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

OneWhiteEye said:
CubeRadio, as others have since pointed out to you, this wasn't the first barn dance with psikey we've had. econ41's interactions go back to 2007, mine to 2008/2009. These interactions involve many thousands of posts spanning multiple forums.

Contrary to what you claim, I've spent a great deal of effort analyzing psikey's experiment in depth, to the point where I could reproduce his model and results in software. See here and subsequent posts, from 2010:

http://www.rationalskepticism.org/post636274.html#p636274
http://[url]http//www.rationalskepticism.org/post636274.html#p636274
After all that effort and explanation, what did psikey do? He ignored it entirely. See for yourself.

It pays to know of what you speak before you speak. You've made a number of incorrect assumptions about those arguing here with psikey and I'd like to know from you that you understand the nature of your error.
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It seems that simply because others point out that psikey modeled a mechanism that was not at all in play in the towers, that it means we are 'rubbishing' his model.

On the contrary, wrong is wrong. His model is good, it simply has no relevance to the tower collapses. Apples are not oranges even though they are both tasty.
 
OneWhiteEye said:
CubeRadio, as others have since pointed out to you, this wasn't the first barn dance with psikey we've had. econ41's interactions go back to 2007, mine to 2008/2009. These interactions involve many thousands of posts spanning multiple forums.

Contrary to what you claim, I've spent a great deal of effort analyzing psikey's experiment in depth, to the point where I could reproduce his model and results in software. See here and subsequent posts, from 2010:

http://www.rationalskepticism.org/post636274.html#p636274

After all that effort and explanation, what did psikey do? He ignored it entirely. See for yourself.

It pays to know of what you speak before you speak. You've made a number of incorrect assumptions about those arguing here with psikey and I'd like to know from you that you understand the nature of your error.
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The hubris in this post is astounding. You expect me to search the entire internet and multiple forums to find your other remarks under various aliases before I make an observation about your contributions to this thread?

And yet when I follow the link you've provided I find the point I make about your comments here is reinforced: you have no constructive criticism to offer with respect to psikey's model. You're happy to critically analyse his work but you've shown yourself incapable of suggesting how it could be improved or made more representative of a principle you and everyone else here seems to believe is terribly simple.

You have a physics degree do you not? Then can I ask you how you would go about building a model of the Towers to experimentally validate the mechanic of their collapse through multiple floors? Do you think it is possible to make a physical scale model that reproduces the effect that occurred twice on 9/11?

Or do you think such a project could only be carried out using software such as Blender?
 
Cube Radio said:
You're happy to critically analyse his work but you've shown yourself incapable of suggesting how it could be improved or made more representative of a principle you and everyone else here seems to believe is terribly simple.
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It has been explained several times. psikey's model is off crushing columns. The actual collapse was stripping floors and slender column bucking or levering then failing at splices. So his (essentially one dimensional) model could be improved by not having the columns fail by crushing.

You seem to be going round in circles here. Perhaps you should re-read the entire thread again?
 
Cube Radio said:
The hubris in this post is astounding. You expect me to search the entire internet and multiple forums to find your other remarks under various aliases before I make an observation about your contributions to this thread?
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Did I say I expected that? No, I didn't. Instead I explained the situation to inform you and offered an example of what I'm talking about.

And yet when I follow the link you've provided I find the point I make about your comments here is reinforced: you have no constructive criticism to offer with respect to psikey's model.
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What is so special about constructive criticism versus simple (and correct) criticism? If an automotive engineer decides to crash test cars using teddy bears instead of vehicles, what constructive criticism would you offer to them? But, the fact is, I've offered constructive criticism many times in many places, including in the discussion I linked. I told him why his model arrested and what would be necessary to change that. That's not constructive? That's giving him the answer!

You're happy to critically analyse his work but you've shown yourself incapable of suggesting how it could be improved or made more representative of a principle you and everyone else here seems to believe is terribly simple.
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Incapable? No. Sometimes unwilling because his attitude and demeanor in discussion is abhorrent. Having made many suggestions, regardless of the manner in which I knew they'd be received, I bristle a bit at the notion that I'm incapable of doing it.

You have a physics degree do you not?
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Yes.

Then can I ask you how you would go about building a model of the Towers to experimentally validate the mechanic of their collapse through multiple floors?
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This can be a tough question to answer, depending on the ultimate objective. To do something at the level of detail of (e.g.) NIST's WTC7 physics simulation seems fruitless to me. I believe the system is too large and complex to expect good results. On the other hand, doing something at the level of detail of psikeyhackr's model is not hard at all in software, I've done it thousands of times with a spectrum of inputs and scenarios. As a result of such exploratory analysis, I understand why it would be difficult to do physically in minature if the objective were to demonstrate complete crushing in the manner of the Bazant analysis. Not difficult if the objective is to model the actual collapse mechanism; Mick's done it here already and you've seen it. Apparently you don't recognize it as such, so I must ask: what was wrong with Mick's model? Do you have any constructive criticism to improve it?

