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."

UK Horizon program

[Matts]

I recently watched a well known (in the UK) documentary series called "Horizon" on the WTC disaster. It basically stated in no uncertain terms that the disaster was caused by the use of drywall for all the fireproof walling. The theory was that the explosions caused by the planes basically blew away the drywalling and so the heat from the flames which would have otherwise been slowed down by the drywall, would have been dramatically slowed down.

I wasn't sure whether to entirely believe the program or not, but it seemed fairly plausible. However I came away asking only one question: "So what would have been better?"

Re:Amazingly

[Grech]

I understand that you were being sarcastic, but the point is a good one. These buildings were designed with short-duration catastrophes in mind. A missile wouldn't have succeeded, but a 767 did. Whether this speaks well of a design that can withstand a heavy impact, or whether it speaks poorly of a design that cannot withstand a kerosene fire, I don't know.

However, now that a 'proof of concept' attack has been performed, it will be interesting to see what engineering tricks can be used to keep a tower standing when a barely sub-nuclear blaze is allowed to burn inside it for an hour or two.

any tower can with-stand an impact of an airliner

[AnimeFreak]

SkyScrapers.com [skyscrapers.com]

On this site there was an Interview done with an engineer who had some knowledge on the World Trade Center. 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.

It is said that the airplanes caused an impact of equal or lesser force than what it would experience from day-to-day wind.

Re:Amazingly

[mgkimsal2]

I think the 'disabled' part meant that the sprinklers couldn't work after the impact, not that someone deliberately disabled the sprinkler system manually. That was just my reading of it. "Disabled" gives the impression that there was explicit intervention to turn something off. Frankly, I would have been surprised if the whole plumbing system could have withstood a blast like that to allow the sprinklers to work on upper floors.

TLC/Discovery Special -- Question ...

[pgrote]

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.

Acually

[gvonk]

For that reason entirely, the towers actually did have water tanks up on the 100th floor for putting out fires. Witnesses describe water rushing down the stairways. So in some way, they were prepared for this sort of thing

Re:Future

[irony nazi]

#1 new feature for skyscrapers:
Redundancy
Redundancy is the key to preventing these types of events in the future.

One extreme example would have been 4 mini WTCs would have required 4 airplanes for massive enough damage to destroy all four buildings before people could safely escape.

Less extreme examples include, multiple water pipes or tanks on each floor. Multiple stairway/elevator shafts, distributed to the corners of the building, rather than the center. Multiple tall television antenea around lower manhattan, so that my television wouldn't have had no reception for the weeks following 9/11/01. Multiple, flexible walkways connecting the two bridges at various levels, including the roof level.

Overall, the NYT says that the WTC withstood some amazing forces prior to collapse. They were built to withstand an earthquake. I was standing on Broadway and Fulton when the second plane struck tower 1. The explosion from ~70 stories up knocked out glass windows around me on broadway, 4 blocks away. This is despite the fact that the millenium hotel was blocking the line-of-sight to tower 1. The forces still knocked out all of the windows, through and around another building.

One interesting part of the article is that tower 1 showed signs of collapse within minutes of being struck (as analyzed from film). They also mentioned that the top part of the building angled first one direction and another prior to collapse. In this case, it is good that the inner structure collapsed, because if it hadn't, the top stories might have tipped to one side and fell into another, non-evacuated building. As it happened, the top collapsed downward and that part of the building had been (thankfully) evacuated (except for the firemen).

Re:WTC & Respect (OT)

[nagora]

A little courtesy and respect is appreciated.

Didn't stop Cameron making up details (and lots of them) for "Titanic"; how long does something have to be in the past before no one cares I wonder. Probably a question Yassir Arafat is asking himself about now...

TWW

Why not down?

[Anonymous Coward]

Cause it's not as impressive.
And most skyscapers are designed
not just for use, but an
as advertisement of the acheivement
of the people who built them.

That, and because having to dig a mile-deep
pit before you put down a building, is costly.
After which, you have to deal with
flooding issues. Unlike a skyscaper,
when this one leaked, it would begin to fill up.

So even if it's just humidity that would
already collect in the basement, you'll have
to have some powerful pumps, to send that water
up a mile etc (not that there aren't some
creative ways of doing this efficiently).

Also, there are the human issues,
such as seeing sunlight, a problem
that's already here... we all want the
window office, else you feel cooped up.
So, you're probably going to need to get
sunlight (or it's spectrum) down there.
Not that this is horrible, it's just the
tradeoff for the protection from the elements
and people...

Certainly would be better, though, in terms
of withstanding a directed attack. It's good
enough for our nuclear silos, and they have to
withstand a good bit, I'd imagine.

Come to think of it, there'd also be a savings
in insulating the building. And after going
down a certain depth, I imagine you'd be cutting
rock, that could be used AS a building material.

Re:discovery channel special

[Billly Gates]

"They made the point that this piece of metal falling just a foot to the ground, shook the ground and the camera 30 feet away. Then they said there was 5,000,000 or some large tonnage falling to the ground at 120mph at the time of the collapse. quite amazing "

Actually, I was unfortunately at ground zero on that horrific day. I was in a hallway in a nearby building about maybe only a block away at the most and it shook like a big earthquake with loud explosions as those beams you described fell. It sounded like a bunch of cannons going off that then turned into a loud hum as 5,000,000 of those suckers fell. Some of the beams and parts of the wall stayed together in very large chunks that sounded like bombs going off when they fell. I really thought that the building I was in was actually collapsing on top of me because it was so loud and the vibrations were so intense. I also thought one of the wings actually did fall of and was crushed from the sound of the large chunks of the wall falling. It turns out the beams that fell were over a block away but I really did think it was gone for at least a few hours until I could get outside. Another thing you may find interesting is one of the long steel beams fell on an adjacent building and it actually bent in a 45 degree angle from the intense force. It looked like a wet noodle just hangling all warped. THe beam was at least 3 to 4 feet thick. Absolutely astounding indeed!

