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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."
if it weren't for the 767s, massive fires, tens of thousands of gallons of burning jet fuel, and the abliteration of the several floors worth of the buildings' structural cores, the towers would have remained standing. But, shhh, this is leaked info. Don't tell anyone.
I think most of us in the construction industry (architecture) were concerned about this as events were unfolding, even before the first tower collapsed. But the saddest part was finding out later that concessions had been made during design/construction in the sizing and configuration of sprinkler systems including the abscense of a rooftop water supply.
Who knows if it really would have helped, but having to second guess now is hardly comforting. As in most things, those that focus on stupid quantitative evaluations of design (cost per square foot for example) are doomed to come up short when all the chips are really down.
There is no need to use a SlashDot sig for SEO...
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.
Perhaps you could take your anti-capitalist rhetoric elsewhere, comrade. If you had any decency, you'd know that in the time period the towers were designed and constructed in they were paragons of efficiency and safety. Far from cutting all costs and maintenance, the towers were meticulously designed to withstand all manner of natural forces, fires, and other disasters. They were even designed to withstand the impact of a fully loaded 707 jetliner, the largest then available. Alas, a 767 is much larger and carries more fuel. Even then, the towers would have stood had it not been for the fire, and the impact and explosion were far more than any designer could've ever dreamed would happen.
My friend, you appear to have a huge chip on your shoulder that is clouding your judgement. People died because madmen hijacked two jetliners and deliberately slammed them into skyscrapers full of thousands of innocent human beings. Corporate greed and stockholders had nothing to do with it, and it is callous, irresponsible, and shallow of you to even suggest such a thing to further your obvious hatred of corporate America.
In the end they will lay their freedom at our feet and say to us, Make us your slaves, but feed us. - Fyodor Dostoyevsky
In the future, we'll just have to build all really tall buildings underwater. Maybe Kevin Costner could offer up some good advice.
He stated that the airplanes could have not brought them down seeing that buildings of a lesser, equal, or greater size get the same sort of impact daily with the force of winds.
Well, this may be true, but when you consider that the airplanes *did* down the two buildings, one must realise that there is something flawed about that statement. I would accept that most skyscrapers are pummeled with the strength of an airplane crash daily, except that the force is spread across the entire structure, or at least one entire face, of the building. Consider what it might feel like if you were walking down the street and suddenly the entire energy of the ~50mph wind gusts that you normally can easily withstand were channeled at a 1cm^2 section of your chest, or even your skull. Wouldn't that at least completely knock the wind out of you? I haven't the time to properly do the math myself right now, but it may work out that such an energy release over such a small space would be enough force to pierce skin and possibly break bones.
And that is what made the difference, aside from the fire and explosions that are discussed elsewhere in the thread.
They ran an hour long program where they interviewed two key people ... the mechanical engineer who built the towers and a forensic mechanical engineer who was looking at the wreckage.
Each had unique viewpoints. The designing mechanical engineer is haunted to the core over this. Most of his sentances trailed off as he was reliving what happened.
The forensic scientist identified the fact that the fireproofing material was blown off from the original impact. This hastened the collapse. He also commented that the support structures for the floors were the first things to fail.
My question is did anyone really think they were going to fall? Remembering back to the day no one in the media raised the question. None of my friends or family I was talking to that day even thought of it as a remote possibility.
This raises a very interesting question about our expectations vs. reality. After the shuttle disaster I think this stands as one of the most shocking slaps in the face to us concerning technology.
Of course the buildings weren't going to survive, but our faith in technology made us think that day that the buildings collapsing wasn't a possibility.
Think for a few moments before posting.
- These buildings received Certificates of Occupancy, had been tested in the prior attack, their systems and procedures were as good as any other in the world.
- There is NO evidence of cost-cutting, sub-standard materials or equipment, etc. This was a public building owned until recently by the Port Authority of NY & NJ and by all reports kept in exemplary condition.
- These were not slip-shod towers built overnight in some 3rd-world country without reviews, standards, or regular inspections.
- Aside from their unusual tube-design (which appears to have been their greatest asset) and height there is nothing special about WTC towers that would separate them from tall buildings around the world. This includes materials.
Finally, before you post realize that 3,000 humans died horribly in this disaster. Perhaps before you post your Monday-morning-quarterbacking, rumor-spreading & conspiracy theories you might show a bit of respect for those folks and the ones they left behind.A little courtesy and respect is appreciated.
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.
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-
Calling the WTC's collapse an engineering failure is kind of like taking C4 to slashdot's servers and saying that the code failed somehow. You just can't reasonably have expected them to anticipate this. Expecting a building of similar requirements (e.g., height, usable space, windows, etc) to withstand both the impact of a modern airliner and the jet fuel may well be an impossible task, especially when trying to do it within any reasonable budget. Please think about what you are saying and try to be a little less arrogant. Thank You
16 days after Sept 11th, I received this in an email from my father, (who happens to be a Mechanical Engineer):
- Professor Thomas Mackin, who currently teaches Failure Mechanisms in Engineering Materials class, made this short presentation (attached) after the World Trade Tower tragedy. This presentation was made in response to the
Chancellor's request for teachers to discuss with their classes the recent events. Mackin was clearly as shaken up about the events as were the rest of us. He only had a short response to his final question: "As engineers, what can we do to prevent this from happening. - Nothing."
There was simply too much energy put into the buildings. bin Laden knew that, the engineers know that... it's a damn shame we're back to the accusations, finger-pointing, and blame-placing that so much plagues our culture.Attached was a .PDF file, "ME 346 - Engineering Analysis of Tragedy at WTC."
The engineers did their job. They did it well. World Trade Center 1 & 2 were good buildings -- I stood on top of one just over 10 years ago. I can hardly believe I never will again.
Osama bin Laden and his cronies are the ones -- the ONLY ones -- responsible for this outrage. Please, let's try to remember that.
"...America's great minds of today, teaching America's great minds of tomorrow. Poor bastards." -- A Beautiful Min
In the History Channel's WTC documentary, they showed large backup generators whose purpose was to briefly power the entire complex in an outage. There were also large tanks of diesel fuel to supply the generators. I'd say it's likely that setup was in 7 WTC or one of the other ancillary buildings.
And now a quick Google search reveals this: Engineers Suspect Diesel Fuel in Collapse of 7 World Trade Center.
~Philly