Tower Collapse Questions for Critical Thinkers

jaydeehess said:
So in your mind it all comes down to how quickly the mass is impigned upon the floor?

Did you see anything happening in slow motion on 9/11?

Furthermore just how many floors did you see above the collapse zone in each case?

Yes, extending the time of momentum transfer lessens impulse force but in this case no matter how slow the upper mass comes down it will eventually see the mass of essentially the entire upper block being impinged upon the next lower floor. (and this then includes sections of the core columns, not just the floors. Column sections would remain pretty much as solid objects throughout the collapse)
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Don't you really mean that one floor hits one floor ? After all A snd C are either two ' blocks ' or they are two assemblies of floors .
 
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bill smith said:
Well obviously they would not have the same sudden shattering impact as the impact that a solid floor would, so in broken pieces maybe six or eight floors could be supported by one.
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What data are you basing this on?

Weight of one floor = ?
Load limit of one floor = ?
 
bill smith said:
Don't you really mean that one floor hits one floor ? After all A snd C are either two ' blocks ' or they are two assemblies of floors .
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If 1 floor will hold the weight of the floor above it you have two options,

1-the floor connections break and the next floor lands on the two stacked floors and this continues until the load exceeds the carrying capacity of the floor or

2-the floor connections survive and the momentum of the entire upper block gets transferred through the structure onto the floor until the load exceeds its carrying capacity.

In no situation will the upper floors magically float above the impact area taking no part in the collision.
 
bill smith said:
Don't you really mean that one floor hits one floor ? After all A snd C are either two ' blocks ' or they are two assemblies of floors .
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Don't you see that, as I explained above in another post, if the floor of the upper block does not get lifted from its seats then you now have the entire mass of the upper block on the first lower floor. If it does then the columns continue downward carrying to our as yet unfailed level, another floor, and another,,,(repeat up to at least ten times)

You are now reduced to argueing how many floor masses it would take to fail one floor. In addition there is of course, the dynamic loading which you are attemptinmg to minimize yet it is still there. Further, of course, if this is more than one floor we simply cannot expect that the perimeter and core columns are sliding straight down the same hole they opened up as they speared downward at the initiation of collapse. They are tearing away more of that originally impacted flooring not to mention that they weakened the floor pan when they punched through in the first place. They are also doing a number on floors lower down.

You, and your mentor, seem to believe that the floor pan can by some magical physics, support the entire upper block. Heiwa has attempted to say that the material will get wedged between the core and perimeter. B.$. pure and simple. How can that possibly transfer the mass load of the block to the columns and not push the perimeter columns outward, snapping their seats to the trusses?
 
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Dave Rogers said:
So can I take it that you have formed no conclusions from the collapse of WTC2?
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First off, I am very grateful for your response to my question, particularly as I was beginning to worry no one would. That said, my only conclusion on the collapse of the towers is that gravity was not the only force involved. However, I implore you to set aside our differences in conclusions there, without any regard to to other matters but these collapses which we all can agree were most certainly caused by gravity alone (aside from the initial push out force of course). So, on to that:

Dave Rogers said:
At the time of impact, let's define our terms such that the upper block is moving downwards with a velocity -V, where positive is defined as upwards, and accelerating with an acceleration -A, which is close to gravitational acceleration.
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I am in agreement with you here, though if we actually go though the math I'd prefer to flip the convention, making down positive and up negative, just to keep it mostly positive.
Dave Rogers said:
The upward force F exerted on the upper block results in an acceleration +A1, which varies with time. This adds to the acceleration due to gravity to give a total acceleration A1-A.
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Surely you mean the force F exerted by the lower block on the upper one subtracts from the acceleration of that upper block? Like if you jump down onto a gymnastics mat it subtracts from your acceleration, slowing your fall. We have two forces here, but only one acceleration. As for the effect of that force F on the acceleration A:
Dave Rogers said:
Since the lower block is able to support the static weight of the upper block, then the maximum value of A1 is expected to be greater than that of A, resulting in an overall deceleration...
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Rather, the upward force of the lower block is expected to be greater than the weight of the upper block, the lower block having held that upper block in place prior to the section between the two being pushed out. It is this net upward force which results in the deceleration you mention. Agreed?
Dave Rogers said:
The velocity of the upper block increases, therefore, up to the impact, then decreases very briefly while the impact takes place. Once the next set of floor supports has been destroyed, the upper block then accelerates with acceleration -A until it hits the next floor of the lower block. The velocity will be observed to increase up to the point of impact, decrease briefly, then increase further up to the point of impact of the next floor (which takes place at a greater velocity), and so on. Averaged over the entire collapse, there is a net acceleration. This has been verified by measurements of the Balzac-Vitry collapse.
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Now, from the bold is where I'm not following you at all. You are speaking of the floor supports being destroyed in instances, with periods of free fall between them. I'd like to see the measurements you refer too, but in these collapses I've been speaking of, it is not just floors falling one on top of each other, but the whole structure being crushed down, concrete walls and all. There is no chance of freefall after the initial collision, as there is constantly mass acting as resistive force in the way. Also, I dug up video of this Balzac-Vitry collapse which I'm guessing might be the one you refer to, but surely you are not suggesting there is any free fall after the initial collision in that?
 
