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  1. Jeffrey Orling

    Jeffrey Orling Active Member

    This is OT... The beginning motion brought the top section and the bottom section together as top descended. It dropped because of insufficient axial support. This was a combination of weakened columns (Mick doesn't/can't model) and mis aligned columns (Mick can't /doesn't model) .

    However I have suggested in the past... and the cartoon diagram posted at IF shows that as these 2 processes were the destruction of the floors in part was taken place to some extent in both the top and the bottom. The tops floors were locally failing and the bottoms floors at its top were locally being destroyed from the falling bits above. The falling of the upper sections was at least partially related to and involved with the warping ergpo the mis-alignment and missing of columns ends (loss of aggregate strength) and absence of resistance when it dropped. This likely led to some extreme concentrated loads where column ends would meet parts of the structure.. dropping top meeting static bottom... static bottom meeting dropping top and punch through anything in their path.. This might lead to sheared beams or further breaking of the slabs into chunks.

    It's hard to conceptualize and to know what and how these mechanics were functioning. You can't have missing columns unless the top is moved laterally.
     
  2. Mick West

    Mick West Administrator Staff Member

    Walls and floors starting to take a little damage.
    20160409-152246-zkfz5.
     
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  3. aka

    aka Member

    Because the question about the "jolts" predicted by some "truthers" came up on /r/towerchallenge, I thought some of you might be interested too.

    I took the file "Fall Clip.mov" from post number 193, separated the frames in Blender, loaded the sequence into Tracker (starting with frame #24), and tracked:

    The left and right edge of the left uppermost floor slab (A & B),

    the left and right edge of the right uppermost floor slab (C & D),

    the same for the second floor from the top (E, F, G & H),

    the lower and the upper edge of the rightmost column (I & J),

    the lower and the upper edge of the middle column (K & L).

    I also set the height of the three lower rightmost columns to 1.83 meters (3 × 24").

    Point E had to be interpolated for a few frames because the arm is in the way. Points L & J don't come into view until the fifth frame.

    The rest of the story shall be told by the graphs for y displacement, v[y] (vertical velocity) and a[y] (vertical acceleration):

    [​IMG]

    Verify by renaming joltz.txt to joltz.trk.
     

    Attached Files:

    Last edited by a moderator: Apr 11, 2016
  4. Mick West

    Mick West Administrator Staff Member

    An impressive amount of work, thank you. What do you think the story is?

    What if you average out all the graphs?
     
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  5. aka

    aka Member

    I mostly arrive at average downwards accelerations of ~4-6m/s², depending on which data points I include (for example excluding I&J post-impact with the floor). Take everything with a few shovels of salt, of course. The motion blur demands interpretation and interpolation, "I" exceeds g at one point for example - and K has only an average downwards acceleration of 1.8m/s² in the interval between 0ms and 800ms.

    Tracker is free, and if you're not using TempleOS, even likely available for your platform: http://physlets.org/tracker/

    Load the trk file (I can zip the image sequence and UL it to my server if you need them), right-drag the a(y) diagram on the right (the third one), click "analyze", mark the points, click "Analyze" and "Statistics". The "average" row in the "vertical" column should give you an average of the values.

    If it is not too much trouble, having a type of yardstick (and a big stopwatch) near the setup in future experiments might help the calibration for these purposes.
    The one about missing jolts - we found them :)
     
  6. Oystein

    Oystein Active Member

    I am sure the following is obvious enough for aka and Mick and most active posters, but I'll say it anyway, for the benefit of possible lurkers:

    The "Missing Jolt" has been claimed and described from videos of the actual WTC collapses, where researchers tracked building features at or near the roofline - that is 12 or more stories away from the collapse zone where most of the impacts would occur, introducing more opportunities for dampening.
    Also, the actual collapse zone had vastly more individual structural member making contact with other structural member. From the measured roof line features, there are multiple paths to multiple impacting members.
    Both factors smear the jolts.
    Finally, there are no videos where one could track the motion of individual floors or even floor joists, as these were obscured by the perimeter.

    Having said that, I appreciate aka's effort :)
    The average acceleration appears to be somewhat lower than the early acceleration of the WTC. It is certainly too early speculate on the reasons (probably both trivial and irrelevant), but suggest that there is too much elasticity in the wood planks. Two or three of the points have brief excursions into positive (upward) velocity, which I don't see as realistic in the real event.
     
  7. Mick West

    Mick West Administrator Staff Member

    The floors are spaced exactly 8 inches apart.

