To add comments or start new threads please go to the full version of: Physics Of 9/11 Events - Part 3
PhysForum Science, Physics and Technology Discussion Forums > General Sci-Tech Discussions > Other Sci-Tech Topics
Pages: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116

wcelliott
QUOTE
evidence of molten iron and you cant Dennie it, funny. Witch means there was 1538 C. Now go and make out with john mccain, mark roberts and the holy ones NIST.


Where are you from, Malmo?

I still have issues with the NIST fire study. I haven't had a chance to read it all, but what I've read reconfirms my suspicions about their assumptions.

They're modeling fire as if it were a linear system, and that's just not a valid approach. They modeled a 1% scale experiment which they validated experimentally to within 10%, and then extrapolated, applying it to the WTC which they acknowledge is 100x as big as anything they could validate.

The assumption that you can scale-up a model is only valid in a linear system, which fire isn't. The Dresden firestorm wasn't (N-buildings)X(one building fire), it was its own beast. Likewise, I suspect that the WTC fires were firestorms in their own right, and I expect that the temperatures reached in specific hotspots were much higher than any linear model would predict. Linear models, after all, are calculating average/nominal temperatures. The "peak" temperatures calculated by the NIST model were the highest instantaneous-nominal temperatures, the model doesn't show vortex flows, which drive temperatures higher than nominal conditions would indicate.

I would be surprised if the fires *didn't* get hot enough to melt steel in certain places. Even so, there isn't evidence that this happened enough that it'd be *The Cause* of the buildings' collapse. It simply wasn't necessary, the structure itself would fail catastrophically when the steel reached temperatures where it couldn't support its load.

No thermite/thermate needed, and no evidence of any found. Not surprising, as thermite/thermate wouldn't be the right choice for a CD in any case, for various reasons. Grumpy is right, it makes a dense molten liquid that goes straight DOWN, not sideways, so it's the wrong stuff to use on a structure where the steel is either embedded in concrete (with sheer vertical walls) or exposed but at ceiling height holding up the floor above. And you'd need an ignition source hot enough to set it off, and means of deploying it a thousand times without getting caught once, and you'd need tons of it to have any effect at all...

It's just a dumb idea on a practical level, even if Steven Hawking came up with it, it wouldn't work on a practical level. Too hard to accomplish without getting caught.
Grumpy
Malmoesoldier

QUOTE
I know you are stupid dont tell me that in every post. Dont talk *** about someone because they do a simple experiment that shows NIST is lying. You cant Dennie that it WASNT aluminum that came out from the tower, the evidence shows that it wasnt. it CANT glow orange like that, like i explained in my last post.


Like the stupid limited experiments of a failed prof of cold fusion physics exhausted the vast number of possible conditions which CAN make molten aluminum glow red. I have already said that I know enough to know there are things I DO NOT KNOW!!! But, neither do you! So you cannot believably say it was or was not aluminum, nor can Jones. That is the value of organizations like NIST, exhaustive experimentation and investigation, using tools you,I or Jones just don't have access to.

By the way, why do you suppose Jones didn't pour molten aluminum onto rusty steel that was itself red hot??? My guess, self preservation.

QUOTE (->
QUOTE
I know you are stupid dont tell me that in every post. Dont talk *** about someone because they do a simple experiment that shows NIST is lying. You cant Dennie that it WASNT aluminum that came out from the tower, the evidence shows that it wasnt. it CANT glow orange like that, like i explained in my last post.


Like the stupid limited experiments of a failed prof of cold fusion physics exhausted the vast number of possible conditions which CAN make molten aluminum glow red. I have already said that I know enough to know there are things I DO NOT KNOW!!! But, neither do you! So you cannot believably say it was or was not aluminum, nor can Jones. That is the value of organizations like NIST, exhaustive experimentation and investigation, using tools you,I or Jones just don't have access to.

By the way, why do you suppose Jones didn't pour molten aluminum onto rusty steel that was itself red hot??? My guess, self preservation.

No because there couldnt be an thermite reaction. He also debunks a theory in his experiments that said maybe the aluminum and steel could make an thermite reaction, indeed it cant, he dropped molten aluminum onto pre-heated rusted steel. the temperature of the molten aluminum in contact with the rusty iron simply cooled at about 25 C per minute until the aluminum solidified. And there was no reaction when he dropped molten aluminum onto crushed gypsum and concrete (wet or dry) and rusty steel.


The steel was not preheated if the aluminum COOLED and solidified, DA. And aluminum and iron scale(a type of rust) ARE Thermite. THINK!!!

By the way, iron rich spheres do not indicate that steel melted on a macro scale, which is your claim. Sulfide erosion, welding, cutting operations and fly ash etc. are just a few of the alternate explanations.

And Buffy is not a credible source for stupid claims about the time it takes for a fire to reach 1000C. Admit it, you pulled that nugget out of your hind quarters.

Grumpy cool.gif
metamars
QUOTE (NEU-FONZE+May 27 2007, 02:01 PM)
Metamars:

I said "This is what I used in my "Energy Tranfer" paper and has also been used by Bazant."

Then I go on to say this is obviously an approximation! I criticize myself and Bazant on this methodology, so I fail to see your point.

Now as for Gordon Ross, this is a different issue since it is the CRUX of his arguement that the collapse should have been arrested.


Not sure what you mean.

Why do you call it the "CRUX" of his argument?

His conclusion is that collapse has been arrested. How can a concept be both a crux of an argument, as well as a conclusion? This implies circular logic, which is also not the case.

Furthermore, he's clear that his paper is not a definitive analysis. From the summary on page 1:

QUOTE

This paper examines the elastic loading and plastic shortening phases of the columns of WTC 1 after impact of the upper 16 storeys of the building upon the lower storeys and its effect on the momentum transfer after the collision. An energy balance is derived showing that there is an energy deficit before completion of the plastic shortenign phase that would not allow the collapse to continue under the constraints of this paper.


(emphasis mine)

While it's good to see that you also identify assumptions used in your paper, this still doesn't exonerate anybody from criticizing unfairly. If you, personally, have not indulged in this, then good for you. However, I sort of doubt this, and furthermore, it's generally true of the OCT camp, even if it doesn't apply to you.

QUOTE (->
QUOTE

This paper examines the elastic loading and plastic shortening phases of the columns of WTC 1 after impact of the upper 16 storeys of the building upon the lower storeys and its effect on the momentum transfer after the collision. An energy balance is derived showing that there is an energy deficit before completion of the plastic shortenign phase that would not allow the collapse to continue under the constraints of this paper.


(emphasis mine)

While it's good to see that you also identify assumptions used in your paper, this still doesn't exonerate anybody from criticizing unfairly. If you, personally, have not indulged in this, then good for you. However, I sort of doubt this, and furthermore, it's generally true of the OCT camp, even if it doesn't apply to you.


Only GR thinks the impact forces during the collapse of WTC 1 & 2 acted precisely in a vertical manner, i.e. the columns were centrally loaded.


See above. Also, see Gordon's theorized CD methodology on his website.
He writes,
QUOTE

Evidence used
    I will include in this report, representative photographs and screen captures of the various phenomena witnessed and in an appendix [to be added], I will include other examples.  The visual evidence is freely available on the Internet and in some cases I have included a reference to the original source.  There are others where I have not, as yet, given credit to the person responsible, in particular for those photographs with added graphics.  I would like to publicly acknowledge their work now and will give further details if the persons so wish and e-mail some details.

The phenomena which I intend to include in my narrative will include the following;

    +    Survival of the lower core structure until an advanced stage of the collapse.
    +  Survival of the corners of the perimeter structure after the collapse front has passed.
    +  Inward bowing of the perimeter walls.
    +  Sagging of floors
    +  Tilting movement of the upper section.
    ....

(emphasis mine)
Is this truly the writing of somebody who "thinks the impact forces during the collapse of WTC 1 & 2 acted precisely in a vertical manner" ??

Rubbish!


QUOTE (->
QUOTE

Evidence used
    I will include in this report, representative photographs and screen captures of the various phenomena witnessed and in an appendix [to be added], I will include other examples.  The visual evidence is freely available on the Internet and in some cases I have included a reference to the original source.  There are others where I have not, as yet, given credit to the person responsible, in particular for those photographs with added graphics.  I would like to publicly acknowledge their work now and will give further details if the persons so wish and e-mail some details.

The phenomena which I intend to include in my narrative will include the following;

    +    Survival of the lower core structure until an advanced stage of the collapse.
    +  Survival of the corners of the perimeter structure after the collapse front has passed.
    +  Inward bowing of the perimeter walls.
    +  Sagging of floors
    +  Tilting movement of the upper section.
    ....

(emphasis mine)
Is this truly the writing of somebody who "thinks the impact forces during the collapse of WTC 1 & 2 acted precisely in a vertical manner" ??

Rubbish!



As for your old favorite "Calladine and English", I have studied that paper, but there are a lot of better, more up to date papers that show the importance of FLEXURAL WAVES under dynamic loading conditions.

See for example:

J. R. Gladden et al. "Dynamic Buckling and Fragmentation in Brittle Rods" in Physical Review Letters 94, 035503, (2005).

and,

W. Anwen et al. "Twin Characteristic-Parameter Solution for Dynamic Buckling of Columns Under Elastic Compression Wave" Int. J. of Solids and Structures 39, 861 (2002)

and,

D. Karagiozova et al. "Dynamic Elastic-Plastic Buckling Phenomena in a Rod Due to Axial Impact" Int J. Impact Eng. 18, 919, (1996)



It would help if you gave more details (assuming you really believe what you wrote). From the titles, only the last one looks particularly relevant. Since you read this paper (right?), what does it tell us about how to improve/correct the models of BZ, Greening, and Ross?
3bodyproblem
QUOTE (einsteen+Jun 1 2007, 11:20 AM)

An other thing that I was thinking about is that the whole E1 model in fact also supports the demolition hypothesis because if you blow away the core in a sequence it becomes much more weaker than the rest and then energy cannot be transferred to the rest of the building and is very nicely lost in the crush of that demolished story.

I don't believe this is the case as the videos clearly show a substantial portion of the core remains standing after the collapse wave. If the core were subjected to any incendiaries it certainly would not have survived the collapse wave? There is a case to made that the free standing core, after the collapse wave, was taken down with explosives, but you see how unnecessarily complicated this is. The explosives would have to remain intact after the collapse wave, then triggered almost immediately after. And to what end? Certainly the core was not capable of free standing or it would not have been designed with a load bearing exoskeleton. The trauma events to the core are the raining debris, the torsional forces from the trusses after they were ripped from the exterior seats and gravity. I have assumed 4 phases of the collapse. 1)The initiating event 2) The first few seconds of the collapse where a considerable portion of the upper mass was churned up (I believe this has been referred to as the crush up crush down) 3) The self sustained global collapse and 4) The impact with the with the ground.
The truss failure would produce a substantial amount of heat. The gusset plate failure as it bent and as it was sheared from the column, or some combination of both. The angle seat as it was bent or sheared from the column, then the bolts sheared or ripped out of the angle plate. Once the truss was freed from the exterior it became the moment arm to the core. In this phase again, a substantial amount of heat would be produced an absorbed by the core at the point of the weld before it failed. I note that the weld failure and deformation of the core is now DURING and slightly AFTER the collapse wave. Assigning a percentage to this ratio is difficult as it is completely unknown. I would agree with Mr. Benson that some, perhaps 50% of the core was swept away during phase 2) as it was being impacted by the upper sections core/floor etc. After phase 2) i believe much of the core remained intact after the collapse wave passed.
Malmoesoldier
I am from sweden. Sorry if my English is bad

Grumpy

QUOTE
I have already said that I know enough to know there are things I DO NOT KNOW!!!


No but i and the rest of the world that knows something about aluminum knows. You cant accept that the government and NIST is lying thats all. You buy everything the government tells you. Turn of the tv

I have already explained why aluminum cant glow, go back and read it again. like SAPA one of the BIGGEST aluminum companys in the world told me "IT CANT GLOW!!!!".

QUOTE (->
QUOTE
I have already said that I know enough to know there are things I DO NOT KNOW!!!


No but i and the rest of the world that knows something about aluminum knows. You cant accept that the government and NIST is lying thats all. You buy everything the government tells you. Turn of the tv

I have already explained why aluminum cant glow, go back and read it again. like SAPA one of the BIGGEST aluminum companys in the world told me "IT CANT GLOW!!!!".

The steel was not preheated if the aluminum COOLED and solidified


Yes the steel was preheated and the aluminum COOLED and solidified

QUOTE
By the way, iron rich spheres do not indicate that steel melted on a macro scale, which is your claim. Sulfide erosion, welding, cutting operations and fly ash etc. are just a few of the alternate explanations.


No it cant be anything of that. cutting operations LOL. Stop the jokes. They took the samples far from the cleanup. READ steven jones report if you want to know the truth about 9-11. But you was in Vietnam so i guess you know everything and the government never lies right, people like alex jones is lieing all the time they never tells the truth because conspiracy theories witch has to do with the government dont exist.

QUOTE (->
QUOTE
By the way, iron rich spheres do not indicate that steel melted on a macro scale, which is your claim. Sulfide erosion, welding, cutting operations and fly ash etc. are just a few of the alternate explanations.


No it cant be anything of that. cutting operations LOL. Stop the jokes. They took the samples far from the cleanup. READ steven jones report if you want to know the truth about 9-11. But you was in Vietnam so i guess you know everything and the government never lies right, people like alex jones is lieing all the time they never tells the truth because conspiracy theories witch has to do with the government dont exist.

And Buffy is not a credible source for stupid claims about the time it takes for a fire to reach 1000C. Admit it, you pulled that nugget out of your hind quarters.


I gave you a source to a women that works with Structural Fire Engineering!!! at ARUP. And now you are saying that she is not a credible source lol. YOU know nothing about fires.

