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Proposed Design for Progressive Collapse Demonstration

Thanks for your analysis and conclusions. Let's assume that S1 does break before S3, which I consider likely.


Why do you consider it likely? There are hints in my analysis, but I didn't calculate which breaks first, so what is your reasoning? Show your analysis. Show the calculations based on that analysis.

This means that M1 is disconnected from the remainder of the structure for a certain time and that thus the structure below can decompress a little before M1 connects (impacts) again (it has to drop h). In my opinion this means that S3 does not break.


M2 and M3 are not disconnected from the rest of the structure until S3 breaks. I have shown that at no time do M2 and M3 stop moving downward with or without any pressure from M1, so there is no decompression before S3 breaks.

Perhaps you meant that after both S1 and S3 break, then M2 and M3 are momentarily disconnected from the rest of the structure, allowing the lower structure from M4 down to decompress so that S4 does not break? If so, show the analysis. Show that the structure below can decompress instead of continuing to compress under whatever momentum has been imparted to M4 at the time S3 breaks. Show that if it does, it decompresses enough to make a difference in what happens next. Show that the entire lower structure from M4 down, even with all its excess strain energy released and damped away, can absorb 1.3 * mgh of strain energy before S4 breaks. (Or show that my methods of calculating the upper bound on strain energy absorbed, which show that M4 down cannot absorb that much strain energy, by a wide margin, are wrong.)

Your opinion is worthless. Show the analysis. Show the calculations based on that analysis.

Furthermore, does all four springs S1 break simultaneously? Let's assume they vary a little and that one break before the others. This means that M1 cannot impact the structure below perfectly; it is tilting.


Your opinion is worthless. Show the analysis. Show the calculations based on that analysis. Show the delta t in when the springs break, based on some reasonable assumed difference in the tolerance of the springs' breaking strain. Show the resulting torques applied to the masses as a result, show the time interval over which they act, show the angular acceleration resulting, show the amount of tilt at the next impact, show how that affects the subsequent impacts (which remember, do not have to be perfect or instantaneous in order to overload the springs below; I have shown the math proving that that even if the collisions are imperfect and spread out over time the springs still break).

Thus the Funny m model will not one-way collapse, reason being that upper part breaks apart first.


Your opinion is worthless. Show the analysis. Show the calculations based on that analysis. I have shown that the breaking of the upper part does not prevent progressive collapse, in the model that you created. Perhaps I've made errors in the calculations I presented. If so please point them out.

Otherwise:

Myriad said:
This analysis refutes any notion that "1/11 of a uniformly constructed structure cannot destroy the other 10/11" is a valid universal principle. Even if there is objection to the features of the model or the specific parameters chosen, and/or doubt that they accurately describe the WTC towers, there is no doubt that with those particular features and parameters in place, progressive collapse can occur and indeed cannot be avoided. For instance, the funny m model does not specify any ratio of width to height, so any objection that collapse must in all cases be arrested by torquing due to asymmetrical breaking of the springs or the loss of mass over the side can be refuted by referring to a funny m structure that is ten times wider than its total height. It has also been clearly established that imperfect collisions that "spread the force out over time" cannot be assumed capable of increasing the energy dissipation via elastic strain enough to make a difference in the outcome, since in the case evaluated, even the best-case dispersion of strain energy into the lower structure given unlimited time and perfect damping was not enough to arrest collapse.

No doubt there are some uniformly composed structures for which 1/11 of the structure falling one story's height cannot cause progressive collapse of the other 10/11. But the proposition that the same must be true for all uniformly composed structures is disproven by the very model that that hypothesis's most vocal proponent has put forward in an attempt to support it.


As an engineer, you should be able to justify your conclusions on an analysis based on the principles of engineering and physics. Not your intuitive opinion. Not what you can imagine might happen. Not made-up principles with your own name on them. Not hand-waving.

When I hire a plumber to fix a leak, I expect her to use a plumber's tools, methods, and expertise to do the job. If instead she puts chewing gum on the leak or does a Native American stop-the-leak dance, then she is not approaching the problem as a plumber, whether she has an actual license to work as a plumber or not.

