Has Anyone Seen A Realistice Explanation For Free Fall Of The Towers?

[Belz...]

Is green OK?

You mean you haven't seen how others use the quote function ?

Yes, I do. The earlier reference to a building that just sat there after the ground floor was CD'd was of course irrelevant as the remaining structure was perched on solid ground, not the upper 90 storeys of a skyscraper.

Trolling, got it.

This is what einsteen is trying to establish, and coming in for unwarranted slagging off (as we say in the UK) while he's attempting reasonable debate.

Ignorance is a valid excuse insofar as one is disposed to getting rid of it.

 

[William Rea]

Hello again, GlennB.

In this post, down towards the bottom, I showed einsteen how to do a rough calculation to see what percentage of material would have to be totally ejected to make much difference in (a) collapse time or (b) halting collapse entirely.

It's a very large fraction.

At collapse initiation, there is no debris falling away from the structure, since the blocks haven't begun to fragment yet. After initiation, even if every new floor hit was completely ejected, the collapse would still progress, and only slightly slower, according to conservation of momentum.

Greening does not require the upper block remains "intact" as you claim. All he uses is the block's momentum, which is the same regardless of its condition, be it a monolithic chunk or a big pile of baby powder.

It's up to you guys to show otherwise. I support einsteen if he wants to go ahead with this calculation. And please don't use Excel... get help from an academic if you don't know what you're doing.

-----

I guess I'll join in on the "qualification" party --

B.A. Mathematics / B.A. Physics
M.S. Aeronautics
Eng. Aeronautics
10 years at NASA, currently senior technical staff, task manager, and PI

I am not a structural engineer, though I have studied related fields of solid mechanics, FEA, etc.

I'd also prefer you try to find holes in my arguments than worry about my resume. But I am not completely talking out of my hat.

One parting comment to make is that although a lot of energy is available it has to be in a useful form to do work i.e. break the preceding floors.

 

[Belz...]

TAM, I have voluntarily decided to withdraw from the thread for a while to let the obvious hostility to my opinions recede and let the hot heads cool down a bit.

After only 25 posts ? Then might I doubt the following statement:

I am not new to debating on forums

I have to say that I trawled through several threads before deciding to join this forum and thought it might be a good place for skeptical debate with adults. it's a real shame that it turns out to be as childish and clique ridden as most other forums including the awful religious fundy sites.

Oh, please don't bundle the others with me. I'm just cynical, that's all. Most other people here are far more reasonable and open-minded than I am.

The pack mentality of rapid posting someone who is trying to formulate an idea is reprehensible.

That's actually quite funny. As opposed to what you may think, there is little or no pack mentality, here, as far as I can tell. You can check the politics section if you don't believe me. But, everyone can chime in, and if someone, say, you, makes a debatable or controversial comment, you can bet every single one of those individuals is going to speak up.

I will be back.

I honestly don't know whether to say "hopefully" or "unfortunately". I'm going to go with the former, though.

By the way I am a BSc (Hons) in Mechanical Engineering, and for the US people I guess I ought to add that I majored in structural properties of materials. I am a practical rather than academic Engineer hence I did not continue with any formal post graduate studies or research). I am currently working with high temperature non-ferrous superalloys as I have gained an extensive practical knowledge of metallurgy in my 20 years work experience (which I have become expert in despite my original degree being mechanical).

As long as you don't build bridges or high-rise buildings, we're cool.

Did I or didn't I, even Belz is arguing that I didn't bring up the tree analogy when I already stated I didn't. Like I also said, I had no idea that Judy Wood even existed when I made the intial description.

You guys are funny.

Why ? Because both Gumboot and I said the exact same thing and are in agreement with you ?

 

[William Rea]

That wasn't a strawman. Get your fallacies straight.



Of course my motive is clear. I'm calling your BS.

And I'm still waiting for answer to this question:

Are you a structural engineer, sir ?

Which fallacy is it when you attack an argument that someone has not made?

 

[William Rea]

Actually the top of WTC2 ROTATES as it falls. It isn't tipping. Don't forget the building had to fall through the four or five impact floors before there were any obvious exterior signs of collapse - the impact floors appear to have given way some time before, leaving only the exterior walls which gave way simultaneously.
-Andrew

Thanks to Arkan for directing me there, check out picture 2.32 at

http://www.house.gov/science/hot/wtc/wtc-report/WTC_ch2.pdf

Noting the picture caption which says the WTC 2 tower top falls to the East and then the South.