    I concur with Oystein above. This model allows you to track the "jolt" on essentially rigid objects (planks of wood) hitting other rigid objects of similar mass. This is radically different to tracking the roofline of what is essentially a highly deformable object - the falling top mass of the tower - which is falling into another highly deformable object. ( deformable at that scale and with the forces involved).

    It's common for truthers to appeal to Newton's laws of motion. However they generally fail to realize that Newton's laws apply to idealized point masses. It gets more complicated when we are dealing with rotating semi-rigid bodies (like in the model), and vastly more complicated when dealing with a vast assemblage of various bodies of varying deformability.

    https://en.wikipedia.org/wiki/Newton's_laws_of_motion#Overview
    So this is an unfortunate limitation of small models like mine. The scale and materials used (as well as the visibility of all parts) means you are going to get measurable jolts (as you would intuitively expect) which might erroneously reinforce the expectation for similar jolts in measurements of the roofline of the original.
     
  8. aka

    aka Member

    If you're all standing in line to make the case for the Twins being deformable objects where stuff would be in the way all the way that can cushion and damp the collision quite quickly, I'm totally with you! :cool:
    Is that not a bit academic? Yes, Euler did a little refining, but they're still commonly known as "Newton's Laws", not Euler's, probably so you can introduce Euler seperately for the buckling stuff, makes for a better entrée. The point truthers are trying to make here - the way I understand it - is just not to drift into Quantum Mechanics, Einsteinian spacetime or metaphysics to describe the tower and its demise.
    The model has a much lower "granularity" (as you called it in one of the older threads, IIRCs), so it was to be expected to see more pronounced effects than in the original (and for that, they even are surprisingly small).

    I found other aspects more interesting, but this was someone's interest and I always wanted to try Tracker anyway so why not share the raw data with you too.

    I'm interested in the elasticity thing. The wood is starting to get damage, the collisions are quite elastic - hypothetically, what would be expected from "cushioning" the floor slabs (not really a mattress, you know, more something like a strip of footfall sound insulation underlay and some duct tape)? Would that be better or worse for the collapse?
     
  9. Mick West

    Mick West Administrator Staff Member

    No, the point truther are making is that they expect the lower part of the tower to push back against the force of the upper part of the tower. There's a number of fallacious conclusion they draw from this - like assuming that since the lower part is strong enough to hold up the tower, it's also strong enough to stop it. They frequently describe the collapse as violating Newtons laws of motion. They are not appealing to some different physics, just explosives.
    20160411-144737-ns20y.

    So it's not at all academic to demonstrate with an actual model that it stand up and be stable, and when locally damaged it can collapse without explosives, and still quite clearly follow the laws of motion
     
  10. aka

    aka Member

    Please take your last comment and mine (this one) and make it an own thread, I don't wish to ruin the model thread, and if you like, please delete this request message.

    It seems clear that essentially, everyone is speaking about the same thing, the same idea, the very same concept, principle and model of the universe, whether they call it "Newton's Laws of Motion", "Classical Mechanics" or "Euler's Laws of Motion".

    Your claim is:
    Your evidence is: https://www.metabunk.org/attachments/20160411-144737-ns20y-jpg.18556/

    The debunking is:

    The first quote says "an official narrative that has been used to ... steamroll Newton's Laws of Motion."

    The second: "that the official explanation of what happened to WTC 7 was in violation of Newton's Laws of Physics".

    The next: "that the official explanation for the collapse of the three WTC buildings is in violation of Newton's..."

    The last one: "Official Story Violates Laws of Physics."

    So they do not, at least in these instances, describe the collapse itself as in violation Newton's Laws of Motion. They say the official explanation of it does.

    So there is not the slightest doubt that both the tower and the model have obeyed the Laws of Motion, our collectively chosen scientific way of looking objectively at the facts, like everything else on the surface of our beautiful, blue home marble does obey.

    What some researchers are claiming is that additional assumptions must be made to explain the collapse within that framework, to make the numbers fit. That is completely different from saying "it is impossible".
     
    Last edited: Apr 11, 2016
  11. Mick West

    Mick West Administrator Staff Member

    It's relevant to the model, as it's something that model demonstrates.

    I apologize for not being clearer. Obviously nobody is claiming that the laws of motion have actually been broken. I though that was clear. However the truthers seem to claim that the collapse as observed and without some form of explosives (i.e. "the official story") could not have happened without violating the laws of motion, and by extension there must have been some kind of explosives involved.

