1. deirdre

    deirdre Moderator Staff Member

    how about some math? how much does each floor weigh? then do the math for me at 10%, 20%, 50%. (I'm asking you to do it because I cant stand doing math)
     
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  2. Mick West

    Mick West Administrator Staff Member

    This brings up another problem with scale models. The granularity of materials. To get a hyper accurate model of what happened, you'd need to have "concrete" which would produce a powder finer than is physically possible. You'd also (I think) have to run it in a near-vacuum to get the same air pressure and resistance effects to scale.
     
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  3. WeedWhacker

    WeedWhacker Senior Member

    I think I am quite satisfied with the notion of computer modeling....it is evident that today it works extremely well in the designing of modern airplanes....when, in the past (prior to computers) the "usual" method was a scale model, in a wind tunnel.
     
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  4. Mick West

    Mick West Administrator Staff Member

    It's especially useful for destruction testing, as you can quickly and cheaply run multiple tests on the same model.
     
  5. Cube Radio

    Cube Radio Member

    Deirdre, I'm not even sure Pete really was suggesting what he seemed to be suggesting: that by the time the destruction wave reached the last ten floors of the towers, the mass above that wave of destruction was equivalent to 100 floors, despite all the pulverisation and ejection that was witnessed. Maybe if he clarifies whether or not that is what he meant to say -- and is able to provide an estimate of just how much of the building had been "lost" through pulverisation and ejection before the destruction wave reached the last ten floors -- we can proceed from there*.

    * but actually, this would be off-topic
     
  6. Mick West

    Mick West Administrator Staff Member

    No we can't. That's an off topic discussion. Stick to models please.
     
  7. deirdre

    deirdre Moderator Staff Member

    you brought it up. so I'm asking YOU to estimate the math. Or are we talking we can ONLY use scale models and no math at all?
     
  8. Cube Radio

    Cube Radio Member

    No, I didn't. I was looking for clarification from Pete in response to a comment he made.
     
  9. Cube Radio

    Cube Radio Member

    What do you consider the best physically-accurate computer model of the collapse sequence of the Towers, Mick (as opposed to a model of the initiation event only, or a model of the plane impact)?
     
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  10. Mick West

    Mick West Administrator Staff Member

    I'm not aware of any (except for a few toy simulations I've seen on YouTube). Nor am I aware of any need for one.
     
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  11. jaydeehess

    jaydeehess Senior Member

    Well yeah!

    It hit at a faster velocity, it hit off center, it hit such that it impacted the short side of the tower's core versus the north tower being hit to impact the long side(in a square exterior building this means a shorter distance of floor to traverse before impacting core), and it hit at a bank thus spreading fuel over more floors at once and thus igniting more floors simultaneously.
     
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  12. jaydeehess

    jaydeehess Senior Member

    I mentioned above that you seem to be under the erroneous impression that the collapse sequence after initial failure was one in which columns were being crushed (which I take to mean buckled) was the primary driver of the progression to global collapse.
    It wasn't.

    Massive overloading of floor space failed trusses and beams which left the perimeter and core columns exposed to various mechanisms of destruction.

    Models designed to test earthquake resistance hardly apply at all to such a scenario.
     
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  13. jaydeehess

    jaydeehess Senior Member

    I already suggested one that would better match what actually occured in the towers, than anything I have seen truthers attempt.
     
  14. Redwood

    Redwood Active Member

    Ironically, this is where Truthers could really shine. Give us a computer model whereby the collapse stops after initiation. Do an FEA and plug in whatever it takes in terms of either springiness, like a trampoline, or impenetrability, like a solid concrete wall, to arrest the collapse.

    Now, given those assumptions, see how the building behaves otherwise. Does it sway in the breeze like a giant palm tree? Do the floors sag in the middle when you walk across them? Does the collapse arrest floor require a separate structure to support it, so it doesn't crush the rest of the building beneath it? Does this bear any resemblance to the Twin Towers as built? If nothing else, having run such an FEA would look good on the résumé of any Truther engineer who did it.
     
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  15. Pete Tar

    Pete Tar Moderator Staff Member

    I thought I made my point clear - the largest demoliton we have is 31 storey building, I was just providing the reference. I was not making any comment that it matches the WTC collapse in any way, except it's the next largest building we have falling down. Meaning, we don't have any collapsing near-110 storey buildings to compare it to as 'expected behaviour', so while you may say I have no similar buildings to compare it to say that is normal behaviour, neither do you have a basis of comparison to say it's not.
    However I do have more evidence to say it's normal, in that at least the two times it did happen are available to see and *that is what happened!*, and there is no equivalent contradicting evidence at this point in time.