 

[GlennB]

One parting comment to make is that although a lot of energy is available it has to be in a useful form to do work i.e. break the preceding floors.

Exactly. "A big pile of baby powder" would not do the same job as large chunks of concrete+steel, *except* in calculations that only consider total mass.

 

[Z]

You know, it occurs to me that all this talk of concrete cores, explosives, etc. is a smokescreen to disguise the REAL conspiracy going on: that the towers were impacted by commercial aircraft and fell as the official report says is not nearly as significant as who bin Laden and his terrorists might have really been working for!

IOW, why are all the conspiracies focused on such fantastical, nonsensical concepts such as nonexistent concrete cores and rapid-placed invisible C-4, when very potentially valid concepts like bin Laden being a pawn of the government is simply flatly ignored?

... Just sayin'...

 

[William Rea]

http://www.house.gov/science/hot/wtc/wtc-report/WTC_ch2.pdf section 2.2.1.4, 2.2.1.5, 2.2.2.2, and 2.2.2.6 are all directly relevant.

As I have stated consistently from the first post I have no problem with the tussed floors between the inner and outer walls pancaking. That seems perfectly rational to me. I don't have a problem with the outer walls peeling since they were designed as buttresses and would be unlikely to be self supporting in the absence of the floor trusses.

The problem that everyone is dancing around is that the central core which was designed to withstand considerable compressive stress should pancake.

Note how they carefully talk in the report about the floors pancaking and the core and outer wall being freestanding.

I will read through it more thoroughly now that someone has directed me there.

Later comment - This is a great report, it seems to bear out everything I have predicted!

 

[Infinite]

9/11 and those towers falling seemed all alittle staged but who really knows. It seemed like a demolition job. I would think that an airplane exploding into a building would demo more than they actually did. I thought the tops of the buildings would fall off in one peice like a tree falling when cut. The whole building just came down like a demo job though. I find that strange. I find the whole darn thing strange, even the Pentagon. What the heck happened to the airplane that supposedly went into the side of the building? What about the aftermath? Everything is so strange and everyone was so evasive?

 

[Mr. Skinny]

By the way I am a BSc (Hons) in Mechanical Engineering, and for the US people I guess I ought to add that I majored in structural properties of materials. I am a practical rather than academic Engineer hence I did not continue with any formal post graduate studies or research). I am currently working with high temperature non-ferrous superalloys as I have gained an extensive practical knowledge of metallurgy in my 20 years work experience (which I have become expert in despite my original degree being mechanical).

[slight derail]Mr. Rea, do you mind if I ask you to describe "high temperature non-ferrous superalloys"

Nothing sinister in my question, I assure you. I'm just not used to the term "superalloy" mostly. A couple of examples would probably satisfy my curiousity.[/derail]

 

[Class]

9/11 and those towers falling seemed all alittle staged but who really knows. It seemed like a demolition job. I would think that an airplane exploding into a building would demo more than they actually did. I thought the tops of the buildings would fall off in one peice like a tree falling when cut. The whole building just came down like a demo job though. I find that strange. I find the whole darn thing strange, even the Pentagon. What the heck happened to the airplane that supposedly went into the side of the building? What about the aftermath? Everything is so strange and everyone was so evasive?

Trees are completely solid objects, the World Trade Center towers have mostly air inside. And the tops of the towers weren't completely cut, they had big holes in them. Structural engineers all agree that the towers fell like they expected them to. The "looked like a controlled demolition" argument is nonsense because the only similarity between a controlled demolition and the WTC collapses was that the towers fell down.

 

[GlennB]

[slight derail]Mr. Rea, do you mind if I ask you to describe "high temperature non-ferrous superalloys"

Nothing sinister in my question, I assure you. I'm just not used to the term "superalloy" mostly. A couple of examples would probably satisfy my curiousity.[/derail]

About 30 seconds on google should answer your question

 

[Mr. Skinny]

About 30 seconds on google should answer your question

Perhaps, but I was interested in Mr. Rea's answer, Glenn.

Thanks for trying to help though.

 

[T.A.M.]