    Shorter: Truthers claim that the observed collapsed violated the laws of motion unless explosives were used.

    My model demonstrates that some tall structures can collapse in a similar manner with no explosives.
     
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  12. drommelsboef

    drommelsboef Member

    Great work guys.
     
  13. Polly Math

    Polly Math Member

    Nice try with the semantics there Mick, collapse VS NIST's explanation of it. Easy mistake to make.
    Your model illustrates nothing of the sort. Ridiculous claim.
    No redistribution, no overstress exchange.

    What exactly is it you think your model demonstrates? Be clear.
    About time somebody put your magnets and wood under some serious scrutiny.
     
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  14. Landru

    Landru Moderator Staff Member

    Perhaps you should be clear as to why you think his claim is ridiculous.
     
  15. Mick West

    Mick West Administrator Staff Member

    That rapid progressive collapse of a stable structure is possible following a small potion of it being dropped on a larger bottom part.

    It's basically a refutation of AE911Truth's "cardboard box" argument. It accounts for scale (in the supporting strength of the floor slabs), and the method of construction (floor slabs support the columns horizontally, columns support the floor slabs vertically).
     
  16. Mick West

    Mick West Administrator Staff Member

    That's the point of this tread. Please feel free to point out problems with the model.
     
  17. Polly Math

    Polly Math Member

    I applaud that. Way too early for you to be making claims re the towers on the basis of this though.
    What capacity do the floors have in terms of live load - sorry if you have already stated that.

    The bigger question though is have you ever studied how the twin towers actually functioned structurally ?
    The proportionality of mass is crucial also. The top 15% of the towers would only be a few % of the mass of the building for example.
    There's nothing tied in at the top and there are no ties at any corners. Do you realise just how much stronger the floors were at the transverse ?

    Define "stable" for example as you use it above. Quantify it - how stable is your model ?
    Saying it's stable is like saying it's wooden.
     
  18. Mick West

    Mick West Administrator Staff Member

    Can you read the full thread and watch the videos. Several of your questions are covered.
     
  19. Polly Math

    Polly Math Member

    Mick. Simply - how many corners does your model have and are they stronger that the edges structurally ?
     
  20. Mick West

    Mick West Administrator Staff Member

    You can see the model, why don't you just explain what the problem is.

    There are some very obvious limitations with this model. However, the primary purpose is to illustrate that a tall stable (withstanding a scale 8.0 earthquake) structure could collapse by an upper part being dropped on the lower part.

    It is NOT intended to be a perfect representation of what happened, it's an illustration of the type of events that happened. It's basically a refutation of AE911Truth's "cardboard box" argument (and other related "laws of physics" arguments) - i.e. the argument that the lower portion would stop the upper portion.

    Perhaps we could establish some common ground here. Would you agree that the "cardboard box" argument is nonsense? Would you also agree that my model demonstrates this?

    Then, would you agree that you think that while a tall building could possible collapse from the top down, there are specific things in the construction of the WTC that would prevent this?
     
  21. Polly Math

    Polly Math Member

    The weakest part of your model is the corners.

    ETA - that's the problem
     
  22. Mick West

    Mick West Administrator Staff Member

    How would you fix it?
     
  23. Polly Math

    Polly Math Member

    Build a structure where the corners are strongest - not weakest.
    What's the strongest bit of a box Mick ?
     
  24. Mick West

    Mick West Administrator Staff Member

    Stop asking rhetorical questions please. If you want to say something, then just say it.

    Are you are suggesting taking the model into full 3D? This is currently essentially a 2D model. I'm not going to 3D because it would be about 100 times as much work. It's meant to illustrate the principles behind a top down collapse.

    Can you explain what you mean exactly by "corners are strongest". Strongest in what way exactly? Can you draw a diagram illustrating a "corner" and the thing that it is stronger than.
     
  25. Polly Math

    Polly Math Member

    So you agree that the strongest past of a box is the corners. That's a start.
    The strongest part of the towers up and down the height is also the corners.
    The WEAKEST part of your model is the corners.
    Like I said. I applaud your attempt at the model.

    ETA I will try to find you a diagram of the overstress redistribution properties of the tower.
     
  26. Mick West

    Mick West Administrator Staff Member

    Please don't paraphrase me. I quite clearly asked you what you mean by "strongest", and in relation to what. Asking a rhetorical question does not mean you are correct, it means you think you are correct.

    That's still not really clear. The "corners" of my model are the outer edges of the wall columns. They are just as strong as any other part of the wall columns.

