What brought WTC 1&2 to the ground?

[adimon]

Really simple poll, but also, with any luck we can use this thread as a scoop for some of the less-discussed theories. NPT has several of its own threads, but I'm sure there are areas of research I've not looked into yet. As always, apologies for my categorisation if you disagree with it.

[killtown]

When has thermite ever been used to help pull a building before or after 9/11?

[cyince]

The fist option should probably be Heat weakened steel...

[john white]

Thermite melted steel after planes hit

This should be "thermite as a precursor for high explosives"

There has never been a "Thermite brought the towers down" theory: certainly not from Steven Jones

[mr_pixie]

This should be "thermite as a precursor for high explosives"

There has never been a "Thermite brought the towers down" theory: certainly not from Steven Jones

So John conventional explosive's turned concrete and steel to fine dust then?
Please answer this question.;)

[supertzar]

So John conventional explosive's turned concrete and steel to fine dust then?

Good question.

[masonfree party]

made a mistake...selected another theory instead of DEW/controlled demolition...can it be altered?

[narcolepticwatchman]

So John conventional explosive's turned concrete and steel to fine dust then?
Please answer this question.;)

i think he has chosen to re-choose the choice he initially decided to choose then recently chose to unchoose.:D

I don't think you will get an answer.....he never elaborated on his theories in my previous debates on the subject....but I was wrong and he was right anyways as usual:confused:

However, he did link to the 'independant' (Government sponsored) Finite Element Analysis video on a previous thread which indicates that he goes along with the official line so we can therefore deduce that according to John White, planes alone brought down the towers. If this isn't the case, he is a walking contradiction who cherry picks evidence to back up his stance in arguments regardless of source.

[cyince]

So John conventional explosive's turned concrete and steel to fine dust then?
Please answer this question.;)

Out of curiosity, what is your source that steel and concrete were turned to fine dust?

I was under the impression that the majority of the 'micro dust' at the site was from a combination of fiberglass and, gypsum board.

I have had difficulty finding a reputable source for a composition of the dust.

[helloperator]

I don't know what brought them down. Those angular cuts on the pictures of beams look interesting....like a deliberate cut. The towers sure look like they were blown up...just exploded.

After a while I walked around my home town in Brisbane, just looking at the tall buildings there...trying to imagine one falling vertically down....in the pancake style we were told about from the towers. Anyway, to my eye there was no way a buidling would keep coming down like that. I mean, surely it would not come ALL the way down like that in a vertical fashion. It's extraordinary when you look at it....when I tried to imagine, I just couldn't see it.

So what brought the towers down? I don't know. But I would like to know.

[snoopsnuffleopagus]

Cordial Felicitations Adimon:

I am not able to vote, because, quite frankly, I haven't the Foggiest Idea of what actually caused the Towers to collapse in the Manner they did. I ascribe to no Theory.

It's an Algebraic Equation and the Values of the Known Integers are not fully Known, and there are probaly Unknown Integers, thus their Values are Unknown.


Tough Equation to solve.

Those who could provide the information we seek will not speak honestly: Rumsfeld & Cheney



Kind Regards: Snoopsnuffleopagus



Addendum: Have you been able to read Karl Kochs Book yet?: Men of Steel.

[mr_pixie]

made a mistake...selected another theory instead of DEW/controlled demolition...can it be altered?

Soft bastard:D

[mr_pixie]

Out of curiosity, what is your source that steel and concrete were turned to fine dust?

I was under the impression that the majority of the 'micro dust' at the site was from a combination of fiberglass and, gypsum board.

I have had difficulty finding a reputable source for a composition of the dust.

http://www.drjudywood.com/articles/dirt/dirtpics/bubbler.jpg

http://www.drjudywood.com/articles/dirt/dirtpics/Image28.jpg

http://www.drjudywood.com/articles/dirt/dirtpics/5710.jpg

http://www.drjudywood.com/articles/dirt/dirtpics/Image38.jpg

Do you believe your own eyes?

