BECAUSE the WTC Twin Towers were on Earth.

 

[Mick West]

\(EDIT)/...Oh, Mick already added this in....using "Jupiter" for instance. Problem is, Jupiter does NOT have a solid surface.....thus its gravity is variable, based on the distance from its center....but, this is not relevant BECAUSE the WTC Twin Towers were on Earth.

My example was of iron balls the size of Jupiter though. Not directly related to gravity.

And you don't need to scale gravity, that just alters time. With the towers is the scaling of mass that is the issue. Square Cube, etc.

 

[WeedWhacker]

My example was of iron balls the size of Jupiter though. Not directly related to gravity.

Actually....an iron ball the "size of Jupiter"? It might compress itself so much as to spontaneously ignite into a small star!!!! (Due to the force of....harumph!...gravity).

 

[Mick West]

Actually....an iron ball the "size of Jupiter"? It might compress itself so much as to spontaneously ignite into a small star!!!! (Due to the force of....harumph!...gravity).

Quite. The effects of scale are not always what you would expect.

Even at a more terrestrial scale, there are other differences besides the square cube law. There's the granularity of materials - like the size of crystal structures in steel, or the grain size of wood.

 

[Redwood]

Where is this computer modelling where complete data on the model has been provided?

Got a link?

Data from before 9/11 says there was 425,000 cubic yards of concrete in the towers. The 10,000 page NIST report does not even specify the total amount of concrete. I know about the SAP2000 model that the NIST says it did but does not provide complete data for.

psik

Nobody has attempted a computer model of the collapses of the lower floors of the Twin Towers, and nobody ever will, least of all Truthers. Unless, in ten years or so, somebody does it as an academic exercise, what with the extra computing power as per Moore's Law.

It will never be done for the simple reason that nobody needs to model the exact details of the collapses. A simple calculation shows that there is no way that the lower section of the building could survive having the weight of a WWII Tennessee-class battleship dropped on it from a height of ~ 4 meters, even under the circumstances most favorable to its survival. That was the point of Prof. Bazant's simple calculation, done a few days after 9-11.

 

[jaydeehess]

That would be the point of using a 3D printer to make a tube-in-tube design. Such a printer would make it possible to control the strength of the columns in the core and on the perimeter and the strength of the connections between the floors and the columns.

Then your EMPTY CLAIM could be tested.

As it is all you have is TALK!

psik

Shout all you want to. Then you can explain to me how the falling upper mass can impinge any significant percentage of its dynamic impact load on the columns.

If it doesn't, and I see no possibility that it can, then tearing out of floor systems is the dominant mechanism of collapse and your paper loop model is irellevant.

 

[jaydeehess]

Actually....an iron ball the "size of Jupiter"? It might compress itself so much as to spontaneously ignite into a small star!!!! (Due to the force of....harumph!...gravity).

Nitpick, nope an iron ball cannot ignite in a fusion reaction. Iron is actually the limit of stellar fusion reactions.( denser elements get formed in more energetic action, nova explosions. Plus, Jupiter is too small.

OT pedantry over

 

[jaydeehess]

While there are issues with Bazant's various papers, yes, he modeled the impact on floorspace and found that in this approximation ( and psikeyhacker, all models are approximation, ) demonstrated the forces were 30+times greater than could be arrested by the falling mass.

He also modeled infinitely strong floors that could transfer all load to the columns and concluded that, at the level of collapse initiation, the columns would have failed under that loading.

So, there's two more models psik has to ignore to claim no modeling.

 

[jaydeehess]

.

And you don't need to scale gravity, that just alters time. With the towers is the scaling of mass that is the issue. Square Cube, etc.

In a scale model , say 100:1, the distance between floors would shrink from 4 meters to 0.04 meters.

The velocity of a mass falling a distance is proportional to the square of the distance it falls so right away the dynamic forces deviate from a linear scaling , due to a fixed gravitational acceleration.

 

[jaydeehess]

As Redwood said, its not required to model the lower floors. Since the dominant mechanism of dynamic forces impact is, that after collapse initiation, those forces are primarily directed on the floorspace components and more than sufficient to fail them, then the same effect will affect the floors below that first one and those forces can only increase due to greater velocity of an even greater falling mass.

 

[Mick West]

The velocity of a mass falling a distance is proportional to the square of the distance it falls so right away the dynamic forces deviate from a linear scaling , due to a fixed gravitational acceleration.

Square root of the distance (V2​ = ugh)

An object falling 12 feet would be at 19 mph.
Scaled object falling 1.2 feet would be at 6mph.

