In theory anyway, can the resolution be found in a mathematical equation?

[Bonobo]

I am no engineer, nor am I a mathmetician (sic).

My question is: Given that the basic formula is that the tops of the towers came down, acting as a sort of "piledriver". shouldn't the forces at work be able to be reduced to an equation that could be determined through mathematics?

For example, surely the amount of mass of X number of floors can be calculated and, based on that, we should be able to derive the energy needed to complete the "work" of driving down the floors below into dust and then STILL having enough power to force a near free fall speed. Right?

So I am just talking theory here? Is such a thing possible?

[Bolo Boffin]

1. The beginning of this was done by Bazant and Zhou a few days after the collapse.

Their short paper was a limiting case set up for optimum survival of the building. It used conditions to best allow the building to fall. Their calculations showed that even under these optimal conditions, the upper section possessed force an order of magnitude larger than necessary to destroy the lower section after falling the length of a single story.

Their limiting case assumed that the upper section fell straight down onto the lower section, without any tilt whatsoever. However, we know that the upper sections tilted. So all of that force wasn't hitting lower columns square on, but in ways that would cause deflection, hitting on angles. This meant that force was being applied to the structure in directions the structure was not designed to deal with.

And this is particularly the case when you talk about the floor trusses:



Having the force of the descending section contact the floor trusses would have ripped them from their supports along the perimeter columns. It would be in effect unzipping the floors from the columns all the way down. Some sections of perimeter column panels are torn loose and fall close to the side of the building:



But eventually the lower section perimeter columns would just peel out like a banana peel:

http://www.youtube.com/watch?v=nIZp6aOibiM (right at the beginning you can see the perimeter columns peel out to the right of the screen)



ETA: Link to Bazant/Zhou: http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/405.pdf (pdf)

[Bonobo]

2. Bolo Boffin (and anyone else interested)...

I haven't gone through this yet and I am afraid I can't for a few days, but...


I haven't gone through this yet and I am afraid I can't for a few days, but I am sending a link that contains quite a lot of numbers and at least we, in theory, should be able to discuss. (Maybe if I bone up on my math).

Here are the links, please take whatever time you need to go through and then let's discuss at some point in the future.

http://www.csi911.info/CSI911.html

http://www.911blogger.com/node/20469


PS. I know you will not appreciate the sourcing on this, but whatever else, they are hard numbers and we should still be able to stay snark free through the process. Do you agree?

[LARED]

5. A reasonably astute 10 grader would reject the first link

as being biased and ridiculously error filled.

The second link automatically requires a laugh track.

[Bonobo]

7. I will NOT be replying to messages worded in that tone.

If you wish to have any communications with me, you will have to rise to a higher level of respectful discourse.

It is no loss to me either way.

[LARED]

26. What did you find offensive?

It's the truth. You're the one looking for some real technical anaylsis. What you posted is nonsense.

[Bolo Boffin]

8. There are hard numbers in Bazant Zhou as well

The paper was published in an actual peer-reviewed scientific journal. Bazant is a well-deserved giant in the field.

Why don't we start with that paper?

[Bonobo]

9. All right. I will agree to begin there.

Let's do just that. When we are done, we will move on to some of mine. Fair enough?

I will come back with some preliminary statements about it soon.

[Bolo Boffin]

11. If you link to what somebody else has said about Bazant Zhou, don't bother.

And see below.

[Bonobo]

12. Well, here's the thing. I don't think that is fair, but I understand your point.

I started the Bazant. I quickly had to admit that I was buried beneath equations that I could not only not understand what they referenced or whether they were warranted in the first place.

I think the "math" can be used to both clarify and confuse.

I have just been reading an interchange between Greening and Chandler, for example.

It brings up issues with regards to the disagreements of mathematic equations to use and why. Having read this, I must admit that the two gentlemen involved (Chandler and Greening) are both able to understand and frame the engineering/math issues than I can. So if I post a link to it, can we discuss some of THEIR disagreements as it pertains to Bazant's paper.