    We need to focus on what parts of the collapse you find suspicious and so want modelled.
    Correct me if I'm wrong -
    you find the idea that ten+ storeys can be the trigger to completely crush a steel-framed building underneath it suspect;
    you find that the collapsing portion maintaining integrity for some or most of that collapse suspect;
    you find the idea that it would not topple over to a significant degree suspect.
    (and maybe you find the idea that load-bearing steel heated enough to start buckling would completely fail suspect?)

    So, maybe those elements can be individually tested - I think the best real-world models we have are already existing structures that have failed or been demolished, though we must be careful to ensure we are focused on the correct behaviours we can study and extrapolate to the Towers, ie, a 30 storey steel-framed building may not act the same as the Towers in total collapse, however some similarities would be valid.
     
    Last edited: Jun 16, 2014
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  16. Pete Tar

    Pete Tar Moderator Staff Member

    I would say, yes, broadly representative, certainly enough to overwhelm anything in it's path less dense than the ground itself. While it may have been losing some mass it was simultaneously gaining it, I don't believe this would have been a net loss.
    The taller the building, the more available energy which it can use to destroy itself. The loss of mass through dust and ejection would not be enough to really change this. And yes that would be a good thing to model, to see where that critical line is.

    I wouldn't say my understanding is based on common sense - I am well aware that common sense is not always reliable - however it is based on the simplest non-technical understanding.
    I am aware that may not always suffice for complex situations, and while I know this one can be analysed in incredibly dense technical language, I do believe a simplified understanding is adequate here.
     
  17. jaydeehess

    jaydeehess Senior Member

    There's the rub!
    In engineering modeling the purpose is, in the vast number of cases, to determine as-designed structure's behavior in various environmental circumstances.
    Rarely is it used to determine building response after the as-designed structure has received damage of various types. The EXACT damage to these structures is unknown and involves a deal of margin of error in the FEAs. That includes both impact damage, fire spread rate and extent, and heating damage. So initial collapse cause analysis is very difficult.

    Progressive collapse analysis is then hampered by the uncertainty of the exact sequence occurring at and following initial collapse BUT, we do positively know that the structures did in fact suffer a progression that resulted in global collapse.

    The truther position then is one of nothing more than incredulity. "It can't happen!" Is the starting position they jump to, and they then demand they be proved wrong. They further propose various and sundry fantastical, read "magic", mechanisms from therm?the, nuclear weapons, and up through sci-fi space-a-beams. The single most obvious cause of initiation is the cumulative effect of impact then fire damage. The single most probable mechanism of runaway progressive collapse is floor failures. Neither requires an unknown , non-evident , cause, but every single truther scenario does.
     
    Last edited: Jun 16, 2014
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  18. jaydeehess

    jaydeehess Senior Member

    Yes, its common sense.
    At initial collapse a small percentage of the upper " block" was ejected. All but certainly mostly perimeter columns and office contents. That was sufficient to fail the first few lower floors. As the collapse progressed more mass was added and, yes more was ejected but iirc, for instance, no core columns were ejected meaning that ejecta consisted primarily of material originally more distant from the core. In addition the velocity of the falling mass was increasing meaning greater transfer of momentum and thus increasing force on lower floors due to BOTH increased mass and mass velocity. Note that at no time after initial collapse , do the columns or their ability to carry a load factor into such a collapse.
     
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  19. Cube Radio

    Cube Radio Member

    It is a probability that has only been modelled unsuccessfully. How long do you imagine it will be before home computers are powerful enough for individuals to model this mechanism easily into a representation of the Towers, and can you understand the reason why some people might seek to do so in the future, given that it has not been achieved yet and it is now already many years since this unique and unprecedented collapse event took place?
     
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  20. jaydeehess

    jaydeehess Senior Member

    Its the model put forth. Prove it wrong or just as good prove another mode of runaway collapse. So far the alternatives all involve very scantly described hand waved arguments. Certainly no models of any sort.

    As I said, the runaway floor collapse hypothesis requires no unknown and non-evident mechanisms. Any scenario that includes such a mechanism, for instance explosives would have to be able to show how it was accomplished in that at least a well described method of installation, of timing and execution of such a collapse plan, taking into account the differences in each structure's collapse and such that it matches the observed collapses. (Perimeter peel away and core destruction lagging exterior destruction.)

    ETA: Twice now I have outlined a physical model that at least would demonstrate the scenario, you have yet to comment on it.
     
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  21. Mick West

    Mick West Administrator Staff Member

    Keep on topic chaps. We don't need another 100 page 9/11 recycling.
     