Pulivised to dust!

http://www.drjudywood.com/articles/dirt/dirtpics/GJS-WTC032.jpg

Please go to Judys Website www.drjudywood.com

[cyince]

http://www.drjudywood.com/articles/dirt/dirtpics/bubbler.jpg

http://www.drjudywood.com/articles/dirt/dirtpics/Image28.jpg

http://www.drjudywood.com/articles/dirt/dirtpics/5710.jpg

http://www.drjudywood.com/articles/dirt/dirtpics/Image38.jpg

Do you believe your own eyes?

Pulivised to dust!

http://www.drjudywood.com/articles/dirt/dirtpics/GJS-WTC032.jpg

Please go to Judys Website www.drjudywood.com

This Judy Wood?
http://video.google.ca/videoplay?docid=-558096240694803017

Clunkity Clunk?

My eyes are incapable of identifying material composistion from pictures.

[mr_pixie]

My eyes are incapable of identifying material composistion from pictures.
Wear some spectacules then:D

[mr_pixie]

Heres some Radio interviews for people:

http://Dr Judy Wood - WTC Pre-demolition Analysis (Dirt5) - Dynamic Duo - 19 Jul 2007.mp3

http://Dr Judy Wood - WTC Pre-demolition Analysis - Dynamic Duo - 19 Jul 2007.mp3

http://Judy Wood & Jim Fetzer - WTC Destruction FAQ - Dynamic Duo - 08 Feb 2007.mp3 (

Go to Andrew Johnsons website Check the evidence http://www.checktheevidence.com/audio/911/

[mr_pixie]

John White Wrote
You have become the anti-truther

Next you will be calling me an Agent:rolleyes:

[mr_pixie]

The Spire turning to dust

http://www.drjudywood.com/articles/DEW/dewpics/Image42.jpg

[cyince]

The Spire turning to dust

http://www.drjudywood.com/articles/DEW/dewpics/Image42.jpg

That looks like the spire collapsing. How much time is between each capture or photo?

[helloperator]

And what kind of charges sit in a spire like that and detonate with that effect? "Turning to dust" implies something to me like it is being exploded....it just dropped and the dust was left in the air I bet.

[adimon]

Just dropped in to have a read...great stuff everyone.

This is exactly the kind of thread I wanted it to be. Keep it coming!

Thank you to everyone who has posted so far. :)

[mr_pixie]

That looks like the spire collapsing. How much time is between each capture or photo?

Fair piont, I'm not sure. But you carnt really disprove what you see in these photos.
Go to http://www.drjudywood.com

The Steel does turn into steel dust.

[cyince]

See my problem with Dr. Judy Wood is that all the webpage is speculation backed by 'analysis' of video stills, and apples to oranges comparisons. (WTC to the King dome demolition). Despite the fact that she is/was a legitimate scientist I would expect more rigor from her empirical analysis. Captioned pictures, and diagrams aren't research or how research is presented.

Her work has been the subject of much debate and the majority of people feel she has been discredited, and her work a joke. Things like clunkity clunk, or telling people calculations are irrelevant make me question her entire thesis.

EDIT: And with all that dust you would think that she would have gotten her hands on some and done an analysis, that would definitively say that the majority of it was concrete and steel.

[helloperator]

I'll take that one step further and say that I don't think any internet site or any internet forum can prove anything at all.

[cyince]

I'll take that one step further and say that I don't think any internet site or any internet forum can prove anything at all.

I believe that they can in fact prove some things, but the scope of things they can prove is limited. For the most part the majority of internet 'research' is simply rehashing and vague subjective interpretation of already existing data. Analysis is limited to the data that is available to them. Unfortunately, Google, wikipedia and youtube simply are not reliable/verifiable sources.

[john white]

So John conventional explosive's turned concrete and steel to fine dust then?

Good question.