NIST is a bunch of liers and it was an inside job. Cant believe they said that lie about aluminum laugh.gif
metamars
QUOTE (Capracus+May 27 2007, 02:56 PM)
Metamars, are you aware of any studies that have been done on concrete comminution in actual professional CDs?

No, but if you find any, please post.

I've have complained about the lack of input from physicists with knowledge of demolitions from the beginning. Isn't it odd that none of them are saying anything? There was the one guy from a Mining college, who first said CD, but then changed his mind, but where are the rest of those guys?

QUOTE

Would the energy input from the explosives used be any more significant than the added energy of the plane impacts and fires of the twin towers? The vast majority of the energy used in a CD is the gravitational potential of the building, not the energy from the explosives used to initiate the collapse.


Not sure what you're getting at, or how to answer. I would think the amount, type, and deployment of explosives would make all the difference in answering your question, no?
metamars
QUOTE (NEU-FONZE+May 29 2007, 07:25 PM)
Metamars:

In quantum chemistry there are two types of calculation: ab initio and semi-empirical. Only the simplest of molecules, such as H2, can be properly treated by full ab initio methods. These calculations are truely remarkable since they predict energy levels accurately to about 1 part in 10^7.  Unfortunately, however, most molecular structure calculations have to settle for a semi-empirical methodology, which is crude, but if done properly is nonetheless capable of reliably predicting geometries, ionization energies and bond strengths to within a few percent.

Well, you know, I feel the same way about collapse calculations, where a WTC tower would be like a DNA molecule. We have to use approximate calculations to get anywhere in understanding how large molecules behave, AND how large buildings collapse! The calculation I use has two variable parameters, E1 and M, but we can estimate a realistic value for each by a number of techniques. Certainly M can be determined quite precisely and I would say its value is known well enough to no longer consider it to be an adjustable parameter. I have, in fact varied the mass of a tower between 350,000 and 550,000 tonnes to see what happens and the effects on the collapse time is quite small. (This is to be expected, since true free fall is independent of mass as we all know.)

This leave us with E1......! Well, I have tried to calculate it, as has Bazant.....
To obtain a precise value is no simple task, but I believe a lower and upper limit can be derived. Actually, the lower limit on E1 is not important, so it all comes down to an upper limit. Now, here, no matter how I cut the cake, or should I say the building, I get an E1 value that predicts a self-sustaining collapse. While that may not be good enough for you, Metamars, its good enough for me!

Will it still be good enough for you if an FEA shows arrest of collapse, or a collapse that takes, say, 2 minutes? If a more sophisticated model is developed that shows a collapse of 3 minutes and median concrete size of 15 cubic inches, will your model still suffice you?

Correct me if I'm wrong, but if you were similarly off in quantum chemistry, you would not be employable. Correct?

If calculations that I have asked for show that concrete pulverisation (say via thermo-barics - I have read your post regarding inefficiencies of pulverisation via 'normal' explosives) and "clean" column separation through weldments require an impulse of a certain duration (for concrete)* and an overpressure of a certain amount (column weldments), and yet neither can be achieved from a gravitationally driven collapse, but both can be achieved via a thermo-baric, will you at that point have some doubts about your model?

Since you have read papers on concrete comminution, can you tell us what you expect pulverisation to look like from a thermo-baric?

from wikipedia
QUOTE

There are dramatic differences between explosions involving high explosives and vapor clouds at close distances. For the same amount of energy, the high explosive blast overpressure is much higher and the blast impulse is much lower than that from a vapor cloud explosion. The shock wave from a TNT explosion is of relatively short duration, while the blast wave produced by an explosion of hydrocarbon material displays a relatively long duration. The duration of the positive phase of a shock wave is an important parameter in the response of structures to a blast.



* in case it's not obvious, I am rejecting the notion (absent a quantitative demonstration) that a compaction of 85-90%, consisting in part of structural steel 30 feet in length, is at all similar to a ball mill. With the diffuse pressures available via thermo-barics, accessing concrete surfaces is far less of a problem. Once accessed, though, are the blast characteristics sufficient to achieve pulverisation?
Grumpy
Malmoesoldier

QUOTE
No but i and the rest of the world that knows something about aluminum knows. You cant accept that the government and NIST is lying thats all. You buy everything the government tells you. Turn of the tv

I have already explained why aluminum cant glow, go back and read it again. like SAPA one of the BIGGEST aluminum companys in the world told me "IT CANT GLOW!!!!".


Jones does not constitute "the rest of the world", in fact he is part of the lunatic fringe.

Pure aluminum can't glow, true. But we aren't talking about pure anything, are we. For all you or I know the glow was produced by a film of molten glass floating on a stream of aluminum(as some REAL scientists have postulated). So, no, you have not exhausted all the possible explanations, and, no, you cannot say with any accuracy what that flow was or was not. And your ignorant ranting means you are an authority on NOTHING.

example...


QUOTE (->
QUOTE
No but i and the rest of the world that knows something about aluminum knows. You cant accept that the government and NIST is lying thats all. You buy everything the government tells you. Turn of the tv

I have already explained why aluminum cant glow, go back and read it again. like SAPA one of the BIGGEST aluminum companys in the world told me "IT CANT GLOW!!!!".


Jones does not constitute "the rest of the world", in fact he is part of the lunatic fringe.

Pure aluminum can't glow, true. But we aren't talking about pure anything, are we. For all you or I know the glow was produced by a film of molten glass floating on a stream of aluminum(as some REAL scientists have postulated). So, no, you have not exhausted all the possible explanations, and, no, you cannot say with any accuracy what that flow was or was not. And your ignorant ranting means you are an authority on NOTHING.

example...


Yes the steel was preheated and the aluminum COOLED and solidified


That has got to be one of the STUPIDEST statements ever!!! If iron is red hot the aluminum poured onto it WILL NOT COOL DOWN until the steel does. I have seen the video of Jones pouring aluminum onto steel, the steel IS NOT RED HOT, therefore Jones still has his arm. WILL YOU PLEASE START USING YOUR BRAIN, THINK!!!

QUOTE
I gave you a source to a women that works with Structural Fire Engineering!!! at ARUP. And now you are saying that she is not a credible source lol. YOU know nothing about fires.


You gave me a source for a photo of Sarah Michele Geller, otherwise known as "Buffy the Vampire Slayer" Your cite is even stupider than your posts, if that is possible.

Grumpy mad.gif
NEU-FONZE
Metamars:

I will try to deal with your points ONE AT A TIME...

On Gordon Ross: I think you are confusing his first, quantitative paper, with his later, descriptive, paper on the WTC collapse. Tilting is nowhere to be seen in his quantitative paper; just centrally loaded columns with elastic compression waves transmitted hundreds of meters down continuous, defect-free columns. This is not the only problem though! GR also double counts his energies, as I have discussed previously, which means that his so-called energy balance is calculated incorrectly -it's as simple as that!
metamars
From http://www.newscientist.com/article.ns?id=dn4785

QUOTE

"A thermobaric Hellfire missile can take out the first floor of a building without damaging the floors above," the US Secretary of Defense, Donald Rumsfeld, told a press briefing on 14 May 2003.


Just guessing, here, but if a thermobaric Hellfire can take out the first floor without damaging the floors above, it can also take out the second floor and not damage the floor below.

If you want to conduct a psyop and create the illusion of a floor-by-floor gravitationally driven collapse, such devices could come in handy.

Grumpy
metamars

Hellfires leave an obvious trail of fire and smoke behind them when fired. Thermobaric weapons look a lot like Hollywood explosions, big and fiery. Neither is a covert weapon.

Besides, explosives were unnecessary, gravity sufficed to destroy the towers.

Grumpy cool.gif
newton
QUOTE (Grumpy+May 31 2007, 11:15 PM)
newton



Here is what I ACTUALLY SAID...



So you lied, I did say there were devices to direct the thermite sideways. Everything I said about thermite is absolutely true.

So where are all of these "heavy, bulky refractory trough(s) which is(are) meant to contain the reaction and direct it sideways"??? Not one of them was found!!!

Grumpy mad.gif

ooo. a madman face.

i've seen the ceramic(i'm guessing by the look of them) pots they use for railway track thermite welding. they're not the big, or heavy.

if theses type devices were used to first weaken key beams, and then thermobarics were used to provide the blasts, then of course these things weren't found, just like 'nothing bigger than a telephone keypad' was found. they were presumably turned instantly into dust along with everything else friable in the towers.

i didn't lie. you handwaved it away as impossible. you just used more words when you said it.
and, then, you did it again.

and, once again, the military always has new toys that the public doesn't learn about for decades, so pointing to the public arena and 'prooving' somethingdoesn't exist, is proof of nothing.


:reason:
metamars
QUOTE (Grumpy+Jun 1 2007, 05:18 PM)
metamars

Hellfires leave an obvious trail of fire and smoke behind them when fired. Thermobaric weapons look a lot like Hollywood explosions, big and fiery. Neither is a covert weapon.


Oh, jeez, Louise!

Besides that, it would have been a huge waste of money to special-order the miniature helicopter/drones needed to fire the Hellfires from within the towers (so as to hide the smoke trail, as you astutely note). Even when you figure that they wouldn't really need the rotors (let's not be silly and assume the helicopter/drones had to lift off!), we're still talking lots of dollars.

And let's not even talk about how you hide all those helicopters inside the buildings, or how you sneak them in with nobody noticing.

So no, you're right, it couldn't have been a Hellfire missile equipped with a thermobarics. The debunkers have done it, again! I'm so embarassed.
Malmoesoldier
QUOTE
Pure aluminum can't glow, true. But we aren't talking about pure anything, are we


No, hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions,glass and computers) CANT display an orange glow like NIST says it can. Steven jones proves this in experiments. So it can only be thermite and there are smoke coming from it, a different smoke then the smoke from the towers, that smoke is what a thermite reaction looks like. And the corner where it comes out collapses minutes after it has appeared in the corner. The only way to get it to glow is to have it in a furnace but when it is flowing out from the furnace it has its silvery color!!. And NIST havent done any experiments that shows that their aluminum "fact" is true, guess why.

And Steven jones stove was made of steel, it didnt weaken or melt of 1000C guess why? wink.gif

"The temperature of the fire at the WTC was not unusual, and it was most definitely not capable of melting steel." FEMA

"Your gut reaction would be the jet fuel is what made the fire so very intense, a lot of people figured that's what melted the steel. Indeed it didn't, the steel did not melt." NIST

QUOTE (->
QUOTE
Pure aluminum can't glow, true. But we aren't talking about pure anything, are we


No, hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions,glass and computers) CANT display an orange glow like NIST says it can. Steven jones proves this in experiments. So it can only be thermite and there are smoke coming from it, a different smoke then the smoke from the towers, that smoke is what a thermite reaction looks like. And the corner where it comes out collapses minutes after it has appeared in the corner. The only way to get it to glow is to have it in a furnace but when it is flowing out from the furnace it has its silvery color!!. And NIST havent done any experiments that shows that their aluminum "fact" is true, guess why.

And Steven jones stove was made of steel, it didnt weaken or melt of 1000C guess why? wink.gif

"The temperature of the fire at the WTC was not unusual, and it was most definitely not capable of melting steel." FEMA

"Your gut reaction would be the jet fuel is what made the fire so very intense, a lot of people figured that's what melted the steel. Indeed it didn't, the steel did not melt." NIST

You gave me a source for a photo of Sarah Michele Geller, otherwise known as "Buffy the Vampire Slayer" Your cite is even stupider than your posts, if that is possible.


Ehm did you see a picture of buffy or are you joking?. It was a screen shot from a mail to arup to a fire structural engineer.

And here are a Professor of fire prevention engineering that says the fires wasnt hot enough.


Professor of fire prevention engineering states the jet fuel could not have caused the collapse alone, and asks for a full investigation.

We must try to find out why the twin towers fell.

--------------------------------------------------------------

THE JET fuel fires in the World Trade Center towers did not bring down those two buildings. Indeed, the fuel burned up in minutes. Why, then, did the towers and their 44-story neighbor, WTC-7, which was not struck by a plane, collapse? It's a question that bears generally on fire safety, the safety of building occupants and firefighters and the vulnerability of our buildings to terror by fire.

I expected the National Response Team of the Bureau of Alcohol, Tobacco and Firearms would participate in an investigation that I surely thought would follow the Sept. 11 attacks. The ATF has the authority to investigate arson involving interstate commerce. Certainly, these horrendous attacks should be construed as arson. I later learned that the ATF was told it would not be needed.

I expected the National Transportation Safety Board (NTSB) to head the investigations. It's noted for its thoroughness, objectivity and know-how with respect to large-scale disasters. But it was relegated to flight issues dealing with the two hijacked aircraft and the aircraft debris. The buildings were not to be within the scope of their investigation.

There is an ad hoc investigative group, which is sponsored by the Federal Emergency Management Agency and the American Society of Civil Engineers. But it does not have the full resources that might be made available, nor does it control the site.

I became increasingly concerned the more I learned about the investigative process, or lack of one. The site teams at the towers were focused on rescue, retrieval and cleanup, not investigation. The structural steel pieces, coded with chalk and stamped numbers to indicate their building location, were being sold as scrap metal.

The evidence needed to identify the cause of the collapse and intensity of the fire was being lost. Had the NTSB or ATF been involved, the site would have been secured, evidence documented and protected. Remember how the pieces of TWA Flight 800 were brought up from the ocean bottom off Long Island and restored to preserve structural evidence essential to identifying the cause of the 1996 crash?

WTC family survivors headed by Sally Regenhard last month urged New York City and federal authorities to launch a formal investigation into the collapse of the towers. As Ms. Regenhard said, her son did not die in a fire because of a collapsed building.

High-rise buildings are required to survive the impact of a modern commercial aircraft. Why shouldn't that include survival from the fire that would erupt? Building codes require that the structural elements of high-rise building withstand a three-hour test in a furnace. Why did the buildings collapse in less time? Was this terrorist attack an isolated event that had no bearing on high-rise vulnerability or on the consequences of fire in general?