For example, my first problem with Bazant is that he hypothesizes an indestructible block falling straight down and impacting symettrically (leading, of course, to a symettrical failure of the load bearing mechanisms on the lower floors, thus explaining how such a rapid and clean collapse could occur.) But this all proceeds from a clearly and visibly wrong premise. Do you agree with that?

[OnTheOtherHand]

16. I think Bolo covered this in the first part of post #1

To quote from the first page of Bazant and Zhou:

However, a computer is not necessary to conclude that the collapse of the majority of columns of one floor must have caused the whole tower to collapse. This may be demonstrated by the following elementary calculations, in which simplifying assumptions most optimistic in regard to survival are made.

So, yes, their analysis proceeds from a clearly and visibly wrong premise, but that in itself isn't an argument against the analysis! If you think about it, you can probably see why they construe a 'straight fall' as "most optimistic in regard to survival."

B & Z didn't set out to explain why the collapse was so "clean" (which is one of those ongoing arguments I never really understood: it doesn't look very clean to me!).

B & Z reason, in essence, that the reason the towers fell is also the reason they fell quickly: plastic deformation could dissipate very little of the kinetic energy. In some ways a 'straight fall' is the best case for dissipation, but there is more to the argument.

[Bonobo]

17. I don't think that is any real rationalization for proceeding from that.

And I don't agree that such a flawed model could possibly be correct. It simply does not mirror reality even by the author's admission.

[OnTheOtherHand]

28. it's not an "admission"

In modeling exercises, one generally strives to be 'as simple as possible, but no simpler' -- and how simple that is depends on the question at hand.

As I've said, Bazant and Zhou argue that their model's departure from reality are conservative: they tend to cut against global collapse. If you have a basis for disagreeing with that, that is germane. But arguing that "such a flawed model" can't be "correct" seems simply to misunderstand, or to reject without a clear rationale, the purpose of the model. "Correct" about what, exactly?

I'm puzzled, because you opened this thread with the question whether the resolution can be found in "a mathematical equation." If one equation suffices, then perforce the model must be very simple. We can add complexity as needed, but... well, you've probably read some of the criticisms of the NIST models, which to me seem weirdly reminiscent of criticisms of Global Climate Models -- and, of course, all these models do have real problems.

[Bonobo]

30. I am unsure of how to respond but here goes.

The model in this case seems to be clearly proceeding from a false set of assumptions. That it is admitted by the author underscores my point.
Yes, I understand the point about simplicity, but at some point, if the model is too far from reality, it cannot be expected to model reality.

I really can't add to that.

It seems to me anyway that the Bazant model relies upon a symmetrical load coming down (symetrically) and, by overpowering the load-bearing capabilities (again symmetrically) it causes a quite fast collapse due to the fact that the shock caused all lower floors to lose their support capabilities at the same time.

But the problem is that it proceeded from claims of symmetry where there wasn't any.

So while I would like to see this worked out mathematically, I don't see the underlying logic behind accepting a set of facts that we know to be untrue and which would (likely) alter the outcome.

Having said that, I am unclear where to go from this point. I intend to read the "other" Bazant paper that SDuderstadt was kind enough to link to.

[SDuderstadt]

31. I think you mean Bolo, Bonobo....n/t

[Bonobo]

33. Actually, I meant Sid...

Sorry, Sid.

[SDuderstadt]

35. Damn...I hate when I am wrong about someone else being wrong.....n/t

[OnTheOtherHand]

36. let me see if I understand you

It seems to me anyway that the Bazant model relies upon a symmetrical load coming down (symetrically) and, by overpowering the load-bearing capabilities (again symmetrically) it causes a quite fast collapse due to the fact that the shock caused all lower floors to lose their support capabilities at the same time.

If I am reading this correctly, your intuition is that, contrary to B&Z's claim, a symmetrical collapse is unfavorable to survival because... well, I'm not quite sure what to do with that last part. They don't say that all lower floors lost their support capabilities at the same time, do they?

At any rate, it's quite a fundamental question whether a symmetrical collapse is most favorable to survival or unfavorable. The issue there isn't whether the assumption of a symmetrical collapse is untrue (which we all agree), but whether it stacks the deck against collapse or in favor. Do those seem to be fair statements, setting aside the answer for now?