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kylebisme said:
...
... , concrete walls and all. There is no chance of freefall after the initial collision, as there is constantly mass acting as resistive force in the way. ...
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Free-fall?; the towers took over 12.08 seconds to fall, not close to free-fall but very close to a momentum transfer. Can you do physics? Didn't think so. You also demonstrated no working knowledge of calculus. Need an example of where you messed up?

The concrete walls you were talking about were in another building not the WTC, right?

The use of modeling the floors of the WTC and then looking at momentum transfer or collapse theories is useful. As you can see on 911 the gravity collapse was a chaotic event. The massive top of the WTC did not have to destroy the entire lower section in 12.08 seconds, it had to destroy the initial surface of the tower below the falling top. In the first 0.87 seconds only 10 feet of lower structure (average) was destroyed by the much larger top section. This piece by piece destruction is all you have to account for to see the lower section is doomed when masses of the WTC seen on 911 start to fall. After 0.87 seconds the mass is now more, and in the next 0.397 seconds the next 10 feet of WTC are destroyed, and that mass is added as the collapse proceeds. Your lack of knowledge in physics and engineering is miss leading you.

If I was totally ignorant on 911 and found the failed ideas of the 911 truth people interesting I would check with the foremost authority on the WTC structure. I would ask Robertson what he thinks. He said -
“the collapse mechanism of the trade center, is as we anticipated it would be, when we first designed it”
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This is what he said! He said the WTC towers failed as it would be after aircraft impacts and large out of control fires initiated the collapse. Go ask him, I have found all of this from google and checking the facts personally. What Robertson has said about the WTC, including designing the WTC for aircraft impacts of 180 mph have been verified by other engineers; you lost this debate and are debunked. You could debunk yourself when you gain the knowledge.
 
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beachnut said:
Free-fall?; the towers took over 12.08 seconds to fall, not close to free-fall but very close to a momentum transfer. Can you do physics? Didn't think so.
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Yet the problem here is your inability to respect context. Dave and I were not discussing the towers, but rather these collapses. Furthermore, I was not claiming any free fall beyond the initial collision, but rather refuting his claims of it.
 
kylebisme said:
Yet the problem here is your inability to respect context. Dave and I were not discussing the towers, but rather these collapses. Furthermore, I was not claiming any free fall beyond the initial collision, but rather refuting his claims of it.
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Good to know you don't have the delusion the towers fell at free fall. I am only a pilot who flew heavy jets with an engineering degree and not too good at these very technical jargon loaded discussions. Sorry, I thought you support the idiotic controlled demolition delusion and were spewing some moronic free-fall ideas.

I was in a hurry making 4 margaritas and a trip to the hot tub; had a date and she like the margaritas! successful mission took 56 minutes to complete. Did you get help figuring out how you messed up the calculus problem?
 
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bill smith said:
Well the broken floor is not really one mass. It is many small masses. These small masses will strike the lower solid intact floor independently as small masses. The small masses will also interaact with each other while falling, losing some energy in the process.

Like if you drop a box of sand on the Tower it will have more effect than the same amount of loose sand which will behave more like a liquid and flow over and around the massive upstanding core columns.
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Isn't EVERYTHING just a grouping of small masses?? I mean, EVERYTHING that we KNOW to exist in the Solar System?? Isn't it??