    Are you just pointing out the model is essentially 2D, but the towers were 3D?
     
  27. Oystein

    Oystein Active Member

    This is FALSE.
    Only the columns got lighter towards the top. Floors weighed essentially the same throughout.
    Offsetting the lighter columns is the hat truss, a heavy bit of structure found only in the top 3 storeys, plus the antenna and other mechanical equipment. As a result, the top 15% of the towers weighed more nearly 15% of the total above-ground mass.

    This is hardly relevant to Mick's model. I am pointing this out anyway to remind Polly Math he shouldn't be so sure of his understanding of the WTC structure.

    Before Mick accepts that "The weakest part of your model is the corners" is "the problem" and ask how to fix it, Polly Math ought to explain why it is the, or just a, problem.
    Besides, a 2D-model can't really be said to have "corners" to begin with, so it's entirely unclear what PM is refering to.
     
  28. Mick West

    Mick West Administrator Staff Member

    The closest thing to a "corner" is the actual corner.
    20160413-111551-j0paq.

    But since this is really a 2D model, the "strength" of corner in the real building is just encapsulated in the "strength" of the outside wall, which is just the left and right sides of this model.

    But again, it's not clear what is being referred to by "strength".
     
  29. deirdre

    deirdre Moderator Staff Member

    i think he means, if you sit on a carboard box that is slightly smaller than your bum, the "walls" of the box will bend in where the reinforced corners stay "strong" and dont bend in. ??
     
  30. Polly Math

    Polly Math Member

    Yes, thank you. At the corners the towers were strong naturally in terms of the shape, but also the floor system was transverse at the corners as illustrated in the floor pan below.
     

    Attached Files:

  31. econ41

    econ41 Active Member

    Polly Math I have a lot of sympathy/empathy with the concerns you express and frustration with the discussions that are taking place.

    This model arose from an evolutionary process proximately triggered by claims from two members - Cube Radio and aka. Reading the two threads could be enlightening - and could also add to the frustrations. They are "Use of Scale Model or Full Sized models for investigating 9/11 collapses" (here) and "Claim: "There is no way to deny the inevitability of progressive collapse" (in Rambles) - respectively.

    Put as briefly and simply as I can there are three defining criteria for a model of this type:
    1) How serious is it? viz "demonstration" of the mechanism for those who need a physical demonstration OR rigorous quantifiable scientific model. This model is a "demonstration".

    2) What is it modelling? This model started life as a specific demonstration of the "ROOSD" sub mechanism of the "progression" stage for the WTC Twin towers. It has drifted outside that scope - recent posts having extended it to "initiation" sage. It was and still is valid for "progression" it is not valid at this stage for "initiation".

    3) Who are the target persons for the demonstration. This aspect has not been explicitly defined AFAICS - I covered the demographic issues in some detail in the Cube Radio thread. I don't think there is a legitimate target - and if there is it is very small - the issues addressed in detail some months back in the Cube Radio thread.

    I have no problem with evolving objectives provided they are explicitly recognised. But the "drifting" process causes both confusion and frustration - hence my lack of participation in recent weeks. Doesn't unduly concern me that my contributions are ignored - I'm content to let others pursue their own preference for a less definite path than I would take.

    So if we agree that it is #1 a "demonstration" NOT a full rigour scientific model lets see the technical status - #2 What is it modelling. I will defer the complex issues of "#3 Who are the target persons".

    A) It meets the original goal - it does model the "ROOSD" process and does it well IMNSHO. "ROOSD" (Runaway Open Office Space Destruction) was the primary sub-mechanism of the "Three Mechanisms" of the "progression" stage of WTC Twin Towers collapses. The model demonstrates that - once started that process does not arrest - a reality of the event that is denied by aka in a parallel running thread. That was one part of the original technical goal and I commended the model for that purpose. Still do. And I concur with the range of improvements which members have agreed with Mick.

    B) It does NOT model the initiation process and I note that recent posts have drifted the objective to include "initiation". That drift concerns me for reasons I can elaborate. Probably the main one being that the model does NOT demonstrate the initiation. In fact it uses in physical form one of the most contentious and confusing aspects of WTC explanations. That is the abstract bit of "cheating" which Bazant used for his paper with Zhou in 2002. It is an artifice to get progression started NOT a demonstration of the actual mechanism. Legitimate for Bazant's purposes in 2002 but NOT a valid model of mechanism. I also doubt that the initiation stage could ever be physically modelled - reasons also explored previously in the "Cube Radio thread". (In brief Bazant in abstract "Dropped the Top Block" to start "progression" so he could explain/quantify progression as inevitable. The "Drop Top Block" never happened but the concept has mislead much discussion for many years. A complex issue from a simple error - we don't need to go there.)