I do think it makes sense to read other articles, so that this model can be interpreted in the context of others.

[Bonobo]

37. If I understand YOU correctly...

B&Z claim that a symmetrical collapse is a proper model to follow BECAUSE it makes a collapse less likely (probably due to the fact that it would allow load bearing mechanisms to operate as they were intended, rather than having to deal with "messy" things like twisting and shearing and stuff like that. Is that ABOUT right?

Does the issue of symmetry make it more or less "survivable"? I don't know, but it sounds like a red herring. Because if you proceed from that set of assumptions, you are creating for yourself a neat little circular argument in which you always will be correct since you supplied the wrong initial facts.

Garbage in, garbage out it seems to me.

The fact is that the top of the tower lost mass as it descende, and it did break up partially. This "work" that sent beams and debris flying, as well as the "work" of pulverising the concrete all has to be added up and equaled out so that the amount of potential energy contained in the the top floors multiplied by its mass multiplied by its speed (or some such equation, I am not an engineer but I understand the principles of conservation of energy) has enough energy to accomplish the work it produced (pulverizing concrete, throwing beams, flattening everything AND still moving so fast that it's acceleration was hardly even slowed.

So anyway, the upshot is, I don't like proceeding from the symmetrical position because I think it obscures the issue. If we go there, suddenly we are in the realm of fantasy in a sense.

[OnTheOtherHand]

43. we may have a really fundamental disagreement

Does the issue of symmetry make it more or less "survivable"? I don't know, but it sounds like a red herring. Because if you proceed from that set of assumptions, you are creating for yourself a neat little circular argument in which you always will be correct since you supplied the wrong initial facts.

Why is it "a neat little circular argument"?

Let me take a much simpler example, although it's so much simpler that the point may be lost. Imagine we're estimating how long it would take for a baseball to fall 500 feet from a dead stop. So I pull out the classic equations, reckon the timing, and add, "Of course, it will take somewhat longer than that due to air resistance, but it can't take less time unless there's some other downward force." Do you say, "That sounds like a red herring, because you supplied the wrong initial fact about no air resistance, and therefore your argument is circular"?

It seems to me that if you really accepted that the assumption of symmetry is the best case for survival, you wouldn't think that the question is a red herring. And if you think that it isn't, or even if you aren't sure, I still don't see how the question is a red herring. It's pretty important.

The fact is that the top of the tower lost mass as it descende, and it did break up partially.

Isn't this a separate issue from whether the tower fell symmetrically? Maybe it's the issue of symmetry itself that is a red herring.

Your discussion doesn't seem to take account of the fact that almost everything ends up falling, not just the top floors -- so the top floors don't have to do all the work. But it's legitimate to wonder about the details.

So anyway, the upshot is, I don't like proceeding from the symmetrical position because I think it obscures the issue. If we go there, suddenly we are in the realm of fantasy in a sense.

To me, the question is whether it's a useful simplification -- and specifically what (if anything) the simplification is useful for. Honestly, I think it's very naive to insist in principle (whether or not you are doing this) that a provably false assumption "obscures the issue."

[Bonobo]

45. Maybe of those things that would be easier to clear up through speaking, but...

I think I am saying that a lack of symmetry would cause a very different result so it isn't really an issue of whether it is more or less survivable, but one of a qualitative difference as opposed to a quantitative one.

For example, I am having a hard time dis-attaching from the notion that that there would have been a more asymmetrical buckling before all floors went . It appeared to drop like they got taken out from below where the concussion of the top and bottom came together.

I tried to explain why I see it as a circular argument and I will try again.

Bazant needs it to be symmetrical to explain the speed at which the floors pancaked nearly unopposed. If there were an non-symmetrical resistance (ie load bearing capabilities retained asymmetrically), I would think it would lead to a slower collapse or to one which displayed more obvious non-symmetrical attributes.

Basically, I do not believe acceleration could have continued AND have so much energy dispersed outward and into the pulverization of the floors AND AT THE SAME TIME drive down with so much energy that no resistance was offered by a building that was designed precisely to withstand loads in a vertical axis.