The scrapping of steel debris should stop immediately, and all of it that has been sold should be impounded. The site should be controlled to conform to standard investigation practices. All records, video recordings and information about those killed and injured should be secured for analysis.

We can learn a great deal from this catastrophe. Many died because they did not expect buildings to collapse. Firefighters should not be the guinea pigs for determining the structural dynamics of buildings caught in flames. The potential for a building's collapse should be known before it happens. Fire safety needs to be incorporated into the normal design process of buildings.

The federal government has a role in developing the needed technology for fire safety. If there ever was a role for government that transcends political ideologies, this is one.

At least let's start with a formal investigation of the WTC collapse.

By James Quintiere
Originally published January 3, 2002

Copyright © 2002, The Baltimore Sun

James Quintiere is the John L. Bryan Professor of Fire Protection Engineering at the University of Maryland, College Park. . E-Mail Address: dgann@jhsph.edu

http**://911research.wtc7.net/cache/wtc/groundzero/baltimoresun_quintiere.html



3bodyproblem
QUOTE (newton+Jun 1 2007, 05:28 PM)

and, once again, the military always has new toys that the public doesn't learn about for decades, so pointing to the public arena and 'proving' something doesn't exist, is proof of nothing.


I think you need to prove that this would exist based on the military's need for it. To presume that the military has branched out into exotic methods of Demolition may be stretching it. You need to show how it would stem directly or even indirectly from some military research. This would go along way to the presumption it exists.
adoucette
QUOTE (Malmoesoldier+Jun 1 2007, 01:12 PM)

Ehm did you see a picture of buffy or are you joking?. It was a screen shot from a mail to arup to a fire structural engineer.


It was a screen shot of Buffy.


QUOTE (moe+)
I gave u that before. Arup.com agrees with me that a fire needs 6-8 hours for it to stay at 1000C. Source: *img169.imagevenue.com/view.php?image=09918_ARUPELD_122_459lo.JPG
adoucette
QUOTE (Malmoesoldier+Jun 1 2007, 01:12 PM)
And here are a Professor of fire prevention engineering that says the fires wasnt hot enough.


--------------------------------------------------------------

THE JET fuel fires in the World Trade Center towers did not bring down those two buildings. Indeed, the fuel burned up in minutes. Why, then, did the towers and their 44-story neighbor, WTC-7, which was not struck by a plane, collapse?

Except he doesn't say the FIRES weren't hot enough.

He says the JET FUEL fires burned up within minutes.

Which NIST agrees with.

SO?

What brought down the towers was the damage from the plane's impact and the fires.

Note that this article was written BEFORE NIST got involved.

NIST did the investigation he was asking for.

Arthur
wcelliott
I still don't think anybody has a clear idea of how hot the fires were.

The NIST model assumes that fire is a linear system, which it clearly isn't. You don't get a Dresden firestorm from adding up each building fire in Dresden, the sum is greater than the component elements.

All this "jet fuel doesn't burn hot enough to melt steel" nonsense only illustrates how little people understand about combustion. The temperature reached is a function of the environment that the fuel burns in. Jet fuel can melt steel, that's why it isn't used in jet engines.

As to the "aluminum doesn't glow" bit, first, where is there an unaltered photograph of molten anything? And if we're talking about the photo that shows something flowing out the side of the WTC, think a second - if that's supposed to be thermite, why is it flowing sideways? Where did it come from? Are you suggesting that that much molten thermite/thermate was concentrated in the building right where it came out, or are you suggesting that molten steel/aluminum flowed across the concrete floor (how many feet?) and never cooled off and froze or melted through the concrete?

Also, this nonsense about thermobaric bombs - The footage of the towers as they collapsed showed no sudden explosion associated with the collapse, the towers' collapse starts out as slow descent accelerating as the remaining structural members gave out. No shock waves are visible in either collapse footage. No shock wave, no thermobaric explosion.

Likewise, no explosives' distinctive odor, no explosives.

No explosives, no CD.

No CD, no conspiracy. (Other than that concocted by Osama bin Laden.)
Grumpy
Malmoesoldier

QUOTE
No, hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions,glass and computers) CANT display an orange glow like NIST says it can.


So now you are the expert on what dirty aluminum can look like AND an expert on what every other material in the building could not look like. All you are exposing is the abysmal ignorance of the under-educated. You cannot POSSIBLY defend this stupid statement with any evidence.

QUOTE (->
QUOTE
No, hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions,glass and computers) CANT display an orange glow like NIST says it can.


So now you are the expert on what dirty aluminum can look like AND an expert on what every other material in the building could not look like. All you are exposing is the abysmal ignorance of the under-educated. You cannot POSSIBLY defend this stupid statement with any evidence.

Steven jones proves this in experiments


No, he doesn't, not even close.

QUOTE
So it can only be thermite and there are smoke coming from it, a different smoke then the smoke from the towers, that smoke is what a thermite reaction looks like


It could be so many other things, you really have no clue, do you???

QUOTE (->
QUOTE
So it can only be thermite and there are smoke coming from it, a different smoke then the smoke from the towers, that smoke is what a thermite reaction looks like


It could be so many other things, you really have no clue, do you???

And Steven jones stove was made of steel, it didnt weaken or melt of 1000C guess why?

"The temperature of the fire at the WTC was not unusual, and it was most definitely not capable of melting steel." FEMA

"Your gut reaction would be the jet fuel is what made the fire so very intense, a lot of people figured that's what melted the steel. Indeed it didn't, the steel did not melt." NIST


I know. Steel did not melt in the towers. That is exactly what I have been saying. But 1000C is hot enough that structural steel loses 85% of it's ability to hold a load and it buckles.

QUOTE
High-rise buildings are required to survive the impact of a modern commercial aircraft


No, they are not. Just another nugget from your backside. CITE A SOURCE. (not Buffy)

"It is better to remain silent and be thought the fool, than to speak and remove all doubt" Ben Franklin "Poor Richard's Almanac.

Grumpy cool.gif
David B. Benson
QUOTE (3bodyproblem+Jun 1 2007, 03:18 PM)
The trauma events to the core are the raining debris, the torsional forces from the trusses after they were ripped from the exterior seats and gravity.

I have assumed 4 phases of the collapse. 1)The initiating event 2) The first few seconds of the collapse where a considerable portion of the upper mass was churned up (I believe this has been referred to as the crush up crush down) 3) The self sustained global collapse and 4) The impact with the with the ground.

The truss failure would produce a substantial amount of heat.

Once the truss was freed from the exterior it became the moment arm to the core. In this phase again, a substantial amount of heat would be produced an absorbed by the core at the point of the weld before it failed.

I would agree with Mr. Benson that some, perhaps 50% of the core was swept away during phase 2) as it was being impacted by the upper sections core/floor etc.

(1) Essentially no torsional forces from the trusses. See NCSTAR1-6, Table 4--1 and following. Also see NCSTAR1-3C, subsection 3.5.6 and Figure 3-51a.

(2) The correct division is between the top block ( zone A ), the crushed materials ( zone B ), and the intact lower block ( zone C ). During crush-down zones A and B move down, crushing into zone C, diminishing it and increasing the mass of zone B. Zone A simply rides down on top of zone B until zone B meets the bottom of the lowest sub-basement. Now zone A undergoes crush-up. These are the two phases of global collapse.

(3) The truss failure would produce only a little heat, if by failure you mean the disconnection from the seats. Use the above NCSTAR1-6 reference and calculate it yourself. Less than 20 MJ.

(4) The trusses had no time to act as much of a moment arm. For the very first floor impacted at 0.8 seconds (WTC 1), half the floor was disconnected, internally and externally, in just 0.2 seconds. Of course, everything occurs faster later.

(5) Almost all of the core of WTC 1 was destroyed during the progressive collapse crush-down and crush-up. The temporary spire is clearly only part of one or at most two (lower down) column lines.
David B. Benson
QUOTE (forthetrees+Jun 1 2007, 03:38 AM)
Calling Dr. Freud on this one. Typo, or something deeper?

Actually, just some thin skinned chain yanking on my part. Wish I was a better person and didn't feel the need to attempt cheap payback shots like this, but what the heck. rolleyes.gif

Typo. r is just to the left of t on the keyboard.

But all mistakes need to be corrected... wink.gif
David B. Benson
QUOTE (3bodyproblem+Jun 1 2007, 03:20 AM)
A large amount of energy would be dissipated into the dust cloud, plenty of energy for pulverization, and according to reports there was a surplus of energy in the pile weeks later in the form of heat. It would be very hard to disprove any of these claims and relatively simple to prove. Relatively.

I agree that the energy consumed was large. But in comparison to the total consumption, only a tiny fraction would go into the dust cloud during the first few seconds of the collapse.

The energy in the Ground Zero debris pile was chemical energy being released in fires. NEU-FONZE went through some smoldering fire calculations a while back. But this has nothing to do with the value of E1 for the first few seconds.

E1 is the energy consumed during the crushing of one story. Strictly, one ought to write E1(s) to indicate the dependence on story s, but as long as we only consider the first few stories impacted, this will be about the same for each story.

This energy is consumed right then and there, not stored someplace. Some part is due to crushing and breaking of columns, call this E1i for inelastic energy. Some part is due to concrete comminution, call this E1c. Some part is due to blowing the dirty air out of the building, call this E1a.

Now for the first few stories both E1c and E1a are small. So E1i is about 500 MJ. Any account of the progressive collapses needs to explain this 500 or so MJ. All I can think of is
-- breaking bolts in exterior columns,
-- collapsing trusses,
-- breaking connections in the core.

However, I am not in a position to assign numbers to any of the above.
3bodyproblem
QUOTE (David B. Benson+Jun 1 2007, 09:01 PM)
(1) Essentially no torsional forces from the trusses. See NCSTAR1-6, Table 4--1 and following. Also see NCSTAR1-3C, subsection 3.5.6 and Figure 3-51a.

(2) The correct division is between the top block ( zone A ), the crushed materials ( zone B ), and the intact lower block ( zone C ). During crush-down zones A and B move down, crushing into zone C, diminishing it and increasing the mass of zone B. Zone A simply rides down on top of zone B until zone B meets the bottom of the lowest sub-basement. Now zone A undergoes crush-up. These are the two phases of global collapse.

(3) The truss failure would produce only a little heat, if by failure you mean the disconnection from the seats. Use the above NCSTAR1-6 reference and calculate it yourself. Less than 20 MJ.

(4) The trusses had no time to act as much of a moment arm. For the very first floor impacted at 0.8 seconds (WTC 1), half the floor was disconnected, internally and externally, in just 0.2 seconds. Of course, everything occurs faster later.

(5) Almost all of the core of WTC 1 was destroyed during the progressive collapse crush-down and crush-up. The temporary spire is clearly only part of one or at most two (lower down) column lines.

1),3) Yes, I see. The progression of the collapse was to quick for the truss to pivot about the fillet weld. Very little heat would be produced. Likewise with the exterior truss connections.
This would also suggest that the floors provided very little resistance to the collapse wave.

2) I am not entirely convinced of "crush up crush down". I maintain that Zone A was converted almost entirely to Zone B within 3-4 seconds. I say almost entirely because the truss hat remained relatively intact until "crush up". I believe this is supported by the video evidence.

5) WTC 1, from the video evidence it appears that a +40 story section (clearly visible over the top of WTC7 in several videos) of it remained freestanding after the collapse wave. Likewise WTC 2 clearly shows a +70 story section. Clearly not contributing to the KE of the collapse wave. I think it is fair to say that this represents 1/2 of the core steel from ground level to the 40th floor and ground level to the 70th floor in WTC1 and 2 respectively.

Has anyone calculated the amount of energy dissipated in the seismic wave?
David B. Benson
QUOTE (3bodyproblem+Jun 1 2007, 10:21 PM)
2) I am not entirely convinced of "crush up crush down". I maintain that Zone A was converted almost entirely to Zone B within 3-4 seconds. I say almost entirely because the truss hat remained relatively intact until "crush up". I believe this is supported by the video evidence.

5) WTC 1, from the video evidence it appears that a +40 story section (clearly visible over the top of WTC7 in several videos) of it remained freestanding after the collapse wave. Likewise WTC 2 clearly shows a +70 story section. Clearly not contributing to the KE of the collapse wave. I think it is fair to say that this represents 1/2 of the core steel from ground level to the 40th floor and ground level to the 70th floor in WTC1 and 2 respectively.

Has anyone calculated the amount of energy dissipated in the seismic wave?

(2) Bazant & Verdure prove it. NCSTAR1 as cited above provides evidence. Also see NCSTAR1-3B for further evidence. The main thing to note this that once about four floors are crushed into the beginnings of zone B, this material, then about 2 meters thick, protects zone A until it hits the bottom at about 50 m/s.

Edited to add: Zone A for WTC 2 certainly took quite a hit, since it fell about 2--3 stories right at the beginning. When it encountered resistance the whole top shook, exterior wall creased, etc. It did, however, stay together after that until (at least) it disappeared into the dust. Zone A for WTC 1 shows but little sign of this initial crush-up, which B & V do consider as well.
There is reason to believe that zone A for WTC 2 actualy fell apart, with only part of it taking the free ride to the bottom. This idea is consistent with some of the video evidence, but the matter is not yet settled.

(5) The video of the temporary spire of WTC 1 I have seen clips from was taken from a park. The top appears to be about 55 +/- 5 stories high to me and others. The very top part is but a single column. Further down it appears to be parts of a single column line. Right at the roof line of intervening structures it might have some of two column lines. The two photos I have seen of the remains of WTC 2 are both obscured by dust.

(6) I haven't seen the actual energy expenditure for the seismic events. The magnitude is known, so the calculation ought to be routine. Why is this of interest?
3bodyproblem
QUOTE (David B. Benson+Jun 1 2007, 10:40 PM)
(2) Bazant & Verdure prove it. NCSTAR1 as cited above provides evidence. Also see NCSTAR1-3B for further evidence. The main thing to note this that once about four floors are crushed into the beginnings of zone B, this material, then about 2 meters thick, protects zone A until it hits the bottom at about 50 m/s.