If STEEL had been turned to dust, it would be: but steel wasnt turned to dust. There were massive amounts of steel debris that had to be removed from ground zero:

Some 185,101 tons of structural steel have been hauled away from Ground Zero. Most of the steel has been recycled as per the city's decision to swiftly send the wreckage to salvage yards in New Jersey. The city's hasty move has outraged many victims' families who believe the steel should have been examined more thoroughly. Last month, fire experts told Congress that about 80% of the steel was scrapped without being examined because investigators did not have the authority to preserve the wreckage. 1

Where is this evidence for steel "dustification"? Judy wood squinting at a photo she cant even understand basic perspective in? Thats not even close to good enough. And concrete been exploded by explosive force isnt much of a mystery at all

the Truth remains: we do not know exactly how the Towers were brought down, but the evidence is clearly pointing towards some kind of charges inside the building rather than non-existant spce beams

And its irrelevant:

All we NEED to know is the impossible implausability for the case for the explanation brought forward by the Official theory

[mr_pixie]

Most of the steel had dissapeared vapourised into thin air its as if what ever weapon was used, was turned off on purpose just before or at lest two thirds down into the towers before it reached the ground, so to leave some debrie. And the the next day they brought in tuck loads of soil Landfill, top soil and even potting compost to mix in with the small about of debrie to bulk it up to make it look like there was mountains of it. When the truth is that there was not much of a debrie pile.


If STEEL had been turned to dust, it would be: but steel wasnt turned to dust.
Steel was turned to steel dust just use your own eyes, the evidence is in the pictures on www.drjudywood.com

[mr_pixie]

the Truth remains: we do not know exactly how the Towers were brought down, but the evidence is clearly pointing towards some kind of charges inside the building rather than non-existant spce beams

The Truth remains: We dont know exactly how the Towers were brought down, but the evidence is clearly pionting towards some kind of DEW weapon rather than using conventional explosives to turn concrete and steel into fine particlues of dust that carry on breaking down into untra fine particules after the dust has settled down on the ground, and then for the dust to start rissing up again into the atmosphere.;)

How do you explain this then matey?

[mr_pixie]

http://www.drjudywood.com/articles/dirt/dirtpics/AASreeetStunnedAP.jpg


http://www.drjudywood.com/articles/dirt/dirtpics/Image39.jpg

Notice dust coming up from the ground.

Please listen to this radio interview and go to Judys site and they will talk you through the stills.

http://Prof Judy Wood - Dynamic Duo - More WTC Rust and Dirt Analysis - 27 Jun 2007.mp3 (

[sensimillia]

The Spire turning to dust

http://www.drjudywood.com/articles/DEW/dewpics/Image42.jpg

couldn´t this simply be dust from the concrete that lay on the steelspire, and when the spire collapsed, the dust spred. sorry for my lousy english, but i think you know what i mean...

[mr_pixie]

couldn´t this simply be dust from the concrete that lay on the steelspire, and when the spire collapsed, the dust spred. sorry for my lousy english, but i think you know what i mean...

No, this is dissoliving before you eyes. The dust coming from the sides.

[sensimillia]

The dust coming from the sides.


dust have a tendecy to stick to all sorts of material, especially steel. so that i comes from the sides proves nothing. but who knows...

[boots]

Hundred tonnes of material falling down at free fall speed 10sec with the help of controlled demolitions, you can see the squibs in the video footage. Will turn 90% of it to dust like a sledgehammer hitting a rock. As for that spire photo inconclusive. as for vaporising it with DEW. yeah right 100s of firemen,police an port authority people would have something to say about that?

[mr_pixie]

Hundred tonnes of material falling down at free fall speed 10sec with the help of controlled demolitions, you can see the squibs in the video footage. Will turn 90% of it to dust like a sledgehammer hitting a rock. As for that spire photo inconclusive. as for vaporising it with DEW. yeah right 100s of firemen,police an port authority people would have something to say about that?


