Scientists and engineers simulate jet colliding with World Trade Center

[RangerSmith]

WEST LAFAYETTE, Ind. — Researchers at Purdue University have created a simulation that uses scientific principles to study in detail what likely happened when a commercial airliner crashed into the World Trade Center's North Tower on Sept. 11, 2001.

The simulation could be used to better understand which elements in the building's structural core were affected, how they responded to the initial shock of the aircraft collision, and how the tower later collapsed from the ensuing fire fed by an estimated 10,000 gallons of jet fuel, said Mete Sozen, the Kettelhut Distinguished Professor of Structural Engineering in Purdue's School of Civil Engineering.

It took about 80 hours using a high-performance computer containing 16 processors to produce the first simulation, which depicts how the plane tore through several stories of the structure within a half-second, said Christoph M. Hoffmann, a professor of computer science and co-director of the Computing Research Institute at Purdue.

<snip>

http://news.uns.purdue.edu/UNS/html4ever/2006/060911.Sozen.WTC.html

[KJF]

1. Thanks for posting this

It looks interesting.

However, the article says:

The researchers are analyzing how many columns were destroyed initially in the building's core, a spine of 47 heavy steel I-beams extending through the center of the structure, Sozen said.

Not all the core columns were "I-beams". In fact, most of them on the impact floors may well have been box columns (although there were probably a few I-columns in there as well). Detailed diagrams of all impact floors are not available (at least AFAIK), so it's impossible to say what the ratio of I-columns to box columns is exactly. Then again, maybe he just misspoke.

Edit: alteration because I read the article wrong.

Also, the speed of 470 mph for American 11 is contentious. MIT came up with a speed of 429 mph.
Link: http://web.mit.edu/civenv/wtc/PDFfiles/Chapter%20III%20Aircraft%20speed.pdf

[RangerSmith]

3. I'm unaware

that there were issues finding the original structural drawings to the WTC towers. Having been a commerical General Contractor for 20 yrs, I admit to being pretty skeptical about that. No less than several hundred different types of contractors would have had these drawings.

Could you point me towards something that furthers why you think "detailed diagrams of all impact floors are not available" ?

I can't fathom them not being able to replicate the structure exactly as drawn on the computer.

[KJF]

4. I mean they're not available to the public

I haven't seen them. I guess they must be somewhere. If you see them, please let me know. There was a diagram about transition from box columns to I-columns in one of the NIST subsidiary reports, but I can't remember which.

On edit: I think there was a problem finding the original structural drawings (because they were kept on site), but some sort of backup was found.

[Ezlivin]

5. "Not available to the public"

Excuse me for asking this, but why the hell not? Why shouldn't the public see WTC blueprints, drafts or structural details? The buildings are no longer in existence.

I just cannot see how that information could aid any terrorist anywhere (if that is the argument for keeping it "classified").

If they want people to believe the official story there should be absolutely nothing to hide.

[FourScore]

7. There is an archietectural firm

who pulled them out for a documentary on the history channel last week. They used the drawings in the documentary to explain the pancake theory. Apparently it was an older documentary. Why they were still showing it I don't know, because someone here on DU suggested that the theories of collapse in that documentary are no longer considered accurate. In any case, they did show the archetectural plans.

[DoYouEverWonder]

11. Here's what the structural engineers who did the modeling of the WTC said

Testimony of Dr. Abolhassan Astaneh-Asl

Professor Department of Civil and Environmental Engineering
University of California, Berkeley
said when he testified before Congress:

Before the Committee on Science of the U.S. House of Representatives


March 6, 2002 Hearing on “Learning from 9/11: Understanding the Collapse of the World Trade Center”


My involvement in the investigation of the collapse of the World Trade Center is to conduct a reconnaissance of the collapsed and damaged WTC buildings and to collect the perishable data. The main objectives of the reconnaissance are to learn as much as possible from the actual collapsed structures and to document the failure modes and performance of the members and connections as well as quality of the construction. The purpose of collecting the perishable data is to collect material samples, photographs, videotapes, drawings and data on design, construction and collapse. Using the information collected and by conducting the necessary analyses and research, we try to establish probable causes of the collapse and most likely scenario for such collapse.

<snip>

I have not been provided with the information made available to the FEMA Building Performance Assessment Team. This includes, videotapes and photographs taken on 9/11and the following days and copies of the engineering drawings. At this time, having the videotapes, photographs and copies of the drawings not only is useful, but also is essential in enabling us to conduct any analysis of the collapse and to formulate conclusions from our effort.

http://www.house.gov/science/full02/mar06/astaneh.htm

[Carefulplease]

12. Core box columns...

Not all the core columns were "I-beams". In fact, most of them on the impact floors may well have been box columns (although there were probably a few I-columns in there as well).