What sort of model wll satisfy you? I'm not trying to be difficult, I want to know. Mick's model is similar in complexity and scale to psikey's, and psikey's level of detail seems okay to you. Based on that, I suggest that what you ask for has already been done unless you're applying different standards depending on who's doing the work. If that level of detail is insufficient, why do you care about means to improve psikey's model? If it's a more sophisticated model you're after, have a look at the work by enik and see if that's more like it:

http://the911forum.freeforums.org/post10861.html#p10861
http://the911forum.freeforums.org/post11030.html#p11030
http://the911forum.freeforums.org/post11868.html#p11868
http://the911forum.freeforums.org/post12000.html#p12000
http://the911forum.freeforums.org/post12213.html#p12213
http://the911forum.freeforums.org/post12340.html#p12340
http://the911forum.freeforums.org/post12443.html#p12443
http://the911forum.freeforums.org/post12488.html#p12488
http://the911forum.freeforums.org/post12526.html#p12526
http://the911forum.freeforums.org/post12925.html#p12925
http://the911forum.freeforums.org/post12956.html#p12956
http://the911forum.freeforums.org/post13265.html#p13265

These are ordered by increasing scale and complexity. Note, in the last one, enik declares "Gravity alone did not bring WTC 1 down" but in fact, his model doesn't arrest so how he comes by this conclusion is anyone's guess. I admire the work very much but I do think his obvious bias could lead others to question the validity.

Do you think it is possible to make a physical scale model that reproduces the effect that occurred twice on 9/11?
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Yes, Mick's model. But since that doesn't seem to satisfy you, you'll need to specify what level of detail would. To make something which self-crushes like psikey's model, but does so without arrest, would be quite difficult to do in small scale (reasons have been explained again and again in this thread). Not impossible, just a lot more effort than psikey's. To make something that arrests is easy; a stack of books will do!

Or do you think such a project could only be carried out using software such as Blender?
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A lot of useful principles can be demonstrated by a game physics engine. I've used PhysX extensively, but only after a long period of experimentation to determine its limitations and weaknesses then confining models to those boundaries. I found that it was really only adequate for the simplest of systems (I kept it to 1D), which incidentally includes metamodeling psikeyhackr's model as well as Bazant's. The same is undoubtedly true for Blender. Most of my work in this area is found here:

http://the911forum.freeforums.org/solid-mechanics-simulacra-of-the-toy-variety-t163.html

Notice the disclaimer of 'toy' right there in the thread title. I'm under no illusions about the nature of the experimentation. However, it replicates Bazant/Greening style analysis perfectly, and psikey's as well. So, it again depends on what you're looking for. If you accept psikey's level of detail, then what you ask for has already been done, years ago. If not, then I'm not sure why we're laboring so much over psikey's model.
 
I feel the need to cover a potential objection in advance, though it has already been covered extensively in this thread. It may seem like the constant appeal to scaling issues is a smokescreen, but it most assuredly is not. While this has been explained in terms of skyscrapers, maybe a closer to home analogy will work better.

When two cars collide head on at high speeds, they crush each other. Now scale that down to toy cars 6" long, made of plastic. Ram them together at speeds proportionally scaled to their size, and they do not crush each other. Why? Steel is unquestionably stronger than plastic and everything else is in proportion. I'm not going to answer 'why', simply point out the obvious.

Skyscrapers are superlative structures. The greatest possible volume of usable space is thrust as high as possible using the least possible materials to accomplish it. This results in a metastable system which, proportionally speaking, is a gnat's ass away from total disintegration - prevented from such only by a relatively small elastic potential barrier. There aren't many analogous systems at everyday scales. An empty aluminum can is something considered fragile by everyday standards, yet it can support (roughly) 7000-8000 times its own weight. Clearly, a tower with an overall factor of safety of 2-3 cannot support thousands like it stacked atop one another. The image of a skyscraper as an immutable monolith is not accurate. It's actually quit fragile.
 
OneWhiteEye said:
An empty aluminum can is something considered fragile by everyday standards, yet it can support (roughly) 7000-8000 times its own weight. Clearly, a tower with an overall factor of safety of 2-3 cannot support thousands like it stacked atop one another. The image of a skyscraper as an immutable monolith is not accurate. It's actually quit fragile.
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I think the failure to understand this is key to suspicions of many people. And there's other factors in there that make it more confusing - like it's true that a soda can will support about 8000 times its own weight, but in real life you'll find it impossible for a 110Kg man to stand on the 15g can. This is because the loading will be highly variable and uneven. The top part of a skyscraper is incredibly precisely balanced on the bottom part - and it's quite hard to replicate this with a tiny soda can.

Edit: just tried it again, I got somewhere over 100 pounds (45 Kg) before it collapsed.
 