[OnTheOtherHand]

52. maybe I'll follow better in the morning

It appeared to drop like they got taken out from below where the concussion of the top and bottom came together.

Say whaa? ;) I just can't tell what this means.

Bazant needs it to be symmetrical to explain the speed at which the floors pancaked nearly unopposed. If there were an non-symmetrical resistance (ie load bearing capabilities retained asymmetrically), I would think it would lead to a slower collapse or to one which displayed more obvious non-symmetrical attributes.

Well, I think they say (in so many words) that a symmetrical collapse gives the lower floors the most resistance, is most optimistic with respect to survival, and by extension leads to the building collapsing (if anything) more slowly than an asymmetrical collapse. I find this view intuitive; apparently you find it counter-intuitive. The disagreement seems to be both qualitative and quantitative. (But maybe you're not sure what you would expect, and that's why you say "or" in the last sentence I quoted.)

As to your last comment... the building was designed to withstand static loads, not the impact of dozens of floors under gravitational acceleration. The falling mass increases, as does the velocity. Just intuitively, I don't see why anyone thinks this process would be arrested due to the energy consumed crushing the concrete. The concrete starts falling, too; plenty of energy is available for crushing, methinks. But presumably the point of this thread would be to try to understand how such arguments can be resolved or clarified quantitatively, so that we get past dueling intuitions.

[Bonobo]

55. You nailed it perfectly with this:

"But presumably the point of this thread would be to try to understand how such arguments can be resolved or clarified quantitatively, so that we get past dueling intuitions."

Yes. Yes. yes.

[Bolo Boffin]

27. "I quickly had to admit that I was buried beneath equations that I could not only not understand..."

"I quickly had to admit that I was buried beneath equations that I could not only not understand what they referenced or whether they were warranted in the first place."

How could you have started a discussion asking if the collapses could be reduced to mathematical equations if this sentence is the case? How would you ever know if the conditions asked for by you in the OP ever were fulfilled?

We will discuss Bazant Zhou. I'm not going to get into a discussion of what Greening and Chandler say about BZ, or what CSI911 says or the Scholars for 9/11 Justice or whatever say. That's your choice with me at this point.

Bazant doesn't hypothesize an indestructible block. Is that the clearly and visibily wrong premise you're talking about?

[OnTheOtherHand]

29. well, isn't that a pretty good reason to raise the question?

It isn't unreasonable for someone who isn't very mathematical to wonder how far mathematics can take us in understanding an issue. But of course you're right that it will be hard for such a person to evaluate divergent perspectives.

[Bonobo]

34. It is hard to follow the math, but the reason for choosing one mathematical approach over another is

not as hard (as of yet).

The math itself can be performed on a cheap calculator. The logic behind doing this calculation over that calculation need not be couched in mystery. This is not magic.

[tenseconds]

38. pulverization

It is my understanding that Bazant does not take in consideration the vast amount of energy needed to pulverize the building(except the steel beams and office paper(?).Some contend that that energy requirement alone would stop the collapse progress in but a few floors. Or does he?

Why would the "pile driver" display such comparable strength of explosive power at the initiation of collapse to that further down? The top section only fell what 12-13 feet...then kaboom...we see an explosive row of pulverized building materials even though the top section according to gravitation rates of speed would just be getting up a speed of 20-30 mph at that time.

[Bonobo]

39. That is a great question.

I think it precisely here that the falsely created SYMMETRY comes to help save Bazant. It was my impression after I read his paper that he conjectured that all of the load bearing supports on the lower floors lost their integrity when the initial "shock pulse" came downwards and reached the bottom floors BEFORE the collapse began. It was this, he claims, that allowed for a near free-fall speed with almost no resistance. Presumable because all load bearing had been so uniformly compromised.

Another question I have is, Bazant hypothesized that the fire insulation surrounding the beams was blown off during the initial blast, but wouldn't this too be asymmetrical, leading to further asymmetry in the way the steel behaved?

[tenseconds]

40. but..

Yes...but does Bazant calculate the amount of energy diverted from his "gravitational" collapse" to pulverize the building into microscopic dust particles?