Edited to add: Zone A for WTC 2 certainly took quite a hit, since it fell about 2--3 stories right at the beginning. When it encountered resistance the whole top shook, exterior wall creased, etc. It did, however, stay together after that until (at least) it disappeared into the dust. Zone A for WTC 1 shows but little sign of this initial crush-up, which B & V do consider as well.
There is reason to believe that zone A for WTC 2 actualy fell apart, with only part of it taking the free ride to the bottom. This idea is consistent with some of the video evidence, but the matter is not yet settled.

(5) The video of the temporary spire of WTC 1 I have seen clips from was taken from a park. The top appears to be about 55 +/- 5 stories high to me and others. The very top part is but a single column. Further down it appears to be parts of a single column line. Right at the roof line of intervening structures it might have some of two column lines. The two photos I have seen of the remains of WTC 2 are both obscured by dust.

(6) I haven't seen the actual energy expenditure for the seismic events. The magnitude is known, so the calculation ought to be routine. Why is this of interest?

2) I had no idea of this, it is very interesting. I do agree the crushed debris would effectively cushion the upper portion, a 60 micron cushion. This begs the question how did the core pass through the upper section? I guess I'll wait until it is settled.


6) I haven't either. And as you have pointed out this should be a fairly routine calculation. It should be a sizable number and give a good estimate of the mass that hit the ground. There is some debate as to the mass of the WTC.
shagster
QUOTE (3bodyproblem+Jun 1 2007, 10:21 PM)


5) WTC 1, from the video evidence it appears that a +40 story section (clearly visible over the top of WTC7 in several videos) of it remained freestanding after the collapse wave. Likewise WTC 2 clearly shows a +70 story section. Clearly not contributing to the KE of the collapse wave. I think it is fair to say that this represents 1/2 of the core steel from ground level to the 40th floor and ground level to the 70th floor in WTC1 and 2 respectively.

The portion of the core that remained didn't contribute to the KE of the collapse front later, but then again energy wasn't dissipated by the front to destroy it. I refer to it as stagnant mass. It's similar to shed mass, but it is mass that is not ejected laterally or downward.

The effect of stagnant mass can be looked at by using a discrete collapse model like Greening's where the lingering core is treated as shed mass but where no momentum is imparted to it by the collapse front. I would expect that the remains of the core wouldn't have much effect on the collapse rate. I've looked at shedding of mass that is ejected laterally and its effect on the slowing of the collapse front. I haven't looked at the effect of stagnant mass such as a lingering core. A mass shedding of 30% of the total above-ground tower mass with momentum imparted to the shed mass by the front throughout stage 1 increases the collapse duration by only about one second.

The lingering cores weren't close to 30% of the entire tower mass, especially for the north tower. The lingering core of WTC1 looked like only a single row of core columns. The lingering core of WTC2 looked like it might have a width of two or three columns in the east-west direction and a length of perhaps two-thirds the original length of the core in the north-south direction. Even so, that probably wouldn't have much effect on the collapse duration.

A lingering core means that the upper block couldn't have remained totally intact before reaching the ground level if any part of the upper block remained over the footprint of the lingering core on the way down. The lingering core would have poked through part of the upper block.

What's important about the lingering cores is that they indicate what type of collapse mechanism was occurring. For portions of the cores to remain, the floor connections failed before the core columns buckled or their splices failed, and most of the mass, which was in the long-span floors and their contents, pancaked past the core columns. There is also some relevance with respect to the effect of the arrangement of the columns on the ability of a structure to resist collapse. The cores had a tight lattice of columns with short-span floors compared with the long-span floors between the core and perimeter which had no intermediate columns. If any part of the tower could be expected to survive, at least temporarily, it would be the core with its tight lattice of columns.

David B. Benson
QUOTE (3bodyproblem+Jun 1 2007, 11:25 PM)
2) ... a 60 micron cushion. This begs the question how did the core pass through the upper section?

6)There is some debate as to the mass of the WTC.

2) I should have stated that Bazant & Verdure prove it for a strictly one dimensional collapse. This is a quite good assumption for the entire collapse of WTC 1. Not good, it appears for WTC 2 after the first 4--5 seconds.
The crushed materials were the steel trusses, still recognizable as such, steel members and connectors from the core, still recognizable as such, and comminuted concrete. However, the particle size of the concrete would still be rather sizable during crush-down. But when zone B hits bottom at 50 m/s, now there is enough energy to make fines (fine powders). Indeed, this is was the videos show.
Somehow zone B moved away from portions of the core so those portions, being heavier than the descending zone A, punched through. I.e., not a one-dimensional collapse anymore. This effect is small for WTC 1 and, it seems, large for WTC 2.

6) The estimates I have seen range from 380,000 tons to 510,000 tonnes. I'll opine that obtaining the seismic energy isn't going to significantly narrow this range... sad.gif
shagster
QUOTE (3bodyproblem+Jun 1 2007, 10:21 PM)
Has anyone calculated the amount of energy dissipated in the seismic wave?

I haven't looked at that area in detail. I suggested a while back that data from field seismic sensors in the area of the WTC could be used as another avenue for studying the collapse. The data could be used to determine when the front hit the ground. There would have been a smaller seismic signal as the front was traveling downward followed by a larger event when the front hit the ground and possibly another event if there was crush-up after the front hit the ground.
David B. Benson
QUOTE (shagster+Jun 1 2007, 11:45 PM)
I refer to it as stagnant mass.

And just how tall is the stagnant mass for WTC 2? If less than 64 stories, I don't need to redo my calculations. But if, say 75 stories, then I should rerun my calculations (using less data sad.gif ) to avoid any effects on estimating E1 that this stagnant mass would create.
adoucette
QUOTE (wcelliott+Jun 1 2007, 02:59 PM)
I still don't think anybody has a clear idea of how hot the fires were.

The NIST model assumes that fire is a linear system, which it clearly isn't.  You don't get a Dresden firestorm from adding up each building fire in Dresden, the sum is greater than the component elements.

All this "jet fuel doesn't burn hot enough to melt steel" nonsense only illustrates how little people understand about combustion.  The temperature reached is a function of the environment that the fuel burns in.  Jet fuel can melt steel, that's why it isn't used in jet engines.


The NIST FDS was tuned for building fires. The heat release rates were confirmed via experimentation. The total fuel was estimated at between 4 & 5 lbs per square ft, it was the LIMITING FACTOR. I see no indication that the model or the programming was "linear" as you claim.

Further, your multi-building Dresden analogy doesn't work with the multi-story fire in the WTC towers.

Dresden was a fire bombing induced multi-building fire burning 1940s era buildings in the open which means it was fuel rich and was not ventilation limited, indeed, that many burning wooden buildings create a 'fire storm'.

But that was clearly NOT the case in the predominately steel & concrete WTC towers and what is clear is that the fires in the towers in fact did vary based on fuel availability (limited) and ventilation.

Finally, considering the models collapsed a little bit quicker than the actual towers, its not that likely that NIST significantly underestimated the heat release rates of the fires.

Which is also somewhat the issue of jet fuel.

Jet fuel burned in OPEN AIR in the towers, not in a COMPRESSED AIR environment of a jet engine.

Arthur
shagster
The sway frequency of the towers is one avenue for estimating the tower mass. There were measurements of the sway period of the towers done on the 90s with accelerometers. The measured period matches closely with that predicted by the NIST global model. The NIST global model accounted for the mass in part by the software adding up the mass of all the structural components that were put into the model. There would need to be some extra mass added for live loads. The tower mass couldn't be too far off from what the NIST model used, otherwise the model would have predicted a different sway period compared with what was measured.

The NIST global model has surfaced on the web after someone requested it from NIST. I ran it briefly on my computer. We should be able to extract the total mass that the model is using. The NIST report only gave figures of mass above certain floors, such as the region where the aircraft impacted.

shagster
QUOTE (David B. Benson+Jun 1 2007, 11:57 PM)
And just how tall is the stagnant mass for WTC 2? If less than 64 stories, I don't need to redo my calculations. But if, say 75 stories, then I should rerun my calculations (using less data  sad.gif ) to avoid any effects on estimating E1 that this stagnant mass would create.

It's also a matter of what fraction of the footprint of the core was remaining. It may have been only 12 columns out of 47. It's difficult to say without photos taken from other perspectives.
shagster
DB, it took a shedding of 30% of the tower mass to increase the collapse duration by about one second for WTC2, and that considered the front moving from the start to the ground level and imparting the same momentum to the shed mass as was imparted to the impacted story being pushed downward. I don't expect much of an effect on collapse rate for a partial lingering core where no energy is expended on destroying it and where no momentum is imparted to it.
David B. Benson
QUOTE (shagster+Jun 2 2007, 12:03 AM)
It's also a matter of what fraction of the footprint of the core was remaining.

Yes. That's why I don't care in the case of WTC 1. But as you have otherwhere noted, there are problems using a Greening-style or B & V one dimensional model in the case of WTC 2. So I'd like to check by recalculating if the stagnant mass is estimated to be taller than I had assumed.

Edited to add: As there is little data, I'd like to get the best value I can for E1 in the first few seconds. Right now, I get agreement between the two towers using a stretch of 0.14 and E1 = 510 MJ. But if I have to give up the special effects of impacting the full mechanical floors, then another stretch and value for E1 may give the better agreement between the two towers. It would be wise to check, if necessary.
shagster
If what is seen in the Zafar photos is the core remnant, it's height is less than the mechanical floors at 75/76. What appears to be the core is outlined in orange and superimposed on the intact tower. That height is probably less than the height of the front at the end of your data set.

User posted image

User posted image
David B. Benson
QUOTE (shagster+Jun 2 2007, 12:27 AM)
That height is probably less than the height of the front at the end of your data set.

Which is floor 64.

Thank you very much! smile.gif
3bodyproblem
QUOTE (David B. Benson+Jun 1 2007, 11:45 PM)
2) I should have stated that Bazant & Verdure prove it for a strictly one dimensional collapse. This is a quite good assumption for the entire collapse of WTC 1. Not good, it appears for WTC 2 after the first 4--5 seconds.
The crushed materials were the steel trusses, still recognizable as such, steel members and connectors from the core, still recognizable as such, and comminuted concrete. However, the particle size of the concrete would still be rather sizable during crush-down. But when zone B hits bottom at 50 m/s, now there is enough energy to make fines (fine powders). Indeed, this is was the videos show.
Somehow zone B moved away from portions of the core so those portions, being heavier than the descending zone A, punched through. I.e., not a one-dimensional collapse anymore. This effect is small for WTC 1 and, it seems, large for WTC 2.

6) The estimates I have seen range from 380,000 tons to 510,000 tonnes. I'll opine that obtaining the seismic energy isn't going to significantly narrow this range...  sad.gif

2) smile.gif I was just ribbing the CT's about the 60 micron cloud. I have however maintained that the cloud of debris would serve as a buffer, effectively "lubricating" the collapse. Try explaining that to people that don't really understand physics.


6) Mr. Urichs estimate was as low as 250000 tons I beleive. He is currently re writing his paper and this new number should be closer to your 380000 tons. I'm not sure how accurate the seismic data would be at determining this, but certainly half the mass would be noticeable.
3bodyproblem
QUOTE (shagster+Jun 2 2007, 12:27 AM)
If what is seen in the Zafar photos is the core remnant, it's height is less than the mechanical floors at 75/76. What appears to be the core is outlined in orange and superimposed on the intact tower. That height is probably less than the height of the front at the end of your data set.


The video I was referencing has been removed from YouTube? I will try to find the footage I was talking about, perhaps i was mistaken. The photo you have posted is one I have seen before and it is very clear. Has anyone done a detailed analysis of the standing core sections? It's so frustrating that all the information from 9/11 has not been compiled in its entirety.

Thanks again for all your help.
David B. Benson
QUOTE (3bodyproblem+Jun 2 2007, 01:00 AM)
Has anyone done a detailed analysis of the standing core sections?

AFAIK, no. sad.gif
3bodyproblem
QUOTE (David B. Benson+Jun 2 2007, 01:17 AM)
AFAIK, no. sad.gif

Well it gives me something to do I guess. I have a B.Sc. Physics and have recently applied to a post grad program in Construction Management. I plan to compile the info I gather in this study of the WTC and apply them to my program requirements, mostly any projects that arise in the process. So thank you all for helping me with my "homework". Keep up the good work. smile.gif
wcelliott
QUOTE
Jet fuel burned in OPEN AIR in the towers, not in a COMPRESSED AIR environment of a jet engine.


In Dresden, it was the fire-induced windstorms that increased the ferocity of the fires, driving temperatures far in excess of what you'd expect in an ordinary building fire. That's why I said that you can't model Dresden by modeling one building fire and multiplying by N buildings in Dresden and achieve accurate results.

If the NIST model didn't take into consideration the fire-induced convection, then it underestimated the temperatures at which the fuel (including office furniture, etc.) burned.

What I've read so far (being time-limited, I haven't finished reading) seems to indicate that the model wouldn't take such effects into account. The model appears to calculate N volumes of space within the towers and calculate expected values for temperature based on the conditions within each volume and tabulate results. I don't see evidence that their model resulted in any turbulent airflows, nor do I see how it could.

Real fires create their own airflow patterns, much like Dresden did, and hot-spots within the burning environment result, due to accelerated airflows. Much like jet engines do.

If someone who's finished reading the NIST description of the model can point me to where their model yielded vortices (mini-fire tornadoes), please do so. Those would act as blowtorches, burning fuel (including the combustible out-gases of office furnishings) at above-nominal temperatures.

As I stated before, I'd trust this sort of model to provide nominal/average temperatures, but those parts of the fire that were vortex-driven turbulent combustion would have higher peak temperatures than the nominal values, and since a critical aspect of the structural collapse was the strength of the steel at the peak temperatures, substitution of nominal temperatures for peak temperatures would underestimate the effect of the fire on the structure.

