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Leaked FEMA/ASCE Draft Report On WTC Collapse
securitas writes "The New York Times obtained a copy of the World Trade Center draft report by the Federal Emergency Management Agency and the American Society of Civil Engineers about the engineering failures that caused the towers to collapse. Among the findings: 'Fireproofing, sprinkler systems and the water supply for hoses were all disabled and the fires generated heat equivalent to the energy output of a nuclear power plant' reports the NYT (Yahoo link). Amazingly, if it wasn't for the fire (or another secondary catastrophic force), the towers would have remained standing."
Pity that:
- The WTC was a public building only "sold" a few months prior to the attack. It was built and owned by the Port Authority of NY & NJ.
- There are likely no other buildings in the world (possibly excepting the Great Pyramid) that could have held up as well/as long to the assault as the WTC did.
So 2 for 2 you were wrong; now please crawl back to your dark corner.I don't read ACs: If a post isn't worth so much as a nom de plume to its author then I wont bother either.
One of the contributing factors is the lack of Asbestos fireproofing above the 70th floors. New EPA laws were enacted during the construction of WTC that prohibited the spray-on fireproofing that was applied to the I-beams. With the fireproofing, the I-beams could withstand an esimated 2000 degree fire, and without they would lose temper and bend at approx. 1200 degrees.
The jet fuel burned at an excess of 2000 degrees,
so it's likely the towers still would have collapsed, but some extra time would have allowed further evacuation efforts.
Burning kerosine swims on water. No sprinkler system would have put out that fire. Halon would have been needed, but this surely would have been too expensive for the whole building to be equipped with. Nevertheless it surely would have delayed the colapse for a certain time if the sprinklers had worked and cooled the fire.
The report seems not to say anything about the fact that the WTC was a steel construction and thus rather unprotected against fire as opposed to ferroconcrete which is safer but would have needed the buildings to be smaller. This is the cause why there are not similar high buildings in Europe where regulations demand ferroconcrete.
TLC ran an interesting program about a month ago that went into detail about why the structures collapsed (beyond the obvious, crash, fire, etc).
The looked at factors like the blast having blown the fire protective coating off the steel and the way the building was designed with the majority of the load being carried by the steel skeleton on the perimeter of the buildings, as opposed to columns within. The achilles heel was reported to be the steel trusses running under the floors connecting the outer steel to the core.
The heat from the fire caused these trusses to weaken and fail, leaving the outer steel frame without the stabilizing and load-transfering benefit. By the time the first floor had begun to collapse, there was so much inertia in the falling portion of the structure that it was inevitable that the each floor below would fail under the crushing pressure.
They interviewed the cheif structural engineer and he said that they had designed the structure to withstand an impact from the largest airliner of the day, the 707... flying at low speed and lost in the fog. They didn't anticipate a modern widebody, loaded with enough fuel for a coast-to-coast flight crashing into the buildings at full speed.
He said that even if they took all that into account, he doesn't think there could have been any way to design the buildings to withstand that. The fact that the structures stood as long as they did is actually a testament to the good overall design (so the program said, anyway).
There is much cruelty in the universe, John.
Yeah, we seem to have the tour map.
Another famous New York Landmark also suffered an airplane collision. Now granted the airplane that hit the side of the Empire State Building was not the same size as the two that hit the World Trade Center, the B25 did quite a bit of structural damage. Enough damage in fact, that if simply the collision caused the Trade Center collapse, then the Empire STate (the plane did hit somewhere between the 78th and 79th floors)building should have also collapsed. In actuality the reason that the Trade Center collapsed and the Empire State building did not, is one of metallurgy. The thousands of gallons of jet fuel that were burning in the Trade Centers got hot enough to anneal the structural steel. When that happened the sheer mass of the floors above the impact zone collapsed triggering the chain reaction. Had the Jets that hit the Trade centers been nearly empty of fuel (ie. getting ready to land, instead of just taking off) the buildings would have survived the impact.
The following excerpt is from "Empire: A Tale of Obsession, Betrayal, and the Battle for an American Icon", copyright © 2001, available from John Wiley & Sons. It describes the impact of the B25 that hit the Empire State Building in 1945.
"Army Lieutenant Colonel William Smith Jr., a 27-year-old veteran of 34 bombing missions over Germany, had been flying a twin-engine B-25 bomber from Bedford, Massachusetts, to New York's LaGuardia Airport, and had secured permission to continue to Newark, New Jersey.
The fog was blinding. When he dropped down out of the clouds, he found himself approaching a forest of skyscrapers. In a panic, he banked away from the Grand Central Building, then from another tower on Fifth Avenue, only to find himself bearing down on the biggest one of all.
In desperation, he pulled up hard, twisting. The 10-ton (9-tonne) bomber plowed into the office of War Relief Services of the National Catholic Welfare Conference on the 78th and 79th floors, 913 feet (278 meters) off the street, tearing a gaping hole in the Empire State Building's north side."
The full article describing the impact in 1945 can be found here: Empire State Building Collision.
The WTC was designed to withstand the impact of the largest airliner of its time, a Boeing 707. A 757/767 isn't much more massive than a 707, but obviously the real problem is the tremendous amount of fuel that a cross-country flight carries.
In fact, it probably wouldn't have mattered what fire suppression system the building used...jet fuel is basically kerosene and it is much lighter than water. You can't effectively extinguish a kerosene fire with water. That's why you see aviation firefighers using something called aqueous film-forming foam. It floats on the kerosene.
Maybe to the layman the fact that the buildings survived the impact was amazing, but in fact it was simply a matter of good, purposeful design. Unfortunately, it's asking an awful lot to expect structural steel to survive the kind of intense temperature that is generated by an aviation fuel fire, particularly when the fuel supply is effectively limitless.
-h-
They're stuffed. Drywall had exactly nothing to do with this one.
However, I find interesting the fact that the lack of asbestos coating for the structural steel above the, what was it, 60th floor is being ignored. That was the insulation that was supposed to reduce the heat impact on the structural elements in just such a fire for ~8-10 hours. And application of which was stopped midway through construction, after NYC passed their "no asbestos" laws.
What I am trying to say is that the people who are thinking "the sprinklers couldn't have been expected to put out the fire because jet fuel was keeping it burning" and "the building collapsed because the fire was especially hot from the burning jet fuel" are wrong, because the jet fuel was gone long before the building collapsed. The sprinklers had a chance to put out the fire after the fuel was gone, but they didn't. The heat that caused the collapse came not from jet fuel, but from combustion of ordinary items. The argument about directness was only tangential to my real point.
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And with my idea if anyone can implment it, then hell that's great and all the power to you. I lost one of my best friends at the WTC, they just recovered his body a few days ago. Anyway, the fire was the problem the building design itself from an architechtual standpoint was brilliant.
Therefore, to solve the problems with the fire we need a fuel that will either burn very very slow when NOT under pressure, or not burn at all unless it's under pressre, ala + 350-450psi.
Slam a jet into the building and you'll have a fire that burns very slowly or no fire at all. And as I said, if someone can make this happen then I'll be happy for you. You'll save some lives.
Om, nomnomnom...
The existence of the jet fuel, in the few seconds for which it existed in the fire, assured that the fire would be unstoppable and most definately not of the ordinary nature that one could expect a firefighting system to be able to stop.
It's not "Fuel fire -> ordinary fire -> collapse, as you claim. It's "Fuel fire-> really huge gigantic fire in an instant with every flammable material available in flame all at once, which would not normally happen in a normal fire -> collapse.
Don't label something "offtopic" unless you know the topic well enough to tell what's on topic.