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The reason it is so hard to build a representative model is precisely because it is so hard to build a skyscraper: the higher and broader the harder with a limit on how high and broad (by the square-cube law).

Any representative model will be very hard to build, and will definitely require a few structural engineers: if not, it is not representative.

While it won't satisfy @Cube Radio, any rational soul can see that scaling height is not the issue [we only need to model 5 floors say with a mass on top], it is scaling the area: once the falling mass falls through the first floor the process continues recursively.

Key to building your model will be the floor: it must be so weak that without supporting struts it crumbles.
 
qed said:
Key to building your model will be the floor: it must be so weak that without supporting struts it crumbles.
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Actually I think the key is the connections - specifically the seats and the splice plates. Getting the failure mechanisms correct for that is important.

Crumbling floors is another detail, but not necessary for the collapse.
 
Cube Radio said:
The hubris in this post is astounding. You expect me to search the entire internet and multiple forums to find your other remarks under various aliases before I make an observation about your contributions to this thread?
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Looking back, I can see how you got that impression from what I said. Perfectly understandable, and I regret giving that impression. Let me clarify. I assumed you had read what I'd posted in this thread which laid out the nature and longevity of my interactions with psikey:

"...after being told at least a dozen times per year..."
"People end up saying the same things over and over year after year..."
"...keeping countless people at multiple forums chasing their tails for years..."
"...debate on many forums over the course of years."
"I've gone back and forth with him for years at about a half dozen forums..."
"For all the thousands of posts we've exchanged in many locations..."

This doesn't count the comments by econ41 and others with similar experience. If you think we're all disposed towards exaggeration, okay, but even so it paints a pretty clear picture when watered down considerably. When I say "It pays to know of what you speak before you speak" I don't expect you go chase down every exchange we've had, I only thought it was reasonable that you take what I've already said here as at least having a grain of truth behind it.

I probably shouldn't have taken your statement "not one was capable of making constructive criticism of his model" quite so literally, as far as the use of 'capable'. It's difficult hearing that with all the history, which I know, and you don't. If you know you don't know something, it pays to consider what you say carefully.
 
Here's an example of a comment I've made which I consider constructive.

Me: Your paper loops consume more energy in crushing than is available from potential energy change during the corresponding descent. Therefore it must arrest.

psikeyhackr: Potential energy is a delusion!

...followed by the obligatory round of mockery for me believing in a "mathematical delusion". No joke. Not just me, either. Here, see for yourself:

http://www.centerforinquiry.net/forums/viewthread/9953/P630/
Potential Energy and the Conservation of Momentum are Delusional.
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http://windenergy7.com/energy-video/video/view?videocode=LXAerZUw4Wc&startpage=4
Potential Energy is based on the ASSUMPTION that the mass in question is FREE TO FALL the entire distance. Since skyscrapers are DESIGNED TO HOLD THEMSELVES UP doing a PE calculation on a skyscraper is a mathematical delusion.
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http://letsrollforums.com/potential-energy-t19752p9.html
It would alter the delusional Potential Energy of the towers.
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http://www.rationalskepticism.org/c...bligatory-9-11-thread-part-ii-t6310-6080.html
Talking about the Potential Energy of things that cannot fall is pseudo-intellectuial bullshit from mathematical delusions.
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(while I'm right there, math is a delusion, too, apparently...)
Physics does incapable of giving a damn about math. It is a stupid delusion from the ancient Greek.
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http://www.rationalskepticism.org/c...-9-11-thread-part-ii-t6310-6220.html#p1661270
You just have to believe in this delusional potential energy reservoir.
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I can also search for "potential energy is fiction" and "potential energy is not energy", too. Starting to get the picture?

It's 100% totally pointless to offer any sort of suggestion to someone with this mindset. But I have, all the same. What you think of as "rubbishing" his model is the end result of cumulative frustration - and yet it still just amounts to dismissing with stated reasons.
 
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I think what it comes down to is this - this experiment of psikeyhackr's is the better part of a decade old. He has done no follow-on work and no other experiments since. If I had a nickel for every useful and reasonable suggestion for improvement he's ignored or mocked in that time, I could skip work this week. He is not soliciting suggestions.

He's not interested in suggestions or improvements, period.
 
OneWhiteEye said:
I feel the need to cover a potential objection in advance, though it has already been covered extensively in this thread. It may seem like the constant appeal to scaling issues is a smokescreen, but it most assuredly is not. While this has been explained in terms of skyscrapers, maybe a closer to home analogy will work better.

When two cars collide head on at high speeds, they crush each other. Now scale that down to toy cars 6" long, made of plastic. Ram them together at speeds proportionally scaled to their size, and they do not crush each other. Why? Steel is unquestionably stronger than plastic and everything else is in proportion. I'm not going to answer 'why', simply point out the obvious.