Maybe I am confused.
 
bill smith said:
Well obviously they would not have the same sudden shattering impact as the impact that a solid floor would, so in broken pieces maybe six or eight floors could be supported by one.
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I am not en engineer, but I understand loads. Ie: My porch can support about 4,000 lbs spread over the entire floor. Now, if I take 5,000 lbs of rocks, and put in on my porch, my porch floor will collapse. It doesn't matter if its sand, or bowling balls, or toasters, it will still collapse.

Why is it that Bill et al do not understand this concept??



Am I wrong in my assumption??
 
beachnut said:
Good to know you don't have the delusion the towers fell at free fall. I am only a pilot who flew heavy jets with an engineering degree and not too good at these very technical jargon loaded discussions. Sorry, I thought you support the idiotic controlled demolition delusion and were spewing some moronic free-fall ideas.
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All good, and I thank you for the apology. I also respect your difficulty with technical jargon as I know many are not comfortable with such things. This is why I've been attempting to speak in common terms, not out of any trouble with the technical descriptions myself.
beachnut said:
Did you get help figuring out how you messed up the calculus problem?
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I didn't mess up any calculus, but rather was simply strawman as being incapable of comprehending calculus while having the argument I did make ignored. Again, find someone to try Mackey's calculations with a given spring dropped from a given height, or rather just ask someone who would know, and you will see how far off his conseptualisation is.

Anyway, in common terms hope you might look at this video and tell me if you see what I am hopping everyone here will. Specifically, when watching the movement of the roof, do you see how it speeds up until the two sections collide, and then it slows down from there?
 
kylebisme said:
(snip)

Rather, the upward force of the lower block is expected to be greater than the weight of the upper block, the lower block having held that upper block in place prior to the section between the two being pushed out. It is this net upward force which results in the deceleration you mention. Agreed?

(snip)
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I'm not a physicist, nor do I play one on TV, but that doesn't make sense to me.

The lower section would not be exerting a force greater than the falling portion; the falling portion has momentum.

The only reason the lower portion held the upper portion (I refrain from using your term, "block"; this would seem to imply that the sections above and below the impacts were far more solid than they were. See picture below.) was that it was designed to carry a static load; the falling section was a dynamic load that completely overwhelmed the lower section.

Note in the Vérinage video the collapse that starts about 3:16 (dang; can't find the website that lets me link to a timepoint in a Youtube vid!). They drop the upper three floors onto the lower section. By about 3:26, the upper portion is almost completely destroyed, and the lower portion has hardly started its collapse by then, yet the lower portion is also completely destroyed by what's left!

Why? The lower portion had been holding the upper portion for (presumably) years. Ahh... it was a static load.

Yet the upper falling portion completely overwhelms the lower section. Why? The static load is transformed to a dynamic load.

Oh, and here's the picture I mentioned earlier; this is why I didn't want to refer to the upper portion as a 'block':

1162750L.jpg

We're not playing Jenga.
 
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triforcharity said:
I am not en engineer, but I understand loads. Ie: My porch can support about 4,000 lbs spread over the entire floor. Now, if I take 5,000 lbs of rocks, and put in on my porch, my porch floor will collapse. It doesn't matter if its sand, or bowling balls, or toasters, it will still collapse.
...
Am I wrong in my assumption??
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You are correct, but you are missing Bill's point. You could take a giant 2,000 pound weight that covered the area of your porch and collapse it by dropping that weight from high enough. However, if your broke that weight into a bunch of pieces, they wouldn't hit at the same time, and hence would have to be dropped from far higher to collapse your porch.
 
kylebisme said:
All good, and I thank you for the apology. I also respect your difficulty with technical jargon as I know many are not comfortable with such things. This is why I've been attempting to speak in common terms, not out of any trouble with the technical descriptions myself.
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:eye-poppi:eye-poppi:eye-poppi:eye-poppi WHAT?? Have you JUST called EVERY SINGLE PERSON on this forum a COMPLETE IDIOT???

I am not often at a loss for words, but trying to describe what I think of this has gotten me speachless.
 
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