How it Fell.

in case you wanted to know.

A good explanation

How the World Trade Center fell

The design of the World Trade Center saved thousands of

lives by standing for well over an hour after the planes crashed into its

twin towers, say structural engineers. But the towers' ultimate collapse was

inevitable, as the steel cores inside them reached temperatures of 800C -

raising questions why hundreds of rescue workers were sent into the doomed

buildings to their deaths. The steel and concrete structure performed

amazingly well, said John Knapton, professor in structural engineering at

Newcastle University, UK. "I believe tens of thousands of lives have been

saved by the structural integrity of the buildings," he said. "They had a

lot of their structure taken out, yet they remained intact for more than an

hour, allowing thousands to escape."

But as fires raged in the towers, driven by aviation fuel,

the steel core in each building would have eventually reached melting point

- 800C. The protective concrete cladding on the cores would certainly have

been no defence in these extraordinary circumstances. "It was the fire that

killed the buildings. There's nothing on Earth that could survive those

temperatures with that amount of fuel burning," said structural engineer

Chris Wise. "The columns would have melted, the floors would have melted and

eventually they would have collapsed one on top of each other."

The building's construction manager, Hyman Brown, agreed

that nothing could have saved it from the inferno. "This building would

have stood had a plane or a force caused by a plane smashed into it," he

said. "But steel melts, and 24,000 gallons (91,000 litres) of aviation fluid

melted the steel.

Nothing is designed or

will be designed to withstand that fire."

Once the steel frame on one floor had melted, it collapsed

downwards, inflicting massive forces on the already-weakened floor below.

From then on, the collapse became inevitable, as each new falling floor

added to the downward forces. Further down the building, even steel at

normal temperatures gave way under the enormous weight - an estimated

100,000 tonnes from the upper floors alone.

"It was as if the top of the building was acting like a huge

pile-driver, crashing down on to the floors underneath," said Chris Wise.

Early in the unfolding horror, some office workers were told

to stay where

they were - dreadful advice, said Professor Knapton.

People's only hope was

to run and keep running - reaching open ground. The building

could have fallen over sideways, he points out, potentially bringing even

greater devastation.

Another 47-storey building belonging to Salomon Brothers

caved in later, weakened by the earlier collapses, and more nearby buildings

may still fall, say engineers.

But the eventual collapse of the twin towers was so

predictable that the order should have been given to withdraw emergency

services within an hour, said Professor Knapton. He watched in horror,

knowing the building would fall within two hours.

The hundreds of dead firemen and police officers should

simply not have been there, he said. "I think they should not have gone in

at all," he said. "If they did decide to take the risk, they should have

been pulled out after an hour."

But in the panic and horror, the order was never given for

rescue workers to abandon the building. "Mistakes were made," said Professor

Knapton. "It sounds harsh - this had never happened in the world, so you

can hardly criticise them. But I would have given the order to get out. You

would have thought someone with technical expertise would have been advising

them." But he acknowledged that the sheer scale of the tragedy probably

overwhelmed the operation commanders. "I think everyone was not thinking. It

was like a horror film and I think people's rationale had gone," he said.

The building's design was standard in the 1960s, when construction began on

what was then the world's tallest building. At the heart of the structure

was a vertical steel and concrete core, housing lift shafts and stairwells.

Steel beams radiate outwards and connect with steel uprights, forming the

building's outer wall. All the steel was covered in concrete to guarantee

firefighters a minimum period of one or two hours in which they could

operate - although aviation fuel would have driven the fire to

higher-than-normal temperatures. The floors were also concrete. The building

had to be tough enough to withstand not just the impact of a plane - and the

previous bomb attack in 1993 - but also of the enormous structural pressures

created by strong winds.

Newer skyscrapers are constructed using cheaper methods. But

this building was magnificent, say experts, in the face of utterly

unpredictable disaster.

Not that I'm an expert or anything but I'd like to point out that the steel doesn't need to melt to lose structural integrity, it starts to become unreliable at 1500 degrees Fahrenheit. (Think of an apple being held up by a chocolate bar over a gap between two tables. Raise the temperature. Long before the chocolate melts, it will be just soft enough for the apple to cave through it.)

nevermind......

thats one thing i was completely surprised at. It didn't topple like a domino. I never thought it would fall into itself like an executed take down by a demolition company.

i think it was more than the planes impact and fire i dont know why its just a thought.

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"Babylon throne gone down" -Rastaman

Thanks TT Boy, that was a concise and well written article that summarized all of the information I have been hearing.