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  22. Cube Radio

    Cube Radio Member

    It's a model that doesn't exist except in your imagination, so it can't be proved right or wrong.

    In fact there are no models that support your ideas. Or, to be more exact:
    What alternatives to this non-existent model you don't have are you referring to here?
    You know, my feeling is debates of this kind are often depressingly polarised. As long as one side is set against the other and it's "truthers" vs "debunkers", all you get is mutual mud-throwing and the arguments are lost: certainly there is no spirit of mutual investigation or an attempt to reach common ground.

    However, I would personally be ashamed to advance an argument from incredulity such as this, given that the topic at hand is modelling the collapses of the Towers. Your non-existent model won't become more experimentally accurate to the facts by you blustering on about explosives.

    If it fails to show that your ideas can have experimental validation, it just fails -- no matter what alternative scenarios there may be.
    Your model doesn't exist except in your imagination. I don't think it would work. Are you going to pretend that your non-existent model has proven something because I'm not going to build it?

    Perhaps you can be the first in more than 12 years to successfully model how the collapses occurred.
     
    Last edited: Jun 17, 2014
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  23. Keith Beachy

    Keith Beachy Active Member

    When it comes to the last ten floors? What is the speed of the debris field. Even if 75 percent has fallen outside the WTC "footprint" (omg, I said footprint) the debris will cause the 10th floor to fail, it can only hold 11 floors of debris, not moving debris. Did you forget the falling debris? Is it easier to carry 100 pounds placed in your arms, or catch 100 pounds from 100 feet up?

    Once the collapse started it was not going to stop until it hit the ground, as seen on 911; no explosives, no thermite, only gravity.

    The model for the WTC collapse is as seen, it is stored on video. I am an engineer, and that is the model I am going with. It is waste of time to model the collapse there is no purpose, everyone knows to get back as far as possible for the collapse, nothing to learn, but run. The steel was not pulverized, only the insulation, wallboard, and some light weight concrete.
    BTW, one pound of wallboard in one piece, weighs the same as one pound of wallboard dust. The mass of the WTC did not disappear.

    I did a model of momentum it matches the collapse for the first period. Math, it is a model. I still like the full up model of the WTC collapse, it is the actual gravity collapse, with no explosives, no thermite. That is the super model, the real collapse. We use math to predict atomic weapons, and then we test them, and even though the sight of the blase looks nothing like the math, the model is good, and the blast is the real experiment. We have two full up experiments due to terrorism on 911, WTC 1 and WTC 2. What you see is how a WTC tower collapses, and the chief structural engineer agrees. You can ask him, or study his work. He says it is normal, thus, the number one expert agrees with me, what you see is how the WTC would collapse. Gee, guess what, it happened as seen. So simple, the full up model trumps any model made up by anyone. The speed of collapse matches my momentum model, and also other's momentum models. it is math, and physics, ...

    Why model the collapse, the horse is already out of the barn.
     
    Last edited: Jun 17, 2014
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  24. Cube Radio

    Cube Radio Member

    Keith, the point of constructing a model would be to gain experimental validation for the theory of how the collapse occurred by showing it is, in principle, reproducible. You can't take the footage of the event you're seeking to model as if it itself is a model of itself -- that doesn't achieve validation of anything. Reproducibility and validation are such fundamental elements of the scientific method that I feel if you were really an engineer you would understand this. Instead you assume the terms of your argument: in philosophical terminology this is called begging the question.
     
  25. jaydeehess

    jaydeehess Senior Member

    It exists as proposed by several researchers. It exists in various similar forms from, among others ,NIST

    I accept the scenario as very plausible. I have no particular impetus to construct the physical model. Those who are looking to model such things however, may wish to give it a whirl.
    That is not an excuse for the failed models put forth by those who cannot be bothered to model what actually happened.

    Bluster about explosives! You imagine that I came up with that out of thin air? It HAS been put forth by others, yet there are no 'models' demonstrating this let alone a thought out description of their use.
    I don't have the impetus or the time to build it. It stands there for anyone to try. I really couldn't care less if that is you or not.
    OTOH it quite obvious that all of the models put forth so far have been designed to illustrate what could not happen rather than tesdt what could happen.
    That is not my fault.
     
  26. Cube Radio

    Cube Radio Member

    Your post is rather confused, Jay. First you say the model
    However there are
    but then there are
    however
    Perhaps you should just post links to whatever models you're on about.
     
  27. Mick West

    Mick West Administrator Staff Member

    I think there's some confusion as to what is mean by "model" here. Perhaps people could qualify their usage with world like "mathematical", "computer", "abstract", "thought experiment", "physical", "scale", "theoretical", etc.?