I would fully expect that temperatures in a fire-vortex could melt steel.

Incidentally, the NIST report itself said that the experimental validation for the model was based on actual fire data corresponding to fires 1% the size of the WTC fire. They acknowledged that applying this model to this fire was a 100x extension of their validated data. That model might well be accurate for fires even 10x as big as their validated dataset, but fire isn't a linear phenomenon, so extrapolations of this sort are inherently flawed.
David B. Benson
QUOTE (wcelliott+Jun 2 2007, 01:40 AM)
I would fully expect that temperatures in a fire-vortex could melt steel.

Isn't common in ordinary frame house fires, but has been known to occur.

NIST arbitrarily cut off the upper end of the most intense fires, preferring to keep columns intact for the subsequent FEA to creep buckle. That's discussed in NCSTAR1-5F, I believe.

One of the important things is to know the floor plan. That is, where there are partitions, which limit the fires rather severely. That's another reason NIST went to so much effort in attempting to determine which parts of which floors smoke or flames could be seen.
Pierre-Normand
(David, did you get my reference on the depth of the steel plate corrugations?)

I just realized that the E1 David B. Benson was talking about is the one Bazant and Verdure use and not the E1 Greening mentions in his Energy Transfer paper.

I'm trying to keep up with the level of the discussion going on here. I have to make up somehow for my lack of engineering knowledge.

I'm reading the Bazant and Verdure paper now. Something got me thinking about the ejection of perimeter wall sections far away from the towers.

"For multistory buckling, the load-deflection diagram has a similar
shape but the ordinates can be reduced by an order of magnitude;
in that case, the framed tube wall is likely to buckle as a plate,
which requires four hinges to form on some columns lines and
three on others see Fig. 2c of Bažant and Zhou. Such a buckling
mode is suggested by photographs of flying large fragments of the
framed-tube wall, which show rows of what looks like broken-off
plastic hinges." p. 310 JOURNAL OF ENGINEERING MECHANICS ASCE
/ MARCH 2007.

I first consider three-hinges buckling where the hinges are located at the splices of the three storey high columns trees. Owing to the staggered construction of the column trees, we must assume rupture of the spandrel connection to (or equi-level web buckling of) the adjacent columns trees. In the case of WTC1, I consider the drop of the 14-storey upper block (53m high) for an arbitrarily chosen distance of 53m. I assume the resisted acceleration to be (2/3)g. The speed of the collapse front then reaches 26m/s after 4 seconds.

Consider some segment of the lower perimeter that is buckling out when hit from above. For the duration of the buckling process I'll keep the speed of descent of the upper block constant at 26m/s, to simplify. When two buckled column trees are protruding out and are then slanted 45 degrees from the vertical, the middle "hinge" connecting them is moving out at 13m/s. That's because sin(45) = cos(45) and only half the downward displacement of the upper hinge goes into deflecting each of the two column trees that are buckling out. At that point I suppose the column trees to break loose from the two external hinges. (Had they broken loose sooner, then the speed of the middle hinge would have been higher). The horizontal component of the speed of the center of gravity of these column trees is then 6.5m/s.

The further drop distance is 295m (total height of the towers: 415m). From that height, free fall lasts 7.9s. The columns trees thus travel 51m away from the tower base (7.9*6.5) before they hit the ground. Had the buckling been 4-hinged, then the center column tree would have remained vertical between two hinges moving at 13m/s at the time of the (arbitrarily set at 45 degree) angle of disconnection of the inner hinges. It would have landed 102m away. (WTC7 was 108m away from the North Tower.) Smaller disconnection angles yield higher velocities for the horizontally ejected perimeter wall segments. 30 degrees of arc instead of 45 already yield 73% higher horizontal velocities of the hinge points.

For other angles (measured from the vertical):

dx/dt = h cos(theta) d(theta)/dt;
2dy/dt = h sin(theta) d(theta)/dt;
and thus: dx/dt = 2dy/dt cotan(theta)
Capracus
QUOTE (metamars+Jun 1 2007, 03:21 PM)

QUOTE (Capracus+ May 27 2007, 02:56 PM)
Would the energy input from the explosives used be any more significant than the added energy of the plane impacts and fires of the twin towers? The vast majority of the energy used in a CD is the gravitational potential of the building, not the energy from the explosives used to initiate the collapse.

Not sure what you're getting at, or how to answer. I would think the amount, type, and deployment of explosives would make all the difference in answering your question, no?
I estimate it would only take about 200 lbs of explosives placed in about 60% of the truss connections of a single floor to initiate a progressive collapse. For example, C-4 will produce about 2.5 mj/lb, if you placed and detonated 2 lbs at 100 truss connections, the failure of those connections would create a static overload of the floor and drop it on the floor below. Each succeeding floor would encounter increasing dynamic loads, and the process would continue all the way to the ground.

This collapse initiation above involved one floor and 500 mj of energy. The impacts of 9/11 involved involved 3 gj of impact energy from the planes, and 3000-8000 gj of thermal over many floors. With this massive amount of energy available to damage the buildings, why is it surprising that the resulting damage was able to duplicate a process that required only a fraction of that energy?

This Sunday, June 03, 12:00 pm, ET, on the History Channel; Modern Marvels: Engineering Disasters of the 70's. They show a video of the 1973 Skyline Plaza Apartment collapse.
Pierre-Normand
QUOTE (Capracus+Jun 2 2007, 09:09 AM)
I estimate it would only take about 200 lbs of explosives placed in about 60% of the truss connections of a single floor to initiate a progressive collapse. For example, C-4 will produce about 2.5 mj/lb, if you placed and detonated 2 lbs at 100 truss connections, the failure of those connections would create a static overload of the floor and drop it on the floor below. Each succeeding floor would encounter increasing dynamic loads, and the process would continue all the way to the ground.

I remember reading that the (undamaged!) truss floors were strong enough to sustain the dynamic load on one floor above (maybe two?) falling on them. I would have to do some research to find back that reference.
Pierre-Normand
--- BREAKING NEWS ---


http://www.civil.northwestern.edu/people/b...0-%205-2007.pdf

I have some problem understanding a few things in the Bazant and Verdure paper. I was going to ask some questions here and while I looked up the URL link to the paper on the web page of Dr Bazant I found this!

I'm delighted.

Congratulation to Benson and Greening for the nice work!

I'll ask my trite questions later.
wcelliott
QUOTE
This collapse initiation above involved one floor and 500 mj of energy. The impacts of 9/11 involved involved 3 gj of impact energy from the planes, and 3000-8000 gj of thermal over many floors. With this massive amount of energy available to damage the buildings, why is it surprising that the resulting damage was able to duplicate a process that required only a fraction of that energy?


With 3000GJ available from the fire alone, why would you think it'd be necessary to have the 0.5GJ in the first place?

Wouldn't it make more sense to consider that the fire's nonuniform thermal distribution of the 3000GJ could have the same 0.5GJ effect?

Even if you don't think the fires were hot enough to *melt* the steel (something I don't think is necessary to drop the towers, but something I don't rule out happening in random hotspots, either), there had to be significant amounts of thermal expansion. Has anyone calculated how much the trusses would've expanded at the hottest parts of the fire, and shrunk once the fire started to cool?

The figure for the coefficient of thermal expansion for steel that I just ran across is 7.8ppm/degreeF. So multiply that number by the peak fire temperature (that you believe to be accurate) and the length of the truss under question, and that's how much it would expand. Trusses aren't designed for compression, so they'll just sag/bow. At peak temperatures, the steel is hot enough for plastic deformation. Once the fire cools off, the same truss, now cooler (and stiffer) will attempt to shrink by the same coefficient, same calculation as before (with the same answer for shrinkage as there was for expansion).

So as the truss cools, it exerts tension on the members holding it to the wall.

Anyone calculate the force one of these would be exerting from cooling? How does that force compare to the strength of the bolts (?) holding them in-place?

I think if you do these calculations, you'll find that the 0.5GJ postulated to drop the trusses aren't needed, and the building collapses progressively without anything other than the impact damage and subsequent fire caused by the hijacked plane hitting the towers.
NEU-FONZE
Pierre-Normand:

Thank you for your kind words!

Frank
Palpatane
NF, an editorial comment:

QUOTE
The fact that the duration of progressive collapse driven solely by gravity does not disagree with observations is further evidenced by formulating and solving the differential equations for the crush-down and crush-up phases of one-dimensional progressive collapse


Replace the double negative "does not disagree" with "agrees."

(good work, BTW)

smile.gif
adoucette
Very good way to start my morning.

Thanks to the excellent work of Bazant, Le, Greening and Benson.

I see the article has been submitted to the Journal of Mechanical Engineering.

David or Frank, do you know the publication date?

Arthur
Malmoesoldier
Grumpy

[QUOTE]So now you are the expert on what dirty aluminum can look like AND an expert on what every other material in the building could not look like. All you are exposing is the abysmal ignorance of the under-educated. You cannot POSSIBLY defend this stupid statement with any evidence.[/QUOTE]

Steven jones proves it. You are under-educated, hes not. Prove him wrong then. NIST is lying. Again!, hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions,glass and computers) CANT display an orange glow like NIST says it can. It is very simple to do this experiment that steven jones did and he proved theme wrong, why haven't nist done any experiments? NIST the holy ones only say that it "can". Understand that NIST is an political document.

[QUOTE]i know. Steel did not melt in the towers[/QUOTE]

Steel melted. But i guess you can explain femas findings. They couldnt do it but you can right. And USGS findings was just a tiny Little sphere so that doesn't matter, and eyewitness isnt evidence, they all had an hallucination.


[/QUOTE]. But 1000C is hot enough that structural steel loses 85% of it's ability to hold a load and it buckles.[QUOTE]

No it does not. Not under 45 minutes. You believe that because NIST says so. If NIST says the world is flat you will believe that to.

Kevin ryan

A. UL's comments on testing WTC steel
September 2001
Loring Knoblauch, UL's CEO, told staff that UL had certified the steel used in the WTC
November 2003
I asked Knoblauch in writing about UL's involvement, and he responded in December confirming details.
"We tested the steel with all the required fireproofing on, and it did beautifully."
"As we did not do follow-up service on this kind of product, we can given an opinion only on the test sample which was indeed properly coated."
"We test the code requirements, and the steel clearly met [the NYC code] requirements and exceeded them."

That test Knoblauch was talking about was 1093C in 3 hours.
Malmoesoldier
Both of the government-sponsored engineering studies of the Twin Towers' "collapses" -- FEMA's and NIST's -- are highly misleading about the core structures. Neither Report discloses dimensions for core columns -- dimensions that are clearly evident in the architectural drawings. Both Reports use a variety of techniques seemingly designed to minimize the strength of the cores or to conceal their structural role entirely.

FEMA, in its explanation of the collapses, stated:

As the floors collapsed, this left tall freestanding portions of the exterior wall and possibly central core columns. As the unsupported height of these freestanding exterior wall elements increased, they buckled at the bolted column splice connections, and also collapsed.

The blueprints show that FEMA's report was inaccurate in stating that core columns were "freestanding" when in fact large horizontal beams cross-connected the core columns in a three-dimensional matrix of steel.

The NIST report into the collapses has also been proven inaccurate by the blueprints as it has implied that the only the corner columns were "massive" and that the core columns decreased in size in the higher stories when, in fact, the sixteen columns on the long faces of the cores shared the same dimensions for most of each Tower's height.

Within each trade tower there were 47 steel columns at the core and 240 perimeter steel beams. 287 steel-columns in total. According to the official story, random spread out fires on different floors caused all these columns to totally collapse at the same time and at a free fall speed, with no resistance from undamaged parts of the structure.

Professor Steven Jones points out that the total annihilation of the building, core columns and all, defies the laws of physics unless it was artificially exploded:

"Where is the delay that must be expected due to conservation of momentum – one of the foundational Laws of Physics? That is, as upper-falling floors strike lower floors – and intact steel support columns – the fall must be significantly impeded by the impacted mass. If the central support columns remained standing, then the effective resistive mass would be less, but this is not the case – somehow the enormous support columns failed/disintegrated along with the falling floor pans."

FEMA's investigation of one of the worst and most pivotal events in history was farcical:

1. No independent investigation was funded: FEMA allocated $600,000 for the BPAT's study, which included the cost of printing their report.

2. Except for an early "tourist trip", The BPAT volunteers were barred from Ground Zero.

3. They did not see a single piece of steel until almost a month after the disaster.

4. They had to guess the original locations of the few pieces of steel they saw.

5. They collected 150 pieces of steel for further study (out of millions of pieces).

6. Their report, which called for "further investigation and analysis", was published after Ground Zero had been scrubbed.


NIST's results strongly indicate a cover-up. NIST's Final Report on the Twin Towers shows that:

1. NIST avoids describing, let alone explaining, the "collapse" of each Tower after they were "poised for collapse." Thus, NIST avoids answering the question their investigation was tasked with answering: how did the Towers collapse?

2. NIST describes the Twin Towers without reference to the engineering history of steel-framed buildings, and separates its analysis of WTC Building 7 into a separate report. By treating them in isolation, NIST hides just how anomalous the alleged collapses of the buildings are.

3. NIST avoids disclosing the evidence sulfidation documented in Appendix C of the FEMA's Building Performance Study.This unexplained phenomenon was described by the New York Times as "perhaps the deepest mystery uncovered in the investigation."

4. NIST has refused to publish the computer models that its report imply show how the fires in the Towers led to "collapse initiation".


NIST admits that it didn't even attempt to model the undamaged portions of the building and only modeled a portion of each tower in any detail -- its "global floor model" which consisted of "several stories below the impact area to the top of the structure." Thus the structurally intact floors 1-91 of WTC 1 and floors 1-77 of WTC 2 were excluded from the so called "global" models of the towers. NIST provides no evidence that its model even predicted "collapse initiation".