Skyscrapers are superlative structures. The greatest possible volume of usable space is thrust as high as possible using the least possible materials to accomplish it. This results in a metastable system which, proportionally speaking, is a gnat's ass away from total disintegration - prevented from such only by a relatively small elastic potential barrier. There aren't many analogous systems at everyday scales. An empty aluminum can is something considered fragile by everyday standards, yet it can support (roughly) 7000-8000 times its own weight. Clearly, a tower with an overall factor of safety of 2-3 cannot support thousands like it stacked atop one another. The image of a skyscraper as an immutable monolith is not accurate. It's actually quit fragile.
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This is such an important concept and so little stated, understood or discussed. It seems counter intuitive to have the most massive structures we build be of such little "strength" able to basically support themselves with a relatively small safety factory. The forces involved (gravity and wind loads) are enormous... The designs essentially have the frame of multiple components share these loads. So of course no single node of member is designed to handle much more than a small fraction of the total loads (forces) encountered. However as these nodes and members fail, for whatever reason... the burden is shifted, the frame will warp as it compensates and this can lead to a runaway progressive failure leading to total system failure. It's the straw that breaks the camel's back concept.
 
Jeffrey Orling said:
It seems counter intuitive to have the most massive structures we build be of such little "strength" able to basically support themselves with a relatively small safety factory.
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It's another example of the non-intuitiveness of scale. The larger something is, the smaller the safety factor is needed.

A soda can needs a huge safety factor because forces exists that are multiple times its weight. Even putting a soda can down on a table involves forces of multiple gs. If a soda had a safety factor of 1.5, then you would not be able to touch it without it breaking. A slight breeze would collapse it. Tilting it 5° to the side would collapse it.

Skyscrapers does not need a large safety factor, because those forces do not exist (in the expected use case). Nobody is picking up skyscrapers and moving them, or putting one on top of another. And while the force of the wind is significant at the component level, it's insignificant relative to the mass of the building.
 
To those who have asked what I would be satisfied by: as I have already said, I am not particularly interested in models that represent only a few floors of the collapses or model the "initiation event" only. This is not because I am unimpressed by the models themselves, but because I would like to see a model that uses an experimental approach to debunk commonly-heard objections to the idea that the collapse must necessarily progress in the way that was observed.

These "commonly-heard" objections would include the suggestion that the collapses would slow or stop because of the large amount of energy used in pulverising and ejecting large amounts of material away from the collapse zone, the suggestion that observed pivoting would draw the collapse off the perpendicular and cause it to slow or arrest, the suggestion that the increasingly strong structure below the collapse zone would slow or arrest the collapse wave, the suggestion that Newton's Third Law would indicate the top portion of the tower should be progressively destroyed before it reaches the ground, and so on.

I am not saying that I necessarily believe all these objections cannot be dealt with without using a model, but I am saying that the mechanic of the collapse must be capable of being modelled, and no physical model exists (to my knowledge) that has modelled this mechanic successfully. Broadly speaking I would be very interested to see any multi-storey tower model (arbitrarily, I'd say of 30 floors or more) that is strong enough to survive a relatively significant lateral impact at a fairly high level but weak enough to then be destroyed by a falling upper section of itself.

It is highly counterintuitive to imagine such a model could be made to collapse in a manner that even vaguely represents what was observed, but physics can be counterintuitive as our discussion of the square cube law has shown -- and that's why I think the modelling effort would be useful as a debunking tool. As I say, the key (for me) would be an experimental, constructive method rather than a purely mathematical or analytical approach to explaining and demonstrating what happened.

In terms of virtual models: I am impressed by enik's work, OWE. As Mick and others have noted on this thread, a virtual model is a much more realistic prospect than a physical model. Why do you think enik concluded gravity alone could not have caused the collapses, having put so much effort into creating models to investigate them?
 
Cube Radio said:
To those who have asked what I would be satisfied by: as I have already said, I am not particularly interested in models that represent only a few floors of the collapses or model the "initiation event" only. This is not because I am unimpressed by the models themselves, but because I would like to see a model that uses an experimental approach to debunk commonly-heard objections to the idea that the collapse must necessarily progress in the way that was observed.

These "commonly-heard" objections would include the suggestion that the collapses would slow or stop because of the large amount of energy used in pulverising and ejecting large amounts of material away from the collapse zone, the suggestion that observed pivoting would draw the collapse off the perpendicular and cause it to slow or arrest, the suggestion that the increasingly strong structure below the collapse zone would slow or arrest the collapse wave, the suggestion that Newton's Third Law would indicate the top portion of the tower should be progressively destroyed before it reaches the ground, and so on.

I am not saying that I necessarily believe all these objections cannot be dealt with without using a model, but I am saying that the mechanic of the collapse must be capable of being modelled, and no physical model exists (to my knowledge) that has modelled this mechanic successfully. Broadly speaking I would be very interested to see any multi-storey tower model (arbitrarily, I'd say of 30 floors or more) that is strong enough to survive a relatively significant lateral impact at a fairly high level but weak enough to then be destroyed by a falling upper section of itself.