Hundred tonnes of material falling down at free fall speed 10sec with the help of controlled demolitions, There wasnt that much in the way of debrie from two 110 story buildings.
Were has all the debrie gone?http://www.drjudywood.com/articles/DEW/dewpics/search2.jpg


you can see the squibs in the video footage. I dont think the squibs were the detonation pionts for the bombs,the squibs might have more to do with the chemical that was used to weaken the steel to bring down the towers. Notice the Squibs are very similar to the dust/fine powder that found everywere.
http://www.drjudywood.com/articles/dirt/dirtpics/0143v.jpg



Will turn 90% of it to dust like a sledgehammer hitting a rock.No thats wrong if you hit conctrete with a sledgehammer then there will be diffrent size chunks of concrete breaking off, and there is no evidence of the concrete breaking into diffrent size peices on 9/11 it all turned into fine powered talc along with all the other contents in the builing.

look at the fine talc on the ground in this picture below?
http://www.drjudywood.com/articles/dirt/dirtpics/Ground_Zero_Streets_17.jpg


As for that spire photo inconclusive. Use your eyes!


as for vaporising it with DEW. yeah right 100s of firemen,police an port authority people would have something to say about that?Your not ment to see it.

[cyince]

Mr. Pixie, what evidence do you have that the dust is in fact concrete and steel?

http://health.usgs.gov/inhalation/wtc_dust.html

Are these studies lies?

[mr_pixie]

Mr. Pixie, what evidence do you have that the dust is in fact concrete and steel?

http://health.usgs.gov/inhalation/wtc_dust.html

Are these studies lies?

Because theres wasnt any concrete left and therewasnt much steel left either. Plus the evidence is in the pictures and video evidence.:)

[moonoodoo]

I think you have all missed the point on this one. Read the question properly and you will probably agree ....

Answer: GRAVITY brought the WTC 1&2 to the ground.

I think the 'Any other theory not mentioned' gets it, only 10% of those that voted got close to the truth!!

[aizzy]

with any luck we can use this thread as a scoop for some of the less-discussed theories.:.
:D

;.the people did'nt knock down tho's towers, the people just have to live in a world which tho's tower have torn apart.::(

[aizzy]

Fictional character biography

[edit] Early life
Ra's al Ghul's early life and exact age are somewhat difficult to recount by writers. The current, in continuity, origin story is told in the graphic novel Batman: Birth of the Demon (1992) by Dennis O'Neil and Norm Breyfogle.

As told in Birth of the Demon, Ra's al Ghul is born over six hundred years ago to a tribe of nomads in a desert somewhere in Arabia, near a city whose inhabitants' ancestors have journeyed to the Arabian Peninsula from China. Ra's is interested in science from an early age. Unable to learn any science living as a nomad, he abandons his tribe to live in the city, where he can conduct his scientific research. He becomes a physician and marries a woman named Sora, the love of his life.

Ra's discovers the secret of the Lazarus Pit, and he saves a dying prince by lowering him into it. The prince, who is sadistic to begin with, is driven completely insane by the Lazarus Pit. He proceeds to strangle Sora, on whom he has already had his eye for some time. The ruler of the city, unwilling to admit to himself his son's culpability, declares Ra's guilty of the crime and sentences him to a slow, tortured death in a cage with Sora's corpse.

Ra's is set free by the son of an elderly blind woman, despite having failed to save her. The son feels that he owes Ra's a debt for easing his mother's suffering during her last few hours. Ra's and the son head into the desert to seek the tribe that Ra's was born into. Ra's convinces the head of his tribe, his uncle, to follow Ra's in his quest for revenge by promising the downfall of the king of the city. By understanding the germ theory of disease hundreds of years before anyone else, Ra's is able to infect the prince with a deadly virus by sending him contaminated fabrics. When the ruler of the city comes to ask Ra's to cure the prince again, Ra's kills both him and his son. Ra's then leads his tribe to raze the city to the ground and kill all of its inhabitants. Subsequently, Ra's declares himself the "Demon's Head."

Note: Batman: Birth of the Demon provides a rough figure of 500 years for Ra's al Ghul's age. Due to living so long, he assumes to have lost track of how old he is. However, Azrael #6 (July 1995; written by Ra's al Ghul's co-creator Dennis O'Neil) places Ra's closer to 450 years old. "I appear to be a vigorous fifty. I am actually a very vigorous four hundred and forty-eight...or is it four hundred and fifty-three? I lost count during the Black Plague. No matter." - Ra's al Ghul to Jean Paul Valley.