The reports by NIST say nothing about how -- and if! -- the collapse was able to progress through dozens and dozens of structurally intact floors without being stopped. If no external energy was available e.g. in the form of explosives, this would have been the opportunity to show that no such energy was needed. On the other hand, if some unaccounted-for energy broke the supporting structures enabling the collapse to progress with the speed it did, there would have been many good reasons not to try to model the impossible, ie. a purely gravitation-driven collapse. Stopping the analysis early enough also saves NIST from trying to explain the symmetrically of the collapses (despite non-symmetrical impact damage and fires), the almost complete pulverization of non-metallic materials as well as the extremely hot spots in the rubble. These remain as inexplicable by the official story as they have ever been.

Despite calls from leading structural and fire engineers, and despite the fact that they published models of the plane impacts, NIST has refused to publish visual simulations from its computer models of the collapses.

Read more here: *www.infowars.com/articles/sept11/wtc_blueprints_leaked_by_whistleblower.htm
Pierre-Normand
QUOTE (Palpatane+Jun 2 2007, 12:36 PM)
Replace the double negative "does not disagree" with "agrees."

(good work, BTW)

smile.gif

I do not disagree with this suggestion.

I've just finished reading the paper. Fantastic work! The combined expertise and talents of the co-authors really shine in this thorough analysis of the collapses.

Should I report here the few small (grammatical) typos I found, or should I rather communicate then directly to NEU-FONZE or David B. Benson?

I have just a few questions for now:

Did the annealing studies performed by NIST reveal temperatures in excess of 600 degree C for columns (or other structural components)? This might be an error. I was under the impression that none of the (rather few) column samples analysed had revealed such temperatures.

Is the "almost 500,000 tons" figure including the sub-grade levels? Is that figure combined with the mu(z) specific mass function in reasonable agreement with the column loading data listed by NIST for the upper floors?

p. 4 "16 of the 48 core columns"
I believe this should read "16 of the 47 core columns"
adoucette
QUOTE (Malmoesoldier+Jun 2 2007, 09:08 AM)
Despite calls from leading structural and fire engineers, and despite the fact that they published models of the plane impacts, NIST has refused to publish visual simulations from its computer models of the collapses.


laugh.gif

NIST never created the visualizations in the first place, so NO, they didn't "Refuse to Publish"

The rest of your arguments have been dealt with in this thread.

They are all bogus.

Arguments like

QUOTE
Within each trade tower there were 47 steel columns at the core and 240 perimeter steel beams. 287 steel-columns in total. According to the official story, random spread out fires on different floors caused all these columns to totally collapse at the same time and at a free fall speed, with no resistance from undamaged parts of the structure.


Were recently dealt with quite nicely by the Bazant, Le, Greening, Benson paper

http://www.civil.northwestern.edu/people/b...0-%205-2007.pdf

But apparently there is a sufficient supply uneducated and gullible young men (even in Sweden) to keep these sites afloat.

Arthur
wcelliott
Malmo -

First, I suggest you follow the link to the paper that the rest of us are talking about, and read it. It addresses virtually every one of your "facts" (none of which stand up to close scrutiny).

Second, I suggest that you examine your own prejudices instead of accusing us of being blindly misled by NIST propaganda. We aren't naive about governments' lies, we expect governments to lie, all of them. That's just politics. Does the Swedish government tell nothing but the truth? Don't assume we're gullible, we aren't, we may be the most cynical citizenry in the world.

I suggest that you would be severely disappointed if rock-solid proof came out that the US government *wasn't* to blame for 9/11. I think you'd be personally saddened to hear that. Ask yourself if that isn't the case? Doesn't that say something about your own objectivity in this matter? You're looking too hard for something to blame on the US.

Find something else to support your unreasoned hatred of Americans. 9/11 isn't it.

NEU-FONZE
Arthur, Palpatane, Pierre-Normand:

Thanks again!

The paper has only just been submitted to J. Mech. Eng. and has to go through a full peer-review before it's accepted for publication; so there is no publication date set until we overcome that hurdle. The version available on the Northwestern Uni. website is something of a first draft and has a few typos for sure.... Hopefully, everything will be fixed in the final version...
Grumpy
NEU-FONZE

WOW!!! What a read!!! Congratulations on this "Tour de Force"!!!

I had always had the opinion,based on my "feeling" that Bell curve distribution of particle size, (with the peak of the curve centered on the average size as determined by energy inputs and calculations(as per your excellent work) that the dust represented only a small fraction of the mass of concrete, as did large fractions of floor on the other end of the curve(~10% each), with ~75% of the sizes within fractions or single digit multiples of the average(and thus NOT dust)), would represent the size distribution of the rubble.

Have I been wrong(don't worry, it won't be the first time)???

Also, while "pancaking" is not the initiating event, there is ample visual evidence that a wave of pancaking floors preceded(At least at first) the zone B rubble, thus leaving the core and outer frames unsupported and pushed aside as the Zone A and B descended. Thus zone B might not have gathered as much mass, but would be "telescoping" into the bottom section, mostly destroying the core and encountering less energy drain(as the floors were taking care of the commutation part).

Grumpy cool.gif

Again, good work!!!
reasonwhy
QUOTE
Acknowledgment. Partial financial support for the energetic theory of progressive collapse was obtained from the U.S. Department of Transportation through grant 0740-357-A210 of the Infrastructure Technology Institute of Northwestern University.
http://www.civil.northwestern.edu/people/b...0-%205-2007.pdf


So, how much did the government pay you for this BS? blink.gif

QUOTE (->
QUOTE
Acknowledgment. Partial financial support for the energetic theory of progressive collapse was obtained from the U.S. Department of Transportation through grant 0740-357-A210 of the Infrastructure Technology Institute of Northwestern University.
http://www.civil.northwestern.edu/people/b...0-%205-2007.pdf


So, how much did the government pay you for this BS? blink.gif

The scraping of insulation, not anticipated at the time of design, is shown by NIST to have been the decisive factor,  without which the column buckling and the subsequent collapse would, most likely, not have occurred. By annealing studies of column pieces collected after the collapse, NIST documents that steel temperatures reached at least 600_C.


Nue-fonze , I recall you arguing against the NIST insulation simulation. Amazing what a little recognition and money can do (or did Arthurs persuade you that you were wrong). biggrin.gif
Pierre-Normand
QUOTE (Grumpy+Jun 2 2007, 02:56 PM)
Also, while "pancaking" is not the initiating event, there is ample visual evidence that a wave of pancaking floors preceded(At least at first) the zone B rubble, thus leaving the core and outer frames unsupported and pushed aside as the Zone A and B descended. Thus zone B might not have gathered as much mass, but would be "telescoping" into the bottom section, mostly destroying the core and encountering less energy drain(as the floors were taking care of the commutation part).

This does not mesh very well with the result that momentum transfer is much more of a factor in resisting the acceleration of the upper block than are other energy requirements -- including the energy consumed in column buckling. This was already a significant result in Greening's original paper and it is also manifest in the continuum model in the form of the force F_m which is the "force required to accelerate to velocity dz/dt the stationary mass accrcreting at the crushing front." (p.3) This force "causes a greater difference from free fall than do [the other forces] combined" (ibid.)

So, if the pancaking of the floors, that are resisted by significant inertial force of the "accreting" lower floors, are allowed to move ahead of the upper block, then what sort of energy consumption per unit length (=force) holds it up? Multi-story column buckling is even less resistive than single-story buckling is.

Could there be some other explanation of the apparent head start of the pankaking of the floors? Could this be the result of compressed air penetration, or could the thickness of the compacted debris mass (the "piston") within the perimeter walls that accounts for this apparent head start?



Malmoesoldier
QUOTE
The rest of your arguments have been dealt with in this thread. They are all bogus.


OK... They haven't been dealt with. Everything you say is bogus. Bazant?? LOL. Read Steven jones report if you want to know the truth about 9-11.

I guess you have dealt with it like you have dealt with people in WTC 7 that heard big explosions below floor 8. And the Fire fighters that felt explosions and got banged around time after time. And the fire fighters that saw flashes, i guess they to had an hallucination like the ones that saw molten steel, So many hallucinations that day.

NIST says. Office material fires would burn out within about 15-20 minutes in a given location. Funny how the NIST report shows how it was an inside job. And the undamaged core columns didnt matter, it was the support columns that made the building stand, the ones they have NO proof of that they reached any hotter then 600 C hehe

3bodyproblem
Excellent job on the paper.
Pierre-Normand
QUOTE (reasonwhy+Jun 2 2007, 03:28 PM)
So, how much did the government  pay you for this BS? blink.gif

This is a paper about collapse progression and you quibble about initiation -- blinking notwithstanding. The paper responds to those who would say "Yeah, but even if the collapse is initiated somehow, it would never proceed in free fall (or such rapid speed) as we observed"

It seems to me too that the 600C claim is in error, but I'd like to be corrected on this.
reasonwhy
QUOTE (Pierre-Normand+Jun 2 2007, 07:59 AM)
This is a paper about collapse progression and you quibble about initiation -- blinking notwithstanding. The paper responds to those who would say "Yeah, but even if collapse is initiated somehow, it would never proceed in free fall (or such rapid speed) as we observe"

It seems to me too that the 600C claim is in error, but I'd like to be corrected on this.

Well, if NF and DBB are correct, it should be easy to prove (especially with the government still wasting tax payers money on the OCT).


Calculate the smallest building crush- up,crush- down would be possible and have a CD company prove it (CD a building from the top down without any explosives below the initiation point).

NIST was not able to simulate it with FEA so a real structure should be used to prove crush- up,crush- down is even possible. biggrin.gif
Grumpy
Malmoesoldier,reasonwhy

You are invited to participate in this informal peer review.

Simply take some point from the paper which you disagree with and explain specifically what is wrong with their hypotheses(fast on it's way to theory) and your assesment of their merit(be able to provide sources, etc) and why your is a better explanation.

Grumpy cool.gif
wcelliott
Did they stop teaching physics in Sweden?

Daru
How much of the mass ejected outside of the Tower's footprint.
reasonwhy
QUOTE (Grumpy+Jun 2 2007, 09:16 AM)
Malmoesoldier,reasonwhy

You are invited to participate in this informal peer review.

Simply take some point from the paper which you disagree with and explain specifically what is wrong with their hypotheses(fast on it's way to theory) and your assesment of their merit(be able to provide sources, etc) and why your is a better explanation.

Grumpy cool.gif

Thanks for inviting me to the OCT Circle Jerk. biggrin.gif

Are you also claiming responsibility for the paper ?

The more attention the paper gets , the better. Now they will need to prove it is possible.

The top block of the WTC was only 15 floors so a 25 story building should be sufficient to prove the hypotheses. let the top 15 floors of a building crush the lower 10 (much stronger and still structurally sound) at 2/3 free fall acceleration(or anything even close). laugh.gif
Capracus
QUOTE (Pierre-Normand+Jun 2 2007, 10:23 AM)
I remember reading that the (undamaged!) truss floors were strong enough to sustain the dynamic load on one floor above (maybe two?) falling on them. I would have to do some research to find back that reference.
They were able to support a static load of about 1300 tons beyond their own weight, which is about 1.5 times the weight of a floor system.

http://www.tms.org/pubs/journals/JOM/0112/...Eagar-0112.html
3bodyproblem
QUOTE (Grumpy+Jun 2 2007, 05:16 PM)
Malmoesoldier,reasonwhy

You are invited to participate in this informal peer review.

Simply take some point from the paper which you disagree with and explain specifically what is wrong with their hypotheses(fast on it's way to theory) and your assesment of their merit(be able to provide sources, etc) and why your is a better explanation.

Grumpy cool.gif

Has this been submitted to 9/11 scholars for truth? They are the foremost authorities on 9/11 physics in the world of academia.
3bodyproblem
I find the analysis of particle size distribution (Fig. 4a) inconsistent with the video evidence for the first 2 seconds. "Dust" ejected during the first story of collapse was certainly smaller than 10mm. I don't believe the analysis accounts for this observation.
Malmoesoldier

Bazant writes things in hes report that he cant prove lol.

From steven jones report.

The 110-story towers of the World Trade Center were designed to withstand as a whole the forces caused by a horizontal impact of a large commercial aircraft. So why did a total collapse occur? (Bazant and Zhou, 2002, p. 2.)

Correct – the WTC Towers were designed to withstand forces caused by large commercial aircraft – we can agree on that. MIT’s Thomas Eagar also concurs “because the number of columns lost on the initial impact was not large and the loads were shifted to remaining columns in this highly redundant structure” (Eagar and Musso, 2001).

We continue with Bazant & Zhou:

The conflagration, caused by the aircraft fuel spilled into the structure, causes the steel of the columns to be exposed to sustained temperatures apparently exceeding 800oC… (Bazant and Zhou, 2002, p. 2.)

But here we note from the recent NIST report that: “The initial jet fuel fires themselves lasted at most a few minutes” and office material fires would burn out within about 20 minutes in a given location. (NIST, 2005; p. 179, emphasis added.) Certainly jet fuel burning was not enough to raise steel to sustained temperatures above 800oC, although air temperatures could have exceeded that value. But we continue:

Once more than half of the columns in the critical floor.. suffer buckling (stage 3), the weight of the upper part of the structure above this floor can no longer be supported, and so the upper part starts falling down onto the lower part below…”(Bazant and Zhou, 2002, p. 2.)

Bazant & Zhou do not explain how “more than half of the columns in the critical floor [can] suffer buckling” at the same time to precipitate the complete and nearly symmetrical collapse observed. There were 47 huge steel core columns in each Tower, and 24 such support columns in WTC 7 (NIST 2005; NISTb, 2005).

The WTC towers were solidly constructed with 47 steel core columns and 240 perimeter steel columns. 287 steel-columns total.