At most 6 of the 47 core columns were box columns in any zone above the 83th floor. They were either 12"x15" or 22" square. They also were built with plates that were thinner (1.31" to 1.5") than the wide flanges of typical I-beams were (1.62"). The four corner core columns were thickest with 4.91" thick flanges.

http://wtc.nist.gov/NISTNCSTAR1-1.pdf
pp. 26-27

[KJF]

14. Thanks

I was looking for that.

I think you mean 8 of 47, not 6 of 47, though.

[Carefulplease]

18. Now I am unsure...

I assumed that those columns that are displayed as box columns but that had their box-to-WF transition level indicated to be on the 83th floor must have been wide-flange above the 83th floor. However the legend also indicates that the icons represent the shape of the columns at the 84th floor. These two contradictory interpretations yield 7 (and not 6 as I said) or 10 box columns at the 84th floor, respectively.

At any rate, people often picture the huge box columns from the sub-levels going all the way up. At the impact floors, the heaviest columns are the corner columns and these are wide-flange. Also, the few box columns that there are, aren't that much heavier than average wide-flange columns and they are at most 22" square.

[DoYouEverWonder]

16. In WTC 2, it was the 81st floor that failed

and initiated the collapse.

What kind of columns & beams did that floor have?

[screembloodymurder]

2. Great, but this should have been done using the actual steel.

I don't believe the south tower's core columns would have been severely damaged. The plane hit the corner and the core suffered a glancing blow. I'm somewhat concerned that an "objective study" would jump to conclusions about how the tower collapsed. Why not do the math and let the chips fall. That said, this is progress.

[Carefulplease]

13. Glancing blow...

This glancing blow on the core of WTC2 was most catastrophic. It most probably resulted in severe damage to two corner core columns located on the same side of the tower. The four corner core columns bear 25% of the load supported by the core. This asymmetric damaged would have been much more stressful on the structure than the damage to the core of WTC1 was. The fires burned most fiercely on the damaged side of WTC2 also.

[KJF]

15. ?

I don't quite see what you mean. Which two corner core columns?

25%? Not quite:

The for massive corner columns bore nearly one-fifth of the total gravity load on the core columns.
NIST main report, p. 8

[Carefulplease]

17. You are right on both counts...

I relied on my memory. I should rather have checked. Thanks for the correction.

Indeed, only one rather than two core columns are presumed by NIST to have been severed. 11 columns total are presumed to have been severed or heavily damaged. This compared with 9 more symmetrically distributed columns in WTC1 that had this status.

You are right also that the core corner columns bore close to 20% of the gravity loads and not 25%.

[FoxOnTheRun]

6. Medium is the Message ( Marshall McLuhan)

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=125x116565

[FourScore]

8. Funded by the NST

I am still skeptical about this research.

The NST is a governmental agency funding the project:

"...the director and all Board members serve six year terms. Each of them, as well as the NSF deputy director, is appointed by the President of the United States and confirmed by the U.S. Senate..."

I still don't see independent research in this.

I guess I am wondering how they will input data for the simulator. If they will first determine what the EXACT heat of the fire was, and WHERE the jet fuel dispersed BEFORE they calculate the results, then I would have more faith in the final simulation. If, however, they plan to input the "official data" of how hot the fires were and where the fuel went, then I just don't have any faith in that.

A simulation is as good as it's data. If they are trying to achieve a simulation of the OCT end result, they will mearely, in the end, have a computer model of that and nothing more. If, however, they are truly searching to solve how the buildings collapsed by means of a methodical, step-by-step analytical approach -- well, then I'm more interested.

I don't trust this.

[FourScore]

10. OOps. I mean NSF of course

Typing too fast and not paying attention.

[FourScore]

9. Looks like this mags prediction has come true

We need the hard, raw evidence -- steel beams and such.

From Paul Thompson's 9/11 timeline:

"...A firefighter trade magazine with ties to the New York Fire Department calls the investigation into the collapse of the WTC a “half-baked farce.” The article points out that the probe has not looked at all aspects of the disaster and has had limited access to documents and other evidence. “The destruction and removal of evidence must stop immediately.” The writer, Bill Manning, states, “I have combed through our national standard for fire investigation, NFPA 921, but nowhere in it does one find an exemption allowing the destruction of evidence for buildings over 10 stories tall.” He concludes that a growing number of fire protection engineers have theorized that “the structural damage from the planes and the explosive ignition of jet fuel in themselves were not enough to bring down the towers.” Yet, “s things now stand and if they continue in such fashion, the investigation into the World Trade Center fire and collapse will amount to paper- and computer-generated hypotheticals....”

http://cooperativeresearch.org/timeline.jsp?timeline=complete_911_timeline&investigations:_a_detailed_look=wtcinvestigation