Similarly, when I engage an engineer in discussion about an engineering matter, I expect you to use an engineer's tools, methods, and expertise to arrive at and justify your conclusions. You have not done so, and by all appearances you are unable to do so. You should be able to do it much better than me. Instead, on those rare occasions you go beyond tap-dancing "maybe this happens" arguments, I can easily see the errors in your reasoning and your math. (Take another look at your funny m calculations for SEmax of the structure. Have you missed something important? Would you like a hint?) That is why your opinion is worthless.

I recognize that my opinion is worthless too. That is why I am the one turning in carefully reasoned analysis and calculations that can be checked and verified (or shown wrong, if I've made mistakes) by anyone who can look up Hooke's Law on Wikipedia and perform basic algebra. I'm now moving on to computer models, with which I'll be able to test such issues as the effect of spring tolerances and tilting. I'll be looking for reasoned criticism of my methods and results as I use them to plan a smaller-scale physical model.

Since you have withdrawn your offers for any prize or wager for proving you wrong, your opinions are of no further concern to my plans for a physical model, unless you can justify them with reasoned analysis and calculations. Otherwise I'm afraid you will not be able to contribute anything further relevant to the topic of this thread. Worthless opinions that are backed by no apparent use of even the most basic engineering tools, methods, or expertise contribute nothing and I'm no longer interested in them.

Respectfully,
Myriad
 
Why do you consider it likely? There are hints in my analysis, but I didn't calculate which breaks first, so what is your reasoning? Show your analysis. Show the calculations based on that analysis.

...


Respectfully,
Myriad

You have to study Experiments 1, 2 and 3 in my Funny m paper on the web, why springs in the upper, weaker part break before the springs in the lower, stronger part.
Or simply, when two bodies collide, the weaker parts in/affected by the contact fail first as the forces applied on the elements in contact are the same (but opposite).
So therefore springs S1 fail first! And this means that top mass M1 is no longer in contact with anything! It has to drop distance h to apply its energy on structure below with M2 on top at a second impact. And when M1 does that the result is a bounce as there are no springs above to break! The energy that M1 applies is not sufficient to break springs S3. You can probably calculate the latter yourself?
 
If I might interject?
It's the "used up" part where you're going wrong. Wreckage from A becomes part of the falling mass, C.
Debris from A in the collapse zone is not "used up" unless all of it is ejected. It isn't. It accumulates, accelerates and adds to the subsequent destruction of the remains of A.
Hope this helps.

I could say 'it depends on which body is eroded by friction to the point of non-viability first' but I find it's not snappy enough.
 
1. As an engineer, you should be able to justify your conclusions on an analysis based on the principles of engineering and physics. Not your intuitive opinion. Not what you can imagine might happen. Not made-up principles with your own name on them. Not hand-waving.

2. When I hire a plumber to fix a leak, I expect her to use a plumber's tools, methods, and expertise to do the job. If instead she puts chewing gum on the leak or does a Native American stop-the-leak dance, then she is not approaching the problem as a plumber, whether she has an actual license to work as a plumber or not.

3. Similarly, when I engage an engineer in discussion about an engineering matter, I expect you to use an engineer's tools, methods, and expertise to arrive at and justify your conclusions. You have not done so, and by all appearances you are unable to do so. You should be able to do it much better than me. Instead, on those rare occasions you go beyond tap-dancing "maybe this happens" arguments, I can easily see the errors in your reasoning and your math. (Take another look at your funny m calculations for SEmax of the structure. Have you missed something important? Would you like a hint?) That is why your opinion is worthless.

4. I recognize that my opinion is worthless too. That is why I am the one turning in carefully reasoned analysis and calculations that can be checked and verified (or shown wrong, if I've made mistakes) by anyone who can look up Hooke's Law on Wikipedia and perform basic algebra.

5. I'm now moving on to computer models, with which I'll be able to test such issues as the effect of spring tolerances and tilting. I'll be looking for reasoned criticism of my methods and results as I use them to plan a smaller-scale physical model.