 

[Redwood]

Nitpick, nope an iron ball cannot ignite in a fusion reaction. Iron is actually the limit of stellar fusion reactions.( denser elements get formed in more energetic action, nova explosions. Plus, Jupiter is too small.

OT pedantry over

To nitpick your nitpicking, you're right on 2 of 3: Iron is the fusion limit, and Jupiter is too small anyway. But heavier elements than iron are created in supernovas, not novas.

Novas are simply white dwarf stars that have accumulated sufficient hydrogen or helium on their surfaces to briefly re-start simple fusion. Unless said white dwarf is just below Chandrasekhar's Limit, in which case the additional mass can start carbon fusion, in which case it becomes a Type 1a supernova.

 

[psikeyhackr]

In a scale model , say 100:1, the distance between floors would shrink from 4 meters to 0.04 meters.

The velocity of a mass falling a distance is proportional to the square of the distance it falls so right away the dynamic forces deviate from a linear scaling , due to a fixed gravitational acceleration.

That is part of why I didn't seriously consider making a collapse model until I gave up an scaling. But then people say the WTC wasn't made of paper. LOL

The supports MUST be strong enough to support the static load, there is no getting around that.

And engineering schools could build a structure 40 or 50 ft. tall. Something totalling 4000 pounds or so could have many levels with each individual level designed to be as weak as possible but still strong enough to hold the accumulated work above.

psik

 

[jaydeehess]

That is part of why I didn't seriously consider making a collapse model until I gave up an scaling. But then people say the WTC wasn't made of paper. LOL

The supports MUST be strong enough to support the static load, there is no getting around that.

And engineering schools could build a structure 40 or 50 ft. tall. Something totalling 4000 pounds or so could have many levels with each individual level designed to be as weak as possible but still strong enough to hold the accumulated work above.

psik

If you don't care about scale models then Mick's model is as good as yours. Better even since it models the actual collapse sequence of the towers while yours doesn't.


If you are going to build something that big then you might as well model a 1/4 scale portion of 5 floors of the actual towers.
However, best modern engineering practice would be to model this mock up in a computer simulation and check computer results against what occurs in the physical mock up.
After all, the world is moving away from physical scale models for a reason. At least this would be more relevant to course study.

What is it that you are proposing is made as weak as possible, and why? Surely not the columns! I would have thought you want to model the actual proposed collapse sequence, not rig the model towards column failure.

 

[Mick West]

That is part of why I didn't seriously consider making a collapse model until I gave up an scaling. But then people say the WTC wasn't made of paper. LOL

The supports MUST be strong enough to support the static load, there is no getting around that.

But strength isn't the only thing that MUST be modeled. There's the type of strength, and the failure mode.

The columns in the WTC got their strength from being A) Exactly vertical, B) Exactly Straight, and C) Laterally supported, as well as the material properties of steel. This gives them a property of being incredibly strong until they come apart at the seams, at which point it's like they are not there.

So rough paper rings on a stick don't really model this. The lateral support is never removed, and the "columns" are essentially already buckled. When they fail they don't just turn to weight, they continue to resist. You might as well have used springs.


And of course the failure of the columns is not what made the collapse progress. It was the failure of the floors. Your floors are not failing.

You need something more like:

https://www.metabunk.org/threads/us...gating-9-11-collapses.3828/page-3#post-110956

Which could very easily demonstrate full progressive collapse if extended to 110 "floors"

The paper+washers might be made to demonstrate something if you use an appropriate material, like very thin and precisely aligned glass cylinders. It would be very hard to build though, as during building it would be nearly impossible to avoid dynamic loads.

 

[psikeyhackr]

If you don't care about scale models then Mick's model is as good as yours. Better even since it models the actual collapse sequence of the towers while yours doesn't.

Can his model be rebuilt with the same because they were not damaged in his "collapse"?

The damaged paper loops must be replaced in mine.

Was the north tower DAMAGED in its collapse?

psik

 

[Mick West]

Can his model be rebuilt with the same because they were not damaged in his "collapse"?

The damaged paper loops must be replaced in mine.

Was the north tower DAMAGED in its collapse?

psik

How is that relevant? The point is that a structure collapsed.

In my model the connectors (tape) were damaged - which was the primary point of failure in the progressive collapse.

In your model the floors were undamaged, but the walls were crumpled - which is pretty much the opposite of what happened. You need to model with strong hinged walls, and weak floors.

Have you read the entire thread, as we seem to be going over old material.

 

[psikeyhackr]

How is that relevant? The point is that a structure collapsed.

It is your website you get to tell everyone what is relevant. They must think what they are told here.