However, in 'Batman Annual 25' (published in 2006), Ra's Al Ghul is described as a "700-Year Old International Terrorist".:confused:

[cyince]

I would argue that there was a large amount of steel and debris.

http://www.zombietime.com/wtc_9-13-2001/ <- still lots of steel and concrete 10 days later
http://www.fbi.gov/page2/nov03/nyhs112703.htm
http://www.americanrecycler.com/11wtc.html
http://wtc.nist.gov/media/gallery.htm#recover
http://www.nytimes.com/2002/05/29/nyregion/29GIRD.html <-- 9 months till the last of the steel is removed



Other debris list
http://wtc7lies.googlepages.com/wtcdebrispilescomposition

Its easy to show 1 or 2 photos out of context to support you hypothesis, but there is an immense wealth of photographic evidence to contradict you claims that there was little concrete or steel.

[christophera]

couldn´t this simply be dust from the concrete that lay on the steelspire, and when the spire collapsed, the dust spread. sorry for my lousy english, but i think you know what i mean...

I've studied this issue for years. This question relates to the likely answer.

That looks like the spire collapsing. How much time is between each capture or photo?

And what kind of charges sit in a spire like that and detonate with that effect? "Turning to dust" implies something to me like it is being exploded....it just dropped and the dust was left in the air I bet.

helloperator has stated what I believe to be the answer.

If STEEL had been turned to dust, it would be: but steel wasn't turned to dust. There were massive amounts of steel debris that had to be removed from ground zero:

the Truth remains: we do not know exactly how the Towers were brought down, but the evidence is clearly pointing towards some kind of charges inside the building rather than non-existant space beams


Having viewed the documentary in 1990 titled, "The Engineering and Construction of the Twin Towers", I'm aware that the towers had a steel reinforced cast concrete tubular core. I'm also aware that there was a "special plastic coating" on the high tensile steel rebar used in the concrete shear walls of the core.

The animation here seems to have a different frame sequence and the steel is seen falling in the dust cloud, just barely.

http://st12.startlogic.com/~xenonpup/spire/dustspire.gif

Here is a still of the spire.

http://home.comcast.net/~jeffrey.king2/wsb/media/56016/site1074.jpg

here is a shot taken from the same camera after the spire has fallen.

http://home.comcast.net/~jeffrey.king2/spire_dust-3.jpg

What stands I know to be the 3 inch high tensile steel rebar. The 1990 documentary talked about the "special plastic coating" on one wall of the core being exposed to a harsh winter, 1969 I think. It stated that the concrete contractor immediately completely tying the steel, formed and poured, THEN, somebody with the PA decided to check to see if the "anti corrosion, anti vibration plastic coating" (I swear to God, that is what I remember) was still viable. It was not. Command decisions were made to not attempt tot break the concrete down and replace the rebar with its "special plastic coating" and to just continue with the towers construction.

I believe that rebar above is the rebar that had the deteriorated coating. To support that some of the C4 coated rebar did not detonate from far up in the WTC 1 core I show this. Witness below the massive triangular piece of concrete of the east core wall falling into the core area. The spire can be just barely seen in the slightly low res image I scanned from a book.

http://algoxy.com/psych/images/wtc.1core.fall.jpg

hypothesis for the spire and dust.
I feel that helloperator is correct and that the explosive circuits of the core were interrupted in some fashion by the bad C4 on some of the rebar and that initiation of the horizontal rebar which was tied to the vertical rebar that was not viable detonated from the circuits below and removed the concrete to expose the vertical rebar in the image above. When that horizontal rebars C4 detonated the heavy structural steel comprising the spire fell, and left the rebar in the image above, ... standing.

The shock wave from the horizontal rebar detonating throws concrete dust and particulate in all directions from behind the heavy steel seen in the still frames which do not have the correct sequence to show the steel falling.