6. Since you have withdrawn your offers for any prize or wager for proving you wrong, your opinions are of no further concern to my plans for a physical model, unless you can justify them with reasoned analysis and calculations. Otherwise I'm afraid you will not be able to contribute anything further relevant to the topic of this thread. Worthless opinions that are backed by no apparent use of even the most basic engineering tools, methods, or expertise contribute nothing and I'm no longer interested in them.

Respectfully,
Myriad

1. I try my best ... in layman's terms. Imagination and opinion are very useful tools to visulize what happens.

2. ?

3. Actually SEmax is a quantity introduced by NIST to explain why global collapse ensues. It, global collapse, apparently happens when energy applied exceeds SEmax. But as shown in my articles it has nothing do with structural damage analysis. There we analyse what element fails first, then establish a path of failures until failures stop, etc.

4. I actually appreciate your opinions ... and calculations to back them up.

5. Very good! That's where the money is = a theoretical, 3-D model demonstrating one-way crush down by part C of part A only due to gravity (and some local failures so that part C can drop)! Not the 1-D nonsense of Bazant & Co and Seffen.

6. There is no prize money in The Heiwa Challenge. Start a new thread with your 3-D computer model.
 
If I might interject?
It's the "used up" part where you're going wrong. Wreckage from A becomes part of the falling mass, C.
Debris from A in the collapse zone is not "used up" unless all of it is ejected. It isn't. It accumulates, accelerates and adds to the subsequent destruction of the remains of A.
Hope this helps.

But what happens if C cannot produce any loose wreckage of A? Why don't you understand that A rips C apart and stops the various, wreckage bits of C one after the other? This happens every time you drop a small part C on a bigger part A of same structure.
 
Mass doesn't disappear no matter what nonsensical phrase you use.

If you look at this video you will see enormous masses of gravel,dust, larger rubble and steel lements being ejected on the right side of the building, Bear in mind that the same quantity is being ejected on all four sides. Most of it is coming from the upper portion pf the building and so therefore the falling mass at this point of collapse is much smaller than it started out as. The mass from the lower 'A' section had always been there and so was not in any way 'added'. Comments ?
http://www.youtube.com/watch?v=dtx_GcFCs6c&feature=channel_page
 
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If you look at this video you will see enormous masses of gravel,dust, larger rubble and steel lements being ejected on the right side of the building,

Fixed that for you.

Yes, some beams got tossed. It was a trivial percentage of the total mass and has been factored in to the the calculations.

The amount of material lost didn't affect the conclusion. The building collapsed.

Ever do calculations, Bill?
 
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I've just noticed something I think may be very significant in that video. At about 9 seconds a white cloud develops roughly where part 'A' should begin. Notice that the cloud remains at the same horizontal level while all the rubble keeps falling.A second or two later it too starts to sall. That shows that that IS the level of the top of part 'A' It is easy to see now that ALL of that rubble is from part 'C'

It looks like we have got a precise location for the top of part 'A'
.
http://www.youtube.com/watch?v=dtx_GcFCs6c&feature=channel_page
 
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If you look at this video you will see enormous masses of gravel,dust, larger rubble and steel lements being ejected on the right side of the building,


How much is coming out?

Bear in mind that the same quantity is being ejected on all four sides.


How much is being ejected?

Most of it is coming from the upper portion pf the building and so therefore the falling mass at this point of collapse is much smaller than it started out as.


How much smaller?

The mass from the lower 'A' section had always been there and so was not in any way 'added'.


"Added" in this context means added to the amount of falling mass, of course.

And I'll tell you how much: about 2.5 million kilograms per floor, plus or minus 10%. I derived this from Urich's detailed estimate of the tower masses, divided by the number of floors, with an adjustment for the vertical structural elements (which is only a fraction of the total mass of each floor) being lighter in the upper sections.

Now, once you fill in the other quantities above for comparison, we can see if your argument makes sense. Please provide your estimates of the values, and explain how you derived them.

Respectfully,
Myriad
 
How much is coming out?




How much is being ejected?




How much smaller?




"Added" in this context means added to the amount of falling mass, of course.