It is highly counterintuitive to imagine such a model could be made to collapse in a manner that even vaguely represents what was observed, but physics can be counterintuitive as our discussion of the square cube law has shown -- and that's why I think the modelling effort would be useful as a debunking tool. As I say, the key (for me) would be an experimental, constructive method rather than a purely mathematical or analytical approach to explaining and demonstrating what happened.

In terms of virtual models: I am impressed by enik's work, OWE. As Mick and others have noted on this thread, a virtual model is a much more realistic prospect than a physical model. Why do you think enik concluded gravity alone could not have caused the collapses, having put so much effort into creating models to investigate them?
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First of course one has to agree what one is actually modeling... Your description suggests that you want to model something which was not what one observed on 911... such as the phrase "ejecting large amounts of material away from the collapse zone".

NB that there was a significant number of steel columns from the core which came down AFTER the floors came "apart" and down... the facade broke apart and fell away.

It is critical to first be able to describe what happened before you can even hope to make progress in understanding HOW or WHY happened as it did.

I would suggest that the FLOORS of the towers did collapse... using the word you chose. I would suggest that the facade mostly exhibited a toppling away from their plan position and this accounts for the material you refer to as "ejected". There was virtually no material laterally ejected. We DO see evidence of the light wight aluminum cladding springing off the facade steel mostly from the impact zone as collapse begins. The remaining aluminum cladding broke away from the steel as the mechanical forces of the panels encountered exceeded the strength of the connections to the steel.

I would further suggest that the mechanisms explaining what you refer to as "pulverization" is well understood. Concrete dust and stone dust and gravel are made commercially in crushers, grinders and tumblers where mechanical interaction of the materials in collisions reduces it to smaller and smaller granular size. This is settled science... Anyone one expects a stack of slabs has no conception of the strength of WTC concrete facing the mechanical interactions it did. NB the same level of granular creation... pulverization was exhibited at 7wtc which was a bottom originating collapse and the twins... where a destructive mass originated at the top sections. That sort of concrete dropping those sorts distances in chaotic mechanical collisions produced the same granular size result. Ergo the behavior of light weight concrete's behavior on 9/11 was predictable. It produced enormous amounts of very fine dust which was carried aloft and disbursed but the winds.

The toppling of the columns and the facade is also settled "science" or engineering... Tall thin structure require bracing to remain true and standing true. All slender columns have less capacity than fatter columns... lower aspect ratio stronger.. higher aspect ratio weaker and too high aspect ratio the column cannot even support itself and stand. High rise columns are multipart... stacked sections of steel one atop the other with not terribly strong splice connections which function to maintain axial alignment and not designed to resist shear or lateral forces. Euler has mathematically modeled the performance of slender columns and describe the resultant strength of a column based on its slenderness ratio... the shortest axis in plan to its unsupported length. If you want to model how this works stack up bricks of sticks one atop the other and see how tall the stack can be made until it becomes unstable and self buckles or topples over.

Slowing the arrest is an absurd concept because it completely ignores the observation. High rise floors are of about the same capacity regardless of their vertical location in the tower. 5th floor is designed to support the same loads as the 55th. And in the case of a commercial tower for office use the floors are designed for 100# / SF superimposed load. If the load is exceeded the system is pushed beyond its capacity..,.it deforms and then fractures losing its integrity. WTC slabs also fractured from dynamic impact... This has been modeled and demonstrated and is settled science. Place a brick on your head and the force is its static weight... 1 kg for example. Drop it from 12 feet and it will crush your skull.

The global destruction of the towers was completely driven by gravity which acts perpendicular to the ground. There was some amount of lateral force as collision vectors are resolved. The grain in a silo will spread "symmetrical" of the structure holding it in a cylindrical form fail. It would form an inverted cone shaped distribution. The symmetrical collapse is settled science but apparently is a mystery to many people. Why?

Those people conceive of the tower like a tree which has a sold trunk structure which doesn't crush itself. When it does fall... it topples to one side... usually were an asymmetry has been introduced such as cutting one side of the trunk with an axe. Once the notch gets too large... ie the remaining trunk cross section can no longer support the forces... the axial forces resolve into lateral forces and the tress topple at the notch in the direction of the notch.

The towers were 95% air... They were a structural cage with infill for floors and the envelope. They would not behave like a solid tree would.