William:
It is too bad it wasn't the experience you were hoping for. I have been talking to a few people about setting up special threads specifically for a single one on one debate. It would have a moderator who would ajudicate any issues, and would make sure only the two who entered the debate were posting, all others could observe only...It is an idea I would like to see occur. I agree, just like when I go into th CT lions den I feel a little overwhelmed, I can see how debating here with so many rapidly posting, can leave one feeling a little "under the microscope". I am not saying you cant handle yourself, I am just saying I know where you are coming from.

Cheers...TAM

INFINITE:

9/11 and those towers falling seemed all alittle staged but who really knows.

The purps know, and for most here, the purps were the 19 hijackers. They staged the attacks alright, and were very successful.

It seemed like a demolition job.

Sounds like an opinion. Won't carry much weight in here unless you can back that statement up with SOLID EVIDENCE.

First, go to Youtube and look up "Landmark tower demolition" then watch an actual "Controlled demolition"...when you get back, look at the following points.

1. Notice how the collapse starts off with a long chain of near continuous flashes and LOUD explosions.
2. This is followed, almost immediately by the building coming straight down BOTTOM FIRST.

Now, go back and look at WTC 1 and 2

Notice:
1. No loud explosions or flashes prior to collapse
2. The collapse begins at the impact zone, not the bottom of the building.

I would think that an airplane exploding into a building would demo more than they actually did.

based on what, an educated guess, and uneducated guess, because apart from the small plane that struck the empire state building many years ago, there were not too many examples of this to compare it with, if any.

I thought the tops of the buildings would fall off in one peice like a tree falling when cut. The whole building just came down like a demo job though. I find that strange.

read through this thread or many others here and you will find solid FACTUAL EVIDENCE AND SCIENCE that will show you why that isn't what should have happened.

I find the whole darn thing strange, even the Pentagon. What the heck happened to the airplane that supposedly went into the side of the building? What about the aftermath? Everything is so strange and everyone was so evasive?

WHo was evasive...show me people being interviewed who evaded the topic. Show me people shying away from making statements.
As for the plane, alot of it disintigrated. The harder, steel and titanium parts did not, and they can be found amongst the wreckage (lots of photos around to confirm it). There are also several large pieces of the plane scattered on the lawn and within the crash site.

happy researching

TAM

 

[Stellafane]

The is no raw evidence for the steel core columns, A fact proven dozens of times right here in this very thread. I've not lied, you folks paint me as a liar when in fact you support lies.
The only core that can be evidenced with images of the demo is the concrete core.

And the only explanaton for near free fall and total pulverization that exists on the web is based on the concrete core. Which is why it's so important to you folks that there was no concrete core.

http://algoxy.com/psych/9-11scenario.html

Nope, you can't get off the hook that easily, liar. You said you saw a BBC/PBS documentary that proves there was a concrete core. No such documentary exists. Therefore you are a liar. Never mind what you think we have or haven't proved. The evidence that you are a liar is stark and unambiguous. You lied, therefore you are a liar -- it's as simple as that. And liars have no credibility at all. Thus Chris, nothing that you say has any significance. That's the price you pay for being a liar. You should have thought of that before you decided to lie.

 

[R.Mackey]

Exactly. "A big pile of baby powder" would not do the same job as large chunks of concrete+steel, *except* in calculations that only consider total mass.

For you and William Rea, the "big pile of baby powder" would have continued the collapse just fine.

Greening's equation demonstrating that progressive collapse is not only possible but likely, and even matches the observed collapse time pretty well, considers primarily the momentum of the falling mass. That momentum is completely insensitive to the structural integrity of said mass.

I explained this in my earlier post.

 

[gumboot]

It's fair to analyse your post the way CT'ers posts get analysed.

I completely agree. There is a difference, however. I was asking for clarification about what the discussion is. All I see is an argument from incredulty that an enormous amount of energy is required to produce collapse. I've never actually seen a calculation that determines how much energy is required to collapse a skyscraper. Have you?

Incidentally, I quite frequently make clear that I have only very basic knowledge of structural engineering and what have you. And I mean very basic. You'll notice I do not contribute significantly to such debates, because I do not feel I have the knowledge to do so. I will ask questions of those that know mroe than me, however, because I want to learn.

I will also call foul when people start throwing about photographs as "evidence" (because that's something I DO know about).

Except for the components that are forced outwards and don't make contact with the standing components that remain. This is what einsteen is trying to discuss.

Certainly. I was speaking in generalisations. Would it be true then that the key questions is "What percentage of the debris was forced outwards and did not contribute to subsequent collapse?"?