A standing structure has Potential Energy. That potential becomes Kinetic Energy when the mass is accelerated by gravity. But since the structure below must be supported against gravity the support components must be disabled or bent or broken in some manner. That requires ENERGY.

That means the falling component must lose kinetic energy in doing damage and therefore slow down.

The 25 second collapse time of the north tower must be explained. It is not just a matter of collapse or not collapse. My model slows the falling mass to the point of arrest.

It takes 0.118 joules to flatten a single paper loop. Where is the data on the energy required to "disrupt" a single level in the WTC? How much did that increase down the tower? I had to make my model stronger toward the bottom to support the accumulating weight. So there were 5 triple loops at the bottom and 17 double loops in the middle.

Even though I raised the top 4 washers the height of the model the single loops were able to arrest the collapse. With the near total destruction of the north tower any model that does not damage its own components in the process of collapse is simplistic garbage. That is what a model made with a 3D printer would be a good idea. It would be easy to make replacement components to repeat the tests.

psik

 

[Mick West]

With the near total destruction of the north tower any model that does not damage its own components in the process of collapse is simplistic garbage.

Well, I could just make the floors and columns out of spun sugar so they would be damaged in the collapse. Would that then be more accurate?

The towers mostly came apart at the connections. So how are you modeling this in your model?

 

[WeedWhacker]

It is your website you get to tell everyone what is relevant. They must think what they are told here.

Wrong. Just.....oh, so wrong.

 

[psikeyhackr]

I think your claim that you model imitates the structure of the towers is pure rubbish.

The core of the WTC was connected by horizontal beams which your model in no way imitates. I knew the structure of the WTC was too complicated to imitate on a small scale so I did not try. But you have your pieces leaning on a smooth surface. Wouldn't they stand up against gravity?

And then you Jenga blocks are far stronger than necessary to hold their own weight. That is why they can't be damage by their own fall. The whole point of my model was using components weak enough to be damaged. But it still arrested.

Your concept of a model is just "Looks Like". Your core is a joke in comparison to the real thing. The dowel I use keeps the stack from tilting but it does not participate in the vertical fall. Your fall is not even vertical. As I wrote in the description I left the stack standing for 4 days and the 4 washers that I dropped were on top of the stack.

psii

 

[Mick West]

I think your claim that you model imitates the structure of the towers is pure rubbish.

That's not my claim. I'm saying it better illustrates the mode of collapse than yours does. Floors stripped away, columns hinging.

I mean, you don't claim that your model imitates the structure of the towers, do you? You were just trying to illustrate a principle, no?

And I'm a little bemused that you object to the used of an inclined plane used to constraint the model to two dimensions, when you have the vastly more restrictive dowel that constraints your model to ONE dimension.

 

[Chew]

Your concept of a model is just "Looks Like". Your core is a joke in comparison to the real thing. The dowel I use keeps the stack from tilting but it does not participate in the vertical fall.
psii

Your dowel "core" is not capable of being damaged. How could that possibly be an accurate simulation?

 

[Redwood]

Mick and Psikey are working at cross-purposes. Mick built a scale model to give a rough demonstration of the collapse mechanism. Psikey is trying to build a scale model to "prove" that collapse should have arrested unless it was assisted with demolition charges.

 

[MikeC]

But since the structure below must be supported against gravity the support components must be disabled or bent or broken in some manner.

According to your theory if you blew out the bottom floor of a building the rest of it would just fall 1 story - because the remaining structure would stay intact - this is clearly not correct.

The structure is certainly supported against gravity when the building is static - but the dynamic load of the falling building is considerably more than the static load of the standing building.

that is why when a building IS demolished they only have to destroy a small part of the structure - the rest collapses just from the dynamic load.

And it is also why an egg is destroyed by dropping from a height but doesn't disintegrate when just sitting there!

 

[psikeyhackr]

Mick and Psikey are working at cross-purposes. Mick built a scale model to give a rough demonstration of the collapse mechanism. Psikey is trying to build a scale model to "prove" that collapse should have arrested unless it was assisted with demolition charges.

So you can obviously choose sides.

Care to provide a link to where I claimed my model PROVED anything? There is a significant difference between a demonstration and a proof. It would take a much better model than mine to qualify as PROOF of something. But I would certainly like to see a model that good.

Mick's "scale" model is a joke for what he claims to be a "core". His core is no different from his perimeter. I have said in many places that a bigger and heavier version of my model would be better and that a 3D printer would be the best way to make a good tube-in-tube design. The falling mass must do damage to the lower mass.