The rebar seen in the lower image was tucked in behind the heavy steel of the spire (see bottom image). It is also visibly lower. WTC 1 had a tapering core wall, as the tower went up, the interior box columns remained plumb and horizontal "I" beams spanned the short distance from the plumb column to the core wall face. Dimensions of the taper changed at the 43rd floor where the heavy mechanical equipment was, just below the spire I think, so there was probably on 2 to 3 feet between the concrete core face and the spire at that elevation.

This image shows that dimension and the end view of the concrete core wall inside the spire.

http://algoxy.com/psych/images/wtc1spirecorewall.jpg

And yes John, non existent space beams. THX!

[cyince]

So exactly when was the C4 re-bar placed in the building? What sort of detonation mechanism was there. What trigger mechanism? Wired, wireless?

[shredmasteruk]

The fire melted steel thing, is not what engineers believe.

Engineers believe that fire's weakened it.

It would help if you changed the wording of your poll, because none of the options in your list fit with my views as a trained engineer.

Please check these out:
http://www.corusconstruction.com/en/design_and_innovation/structural_design/fire/steelwork_fire_resistance/

http://www.mace.manchester.ac.uk/project/research/structures/strucfire/materialInFire/Steel/default.htm

[helloperator]

Weakened the steel at around the impact zone/ fires....but the steel 30 floors below would have been as strong as ever...why didn't any of that steel, any of the core put a stop to the pancaking? I can imagine a collapse at around the weakened steel...but the hundreds of tonnes of still robust steel below surely could and should have stood up for itself, rather than just caving in. I don't think the weight of all the mass at the top is a good excuse either because, as we saw, a shit load of material flowered out and away from the building. What happened to the perfectly good condition steel 20, 30, 40, 50, 60 floors below the weakened fire/ impact steel? It held the trade centre up for decades, yet caved in twice in a day in 50 odd minutes.

Also, does anyone know how many floors survived? Did any floors survive? Even the first 5 or something?

[shredmasteruk]

Yes mate the floors below the impact zone were as strong as ever, but the only thing you don't realise here, is that they were not designed to recieve such an impact, and the truss bolts which held everything together, were exposed to shear force & bending force way beyond the safety limits.

As can be seen in the photograph below, those bolts failed:

http://www.iridescent-designs.co.uk/images/wtc/trussbolt-failiures.jpg

When the floors above fell onto the floors below, there was not sufficient reinforcement to arrest the collapse, and the stuff below fell with it. Momentum was transferred and it just kept going.

The same thing happened with a corner of the Ronan Point building when that collapsed after a gas explosion in the 1960's.

[shredmasteruk]

Here's some stills of WTC 2 collaping, they clearly show a bending moment takes place in the impact region:

http://www.infowhores.co.uk/images/collapse/justbeforecollapse.jpg

http://www.infowhores.co.uk/images/collapse/compressing.jpg

http://www.infowhores.co.uk/images/collapse/collapsing.jpg

http://www.infowhores.co.uk/images/collapse/collapsing2.jpg

http://www.infowhores.co.uk/images/collapse/collapsing3.jpg

http://www.infowhores.co.uk/images/collapse/largechunks-falling-slower.jpg

[helloperator]

The bolts failed in that particular piece of steel. There's shots of angular cut steel too.

Those collapse sequence pics make me really question the pancaking...because of the angle there it seems as if the required force on the other side would not have the same impact...yet the pancaking implies that every floor was impacted squarely and therefore unharmed steel core material strong enough to hold the weight of the building up for so many years suddenly fails in all areas...despite those photos above showing that only one section of steel gave in. I think it's questionable that such a collapse initiation kinking in as it did in one area, on one side spells the end also for uncompromised areas of the structure.

So much material flowered out and away. Mind you I'm sure a shitload was still central.

The angle of the fall says to me that half the building should have stayed up. Something should have stayed up. But it didn't. The whole lot came down. Not with the jaw dropping precision of wtc7...but still....it alllll came down.