There were several mechanisms of system failure in play. Each one is well understood and settled science and engineering. The collapse of the twins was unstoppable BECAUSE of the magnitude of the forces involved... far exceeding the reserve capacity of each sub system or node. It mattered not that the columns were stronger and stronger moving down the tower.... the floor system's strength was the same at each floor. Once the threshold mass... strong enough to destroy one floor or portion of a floor presents... that floor or portion (mass) will collapse on to the one below encountering a floor of the same capacity and destroy it and so on and so on to the ground. The destruction rate will accelerate as gravity... slowed by the (small resistance) of the slab. The mass will growing and dropping close to free fall but never reach FF because of the resistance of the floors slowing it ever so slightly as the destructive mass grows. Nothing mysterious or counter intuitive if one understand physics and strength of materials.

Runaway system failure is a well understood phenomena. It happens in electrical grids and it can and does happen in structural systems which are elements connected at nodes... Those elements have fixed capacity as do the nodes. As the mass does not disappear... the destruction of the system's integrity is the result the mass/force presenting which exceeds the element or the nodes capacity. As the element and node destruction takes place... with no loss of mass/force... the remaining system (elements and nodes) becomes over totally overwhelmed.

house of cards... row of dominoes... hip bone connected to the thigh bone... straw that breaks the camel's back...
 
Cube Radio said:
the suggestion that observed pivoting would draw the collapse off the perpendicular and cause it to slow or arrest
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Just a note that Tony Szamboti has gone to great lengths on this forum to try and argue that there was almost no pivoting since even he can see that the more the pivot the less the chance of halting the collapse. Rate of fall of crush

@Cube Radio
  • Do you understand why building a representative scale model will be a hugely difficult engineering task (it will always be collapsing if you are not extremely careful)?
 
Jeffrey: if the system is well understood it must be capable of being modelled. My observation is that no-one has been able to model it successfully. Qed: I do not think a representative scale model is impossible to achieve as a computer model, and Mick at least agrees with me on this point. I have explained at length that I think the model could be simplified, although how much simplification could be made is open to debate.

A physical model need not be particularly representative of the towers in terms of detail: any scale model of a multi-storey building at any resolution would be interesting to me if it can be shown to have a degree of lateral stability and still made to collapse totally when an upper section is "dropped" a short distance onto the remainder.

I feel as though contributors to this thread should clarify if they believe the mechanic of the collapses is essentially simple (and therefore should be capable of being modelled simply, if a lot of detail is left out) or an incredibly complex phenomenon (which would raise the question as to why and how it could happen twice in remarkably similar ways, despite relatively different impacts/fires).
 
If the system is well understood what reason is there to model it? It could be done, but there's a general consensus on the results (an understatement to be sure but I don't want to generalize) and the RoI would be terrible. No one's done what you've asked because it's unnecessary, not because they can't.
 
Cube Radio said:
...Broadly speaking I would be very interested to see any multi-storey tower model (arbitrarily, I'd say of 30 floors or more) that is strong enough to survive a relatively significant lateral impact at a fairly high level but weak enough to then be destroyed by a falling upper section of itself.
...
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The lateral impact has been calculated to be no larger than the equivalent of a within-design-envelope storm. Is that "relatively significant"?
The momentum p = m*v of UA 175 was approximately 116,000 kg * 243 m/s = 28,000,000 Ns.
The weight of the about 30 stories above the impact zone was (my rough estimate) 50,000,000 kg, so the momentum of the plane would be roughly equal to the top block falling at (50,000,000/28,000,000)m/s = 1.8 m/s. For perspective, that is the velocity attained after 0.18 seconds or 0.16 m (0.5 ft) of freefall.
Leaving aside the question of how the collapse initiated (i.e. drop velocity > 0 for a drop distance sufficient to exceed max. elastic vertical deformation of the members involved), once you picture that drop velocity exceeds that small amount by a factor of, say, 2 or 3, the "relative significance" of the lateral impact diminishes. Especially given the fact that the structure was designed for that magnitude of lateral loads, but not designed for the same magnitude of vertical, dynamic loading - especially not the floors.
 
There were 10s of thousands of nodes and elements. The structure was simple. ..but with so many elements and notes complexity is introduced. It resembles chaos. ... let's say like the way a star works.... or a weather system... almost impossible to model and predict.
There is no point to model detail failures.... they have all been modeled and explained. So we know, for example. ..that air rises over heated land... this creates wind. We understand how dry air becomes humid... and so on... but we can't predict or model the entire earth's weather.
We know how concrete behaves when massive things impact it...or bolts under shear and so on.
Progressive runaway collapse...system failure is settled science ....well understood.

Do you doubt this?
 
Cube Radio said:
To those who have asked what I would be satisfied by...
Click to expand...

I'll be honest: I don't envision any scenario by which you are satisfied.

And I absolutely do not mean that in a disrespectful or even snarky way... :)
I mean simply that your almost 200 consistent posts on this, over the course of more than one year,
suggests that you're quite entrenched...and I can envision no scenario that changes that:

Most people--including most posters here--see that 9/11 footage over and over and see no need
for an expensive, highly detailed re-enactment to reinforce what was witnessed and filmed that day.