And I'll tell you how much: about 2.5 million kilograms per floor, plus or minus 10%. I derived this from Urich's detailed estimate of the tower masses, divided by the number of floors, with an adjustment for the vertical structural elements (which is only a fraction of the total mass of each floor) being lighter in the upper sections.

Now, once you fill in the other quantities above for comparison, we can see if your argument makes sense. Please provide your estimates of the values, and explain how you derived them.

Respectfully,
Myriad

Not being an engineer of course I can't mke a numerical calculation. However I am savvy enough to know that a large percentage of the top portion of the building is contained in the falling mass that we see . And of course that amount of mass is falling on all four sides. I think I read somewhere that Frank Greening calculated that there was about 120,000 tons of dust produced in he total collapse. I read it on a thread on the jref somewhere. That would mean that a lot of that must have been from the top considering the absolute masses we can see falling in the video.

Whoops....found it.

http://www.internationalskeptics.com/forums/showthread.php?t=93119
 
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So therefore springs S1 fail first! And this means that top mass M1 is no longer in contact with anything! It has to drop distance h to apply its energy on structure below with M2 on top at a second impact. And when M1 does that the result is a bounce as there are no springs above to break! The energy that M1 applies is not sufficient to break springs S3. You can probably calculate the latter yourself?


I did calculate it myself, see post 178, and the result of the calculation was that M1's energy is not needed. The energy of M2 alone, which also falls a distance h, can progressively collapse the entire structure below.

My conclusion in post 178 stands:

This analysis refutes any notion that "1/11 of a uniformly constructed structure cannot destroy the other 10/11" is a valid universal principle....

No doubt there are some uniformly composed structures for which 1/11 of the structure falling one story's height cannot cause progressive collapse of the other 10/11. But the proposition that the same must be true for all uniformly composed structures is disproven by the very model that that hypothesis's most vocal proponent has put forward in an attempt to support it.


Do you wish to challenge it? Then show your analysis and your calculations based on that analysis.

Respectfully,
Myriad
 
For this I only HAVE observation ON YOUTUBE . In any case we have at least one top engineer on this thread.

I fixed that for you.

If you are referring to Heiwa, he has shown no signs of being able to applying any numbers to his handwaving, either.
 
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Bill, that same post by Greening concludes:

It suggests that more than 80 % of the mass, (concrete and steel), in the damage zone created at each impacted floor was retained by the descending “hammer” thereby sustaining the progressive collapse of WTC 1.

So, we can fill in those missing quantities: unless you are challenging Greening's assessment or you can find a rationale why the later stages of collapse would produce less dust and other shed mass per floor, the upper mass is 20% "smaller" by the time it reaches the ground, and 80% of the mass of each floor that collapsed (which of course is all of them) added to the falling mass inside the tower's footprint.

See, that wasn't so hard. You don't have to be an engineer to use numbers.

Respectfully,
Myriad
 
1. I try my best ... in layman's terms.


Heiwa, this thread is about helping me design models. There is no need to restrict your arguments to layman's terms or basic math, and I request that you stop doing so. Instead please present your actual analysis and calculations.

The actual engineering and math is more important than a summary in layman's terms. If I have the analysis without the layman's explanation, I can learn the needed math and terminology to understand it, and/or I can get other experts to verify your analysis and explain any unclear points to me. But the layman's summary without the analysis is useless.

Respectfully,
Myriad
 
Bill, that same post by Greening concludes:



So, we can fill in those missing quantities: unless you are challenging Greening's assessment or you can find a rationale why the later stages of collapse would produce less dust and other shed mass per floor, the upper mass is 20% "smaller" by the time it reaches the ground, and 80% of the mass of each floor that collapsed (which of course is all of them) added to the falling mass inside the tower's footprint.

See, that wasn't so hard. You don't have to be an engineer to use numbers.

Respectfully,
Myriad

If you noticed the post in which I mentioned the white cloud you may see that the upper portion was disintegrating and pouring off the lower portion before that portion even started to move downwards. That would have to mean that the upper ' C' portion was already the putative 20% lighter before it even impacted the fully intact part 'A'
 
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