But that still leaves the problem of not having accurate data on the distribution of mass down the towers. It is certainly curious that we have had 13 years of this nonsense without everyone pointing out the importance of that information. At least my model does get heavier toward the bottom since I sorted the washers that way and I had to make my model stronger toward the bottom. Does Mick's model meet those criteria.

psik

 

[psikeyhackr]

According to your theory if you blew out the bottom floor of a building the rest of it would just fall 1 story - because the remaining structure would stay intact - this is clearly not correct.

My are you brilliant!

My model demonstrates that it took multiple levels being crushed to bring the falling mass to a halt.

psik

 

[jaydeehess]

Your dowel "core" is not capable of being damaged. How could that possibly be an accurate simulation?

Nor are his "floors".

His model has 'columns that can be damaged, and lateral support , the dowel, that cannot be damaged (oddly enough its also lateral support for the floors AND the paper loop columns) , and floors that cannot be damaged. He has nothing in it to model floor to column connections as the floors cannot detach from the paper loops since the lateral support, the dowel, holds them in place.

In Mick's model he has column sections that cannot be damaged and only friction holding those sections together. He has floors that are very elastic and will not shatter. The floor to column connection is what can fail.

psykeyhacker modeled a strict column crush mechanism.
Mick modeled a strictly floor-column connection failure.

Mick's model illustrates that its failure mechanism more closely resembles that of the tower collapses in that it does fail all the way down and overcomes the, admittedly light, column-column connections.

 

[psikeyhackr]

Your dowel "core" is not capable of being damaged. How could that possibly be an accurate simulation?

It is a demonstration of physics. What are you saying is inaccurate about it? It should be obvious that the dowel was not intended to participate in the "collapse". It keeps the stack from falling over.

But it also prevents the top falling portion from falling down the side which is what should have happened to the south tower. My physics demonstration is 12 times as tall as it is wide. The WTC was 6.5 times as tall as it was wide. So obviously my model would not be as stable as the real building without the dowel.

Engineering schools that charge more than $100,000 for 4 years of "education" should have been able to afford models much better than mine in 13 years.

psik

 

[MikeC]

My are you brilliant!

My model demonstrates that it took multiple levels being crushed to bring the falling mass to a halt.

Sarcasm is unnecessary.

Observed demolitions do not show what you have claimed - floors are crushed and added to the falling mass so the energy of that mass is increasing, not decreasing.

Unless you can demonstrate why that happens it does not matter what specific parts of your model are good, bad or indifferent - it is simply not correct overall so can be dismissed.

Engineering schools that charge more than $100,000 for 4 years of "education" should have been able to afford models much better than mine in 13 years.

they have - yours is wrong.

 

[psikeyhackr]

Mick's model illustrates that its failure mechanism more closely resembles that of the tower collapses in that it does fail all the way down and overcomes the, admittedly light, column-column connections.

The floors in the WTC were single concrete slabs. Opposite sides could not fall independently but they can in Mick's model. If they tilted they would squeeze the core increasing friction and slowing the fall.

psik

 

[jaydeehess]

It is your website you get to tell everyone what is relevant. They must think what they are told here.

Really? I do not own this site and yet I have also maintained that your model is irrelevant.

A standing structure has Potential Energy. That potential becomes Kinetic Energy when the mass is accelerated by gravity. But since the structure below must be supported against gravity the support components must be disabled or bent or broken in some manner. That requires ENERGY.

So messed up a description its hard to correct it but wth.

A building is a "structure" that is to say it is a connected collection of systems which are in turn connected components. Floors are where the business of the structure is performed and contribute the greatest percentage of mass to ethe structure as a whle. That mass from each floor must be transferred to the columns which are responsible to carry the sum of all floor mass as well as column mass itself.
To accomplish this the floors have connections to the columns that are capable of transferring the mass of the floor to the column. This is true whether the floor is composed of slab and truss, or slab and beam.

A floor that fails by failure of the connections to the columns will of course fall down through the inter-level height and that mass will now reside on the next lower floor. In addition to this static load one must add the dynamic load, the result of transferring the momentum of the moving mass to the next lower floor.
If that next lower floor is capable of withstanding these forces then collapse arrests, if not then this next lower floor connections to the columns also fail and you now have the mass of two floors travelling through the inter-level height and not starting at zero velocity thus hitting the further floor at greater velocity, thus greater dynamic force to add to the now approx doubled static load.

This applies to floors between core and perimeter and to floors in the core area.

Because this destroys the components responsible for transferring floor loads to the columns, the strength of the columns is never in play to arrest collapse.
Instead, as floors collapse the unbraced height of column gets greater and greater until Euler buckling is ensured.