Modest, simple, affordable models that demonstrate the general concepts are inadequate for your desires,
yet incredibly detailed computer simulations--never mind large physical models--are never going to happen
because no one can justify the massive expense merely to satisfy the idle curiosity of a small number of people.

I have no complaint about your persistence on this Cube, I just also have no fantasy at this point
that your particular desires will ever be satisfied...
 
Cube Radio said:
Qed: I do not think a representative scale model is impossible to achieve as a computer model, and Mick at least agrees with me on this point.
Click to expand...

I do? That depends on what you mean by "representative".

Cube Radio said:
A physical model need not be particularly representative of the towers in terms of detail: any scale model of a multi-storey building at any resolution would be interesting to me if it can be shown to have a degree of lateral stability and still made to collapse totally when an upper section is "dropped" a short distance onto the remainder.
Click to expand...

 
And this one is quite interesting in that it (accidentally) demonstrates some of the mechanism of the WTC7 collapse. Ignore the initial spiral (although you could view that as "damage gradually caused by fire"), at about 1:05 the "penthouse" collapses, shortly followed by the collapse of the lower floors columns, and the rest of the building falls as one, almost like free-fall.

 
NoParty said:
Modest, simple, affordable models that demonstrate the general concepts are inadequate for your desires
Click to expand...
No, that's exactly what I want to see. It's just that the general concept of how the towers collapsed so totally has never been modelled successfully -- only a few floors.
NoParty said:
yet incredibly detailed computer simulations--never mind large physical models--are never going to happen
because no one can justify the massive expense merely to satisfy the idle curiosity of a small number of people.
Click to expand...
I've talked about Blender (free) and Moore's Law from the outset. You just haven't been paying attention.
NoParty said:
I just also have no fantasy at this point
that your particular desires will ever be satisfied...
Click to expand...
I have no fantasy that you will ever be courteous. That's not relevant to the topic at hand either.
Mick West said:
I do? That depends on what you mean by "representative".
Click to expand...
You've given your reasons why a modelling effort might be worthwhile.
Trigger Hippie said:
Interesting that it collapsed into its own footprint.:)
Click to expand...
It doesn't really. But then many people think the towers didn't either.
 
Cube Radio said:
No, that's exactly what I want to see. ...You just haven't been paying attention....I have no fantasy that you will ever be courteous.
Click to expand...
No, you've repeatedly denied applicability of simpler models.

And I'll just have to take comfort in the fact that I've been more courteous to you than vice versa. :rolleyes:
 
Just a laymans question here...

Do not the collapse of all the towers, 1, 2 and 7 result in a 'chaotic system' as the collapses progress and are not chaotic systems very difficult to map and even harder to predict; with the added complication that the larger and more complex the system being modeled the more chaotic the collapse will become?

Therefore the larger and more complex a model of any of the WTC towers is, the less use it would be in reality?
 
Yes and no. If you're looking for exact replication of the event, you will probably never find it. Chaotic systems are often fairly consistent in the gross details, however.

One way to test this is perturbation testing, in which initial conditions are varied slightly to check how consistent the result is. Numerical weather models do this, as it allows forcasters to netter assign a confidence level to a forecast, and the same technique could be applied here.
 
Whitebeard said:
Just a laymans question here...

Do not the collapse of all the towers, 1, 2 and 7 result in a 'chaotic system' as the collapses progress and are not chaotic systems very difficult to map and even harder to predict;...
Click to expand...
I get deja vu - think I've made this comment before BUT non of those collapses were fully chaotic. There were without doubt unpredictable elements but the overall scope of each of the three collapse mechanisms was bounded as to scope and predictable within a range of knowable variances. I hope that makes sense.

Whitebeard said:
was with the added complication that the larger and more complex the system being modeled the more chaotic the collapse will become?
Click to expand...
IMO Not necessarily so!

Whitebeard said:
Therefore the larger and more complex a model of any of the WTC towers is, the less use it would be in reality?
Click to expand...
Larger and more complex not the issue I have addressed in previous [posts. I have discussed a model of the scale and complexity needed to explain the WTC collapses in order to persuade CubeRadio. Note the two legs - model and persuade - BOTH are needed to meet the challenge under discussion. The issue is "What is the reality" that we are trying to "use" the model for.

CubeRadio's latest attempt at clarification remains as confused as ever.

Are we modelling the real event - for whatever purpose of persuading CubeRadio?

That is not what his self contradictory explanation says.

We have been trying to address how to model what actually happend BUT in the first paragraph CubeRadio says: "I would like to see a model that uses an experimental approach to debunk commonly-heard objections to the idea that the collapse must necessarily progress in the way that was observed."

So he wants to debunk what did not happen??? which is a far different challenge than "demonstrate what DID happen in a way which persuades CubeRadio."

THEN - in the third paragraph he says:
"but I am saying that the mechanic of the collapse must be capable of being modelled, and no physical model exists (to my knowledge) that has modelled this mechanic successfully."