[Bonobo]

41. I don't know whether he does or not. Let's wait and see what answer we get here. nt

[OnTheOtherHand]

47. I can start

I'm hardly the best informed on these issues, but I don't mind making mistakes, so that's OK.

The way I read B & Z, there are a series of buckles and collapses, each involving one or more floors -- not all the lower floors giving way* at once. I don't see where you're getting that interpretation from. Maybe if you quote something?

I think it's true that B & Z don't consider the energy dissipated in crushing materials. Bazant discusses that elsewhere (along with lots of other people).

* ETA -- Arrgh, I'm worn out on flipping back and forth between messages, but your language was something like "lose load-bearing strength." Apparently you don't mean that they immediately begin to fall, just that they lose their capacity to resist a falling object? I'm not sure.

[tenseconds]

49. is this true?

B&Z don't discuss and calculate the energy to pulverize and yet conclude that the buildings fell at virtual free fall in respect to their "theory"?

[OnTheOtherHand]

54. ?

"conclude that the buildings fell at virtual free fall in respect to their 'theory'?"

This just seems muddled. They conclude that the buildings fell at virtual free fall by comparing the reported collapse times to a free-fall time.

As for the debate whether pulverization would significantly delay the collapse, I don't see that they explicitly address it one way or the other in this paper. I think it's worth bearing in mind that they originally submit the paper on 9/13/01 to discuss why the towers collapse. If you think that energy dissipated pulverizing materials would actually arrest the collapse, well, go ahead and make your case, but I don't think they were somehow obligated to rebut that here.

[tenseconds]

59. all this?

They ignored all this?

[Bonobo]

60. That is a helluva a lot of dust to ignore.

And the thing of it is that it wasn;t created when a bunch of pancaked floors hit the ground.

You are looking at pulverised dust being expelled IMO. But what is crushing it and what is expelling it at those angles. Why the Y axis at all? Let alone a 55 mph ejection of tons of materials including huge girders?

If the energy was going in the X axis, where is the additional force that propelled it in those vectors and can it be explained through equations that work out the energy balance?

[OnTheOtherHand]

67. I'm sort of mystified by the mystery

If you dropped a marble onto a pane of glass, would you be startled if the marble cracked the entire pane instead of drilling a hole in it? If you've ever broken a glass on the kitchen floor, were you surprised by how the shards scattered across the room instead of lying neatly in the 'footprint' of the impact? Have you ever clapped two chalkboard erasers together? It's common for forces to be translated in all directions.

Note that as the towers collapse, collisions are happening in mid-air, so there's no reason for the dust to 'wait' until the building hits the ground. A huge material mass is being gravitationally accelerated through a building that was designed to withstand static loads, and the building comprises and contains all sorts of materials and objects. Why would one not expect a huge mess?

That entire mess is going to be very hard to describe mathematically, much as Earth's climate is hard to describe (giving rise to the common gibe, "They say they can predict how CO2 will affect climate, but they can't even tell me the weather day after next!"). What B & Z had done very early on was to reckon that the energy required to destroy the supports was a tiny fraction of the kinetic energy generated in the collapse. That leaves vast quantities of energy to hurl girders and such. Nevertheless, it isn't obvious how much energy is dissipated in crushing materials; later pieces do address that issue.

[Bonobo]

50. I'm worn out for the night, OntheOtherHand.

I'll try again tomorrow. It is tough stuff and I am busy and late to the party.

But I am starting from a place of honesty and open-mindedness and I don't mind making mistakes either. I make no claim to be an expert -still a beginner in this.

[OnTheOtherHand]

57. I'm extra crispy myself

Catch ya tomorrow.

[Bonobo]

32. I think that is part of it and I see no contradiction in my statement.

He posits a sledgehammer of the top floors coming down and bearing upon the structures below symmetrically.

As for the unwillingness to discuss Greening and Chandler, are there any other resources you would like me to not discuss? That hardly seems fair.

As for the issue of the equations, as I said, there must be reason behind choosing certain formulas to use. Not all formulas or approaches, mathematically complex or not, are appropriate to the issue.