    C) It does NOT address the R Gage boxes issue. The Gage model does not even initiate so how can a valid model of "progression" which is not a valid model of "initiation" do anything to model something which is "pre-initiation"?

    I'm prepared to expand all those technical issues PLUS the demographic issues of "who is the target audience" either by PM or separate thread OR here if Mick wants it here. However I'm confident that I have already addressed the principles involved on the earlier Cube Radio thread and earlier in this thread.

    Au contraire - if the issues are of little interest to you or other members I'll retire back to watching from the bleachers. ;)
     
  32. deirdre

    deirdre Moderator Staff Member

    where did you get that Polly Math is talking about initiation? Did i miss that part?

    or Mick?

    Then, mayhaps, you should take it.
     
  33. Polly Math

    Polly Math Member

    Yes. And therein lies the problem here. The proportionality of the elements.
    Even in a 2D sense the top 10% of the towers would hold what % of the mass of the building. I am going to guess maybe 2 or 3% max. I find the model interesting, and I was just cautioning about exactly what it is and is not establishing.
    There's no reason why it shouldn't develop.
     
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  34. econ41

    econ41 Active Member

    That is "progression" stage - my post was intended to offer help to Polly Math.

    Multiple implicit references by several members show confusion of the stages. Mick at post #136 and your comment at #138 go to the Bazant derived "dropping" which is a legitimate way of starting progression BUT not a model of initiation.

    I'll make my own call - my comment was neutral. The pre-emptive aggression is not needed.
     
  35. econ41

    econ41 Active Member

    Exactly my position.

    I'm unsure what problem you are addressing. The comments about "top x%" should not be relevant to progression stage.
     
  36. Polly Math

    Polly Math Member

    In terms of the sides, they would be progressively hollowed out more with height.
     
  37. jaydeehess

    jaydeehess Senior Member

    I cannot understand what this means. Could you rephrase, please.

    Econ is addressing, and Mick is modeling, the progressive collapse initiated by falling debris taking out the 'floors' which in turn removes lateral support for the 'column'. The axial load bearing ability of the columns is bypassed by such a collapse, they simply do not have any capability of halting the progression.

    Each floor, which is to say the horizontal members of this model or the actual office floor space of the towers, are all essentially the same and are capable of the same load, no matter if its the lowest or uppermost floor. Only the columns are under greater load at lower levels than at higher ones.
     
    Last edited: Apr 13, 2016
  38. Oystein

    Oystein Active Member

    Did you not read my previous reply?

    Your assertion is plain FALSE. The top 10% of the WTC towers were not lighter than the average of the bottom 90% on account of the hat truss, mechanical add-ons, and all floor assemblies being more or less uniform from bottom to top.

    In addition, your assertion is irrelevant to the model, or at least you have not established its relevance (relevant with regard to what?).

    Furthermore, you have not addressed the question about the corners - your claim that the corners were "stronger": In what way do you claim they were stronger? In what way do you think the "corners" of Mick's model are weaker? Weaker than what? And what corners, anyway? And why would this be relevant for the model?
     
  39. Private_Hudson

    Private_Hudson New Member

    Can I ask what you're basing that guess on?

    Not that it matters much, but the floor spaces in the top 10 percent of the towers had roughly the same load per square foot as the lower floors did. The core columns were lighter towards the top, but the top 10 percent of the towers also contained the hat truss and the heavier mechanical floors.
     
  40. Oystein

    Oystein Active Member

    I think you are confusing yourself by needlessly dragging in your own obsession - the irrational belief that every debunker except you takes Bazant as da Truth and refers to Bazanz as holy gospel in their every thought and deed (slight hyperbole acknowledged).

    Post #136 merely discusses an idea how to start the model's vertical motion ("drop") in a more controlled, repeatable manner. There is no reference at all to any WTC initiation mechanism nor to anything Bazant. That's all in your head exclusively - stop projecting!

    "Drop mass" is quite simply how the demonstration starts - and a valid concept.
    If you disagree, please suggest a drop-free method of starting the model demonstration!

    (I realize I am slightly out on a limb, as I cannot look into Mick's head to rule out he doesn't have total faith in Bazant and offers his model as a sacrifice to this God)
     
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