That means the falling component must lose kinetic energy in doing damage and therefore slow down.

How does one manage to "lose" energy? How much energy is "lost"? What you mean is that energy is used to destroy the floor to column connections. This changes the energy from kinetic to sound and heat in the deformed components. That is a small amount of the kinetic energy involved. The energy to destroy a column via Euler buckling comes from the gravitational potential energy of the unbraced length of the columns itself.

The 25 second collapse time of the north tower must be explained. It is not just a matter of collapse or not collapse. My model slows the falling mass to the point of arrest.

Yes your model shows a system by which the columns are the components responsible for progression. Again, irrelevant to the tower collapse mechanism.

It takes 0.118 joules to flatten a single paper loop. Where is the data on the energy required to "disrupt" a single level in the WTC?

Bazant did a first approximation of the energy to destroy a floor. He calculated in that a 30X greater force was available than the floor could withstand.

How much did that increase down the tower?

Slightly greater for core floor area and slightly greater for mechanical floors. Otherwise the majority of floor space was all the same.

<< snipped irrelevance>>

 

[jaydeehess]

The floors in the WTC were single concrete slabs. Opposite sides could not fall independently but they can in Mick's model. If they tilted they would squeeze the core increasing friction and slowing the fall.

psik

Single concrete slabs across an entire floor? Really? Citation please.

"If" they tilted? Describe what occurs when the building sways with wind loading then?

 

[Keith Beachy]

... my model stronger toward the bottom. Does Mick's model meet those criteria.
psik

A floor can hold 29,000,000 pounds. Thus the floors don't get stronger, the core and the shell get stronger, not a floor. The floors are the key to holding the system together. If the floor is gone, the system fails. The washers are not even close to a WTC model. The real WTC towers don't need a model to understand the collapse. Anyone can make a rational estimate of WTC weight. There is no point in repeating there is not way to estimate the weight, others have estimated the weight, good enough for models, it is what engineers do.

With the fact a floor can only hold 29,000,000 pounds, and understand the system, one can do a mental model, and understand why the WTC collapsed as it did; a gravity collapse. The core, shell and floors formed a system; the washer model fails to represent that system.

 

[Redwood]

Redwood said: ↑
Mick and Psikey are working at cross-purposes. Mick built a scale model to give a rough demonstration of the collapse mechanism. Psikey is trying to build a scale model to "prove" that collapse should have arrested unless it was assisted with demolition charges.

So you can obviously choose sides.

Care to provide a link to where I claimed my model PROVED anything? There is a significant difference between a demonstration and a proof. It would take a much better model than mine to qualify as PROOF of something. But I would certainly like to see a model that good.

OK fine; you're not trying to use your model to prove anything - it's merely a demonstration. In that case, all you need do is a relatively simple engineering calculation showing how the lower structure of the Twin Towers could have dissipated the kinetic energy of the upper structure falling on it, and remained intact. Your model will then be just a demonstration of your engineering calculation. You've been at this for a long time, haven't you? More than long enough to have completed a course of engineering study, even part-time? Shouldn't you be able to do such a calculation by now?

But that still leaves the problem of not having accurate data on the distribution of mass down the towers. It is certainly curious that we have had 13 years of this nonsense without everyone pointing out the importance of that information.

Distribution of mass in the towers isn't important. The limiting factor is the strength of the connections holding the structure together. By definition, we know that the connections were more than adequate to handle the ordinary load on the building. The question is, what happens under a dynamic load? Mass distribution doesn't really enter into it, there.

 

[WeedWhacker]

The limiting factor is the strength of the connections holding the structure together.

Bingo! A key fact, often ignored by "CD" believers, yet this has been explained many times.

Of course, to keep in line with the thread posting guidelines, and staying on-topic? I will just say that perhaps 'THAT' (meaning, connections, and their inherent vulnerability when a structure is stressed, by gravity, beyond its original design specifications) is the next thing to attempt to "model".

As I was posting, another thought occurred to me. Earthquakes. And, the way a tall structure may fail, due to (again, as seen on 9/11) un-planned for, in the design, added stresses.

 

[psikeyhackr]

Bingo! A key fact, often ignored by "CD" believers, yet this has been explained many times.

Who said anything about a CD?

How are "collapse" believers any different?

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

 

[Keith Beachy]

... When does anyone ever specify the number of connections around the inner and outer edges of the floors?
... psik

This is easy to figure out. Even NIST did it. Robertson had to specify the number of connections when he designed it.