[Bonobo]

3. Here is a link to a "proof" that should provide us a common reference.

http://www.journalof911studies.com/volume/200704/ProfMorroneOnMeltingWTCsteel.pdf

I am not offering this as PROOF of anything since at the current time. I am submitting for "peer review" if you will.

[SDuderstadt]

4. Sorry....

I reject it due to the reference to "melted steel".

[Bonobo]

6. Well, please reconsider based on the below.

Evidence That Molten Steel Was Found in the WTC Debris


In James Glanz's New York Times 11/29/2001 Article “A Nation Challenged:
The Sight; Engineers Have A Culprit in the Strange Collapse of 7 World Trade
Center: Diesel Fuel.” The next to last paragraph reads “A combination of an
uncontrolled fire and the structural damage might have been able to bring the
building down, some engineers said. But that would not explain steel members in the
debris pile that appear to have been partly evaporated in extraordinarily high
temperatures, Dr. Barnett said.”

In the website
http://911research.wtc7.net/wtc/evidence/moltensteel.html
several references to reports of molten steel are cited. Here are a few examples:
A report by Waste Age describes New York Sanitation Department workers moving
“everything from molten steel beams to human remains.”
A report on the Government Computer News website quotes Greg Fuchek, vice
president of sales for LinksPoint Inc. stating: In the first weeks, sometimes when a
worker would pull a steel beam from the wreckage, the end of the beam would be
dripping molten steel.

A Messenger-Inquirer report recounts the experiences of Bronx firefighter “Toolie”
O'Tolle, who stated that “some of the beams lifted from deep within the catacombs
of Ground Zero by cranes were dripping from molten steel.” See also:
http://www.pnacitizen.org/john_gross_nist_pnac.php

[Bolo Boffin]

10. Here is an example of one problem I have with 9/11 Truth advocates

You said, let's talk numbers. I presented one of the very first scientifically accepted papers on the collapse of the towers, written by one of the very top people in the relevant field.

And you have now posted four times with several different links, presented here and other places many times before, all before any discussion can begin. This is what I regard as Google-bombing, someone who posts links to help direct traffic to sites. Google-bombing is, of course, not conducive to a honest conversation.

Let's start with Bazant Zhou. Let's work our way through that. Or you could ask some questions about the rest of my first post. Otherwise, I will just interpret this as one more 9/11 Truth advocate posting a bunch of links to surround a topic, keep it on their own terms, and boost the search engine rankings of the links in the process.

[Bonobo]

13. I don't think that was entirely fair.

I do take your point though.

This is a message board. I will try to digest material before presentation.

[SidDithers]

14. But math is HARD....nt

Sid

[Bonobo]

15. Sid...

Did you know I love SCTV too? Sid Dithers was one of my favorites. I am sure we would enjoy it together, but...

I will ask you to please raise the level of your discourse here. Yes, math is hard. So is Japanese. I am a Japanese translator and I started at 19. So please do not patronize me.

I have little background in math, but it should not preclude my trying to discuss the issue.

However I find that juvenile assholes sometimes are an impediment.


So please back off with that, ok? I am NOT in the mood and I am NOT here for that.

You may be able to drive me away if that is your intention. If it is, it says a lot more about you then about me. OK?

Do we understand each other better? I will put you on ignore if I must, but I prefer to engage anyone that is serious (but not a serious asshole).

[SidDithers]

19. Ignore me if you wish. It's no skin off my nose, either way...

however, math, like Japanese, is a language of it's own. Without that background, your efforts at understanding the complicated and complex engineering issues involved with the collapses of the WTC buildings will be in vain.

Your intentions of discussing a mathematical model for the collapses may be noble, but you may not be equipped to engage the issues.

Sid

[Bonobo]

20. Incorrect.

"Math" is a system for modelling reality, like language.

First one must proceed with a correct understanding in order to model these things. The calculation is blue collar work. Complex, but the math doesn't represent the reality if it proceeds from wrong assumptions.

Garbage in garbage out, correct? First the principles must be agreed on. Isn;t that correct? Even someone like myself should be able to handle that, Sid. So

In either case, I hope my message about your tone was at least clear. Your condescension is misplaced. Mama didn't raise no dummy, so if you continue to make snarky comments like "But Math is hard!", I will be forced to conclude that you have little of value to say.