Many doubt that random fires/damage could cause them to collapse completely and straight down (official theory), and suspect that explosives were used to cause the complete collapse of these buildings

Steel-frame: Huge core (left) is an enormous heat sink. Notice workers standing on floor pan which is firmly attached to the interconnected core columns. Clearly, the Towers were not “hollow tubes.”

Picture: *www.911readingroom.org/jones/images/9-11%20Picture6.jpg

They do NOT explain how steel-column temperatures above 800oC were achieved near-simultaneously due to burning office materials. NIST notes that office materials in an area burn for about 15-20 minutes, then are consumed away (NIST, 2005, pp. 117, 179). This is evidently not long enough to raise steel column temperatures above 800oC as required in the Bazant & Zhou model, given the enormous heat sinks of the structures. And to have three buildings completely collapse due to this unlikely mechanism on the same day strains credulity. Moreover, the Final NIST report on the Towers admits:

Of the more than 170 areas examined on 16 perimeter column panels, only three columns had evidence that the steel reached temperatures above 250ºC… Only two core column specimens had sufficient paint remaining to make such an analysis, and their temperatures did not reach 250 ºC. ... Using metallographic analysis, NIST determined that there was no evidence that any of the samples had reached temperatures above 600 ºC. (NIST, 2005, pp. 176-177; emphasis added.)

Relevant to this point, Eagar noted that "Factors such as flame volume and quantity of soot decrease the radiative heat loss in the fire, moving the temperature closer to the maximum of 1,000 ºC." (Eagar and Musso, 2001) While this is the maximum air temperature possible in the WTC fires, this does not mean that the structural steel reached this temperature in the time the fires acted. Indeed, NIST emphasizes that there was no evidence that "any of the samples had reached temperatures above 600 ºC." This statement is consistent with their data plots of "predicted column temperatures", which "shows maximum temperature reached by each column" in that no temperature above 600 ºC is given for any of the steel columns. (NIST, 2005.)

As for WTC 7, Bazant & Zhou say little but mention in a separate “addendum” that burning natural gas might have been a source of the needed heat (Bazant and Zhou, March 2002, p. 370). The FEMA report (FEMA, 2002) addresses this issue:

Early news reports had indicated that a high pressure, 24-inch gas main was located in the vicinity of the building [WTC 7]; however, this proved not to be true." (FEMA, 2002, chapter 5; emphasis added.)





Malmoesoldier
QUOTE
Has this been submitted to 9/11 scholars for truth? They are the foremost authorities on 9/11 physics in the world of academia.


The truth movement has many structural engineers and Architects

Dr. Michael Voschine, PhD., Structural Engineer, of Miami, Florida

Charles Pegelow, structural engineer, of Houston, Texas

Doyle Winterton, structural engineer (retired)

Architect & structural engineer Haluk Akol, of Lafayette, California

Joseph M. Phelps, MS, PE. Structural Dynamicist (ret.), Charter Member, Structural Engineering Institute of the American Society of Civil Engineers

William Rice, P.E., structural engineer, former professor of Vermont Technical College

Hugo Bachmann and Jörg Schneider, both emeritus professors in structural engineering at a prestigious Swiss university

Richard Gage, AIA, Architect
Walnut Creek, CA

Don Gibbons, Architect
Pleasant Hill, CA

Jeff Arnold, Architect
Orinda, CA

John Cole, Architect
Walnut Creek, CA

David Crawford, Architect
Walnut Creek, CA

John Eisenhart, Architect
San Diego, CA

Joe Bellows, Architect
Martinez, CA

John Howland, Architect
Walnut Creek, CA

Eric Douglas, Architect
Howard Beach, NY

Peter Hendrickson, Architect
Santa Rosa, CA

Osvaldo Valdes, Architect
New York, NY

Lily Livingston, Architect
Oakland, CA

Chris Swigert, Architect
Oakland, CA

Jim Bedinghaus, Architect
St. Petersburg, Florida

Christian Mungenast AIA, Architect
Arlington, MA

Scott Page, M. Arch / Designer
Berkeley, CA

J. Marx Ayres, PE, Mechanical Engineer
Santa Monica, CA

Robert Nielson, PLS, Land Surveyor
Walnut Creek, CA

John F. Shanahan, PE, Electrical Engineer
Rancho Cucamonga, CA

Joseph Testa, P.E., Civil Engineer
Thousand Oaks, CA

Peter D. Morse, P.E., Mechanical Engineer
Tucson, Arizona

Richard Gage is the founding member of ae911Truth.org. He has been a practicing Architect for 20 years and has worked on most types of building construction including numerous fire-proofed steel-framed buildings.

There are many more Engineers and Architects at: http*://www.ae911truth.org/joinus.php

Along with many other prominent scientists.

And all these Senior Military, Intelligence Service, Law Enforcement, and Government Officials questions 9-11: *www.patriotsquestion911.com
adoucette
So you give us a list of over 2 dozen architects or engineers and yet not ONE has published a paper in a PEER REVIEWED ENGINEERING JOURNAL that disputes either Bazant or NIST.

Now why is that?

laugh.gif

Arthur
Pierre-Normand
QUOTE (Capracus+Jun 2 2007, 05:49 PM)
They were able to support a static load of about 1300 tons beyond their own weight, which is about 1.5 times the weight of a floor system.

http://www.tms.org/pubs/journals/JOM/0112/...Eagar-0112.html

Thanks Capracus,

Where did you get the self-weight of the floor systems?


3bodyproblem
QUOTE (Malmoesoldier+Jun 2 2007, 06:51 PM)

The truth movement has many structural engineers and Architects

yada yada yada...

There are many more Engineers and Architects at: http*://www.ae911truth.org/joinus.php

Along with many other prominent scientists.

And all these Senior Military, Intelligence Service, Law Enforcement, and Government Officials questions 9-11: *www.patriotsquestion911.com

Yes, I've been to the website. I actually have a screen shot of the list you just mentioned with Osama Bin Laden as member. Due to the NSPE code of ethics I think you will see many of the names on that list dwindle even further.
Pierre-Normand
QUOTE (3bodyproblem+Jun 2 2007, 06:46 PM)
I find the analysis of particle size distribution (Fig. 4a) inconsistent with the video evidence for the first 2 seconds. "Dust" ejected during the first story of collapse was certainly smaller than 10mm. I don't believe the analysis accounts for this observation.

I believe it is mostly smoke that is being ejected during the first two seconds of the collapse. Thick dark smoke saturated much of the volume of the impact floors as well as many floors above.

Shortly after that, it is mostly drywall and spay-on fire-resistive material that would be ejected.

One third point: you can not reasonably estimate particle size distribution from the appearance of the dust that is ejected, especially not in the very early stages, I believe. Air flow would pick up preferentially the finest particles, and these would of course settle at a lower speed and make up an opaque layer, thus masking the larger ones, which fall faster.

Also, concrete is grey, I think. So, you can see the ejected cloud vary in composition while the collapse progresses: black smoke, then white drywall/SFRM, then concrete.
wcelliott
QUOTE
Bazant & Zhou do not explain how “more than half of the columns in the critical floor [can] suffer buckling” at the same time to precipitate the complete and nearly symmetrical collapse observed. There were 47 huge steel core columns in each Tower, and 24 such support columns in WTC 7 (NIST 2005; NISTb, 2005).


Are you so dimwitted that you can't grasp how a weakened structure buckles under a load, then fails?

Are you still too naive to realize that the structure was sized to carry the nominal load under nominal conditions? Don't you understand how anything is designed? They figured out how much steel and concrete they'd need, then they put that much in the design. When most of the columns on one side were taken out by the impact of the plane, that side of the structure was weakened. The loads formerly carried by the columns destroyed in the impact were transferred to the remaining members, but NOT EQUALLY. Those members closest to the load would've been overloaded the greatest, so when the fire heated the remaining structural steel, the most-overstressed members FAILED FIRST. When they went, the remaining structural members were themselves overstressed, and this led to the remaining members slowly giving-way, buckling under the excess load until the geometry of the original structure no longer provided the support necessary to hold the load.

The failure wasn't instantaneous, it started out as a slow descent measured at mm/minute, accelerating to mm/second, then inches/second, to feet/second. At some point in that range we human observers started noticing the movement and chose, arbitrarily, when the tower "started" to fall. There was nothing instantaneous or simultaneous about it.

Nor was there any eruption of dust or blast heard when the buildings started to fall, because they started to fall before anybody can tell on the video footage of the collapse. They started to fall when the descent rate was only measurable in mm/minute. From that point on, collapse was inevitable.

Learn something before you go shooting-off your mouth.
reasonwhy
QUOTE
The vent ratio   is hard to estimate. It surely varies from story to story, and also during the crushing of one story. Its effective, or average, value could be much less than 1 (because some of the perimeter area is doubtless still obstructed early in the crushing of one story, and because much of the air escapes only after the story height has been reduced greatly). Clearly, the fluctuations of air speed can reach the speed of sound, and thus create a sonic booms, which
are easily mistaken for explosions (attaining supersonic speeds requires that the orifice through which the air is venting be shaped somewhat like convergent-divergent nozzles, and it is not impossible that such configurations might intermittently develop).


What do we have now, “intelligent Building collapse". laugh.gif


I also like the part about ”vent ratio” of a mostly GLASS wall. As if this could realistically build up pressure (causing sonic booms, no less). laugh.gif

If this paper passes peer-review, it will give new hope to the Intelligent Design supporters.
wcelliott
QUOTE
easily mistaken for explosions


Something else that's easily mistaken for an explosion is when something heavy strikes something big. I heard a guy, standing on the top of an open U-Haul truck, drop a wrench on the top of the truck, it sounded like a cannon went off.

Let's see, could there have been any circumstances where something heavy hit something big in the collapse of the WTC towers?

DUH!
Pierre-Normand
QUOTE (reasonwhy+Jun 2 2007, 07:58 PM)

What do we have now, “intelligent Building collapse". laugh.gif


I also like the part about ”vent ratio” of a mostly GLASS wall. As if this could realistically build up pressure (causing sonic booms, no less). laugh.gif

If this paper passes peer-review, it will give new hope to the Intelligent Design supporters.

The inertia of the mass of air fully accounts for the pressure buildup. (One cubic meter of air weigh one kg. You need a pressure differential to put this mass into motion.) The vent ratio just allows for speed buildup. You did not read the argument carefully.

Further, not allowing for pressure buildup can not result into comparatively *reduced* exit velocities of the air. Did you expect that no pressure buildup would result into the air not exiting as fast as the paper proposes even though the containing volume is being reduced at the same rate? Where would the air go in your isobar scenario?
Malmoesoldier
QUOTE
Learn something before you go shooting-off your mouth.


It is you that needs to learn something. You are thinking like a 10 year old right now. Bazant is wrong. Funny how all people like you that believes in conspiracy theories can explain stuff that bazan/NIST/FEMA havnt done. you dont even understand what your self is talking about, if you had talked with steven jones or somebody els they would prove you wrong on whatever you said.

QUOTE (->
QUOTE
Learn something before you go shooting-off your mouth.


It is you that needs to learn something. You are thinking like a 10 year old right now. Bazant is wrong. Funny how all people like you that believes in conspiracy theories can explain stuff that bazan/NIST/FEMA havnt done. you dont even understand what your self is talking about, if you had talked with steven jones or somebody els they would prove you wrong on whatever you said.

So you give us a list of over 2 dozen architects or engineers and yet not ONE has published a paper in a PEER REVIEWED ENGINEERING JOURNAL that disputes either Bazant or NIST. Now why is that?


That just shows how you believe in whatever the government tells you laugh.gif . i dont understand why wacko.gif. THINK!!! because the government has its official story already and people dont question it, and you cant publish whatever you want, there will be concavenesses. Thats the most stupid question i have heard "why is that?". You need someone to published a paper in a peer reviewed engineering journal or els you cant believe it. The most people that buys the official story without question it in america is people that hates arabs and thinks they are "patriots" but in reality they are nothing but idiots that knows nothing about history or the new world order. You haft to look at the big picture all the lies sorounding 9-11. PNAC, the war games, the patriot act, foreknowledge of the attacks AND that the building was coming down long before it collapsed. All the Rumsfelds and Giuliani lies, the list goes on.

I guess you have dealt with all that like you have dealt with the people in WTC 7 that heard big explosions below floor 8. And the Fire fighters that felt explosions and got banged around time after time. And the fire fighters that saw flashes, i guess they to had an hallucination like the ones that saw molten steel, So many hallucinations that day.

NIST says. "Office material fires would burn out within about 15-20 minutes in a given location!!!". So how did the steel get to 1000C and stayed at that temp???. It was typical office fires. And the undamaged core columns didnt matter?, it was only the support columns that made the building stand, the ones they have NO proof of that they reached any hotter then 600 C laugh.gif
wcelliott
OK, so the CDiots think explosives initiated the collapse of the towers.

When did the explosives go off?

If the explosives were the initiator of the collapse(s), then they had to go off before the building(s) started collapsing.

The building(s) started collapsing when the angle(s) of the upper floor(s) started deviating from vertical, not when the floor(s) started noticeably descending. The descent rate can be inferred from geometry (trig, actually) by the deviation angle(s), and those angles should be easier to measure than the mm/minute rates associated with the initial descent velocities.

If the CDiots want to do some calculations of their own instead of carping about the assumptions that the serious researchers made, then they can determine exactly when the structures started their descent by measuring those angles and plotting them versus time.

If the angle-rates have a flat-spot after the impact, then the buildings had stopped descending post-impact. If the angle-rates suddenly start up again, it's at that point in time that the "explosives" were detonated. Then, all the CDiots need to do is find the shockwave coming from the explosions, and they can make their case.

But I'm pretty sure that what they'll find is that the angle-rates start out slow and increase monotonically, accelerating to the point where the buildings' collapse is noticeable directly.

Which would mean that no explosives contributed to the buildings' collapse.