By the way Cracked-according to experts (I know a few engineers and architects) steel weakens at 1000 Degrees and melts at 1500 Degrees. They estimate that the fire which was being fed by the jet fuel was 2000 Degrees or higher.

how would a demolition company take down such buildings if they needed to be demolished, that is a question which has been bothering me lately. it clearly fell in on itself, but the collateral damage was immense. i heard the guy from the demolition company that took down the oklahoma city federal building on the radio talking about it, he said his company had never attempted this scale of a project before. incidentally, the architects who designed the building did worry about what would happen if a airplane hit the building, dismissing the possibility that the structure would be weakened further due to the resultant fire. anyway if the fire was burning at 2000 degrees, the steel was insulated from direct contact by cement which has thickness the heat would have to come through before the steel sees it, then the steel which also has thickness, i'm sure somebody has to have done the math and i doubt any substantial amount had a chance to melt in that short period of time, and certainly not the entire core http://www.12ozprophet.com/ubb//smile.gif'>.

Originally posted by 23578:

…what if it was left intact, but damaged enough to require demolition? how would such a task be accomplished? i always have had my suspicions that we are implementing technology without considering the legacy of problems, but this seems now to be far more of an issue than i had previously considered…

i have been thinking of that as well..

i ran into a construction worker last night near the disaster center of wtc, and he started to explain some of what was going on at the moment, then it caught up with him and he got mad emotional... i felt really bad for that guy, and all the other people cleaning up that place, with body parts and whatnot.. there are going to be mad people who become emotional wrecks because of this, myself included.

23578.

so what i wonder, in your existence on earth, has prepaired you to understand the weakening process of iron and concrete better than scientists, architects and engineers the world over? the math had been done, and the estimate was two hours. they believe that the building would hold itself up for two hours. as cracked stated, you dont have to get the metal so hot that it melts back into a liquid state, just hot enough that it starts to loose its integrity. when that happens, you have thousands of tons of concrete bearing down on it and gravity does the rest. it wasnt poor planning or bad design, there are simply some things that you can design around. also, there is really no comparison to the OKC bombing, that building was a fraction of the height of this one. and how would they take it down? there is no precident for such a thing. no one has ever had to manualy take down a 110 story building before.

"My opinion is, based on the videotapes, that after the airplanes hit the World Trade Center there were some explosive devices inside the buildings that caused the towers to collapse," Romero said.

A demolition expert, Romero is a former director of the Energetic Materials Research and Testing Center at Tech, which studies explosive materials and the effects of explosions on buildings, aircraft and other structures.

He said he and Denny Peterson, vice president for administration and finance, were en route to an office building near the Pentagon to discuss defense-funded research programs at Tech. Romero told the Albequerque Journal that he based his opinion on video aired on national television broadcasts.

The detonations could have been caused by a small amount of explosive put in more than two points in each of the towers, he said. "It could have been a relatively small amount of explosives placed in strategic points," Romero said.

so before the attacks, someone placed explosives inside the buildings at the very points where they hit? expert or not, thats pretty far fetched. especially considering the amount of fuel the planes were carrying and how the set up of a building and its compartmentalization (is that even a word?) would direct the burst of an explosion and perhaps make it look like smaller detonations in other parts of the floor...

Originally posted by seeking innocence:

23578.

so what i wonder, in your existence on earth, has prepaired you to understand the weakening process of iron and concrete better than scientists, architects and engineers the world over? the math had been done, and the estimate was two hours. they believe that the building would hold itself up for two hours. as cracked stated, you dont have to get the metal so hot that it melts back into a liquid state, just hot enough that it starts to loose its integrity. when that happens, you have thousands of tons of concrete bearing down on it and gravity does the rest. it wasnt poor planning or bad design, there are simply some things that you can design around. also, there is really no comparison to the OKC bombing, that building was a fraction of the height of this one. and how would they take it down? there is no precident for such a thing. no one has ever had to manualy take down a 110 story building before.

mr. seeking, i did in no way try to offend you personally by making the statement that no one can determine what exactly caused the building to collapse without some sort of simulation, reconstruction of the impact and subsequent fire. i feel i need to make myself clear, the variables are too great to consider at this time, the damage sustained by the core by the impact and subsequent explosion in the vertically confined space at the time of impact, subsequent temp. of fire, location and intensity of fire, and a whole lot of other stuff i am sure. it doesn't take an engineer to see that what they are telling us at this time is mearly circumstantial evidence. maybe there are lessons to be learned from this as relates to building of said skyscrapers in the future. as for the poor planning and design, i will say this: my opinion is that these type of buildings are not permanent structures, and that they can't be taken out, so why do they build path stations underneath them and in their shadow, bus terminals, etc. i don't think that cities are realistic in their planning, no. if you have a building like this it should be not be jammed up against many others, and certainly no transportation infrastructure should be built underneath it.

"no one has ever had to take down a 110 foot story building before"-my point exactly.

Yeah that sounds far-fetched. I think the original explanation was adequate.

I'm just really surprised they fell, I never thought I'd outlive the Twin Towers, they always fascinated me even from childhood. I never did get to go up in them.

The Empire State building was hit by a small plane a long time ago, maybe the 1930s, and the structural damage was next to nothing, even with a subsequent fire. I guess the size, speed and jet fuel factors of a 767 make all the difference.

then there was also the time that ginat monkey climbed up. that was nuts. thank god it made it through that too.