If a CT'er expressed such an opinion here they would be quietly put in their place. "I really don't see..." is just waffle. Have you done the calculations? Please present them.

As I've said many times, I lack the expertise for such a calculation. Have you done them? How much energy is required to collapse the WTC?

I certainly don't expect my ignorant musings to be held up as any sort of credible argument. Quite the contrary, if I am incorrect, and large amounts of energy ARE required, I would dearly hope my fellow JREFers will put me to rights about that fact.

You are right though, perhaps I should have asked a question, to make it more clear I wasn't trying to produce a solid argument.

So to everyone here, for the benefit of laymen...

1) Am I correct in asserting that failure of structural integrity will result in a structure collapse?
And if yes to above:
2) What magnitude of energy is required to undermine structural integrity of a building like the WTC towers?

So you're likening a 400m steel-framed building, with considerable cross-bracing, to a horizontal line of dominoes each of which is unconnected to its neighbour? Lines of falling dominoes don't accelerate. The analogy is flawed in so many ways it's nearly pointless discussing it.

I think you're exaggerating the significance of the anology. It was an expression of structural integrity, nothing more.

A CT'er would point out that the Windsor building in Madrid suffered some collapse in the upper levels but maintained its integrity.

True. Structural componants certainly do not interact as equally as a collection of dominoes. Some componants are of more importance than others - I would not, for example, to expect a collapsed drywall to bring down the entire WTC.

I merely wanted to point out that a building is a STRUCTURE - not a single entity. It is comprised of many componants that interact. The force required to disrupt integrity of given componants can be very small, but those disrupted componants then disrupt surrounding componants and so on, like a domino. How significant such a disruption will be depends on a number of things.

One of those things is building structure redundancy.

Anecdote time. I'm not sure if you're familiar with the Burj Dubai? It is slated to become the tallest building in the world.

The unofficials story of its origins is a little interesting. As you may or may not know, Dubai has poured billions into enormous developments and to do this they have assembled an enormous international team of experts.

Two of those experts were my cousin (a computer graphic artist) and his wife (a civil engineer).

While playing around with various ideas, my cousin and his team produced a computer graphic of a helix shaped skyscraper. Various officials (supposedly including Sheik Al Maktoum himself) rather liked the look of it and decided they wanted it built.

An Australian guy who built the physical models of all the buildings made a model by have a central pillar in a particular shape as a "key" and simply slightly rotating the orientation of the keyhole on each floor, thus creating a helix.

Great for a model. Impossible for actual engineering.

With things heating up in Iraq etc. my cousin and his wife decided to leave (she's now designing a new runway for Heathrow Airport or something...). They left the team doing wind tunnel tests on this skyscraper model. why? They were unsure if the building was even capable of standing up.

Now what was the point of this rambling narrative?

Skyscrapers are not as robust as some here seem to think. Sometimes just getting them to stand up takes some incredible skill. Basic language comprehension is all you need to know that the less stable something is, the easier it is to make it lose that stability.

-Andrew

 

[gumboot]

The simplest examples are usually those least understood. His point, if I may, was to illustrate how little energy can be required to initiate a chain reaction.

Precisely.

-Andrew

 

[einsteen]

For you and William Rea, the "big pile of baby powder" would have continued the collapse just fine.

Greening's equation demonstrating that progressive collapse is not only possible but likely, and even matches the observed collapse time pretty well, considers primarily the momentum of the falling mass. That momentum is completely insensitive to the structural integrity of said mass.

I explained this in my earlier post.

Oh yeah, black holes have no hair... and mass is mass of course. Have you read my reply why those collapse times match pretty well ? Because all baby powder is assumed to travel in the same direction, in fact this is a theoretical model where the whole collapse occurs in a space

[0,A] x [0,B] x [0,C]

And the upperblock perfectly fits in it and doesn't allow the baby powder to escape.

Even in this model there wil be scattering (some particles do, some don't), it will bounce back but Greening assumes it just merges and the speed is in the same directory and then we get da funny growin' block again

I would not like it if I get such a block on my head, however if you empty a bucket baby powder on my head, with particles reaching terminal speed quickly I'm fine.

It's a desperate remedy to explain the collapse time.

 

[gumboot]

Isn't that what I said?

No.

You said Belz... brought up the tree analogy. I am Gumboot.

we are different people

-Andrew