Have at it! Prove me wrong.
3bodyproblem
QUOTE (Pierre-Normand+Jun 2 2007, 07:41 PM)
I believe it is mostly smoke that is being ejected during the first two seconds of the collapse. Thick dark smoke saturated much of the volume of the impact floors as well as many floors above.

Shortly after that, it is mostly drywall and spay-on fire-resistive material that would be ejected.

One third point: you can not reasonably estimate particle size distribution from the appearance of the dust that is ejected, especially not in the very early stages, I believe. Air flow would pick up preferentially the finest particles, and these would of course settle at a lower speed and make up an opaque layer, thus masking the larger ones, which fall faster.

Also, concrete is grey, I think. So, you can see the ejected cloud vary in composition while the collapse progresses: black smoke, then white drywall/SFRM, then concrete.

Sounds fair Pierre. I had hypothesized that the exterior truss failures were the main cause of this expulsion, as the exterior columns "snapped" back when the bolts/angle seats were sheared.

I just wanted to point out this observation about particle size before someone used it to suggest explosives.
Grumpy
Malmoesoldier

So PRATTs are all you have, plus spam from a truther site? You are a joke, ignorant of the facts and unable to think for yourself. IE a total waste of time.

If you cannot pick a single point from the paper and even make an attempt at refutation you are useless to any reasoned discussion.

Grumpy cool.gif
Pierre-Normand
QUOTE (wcelliott+Jun 2 2007, 08:25 PM)

Something else that's easily mistaken for an explosion is when something heavy strikes something big.  I heard a guy, standing on the top of an open U-Haul truck, drop a wrench on the top of the truck, it sounded like a cannon went off.

Let's see, could there have been any circumstances where something heavy hit something big in the collapse of the WTC towers?

DUH!

Of course, the process you and the authors are talking about is the same. Slabs hitting slabs -- it's just hand clapping by another name. (Although your U-Haul truck example illustrates something else: It is not the air being expelled from between two closing surfaces that generate the pulse -- it is rather the induced vibration of the truck roof that produces the sound)

The authors do not overlook anything. They just speculate that the pulse's possibly being supersonic would account for a more explosive sounding bang -- because explosive detonations also are supersonic phenomena. Mere acre sized hands clappings to produce sub-sonic pulses might sound more akin to low pitched "poofs". Compare this to the mere subsonic deflagration of the fireball right after the second plane impact.

http://www.fireandsafety.eku.edu/VFRE-99/T...finitions-1.htm
adoucette
QUOTE (Malmoesoldier+Jun 2 2007, 03:44 PM)
Bazant is wrong.


Sorry, you need a little more than that to disprove Bazant.

Which is why we DO rely on papers published in respected Journals.

Which is why your GOD, Steven Jones, has YET to publish any of his WTC theories in a RESPECTED ENGINEERING JOURNAL, and he's been at this now for almost 2 years.

But still, there is NOTHING published from any of them.

NADA

ZIP

ZILCH.

laugh.gif

Arthur
David B. Benson
Thank you! smile.gif

Assuming the paper passes peer review, it should appear in about 9--11 months from now.

If you notice anything wrong (typos, etc.) with the paper, please send the errata to me and I'll compile a list. We'll have a chance to fix these in about 3 months (peer review process time).

It will be more convenient for me if you send e-mail rather than PM, as I have no copy-n-paste capabilities on this computer. Thanks.
reasonwhy
QUOTE (Pierre-Normand+Jun 2 2007, 12:36 PM)
The inertia of the mass of air fully accounts for the pressure buildup. (One cubic meter of air weigh one kg. You need a pressure differential to put this mass into motion.) The vent ratio just allows for speed buildup. You did not read the argument carefully.

Further, not allowing for pressure buildup can not result into comparatively *reduced* exit velocities of the air. Did you expect that no pressure buildup would result into the air not exiting as fast as the paper proposes even though the containing volume is being reduced at the same rate? Where would the air go in your isobar scenario?


OBVIOUSLY OUT THE BROKEN GLASS WINDOWS !!! biggrin.gif

The OCT believers are so detached from reality it is scary.
Grumpy
David B. Benson

Kudos for such a well written and researched paper!!! A breath of fresh air after the barnyard odor eminating from the posts of the CTer crowd.

Grumpy cool.gif
Malmoesoldier
[/QUOTE]But still, there is NOTHING published from any of them.[QUOTE]

Yes i know that you are stupid and believes whatever the government tells you. You will read about 9-11 in history books in the future after the revolution has come, this is a very big crime and the people that did it is still in power and as long as they run things we wont read about it in schools and they will of course not talk about it as fact in the american media. Why do you think they didnt learn anything about the hitlers Reichstag in germany some years after it had happen? it takes time for things like that to be accepted and talked about, especially if the ones that did it is still in power. i cant remember when the evidence of that it was hitler that was behind the Reichstag came to light. but there are many examples of things that are proven with evidence and they dont talk about it, Not until the NWO i gone will we hear about all their crimes, until then we will only hear BS and propaganda.

The most people that buys the official story without question it in america is people that hates arabs and thinks they are "patriots" but in reality they are nothing but idiots that knows nothing about history or the new world order. You haft to look at the big picture all the lies sorounding 9-11. PNAC, the war games, the patriot act, foreknowledge of the attacks AND that the building was coming down long before it collapsed. All the Rumsfelds and Giuliani lies, the list goes on.

And dont hide from this, the third time im writing it now.

I guess you have dealt with all that like you have dealt with the people in WTC 7 that heard big explosions below floor 8. And the Fire fighters that felt explosions and got banged around time after time. And the fire fighters that saw flashes, i guess they to had an hallucination like the ones that saw molten steel, So many hallucinations that day.

NIST says. "Office material fires would burn out within about 15-20 minutes in a given location!!!". So how did the steel get to 1000C and stayed at that temp???. It was typical office fires. And the undamaged core columns didnt matter?, it was only the support columns that made the building stand, the ones they have NO proof of that they reached any hotter then 600 C laugh.gif
wcelliott
QUOTE
it is rather the induced vibration of the truck roof that produces the sound)


I didn't mean it as criticism of the paper, but as an alternative explanation that doesn't invoke sonic booms.

Any impulse will approximate an explosion, and in the case cited (U-Haul truck), it was actually the impulse-loading of the flat roof that caused it to deflect, producing an impulse of air coming from the back of the truck. It's a bit more rigorous an analogy to a ceiling being struck by a heavy weight, producing a shock wave from the sudden deflection.

You can't really differentiate between sources of impulse-sounds in a cluttered environment, as pure impulses turn complex when they reflect off multiple surfaces. All "bangs" end up sounding like "thumps" sooner or later.

Other sources of impulses include members under tension/compression tied to diaphragms (any flat-surfaced structure, e.g., floor, wall, ceiling, curtain-wall, etc.) will generate an impulse when that member is severed. It's the same as a string tied to the bottom of a tin can, and the string being plucked. The diaphragm suddenly moves, displacing air, and a "bang" results. Trusses tied to the curtain wall will make the curtain wall go "bang" when the trusses fail. The speed of sound is something like 20,000fps in steel, compared to about 1000fps in air, so when a truss fails 70 floors above the ground, you hear a "bang" at ground level faster than you hear the "bang" directly.

(As for typos, do a search for "the this".)

Simple physics, Malmo. So what level/type of education do you have?

What do you do for a living Malmo?

I'm a Senior Engineer with a Masters degree and 30 years' experience.

I know what I'm talking about. Do you know what you're talking about, or are you just a no-nothing-bozo who's fallen for politically-motivated BS, and you're just really eager to believe that the US government is the most evil thing that ever existed on earth?

Pierre-Normand
QUOTE (reasonwhy+Jun 2 2007, 09:19 PM)

OBVIOUSLY OUT THE BROKEN GLASS WINDOWS !!! biggrin.gif

The OCT believers are so detached from reality it is scary.

Reasonwhy,

The vent ratio precisely is the ratio of the window area to the total perimeter area of one story.
Malmoesoldier
QUOTE
What do you do for a living Malmo?. I'm a Senior Engineer with a Masters degree and 30 years' experience.


I am a alcoholic and drug addict and i have 124 kids and in my past life i was albert einstein and thats why i understand that it is an inside job because the fires in wtc could not melt steel and indeed it melted steel and you need a very high degree in Engineering to understand stuff like this laugh.gif

You are a very BAD Engineer if it is true that you are a Engineer. NIST/FEMA are saying the fires in WTC could NOT MELT STEEL, Offcourse they couldnt. And you are saying that they could melt the steel, PRICELESS!!. I think you are a disinformation bitch like mark roberts that hates arabs to, and thinks you are a patriot.

QUOTE (->
QUOTE
What do you do for a living Malmo?. I'm a Senior Engineer with a Masters degree and 30 years' experience.


I am a alcoholic and drug addict and i have 124 kids and in my past life i was albert einstein and thats why i understand that it is an inside job because the fires in wtc could not melt steel and indeed it melted steel and you need a very high degree in Engineering to understand stuff like this laugh.gif

You are a very BAD Engineer if it is true that you are a Engineer. NIST/FEMA are saying the fires in WTC could NOT MELT STEEL, Offcourse they couldnt. And you are saying that they could melt the steel, PRICELESS!!. I think you are a disinformation bitch like mark roberts that hates arabs to, and thinks you are a patriot.

US government is the most evil thing that ever existed on earth?


No the NWO has power in Europe to not just usa. I am against all terrorist, bin laden, bush, dic k cheny, and all the al-ciada groups the us are funding like the Jundullah. Not just terrorist from us.
adoucette
QUOTE (Malmoesoldier+Jun 2 2007, 04:42 PM)
The most people that buys the official story without question it in america is people that hates arabs and thinks they are "patriots" but in reality they are nothing but idiots that knows nothing about history or the new world order. You haft to look at the big picture all the lies sorounding 9-11. PNAC, the war games, the patriot act, foreknowledge of the attacks AND that the building was coming down long before it collapsed. All the Rumsfelds and Giuliani lies, the list goes on.

And dont hide from this, the third time im writing it now.


No one is hiding from it, its just too stupid of a post to generate a response on a PHYSICS site.

Arthur
reasonwhy
QUOTE (Pierre-Normand+Jun 2 2007, 01:59 PM)
Reasonwhy,

The vent ratio precisely is the ratio of the window area to the total perimeter area of one story.

WOW, you figured that out.

I am impressed.


Now explain how an area surrounded by walls made up of mostly vents can build up pressure (to infinity as the paper suggests).
Malmoesoldier
QUOTE
No one is hiding from it, its just too stupid of a post to generate a response on a PHYSICS site.


I was talking about this when i said "And dont hide from this, the third time im writing it now."

there where people in WTC 7 that heard big explosions below floor 8. And there where Fire fighters that felt explosions and got banged around time after time. And there was fire fighters that saw flashes, i guess they to had an hallucination like the ones that saw molten steel, So many hallucinations that day.

NIST says. "Office material fires would burn out within about 15-20 minutes in a given location!!!". So how did the steel get to 1000C and stayed at that temp???. It was typical office fires. And the undamaged core columns didnt matter?, it was only the support columns that made the building stand, the ones they have NO proof of that they reached any hotter then 600 C laugh.gif

I also talked with James A. Milke from: *www.fpe.umd.edu

He is an Associate Professor, and Associate Chair, P.E., Ph.D.
Dept. of Fire Protection Engineering
Research Interests: Smoke management and analyzing the response of materials exposed to fire conditions

He said this.

"The best estimates of the fires in the World Trade Center indicate that the
temperatures attained were fairly typical of office fires, and maybe even a
little low (about 800 C) after the initial fireballs, given the large amount of
ventilation available as a result of the broken windows."

J Milke
Pierre-Normand
QUOTE (wcelliott+Jun 2 2007, 09:43 PM)
Any impulse will approximate an explosion, and in the case cited (U-Haul truck), it was actually the impulse-loading of the flat roof that caused it to deflect, producing an impulse of air coming from the back of the truck. It's a bit more rigorous an analogy to a ceiling being struck by a heavy weight, producing a shock wave from the sudden deflection.

Yes, that makes sense. Thanks for the further useful explanations.

I've signaled that typo to David B. Benson already. (Also the missing "the" and the "during within").

There aren't many mistakes in the physics! Although I must give some more thought to the comminution of the concrete in relation to the energy lost through inelastic colisions. There still is a gap in my understanding.
David B. Benson
QUOTE (Pierre-Normand+Jun 2 2007, 03:59 PM)
It seems to me too that the 600C claim is in error, but I'd like to be corrected on this.

The fire progression scenarios are graphed in NCSTAR1-5F, I think.

I'd appreciate your checking the worst case scenarios. (It seems NIST limited these to 750 F for the core columns, which is, if I didn't make a mistake, (434+273) K.) Hmm. Maybe it is truss temperatures?
Capracus
QUOTE (Pierre-Normand+Jun 2 2007, 07:20 PM)
Thanks Capracus,

Where did you get the self-weight of the floor systems?

The lightweight concrete is about 33lbs/sf @ 4" thk x 43200 sf floor area =713 tons.

I can't remember where I got the number for the steel in a floor system, but the number I have is 117 tons. Other posters may have some better numbers.
David B. Benson
QUOTE (wcelliott+Jun 2 2007, 09:43 PM)
... but as an alternative explanation that doesn't invoke sonic booms.

The main point behind sonic booms is the calculation that near the end of the collapse, at about 50 m/s, all the air needs to escape in 0.07 seconds from each story, assuming the floor below doesn't collapse first. That leads to Mach 1.0 speeds, hence a potential for sonic booms.
PhysOrg scientific forums are totally dedicated to science, physics, and technology. Besides topical forums such as nanotechnology, quantum physics, silicon and III-V technology, applied physics, materials, space and others, you can also join our news and publications discussions. We also provide an off-topic forum category. If you need specific help on a scientific problem or have a question related to physics or technology, visit the PhysOrg Forums. Here you’ll find experts from various fields online every day.
To quit out of "lo-fi" mode and return to the regular forums, please click here.