    Cube, do you have a point beyond "I think there should be a (scale or computer) model of the collapse, because it looks suspicious to me and others"?
     
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  28. jaydeehess

    jaydeehess Senior Member

    My outline for a model above would be a thought experiment that could be constructed as a physical model.

    Bazant had a paper in which he approximated that the force on the floors was 30X that which they were designed to carry.
    NIST reported that once the collapse initiated that there was no mechanism by which it could be halted.

    Several others have further detailed a runaway floor collapse. This thought model is supported by what can be observed in that it would suggest that floor collapses lead the perimeter peel away which is evidenced by the supposed 'squibs', which are visible evidence of internal collapse ahead of the observable collapse zone at the perimeter. It (a floor failure led progressive collapse) also would suggest that the core collapse lagged both the floor failures and the perimeter failure due to it (the core) primarily failing by Euler Buckling. That is evidenced by the so called "spire", of core structure of one tower, which (the 'spire') fell after the rest of the building had collapsed.

    As I said, any model, computer, physical, thought experiment or calculated mechansim of failures, should have some relevance to the observed collapses.
    "Crushing" of columns is not indicated by the available evidence and that is what, for instance, Psikey was modeling.

    Perhaps that's clearer.
     
    Last edited: Jun 17, 2014
  29. Keith Beachy

    Keith Beachy Active Member

    Two gravity collapses, oops, reproducibility. A floor of the WTC can hold so much weight, that is the key to collapse of the WTC. The video of the WTC collapse shows a gravity collapse, if you struct the WTC at the top and only had 5 or 6 floors slowly collapse to the lower section, maybe the collapse would stop. You can do the math, no need to waste money on a model.

    I am really an engineer, and since I can calculate what floor in the WTC can hold, there is no need to study the collapse, only the start. The collapse is the full up model. It would be a waste of time to model the collapse, it serves no purpose. As an engineer, I would stop your model work, it is waste, unless you are doing some hollywood CGI to make lots of money. Once started given the condition of 911, the collapse would not stop until the bottom. AND, we have two examples of full up MODELS to prove it. I only have a masters degree in engineering.

    Why would you model the collapse anyway. 911 truth can't understand the model for WTC 7, and have no idea it is a model of initiation, and get all upset the model doesn't look right. You would not be happy with a model anyway, it would not look right. Thus, I did a math model, and understand why the WTC collapsed like it did.

    Reproducible. - Bingo, WTC 1 and 2 both collapsed, and the collapse part looks similar, the initiation is different. Reproducible is met with full up models.

    You make no sense.

    E=mc2 the simple math model for an atomic weapon. We can fill the entire room with equations if you wish, go get a physics - he can show you.
    And here is the full up model - https://www.metabunk.org/data/MetaMirrorCache/8ea139507d5b54224dd3a707da0ebb91.jpg
    [​IMG]
    You are saying a full up model is not good enough, and you say the math model is not good enough. What do you want? I can show you many atomic tests, do you still need a model.

    Okay, we take flight, we work on the EoM for flight, and seriously we use all the boards on 4 sides of a room doing the equations of motion for flight so we can build flight control systems, or a simulator. We take terms of lift due to the rotation of the earth and cross them out, they are negligible except for flight at MACH 3 and above. Are you upset we dropped out terms, gee, the autopilots used for your flights use this model, are you going to accept dropping out terms?
    We now have filled up all the space on the boards, and have the answer; we had to linearize some things, and make assumptions. We had to base the equations on some big assumptions - we can't really model flight perfectly, but we can try.
    Then I show you the model, and you are happy?
    Wait, I have a plane and it flys, full up model, and it works.

    I have a 767, it flies, and you want a model to prove it flies?

    I have the WTC, it collapsed due to fire, a gravity collapse, full up model. Now you want to model something we already have seen is possible; for what reason.
    Reproducibility and validation are the end result, you have it backwards, the full up model are the Reproducibility and Validation of any model you can build. So go to engineering school and model the WTC collapse, I think pure study is great, and out of big studies comes great things like Tang, WD-40, STP, etc.

    Do you what a computer model, or a scale model? I already have two full up gravity collapse models on 911, now what kind of model do you need...
     
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  30. Pete Tar

    Pete Tar Moderator Staff Member

    Are there any existing models or demolition examples that 9-11 sceptics can point to as evidence of something being wrong with the collapses?
     
  31. jaydeehess

    jaydeehess Senior Member

    None that can be said actually model something that occurred in the structures.
     
  32. Cube Radio

    Cube Radio Member

    No, Keith. The collapse of Tower 1 was not a modelled experiment set up to establish whether or not the collapse of Tower 2 was reproducible. That's just absurd.
     