[veritas2007]

Please excuse my crude diagram and ignorance of structural design, but wouldn't we have expected to see something like this happen based on the photos above?:

http://img507.imageshack.us/img507/5123/wtccollapsevh0.gif

Would the upper half of the tower (above the damage) simply have fallen away, possibly damaging several floors directly below the buckling point?

Genuine question.

[shredmasteruk]

Veritas, I can understand why you'd think that, but no, the downward momentum of the heavy core was too great, as the following paper expains:

http://www-math.mit.edu/~bazant/WTC/WTC-asce.pdf

Helloperator, do you mean these angled cuts: http://www.whatreallyhappened.com/IMAGES/thermiteonwtccolumns_small.jpg
? because they were made by flame cutters during the clean up operation.

Here's some more pics of flame cutters at work:
http://www.iridescent-designs.co.uk/images/wtc/flamecutter-wtc-1.jpg

http://www.iridescent-designs.co.uk/images/wtc/flamecutter-wtc-2.jpg

http://www.iridescent-designs.co.uk/images/wtc/flamecutter-wtc-3.jpg

http://www.iridescent-designs.co.uk/images/wtc/flamecutter-wtc-4.jpg

[veritas2007]

Thanks for the info shredmasteruk.

Veritas, I can understand why you'd think that, but no, the downward momentum of the heavy core was too great, as the following paper expains:

http://www-math.mit.edu/~bazant/WTC/WTC-asce.pdf

From the paper:

Abstract: This paper3 presents a simplified approximate analysis of the overall collapse of the towers of World Trade Center in New York on September 11, 2001. The analysis shows that if prolonged heating caused the majority of columns of a single floor to lose their load carrying capacity, the whole tower was doomed. The structural resistance is found to be an order of magnitude less than necessary for survival, even though the most optimistic simplifying assumptions are introduced.

The "prolonged heating" theory needs to be established for this hypothesis to apply. The South tower collapsed 57 minutes after it was attacked and it can be seen from the videos that a huge fireball erupted outside of the tower. So, was there sufficient fuel ignited inside of the tower to cause the prolonged heating required for "the majority of columns of a single floor to lose their load carrying capacity"?

I'm interested to know whether the design of the towers were uniquely susceptible to fire or if the hypothesis in the paper can be applied to other tower block fires (and maybe subsequent collapses). If the design was not unique in this regard, then it has to be questioned why other tower block fires have not resulted in the same demolition.

The mathematics used in the paper were beyond my elementary knowledge unfortunately, but did the calculations show why the chain reaction of failures would result in collapses in under 10 seconds?

[shredmasteruk]

Veritas, I don't think they were uniquely susceptible to fire, other buildings have also collapsed due to fire, I don't know if I've already mentioned this fire, but the ESP paper factory near malvern collapsed due to fire last year, main fuel there, was toilet roll...

http://news.bbc.co.uk/1/hi/in_pictures/6106898.stm

The nonreinforced section of the Windsor Tower in Madrid also collapsed due to fire, though the reinforced concrete floors below floor 17 were able to arrest the collapse of the steel section:

http://www.mace.manchester.ac.uk/project/research/structures/strucfire/CaseStudy/HistoricFires/BuildingFires/default.htm

And on the 3rd of november this year, in warwickshire, four firefighters died in a warehouse fire, after a roof partially collapsed due to steel supports weakening due to heat.

The cable fire research association http://www.cablefireresearch.org/ are concerned by the proximity of plastic cabling next to steel load bearing members. Think of a large office building with hundreds of computers on each floor, with all the cat 5 cables that go with it, then the large amount of redundant BNC cabling in from the obsolete network they had before, but did not completely remove due to the costs involved, all the telephone cabling, electrical mains cabling etc ? all that going next to load bearing steel...

Some buildings perform better than others in fire, regardless of whether or not planes have crashed through, causing structural damage to it aswell.

[helloperator]

Helloperator, do you mean these angled cuts

Yeah, got any pics of cleanup guys making an angular cut like that first pic? Sure, the rest of the pics show them using cutters...but the angled one is still in the debris...etc. Looks a bit strange.