23578. i wasnt taking it personaly at all, just arguing for the sake of factual representation. no offense i hope.

absolutely, i guess if you thought i took offense it was probably because i normally do with you (you literally asked for it once, i just kind of took it to heart more than everyone else). i'm just about keeping things interesting and keeping people involved in this there are some pretty far reaching ideals that have to be forged out for the way we think about the world, and it's only going to profit from this, i hope.

man these topics are building up a bit fast, i've got to step out for a while as well, peace.

the twin towers were actually extremely structurally sound buildings.

i know that they fell, so before anyone goes jumping down my throat, let me explain. the twin towers were highly reinforced, more so than other skyscrapers of its kind. As everyone probably knows, the structure was built with steel that allowed for a certain ammount of leniency for swaying. This gave the towers great structural integrity, since they were made of an extremely strong steel armature and reinforcements, yet were still capable of a certain degree of elasticity.

the towers actually handled the damage from the 2 planes quite well. The strength of the beams managed to withstand the impact of these large commercial aircrafts. The tower did not topple from the force.

the reason why the towers fell was from the heat of the fire. the steel was eventually weakened from prolonged exposure to extremely high temperatures. This is what caused the steel frame to buckle and fall in upon itself. From there, it was all dominoes. As each floor fell, the weight got heavier, and the steel beams closer to the middle and bottom, which were not heated by the fire, could not withstand the outstanding force.

i am not an engineer, but i got my information from 2 sources: the engineers who designed the building and another engineer who was in the news.

Demolitions can be done in many ways,if the area is clear they use explosives,if not,it may take 6 months but they can bring everything down.It aint that hard.As far as security goes...The twin towers took 2 airplanes and stood on their place,the design and structure of the building prove excellent(if you have earthquakes where you live you know what i mean)Can you think of could have happened.

Now as far as iron melting,Thats just life.

All reasons can be understood by an autopsy(sp?)The collapse of a buiding when a plane with enough fuel to travel from one coast to another crashes on it,Doesnt belong to metaphysics and paranormal activity,Its plain data.You think the terrorists didnt thought of all of this?

And to return,i dont understand why are you being so negative and suspitious when history of architecture proves you wrong?

Which incident makes you afraid?

"it may take 6 mos."-that may be true, but they won't be demolishing it then will they, more like dismantling.

building "autopsies" take months, and that's even if they can isolate the area affected by the burn out of all of the rubble and determing what resulted from the impact, explosion and burn not from the collapse. i'm sure there are trained scientists that would be able to gleen knowledge from this, but with the rush to find bodies and remove the rubble preparing for the precious skyline. maybe someone who has experience with this could tell me that nothing can be done which would ease my fear that nothing will be learned. computer modelling probably hasn't progressed to the point of being able to recreate something like this but could give some data i'm sure, actual model building like they do for movies would give some data as well.

as for rebuilding the skyline, i think people have to start to think out of the box on how cities should be safely built, whether they NEED to be rebuilt, and what can be done to limit our reliance on cement and steel. cement is really sturdy but cannot withstand impact, steel is really tough and strong, but it melts.

i'm not sure i know what you mean when you say the history of architecture has proven me wrong. i was just commenting on this article which seems to be written by a layman, trying to point out where the facts are poor, and wondering out loud. sorry if i came off negative we all have to try not to come off that way. i thougth it was a pretty good article.

i wonder what revs is doing right now. much love goes out to anyone working to relieve the suffering of those who were affected.

here's an image showing the WTC's structure.

i took this image off of a website, but i can't remember what site...sorry.

http://www.kastsystem.com/structure.gif'>

[This message has been edited by KASTsystem (edited 09-14-2001).]

nice picture, sort of like giant rebar reinforced concrete. the composite nature of the structure would probably have not been able to sustain impact from a plane loaded with that much fuel exploding in close proximity, in the end maybe it was just the steel holding it up, who knows, not i said the fly, but maybe one steel beam melted and the remaining three fractured due to the added stress and already weakened steel. i don't think anyone can say for certain. maybe we'll have more information in a couple of months. i think that's enough speculation for now.

what if it was left intact, but damaged enough to require demolition? how would such a task be accomplished? i always have had my suspicions that we are implementing technology without considering the legacy of problems, but this seems now to be far more of an issue than i had previously considered. When was the Empire State built, 1920's?

bumperooni.

i'm doing a project on this shit, and was wondering if anyone had read anything new.

Also kast - you're picture isn't on your server anymore!! do you know where it was, or how i can grap it, or anything?

Originally posted by ShitFuck

Also kast - you're picture isn't on your server anymore!! do you know where it was, or how i can grap it, or anything?

yo, i'm sorry...i think i deleted it. so stupid of me to do that--i never delete my shit, and the one time i do it, someone needs it. anyway, it was a real good picture, i think i got it from cnn...check there.