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  33. deirdre

    deirdre Moderator Staff Member

    it's absurd to think you can make a physical scale model to mimic the WTC collapse. As Mick pointed out just trying to 'scale down' the sheetrock/cement dust would leave you with a necessarily HUGE scale model.

    I'm not being sarcastic here, a genuine question- have you ever seen a skyscraper up close? I think for a lot of truthers, perhaps not understanding the SIZE of the WTCs ie. the SIZE of the hole, the weight of the tower, is an issue. On tv they look pretty small.
     
  34. jaydeehess

    jaydeehess Senior Member

    I believe that Keith is referring to the fact that two identical towers suffered very similar global collapses. That, in and of itself indicates that such design was inherently susceptible.
     
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  35. Cube Radio

    Cube Radio Member

    The thing about reproducibility is you prove you've understood a mechanism by being able to do it again and again (including on a day that isn't 9/11). That's why reproducibility is so central to the scientific method. If it's your impression that the design was weak, Jay, perhaps that weakness could be incorporated into your thought-experiment-that-definitely-works-in-the-real-world model.
     
  36. jaydeehess

    jaydeehess Senior Member

    Iirc, As far as the NIST fea goes it shows massive overload of the floor. If you know of a mechanism by which further floor destruction could be halted then yes, perhaps a model physical scale model would be in order.

    Do you?
     
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  37. Cube Radio

    Cube Radio Member

    Obviously, how far the destruction must continue through the floors is among the more significant aspects of what a model could establish.
     
  38. Cube Radio

    Cube Radio Member

    I can make a simplified model out of paper, cardboard and an elastic band to show in principle that an aeroplane can fly. That's easy for me. I want a simplified model of the Towers that can be shown in principle to destroy itself under the dynamic momentum of a falling upper section. That's apparently impossible for you.
     
  39. Keith Beachy

    Keith Beachy Active Member

    After learning what a floor can hold, and knowing the design, the collapse see of the full up real towers is how they would collapse. No model is needed to understand how they collapse. We can model it if you wish, but it will collapse the same as seen on 911, the real model. No model can collapse as good as the real models did. Twice, Reproducibility and Validation, if you wish, you can reverse the order, and use 1 or 2 as the Reproducibility and Validation for 2, or 1.

    Why do we need to model something we saw happen? I always knew the CD of buildings was a gravity event, they use much less explosives for CD than you get from E=mgh. oops, another very simple model for what we saw. The WTC collapse was the release of E=mgh. When I see the collapse, I see E=mgh released, over 130 Tons of TNT per building being released, which accounts for all the damage beyond fire damage.

    I present the simple model for the energy we saw during the collapse: E=mgh Model complete, and it matches the event. I see 130 tons of TNT twice at the WTC, not counting the heat energy which is an order or two of magnitude more energy.
    I like engineering conclusions being called absurd. I would ask Leslie Robertson if he thinks the collapse was as it was suppose to be, and as we saw it. It is absurd to think the building did not collapse the way it did based on the model of what a floor can hold. How could the building not fall the way it did? What is wrong with the gravity collapse?

    One of your implied models is the shedding of mass... did you model it. A floor in the WTC can hold 11 floors, not moving floors, static carefully placed 11 floors of mass. Guess what happens when things are moving, as seen on 911, on record.
    As the collapse starts most the top section comes to the lower floors. If only 11 percent of the WTC remains in the WTC footprint, the WTC collapses to the ground. You can shed over 80 percent of the mass and the WTC collapses to the ground. Model complete, WTC collapses. When you add in the speed of the mass, what do you need to collapse the WTC to the ground; less mass.

    Much as the second impact of an aircraft verified an attack, the second collapse confirms that is how WTC towers fall if we didn't get the clue the first time; I studied the chief structural engineer and he agrees with how the WTC collapsed. He needs no model, he is an engineer too. But if you got the money, engineers will do the study. Have at it. What is the purpose? Goal? Did anyone search for any models past Bazant, and the simple momentum models many engineers have done? Are those good enough? The WTC design makes it ideal for a momentum model.

    What is the problem with using the real thing?
     
  40. Mick West

    Mick West Administrator Staff Member

    How big would the model be?

    It's an interesting exercise. I demonstrated earlier that it's impossible to have the correct floor loading on a 1/200th scale model. So what scale do you suggest?

    What's the principle you want to demonstrate? Just that a structure can destroy itself? Can't you visualize a model that would do that? Very heavy floors supported by very fragile columns would do the trick (but not exactly be accurate).

    Can you make 1" paper plane that flies?
     
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