[SidDithers]

22. Alright, then....

Bazant & Zhou have published subsequently more detailed collapse models since their first paper. The most recent, published in the Journal of Engineering Mechanics in October 2008, is:

http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/476%20WTC%20collapse.pdf

I look forward to your critique.

Sid

[Bonobo]

25. Thanks. I will be very happy to look at that and get back to you. nt

[Bonobo]

18. Your "objection" is noted, but I think you still need to address it.

Or at least link me to where you address it elsewhere.

Basically there are witness and material evidence of steel that melted. A big ass boulder of steel, melted girders, witnesses who saw flowing metal both from the building and in the wreckage. Also as reported, beams with dripping ends. So, how can you deny that there was molten steel?

Anyway, I only produced that to get SDuderstadt to consider the article I linked to. That is not google-bombing, and it still hasn't been addressed because now you have me defending my defense. So it's getting rather circular from my perspective as well if you can try to appreciate that.

[SDuderstadt]

23. Given the large number of materials present at the Towers....

any of which, to my knowledge, have lower melting points than steel, make it virtually certain that whatever was observed were "pools of molten steel".

[SDuderstadt]

21. I'll reconsider when someone produces metallurgical tests that..

establish precisely what was molten.

[Bonobo]

24. Ok. For now.

Reasonable. I will get back to you.

Pls. respond to my objection about Bazant. I am having trouble accepting the innacurate model. Fair is fair.

[LARED]

42. I will never understand why truthers can never make the distinction

between the fires in the debris pile and the fires in the building on 9/11. They are constantly conflated without any logical reason.

[OnTheOtherHand]

44. "never"? can we try dialing stuff down?

It's not as if I expect civility to break out all over the 9/11 forum, but I think Bonobo's giving this a fair shot, so I'll go with it.

[Bonobo]

46. Hey, much appreciated. I just got enough stress in my life already.

I want to discuss 9/11 but I don't need pissing contests, and a match of wits. You know? I'm old and I got kids and a mortgage.
I'm just too tired to fight and barely got enough energy to hold it together.
So thanks.

[LARED]

48. Ok, hows this

9/11 inside job advocates often conflate the fires in the building the day of the attacks with the subsequent fires that burned for many weeks in the debris pile. Theses are two different, almost, completely unrelated events. Particularly around the issue of melted metal.

In the paper referenced above the fires during 9/11 and melted "steel" is once again used to advocate a controlled demolition theory with no factual basis.

Can anyone on the truther community provide an explanation?

[Bonobo]

51. An explanation of what?

Why people confuse fires in the building with fires on the ground?

Where is your evidence that they do such a thing? It sounds like a "When did you stop beating your wife" question so why would I approach it?

[LARED]

53. The conclusion of your post 3 states

Conclusions

Since there was molten steel in the wreckage of the World Trade Center,
and since the temperatures of the fires were insufficient to melt steel, and since
the gravitational energy was shown to be very much smaller than the energy
needed to melt steel, the Twin Towers and 7 WTC could only have been brought
down by explosives or cutter charges.

Can you explain this?

[Bonobo]

58. It was not my conclusion.

And I don't understand what you are asking for.

To defend another person's thesis in a quick response?

I don't see why I would do that.

Why don't you comment on it since that seems to be what you want to do.

[LARED]

66. I was not clear. The conclusion of the paper you posted

as a common reference stated that conclusion.

The conclusions drawn is based on either outright sophistry or a serious misunderstanding of the events on and subsequent to 9/11.

It is unclear to me how this paper can be used as a common reference for discussion (The purpose of your post) given its misdirected thought process, inaccuracies and silly conclusions. Please enlighten me if you see a possibility.

[OnTheOtherHand]

56. my impression is that this version is spot on n/t

[szatmar666]

61. WTC investigators resist call for collapse visualisation

I am no civil engineer but the ones I know tell me privately that this is a major problem in the official theory:

http://www.nce.co.uk/wtc-investigators-resist-call-for-collapse-visualisation/537313.article

[szatmar666]

62. just in case

the original link stops working:

WORLD TRADE Center disaster investigators are refusing to show computer visualisations of the collapse of the Twin Towers despite calls from leading structural and fire engineers, NCEI has learned.