...clearly meaning the actual collapse mechanism.

well which is it?
-- Model all the objections which did not happen; OR
-- Model one mechanism which did happen.

-- OR both??

And there is yet another partial self contradiction in "must necessarily progress" - it DID progress that way. Why it did go that way is:
-- Easily explained;
-- Easier without models.
-- as has been explained by me and others several times.

YES it MAY be possible to model it;
The difficulties are such that the model most likely will not be as good as reasoned explantion without a model;

Then again there is confusion between those arguing:
A) that a model is possible BUT NOT explaining how it would meet CubeRadio's personal need for understanding; and
B) me (maybe others) saying that a model is NOT the best way to help CubeRadio understand. And that is the opinion of me - an experienced technical trainer and explainer. Who has done it at least dozens of times with persons of similar style to CubeRadio.
 
Spectrar Ghost said:
Yes and no. If you're looking for exact replication of the event, you will probably never find it. Chaotic systems are often fairly consistent in the gross details, however.
Click to expand...

Thanks - crossed in posting and that explains simply what I stated in somewhat less clear language. :rolleyes:

Spectrar Ghost said:
One way to test this is perturbation testing, in which initial conditions are varied slightly to check how consistent the result is. Numerical weather models do this, as it allows forcasters to netter assign a confidence level to a forecast, and the same technique could be applied here.
Click to expand...
Take care. We are seeking to explain a specific one off event (or three of them) NOT build a replicable model for testing a new scientific hypothesis.

The requirements of forensic engineering are similar to - a subset mostly - of scientific method. But not identical.

F'rinstance "check how consistent the result is" is more relevant to testing an hypothesis for replicable events with slight variation. We are explaining one (or three) specific one off events. Not forecasting how the next WTC"x" will collapse if hit by a slightly different aircraft....
 
Last edited:
Correct, but making a model (probably digital) and testing the known (or suspected) failure modes with differing degrees and types of damage should allow a spectrum of predicted outcomes they we could point to and say, "it looks sort of like one of these in here.", right?

Ultimately we can never determine the exact events, but we could potentially say "WTC could be expected to collape in a similar fashion to the actual events when parameters x, y, and z are within certain values. We have reason to believe the actual values also fall within these criteria."

Now that said, I expect that's already been done and dismissed by those with a vested interest in disbelieving the official account, so I'm not really adding anything new to the discussion.
 
Spectrar Ghost said:
Correct, but making a model (probably digital) and testing the known (or suspected) failure modes with differing degrees and types of damage should allow a spectrum of predicted outcomes they we could point to and say, "it looks sort of like one of these in here.", right?
Click to expand...
Possibly BUT there is a more fundamental problem still dominating WTC collapse discussion. It is the reliance on abstract modelling/calculations/FEA whatever BEFORE those using those techniques determine what is the model of collapse which actually happened. AND if you don’t know what you are FEAing/Mathing or abstract modelling how can you progress anything reasoned and rational?

Spectrar Ghost said:
Ultimately we can never determine the exact events, but we could potentially say "WTC could be expected to collape in a similar fashion to the actual events when parameters x, y, and z are within certain values. We have reason to believe the actual values also fall within these criteria."
Click to expand...
I comprehend and have some sympathy for your approach. However for the big issues of WTC collapse we know the events and numbers to sufficient accuracy. One thing which makes that easy/possible is that the energies available for progressive collapse were overwhelming. When you have orders of magnitude more than you need THEN finesse to the few percent/few tens of percent accuracy is not needed. Way back I satisfied my own professional standards when I ball park guestimated that the energy available for Twin Towers progression was (IIRC) 30x what was needed.

If you have 30x and 5x is sufficient who cares if it was really 20x? 15.75x? 45x?

Spectrar Ghost said:
Now that said, I expect that's already been done and dismissed by those with a vested interest in disbelieving the official account, so I'm not really adding anything new to the discussion.
Click to expand...
If only it was that simple. Sadly the majority of academic and professional explainers of WTC collapse seem to be locked into abstract modelling which has near zero regard for what actually happend.
 
econ41 said:
CubeRadio's latest attempt at clarification remains as confused as ever.
Click to expand...
Econ41, my language is clear: your comprehension is at fault. I am offering reasons why modelling the complete tower collapse might be worthwhile from the perspective of a debunker. Mick offered similar reasoning many pages ago.

NoParty said:
you've repeatedly denied applicability of simpler models
Click to expand...
I suggest you quote an example of my denials from this thread or accept that the contribution you have made to it here is no better than that of a troll. If you are unable to do so I will not respond to you further.

I have repeatedly said that I am interested in simplified models of the complete collapse sequence, both physical and virtual. We have discussed psikeyhakr's model as an example of the first and One White Eye has recently posted an interesting example of the second.
 
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