To sum up....

[phillymjs]

...the report more or less concludes that the buildings collapsed because of the way they were designed, but withstood the damage for as long as they did before collapsing because of the way they were designed. Talk about, "Damned if you do, damned it you don't."

The worst-case disaster scenario for those towers was a 707 accidentally blundering into one, not a bunch of crazy religious-zealot, martyr-wannabe motherfuckers purposely plowing a much larger, fully-fueled aircraft into it at full speed.

If anyone who lost someone in the collapse even thinks of trying to sue anyone involved in the design or construction of the twin towers, they ought to be drawn and quartered. Sure, they could build a building that could stand up to worse than the WTC got, but proofing it against everything would cost a mint and leave a few phone booths' worth of usable space per floor. Don't forget that there wouldn't be any windows. The rent would be so expensive that nobody would be able to afford to put an office in it.

IMHO, when you step back and look at the big picture, you simply cannot fault the design of the buildings for the fact that they catastrophically failed in the face of an unprecedented, unimagined, deliberate action that was well beyond the scope of their design.

~Philly

Re:Engineering analysis

[Anonymous Coward]

That's an impressive PDF.

One note- it is copyrighted by the professor with a year of 2000. Does this UIUC professor speak with a foreign accent?

Spontaneous collapse of WTC building 7?

[alexgp]

While there may be explanations for the collapse of the twin towers, I have seen no explanation for the collapse of World Trade Center Building 7 on the afternoon of September 11. It was across the street from the rest of the center, and physically separate. The building next-door to it did not collapse.

(see here [akamaitech.net] and
here [fwdodge.com]. )

It seems insurance companies will need to charge higher premiums for buildings that house CIA, US Secret Service, IRS and Securities & Exchange Commission files, now that they have a propensity for spontaneous collapse.

(see here [commondreams.org] and
here [cnn.com]. )

Prolonged, uncontrolled fire & structural dama

[phillymjs]

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 [wirednewyork.com].

~Philly

Re:Amazingly

[Reziac]

I was rather impressed that the design let the towers collapse coherently (almost as tidy as a commercial demolition), rather than keeling over sideways in any which direction and taking out the entire neighbourhood.

Re:TLC/Discovery Special -- Question ...

[alcmena]

The shuttle failed in it's normal operation.

Not exactly. The O-ring seals had never been tested at as cold of weather as it was on the day of the Discovery disaster. Engineers tried to point this out. They also tried to point out that the temperature was well below that of the approved specs. The problem was political. A former president was there for the launch (Nixon if I remember correctly), and NASA was not about to disappoint him. Upper level people ignored the engineers warnings about the O-rings and the launch took place.

The O-rings then failed because of the low temperature, and the shuttle exploded.

Re:Amazingly

[Pig Hogger]

Surprise! I lived in Germany for two years, Korea for 1 year, and Saudi Arabia for 6 mo. I've been all over the world. What, you haven't? Well then let me assure you, Europeans and Arabs are far more arrogant than Americans. That's been my experience.

Normal, middle-class americans are real nice people. It's when they get uppity with their money that they display the arrogance that is typically attributed to americans overseas (and there aren't much middle-class americans who go abroad).

And that "arrogance" displayed by europeans (and arabs) is the normal "arrogance" displayed when one comes from a country with virtually no history (at least, when compared to the thousands of years of history one finds in Europe and the middle-east), totally clueless, and begins criticizing everything in sight. I wonder how a Berlin suburbanite whining about everybody carrying guns on a rack in the back-windows of their pickup trucks in (put your favorite hickstate here) would be catalogued ("arrogant" would surely be a choice pick).

The first time I went to Europe, I was totally aghast at the sight of an older woman, in an airport, who was ready to die because there was no coca-cola available at 10 in the morning...

Re:Amazingly

[Pig Hogger]

My opinion is that anytime a large structure or construct fails, no matter what the reason, it should be seriously studied so that we know what works and what doesn't so that future structures can incorperate the helpful features and remove the extra features so that stucture can be build cheaper, faster, better and quicker.

The obvious answer, in the case of the WTC, is that feeding the sprinkler systems from standpipes located in the thick building skin would have made a hell of a difference, as they would not have been concentrated in the building core.

Let's bet that future design guidelines, if not advocating such a design, will definitely promote a wider distribution of emergency gear throughout the building.

* * *

When one looks at the structural design of the Twin Towers (one could build an argument about them NOT being a skyscraper by the mere fact that the outer walls were load-bearing - a definition of a skyscraper is that the walls are not load-bearing), with it's thick walls and a center core (no intermediate columns), one wonder why the express elevator (that whisked people to the two "sky lobbies") could not have been situated, say, on each corner (or in the middle of the outer-wall, to preserve the sacrosanct "corner offices"), for a panoramic view when going up, à la Hyatt-Regency/Bonaventure hotels.

Such a configuration would definitely have withstood the blaze much better than the central-core-with-all-the-vitals; for it is certain that designers would have ran the standpipes along the exterior elevator shafts, if only because of the blazingly obvious reduntancy it offered.

It would have taken more than one direct aircraft hit to sever all standpipe systems.