Visualisations of collapse mechanisms are routinely used to validate the type of finite element analysis model used by the investigators.

he collapse mechanism and the role played by the hat truss at the top of the towers has been the focus of debate since the US National Institute of Standards & Technology (NIST) published its findings (see page 10).

NIST showed detailed computer generated visualisations of both the plane impacts and the development of fires within WTC1 and WTC2 at a recent conference at its Gaithersburg HQ. But the actual collapse mechanisms of the towers were not shown as visualisations.

University of Manchester, UK, professor of structural engineering Colin Bailey said there was a lot to be gained from visualising the structural response.

'NIST should really show the visualisations; otherwise the opportunity to correlate them back to the video evidence and identify any errors in the modelling will be lost, ' he said.

iversity of Sheffi eld professor Roger Plank added that visualisations of the collapses of the towers 'would be a very powerful tool to promote the design code changes recommended by NIST.' NIST told NCEI that it did not believe there is much value in visualising quasi-static processes such as thermal response and load redistribution up to the point of global collapse initiation and has chosen not to develop such visualisations.

But it said it would 'consider' developing visualisations of its global structural collapse model, although its contract with the fi ite element analysis subcontractor was now terminated.

A leading US structural engineer said NIST had obviously devoted enormous resources to the development of the impact and fire models.

'By comparison the global structural model is not as sophisticated, ' he said.

'The software used has been pushed to new limits, and there have been a lot of simplifications, extrapolations and judgement calls.

'This doesn't mean NIST has got it wrong in principle, but it does mean it would be hard to produce a definitive visualisation from the analysis so far.'

[Bolo Boffin]

63. On the "inaccurate model" in Bazant Zhou

As I said in post #1 of this now sprawling thread, Bazant Zhou is "a limiting case set up for optimum survival of the building."

A limiting case is something meant to rule out a whole range of options. It may or may not reflect the reality of the situation. It WILL, however, tell you where the reality of the situation ISN'T.

It is as if you are looking for a dropped watch in a field, and the person tells you that he walked along the path and didn't go out into the grass. Right away you know (assuming his account to be accurate) that you don't have to search the entire field. You just need to search along the path and a few feet to either side of the path. Without this limiting information, the entire field would have to be searched.

This is what limiting cases do. In the case of Bazant Zhou, it's seeking the reality of what happened in a way that helps architects and engineers design better buildings. This paper is the beginning of that process. It's not meant to actually portray what happened. But it does tell us very important information about the nature of that building and the actual circumstances of the collapse, i.e., under the reasonable assumptions made to give the structure the best chance possible to resist the falling mass, the building could never have hoped to have done it.

For example, if you conduct an experiment with a dry paper towel and discover that it cannot support the weight of a bowling ball, there is no need to demonstrate that it cannot support of the weight of an anvil. There is no need to demonstrate that it cannot support the weight of a bowling ball when it is wet. You have already done this with the first limiting case. If someone reads of your experiment and scoffs at your statement that the paper towel couldn't hold up an anvil because, they say, "you never tried to support an anvil with the paper towel," then this person is quite silly, I think we would all agree.

Bazant Zhou demonstrate that the force of the falling upper section could not be stopped by the structure of the lower section under optimum conditions for it doing so. Therefore any other scenario that conforms more to reality including the actual scenario is shown to be doomed as well.

Is that clear?

[Bonobo]

64. Not really.

I understand what you are saying, but I never claimed that they towers shouldn't have fallen.

I am talking about they way they fell as being odd-looking. So I really don't know how that "limiting case" business applies.

[OnTheOtherHand]

68. this "odd-looking" is enigmatic

One can't get very far with quantification that way!

My impression is that you think the towers fell too fast, at least given the amount of energy that went into crushing materials and 'expelling' matter horizontally. Is that fair?

[greyl]

65. Faith is immune to math.

Can you point to the math that convinced you to believe in CD theories? No.
You arrived at this point due to other forces, and math won't cure it.