New York City activist

December 1, 2007

Twin Towers demolition hypothesis: Discussion with Pat Curley

Pat Curley wants to talk to me about the Twin Towers now. So, I guess I’ll take a break from my promised discussion about WTC 7 to talk about the Twin Towers for a little bit, at least in this one post.

Replying to this earlier comment of mine in the thread following my post Richard Gage’s slide show, WTC 7 section: Reply to charlienneb, patslc (Pat Curley) wrote:

Exterior. Columns. You know those huge things around the outside of the buildings, quite visible to the world, not hidden in some crawlspace.


Actually, the perimeter columns were not directly visible to the world. They were covered with, at the very least, fireproofing plus aluminum cladding. And, if I’m not mistaken, the windows were directly between the perimeter columns. Thus, one side of each perimeter column would be accessible from inside the building possibly from crawlspaces between at least some floors.

The scenario I’m suggesting involves placing incendiary devices (possibly involving thermite) on the inner side of each perimeter column, possibly from within crawlspaces on some (by no means all or even most) floors. Their purpose would not have been to break the columns immediately, but merely to weaken them a few minutes before the collapse, at which time the perimeter columns would then break more easily than they could otherwise (thereby guaranteeing that the columns would in fact break at that later time). Thus it would not have been necessary to cut all the way through a perimeter column, or even most of the way through. Perhaps just a slight cutting plus some additional heating (beyond what the columns were already being subjected to by the fire) might have been quite enough for the perimeter columns, in preparation for a collapse, a few minutes later, that could have been caused mainly by breaking the outermost core columns (the ones attached to the floors).

Thus the incendiary charges could remain mostly concealed, although occasionally some bright shining liquid might leak out as was, in fact, observed on the 82nd floor of the South Tower shortly before it collapsed.

You have to convince yourself they could be severed as is shown in numerous photographs, in some other manner than the obvious, which is that as the trusses failed they pulled in the exterior columns and broke them.

NIST’s hypothesis (at least for the initiation of collapse) does not involve trusses failing. Rather it involves floors sagging and thereby pulling on the perimeter columns.

Pat posted a link to this photo on his blog.

Indeed it shows a section of the outer wall in process of being broken and pulled inward. This is not at all inconsistent with my hypothesis, which (1) would also involve floors pulling on outer walls and (2) would make the observed breaking of the outer walls easier.

Sigh. Except that they were “cut” (severed really) all the way; look at the photographs.

I think you misunderstood what I was suggesting, or perhaps I wasn’t clear. See above. Again, my hypothesis is that thermite (or something similar) was used not to break the columns, but merely to make it easier for the columns to break later.

The big question is whether a hypothesis like mine is necessary, or whether NIST’s hypothesis is sufficient. Kevin Ryan’s critique suggests that NIST’s hypothesis might not have been sufficient. Again, are you aware of any good countercritiques?

And then there’s the further big question of whether, once the collapse got going, Bazant’s hypothesis would be sufficient to ensure that it progressed all the way down, without a little extra help of some kind.

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17 Comments »

  1. It strikes me you may be employing a double standard. In a previous thread you said that if they built a dozen WTC’s and knocked them down with airplanes, wrecking balls and fire, you might be convinced of the NIST theory. Now you’ve come up with your own theory, would it be improper of me to say I’ll believe it if you could build a dozen WTC’s and take them down this way? What if I cut my requirement to just do it on one skyscraper anywhere in the world? Barring that, I will for the present note that I think it is highly unlikely that you could take down a building using thermite at all. As far as I know,No building in history has ever been demolished with thermite, and you’d think they’d use it all the time if all you had to do was put thermite on a few perimeter columns, set off a great big bomb, then set the thing on fire and have the whole thing fall more or less straight down. Maybe with a little bit of extra care, they could do a textbook perfect CD. And unlike regular demolitions, the building could even remain occupied to the very last day without disturbing the occupants.

    Regarding Kevin Ryan, what specifically do you want a critique of? Can you name specific points you think or good, or at least a specific article to look at?

    Finally, the trusses that failed were the ones that held up the floor, allowing the floors to sag, so that’s why NIST’s theory is all about failed trusses.

    Comment by anonanonanon — December 1, 2007 @ 2:57 am | Reply

  2. anonanonanon wrote:

    It strikes me you may be employing a double standard. In a previous thread you said that if they built a dozen WTC’s and knocked them down with airplanes, wrecking balls and fire, you might be convinced of the NIST theory.

    If they all were to collapse in an appropriate manner, resembling closely the way the actual WTC buildings came down and if I were assured that the construction of those buildings was at least as strong as the originals; hence the need for an appropriate supervising committee then, in that case I would (not just “might”) be convinced that the observed structural damage plus fire would have been capable of bringing the WTC buildings down in the manner observed.

    I also acknowledged that my proposal was unrealistically expensive, and that a smaller-scale demonstration might be possible, although I would need to study the relevant issues more in order to decide what a suitable smaller-scale demonstration might me. (Once again, if you hear of any good, substantive critiques of Kevin Ryan’s objections to the NIST report, please let me know.)

    Now you’ve come up with your own theory, would it be improper of me to say I’ll believe it if you could build a dozen WTC’s and take them down this way?

    Given that you’re already a believer in the NIST theory, this doesn’t seem like a logical question for you to ask. If you believe that airplane impacts plus subsequent fires were sufficient to bring the towers down, then all the more so could they have been brought down by airplane impacts plus subsequent fires plus thermite plus explosives unless you believe that the thermite and/or explosives could somehow make the building more resistant to collapse than it would have been already, which is highly unlikely.

    The question being explored in this thread is not whether my hypothetical scenario could bring the towers down, but whether it could bring them down in a manner consistent with the observed collapse phenomena including the phenomenon shown in the photo Pat showed me, e.g. perimeter columns breaking as they are pulled on by sagging floors.

    I will for the present note that I think it is highly unlikely that you could take down a building using thermite at all.

    My hypothesis does not involve just thermite. It involves thermite on the perimeter columns and explosives on the outermost core columns, together with a large preceding fire on some upper floors.

    As far as I know, No building in history has ever been demolished with thermite, and you’d think they’d use it all the time if all you had to do was put thermite on a few perimeter columns, set off a great big bomb

    Not just a few perimeter columns and not just one great big bomb. Please re-read.

    Anyhow, no professional demolition team would want to do a Twin Towers-style demolition “all the time,” given that debris were spewed all over the place.

    then set the thing on fire and have the whole thing fall more or less straight down.

    If NIST’s scenario could make the whole thing fall more or less straight down, then, most likely, all the more so could mine, which basically would have the effect of greatly amplifying the phenomena described in the NIST hypothesis, e.g. there would be more floor-sagging, more pulling on the outer walls, and easier breaking of the perimeter columns.

    And unlike regular demolitions, the building could even remain occupied to the very last day without disturbing the occupants.

    Another problem that perhaps could be easily solved if there are crawlspaces between the floors, although I’ll need to check this at some point.

    Work on the core columns would be a much simpler matter in any case. Could easily be disguised as elevator maintenance.

    Regarding Kevin Ryan, what specifically do you want a critique of? Can you name specific points you think or good, or at least a specific article to look at?

    For now, I would be interested to see any substantive critiques of any of his points. (If you overwhelm me with too many papers to read, then I’ll ask your help in narrowing the list down a little.) Again, see the section on The NIST report in my post Demolition of WTC: Let’s not overstate the case, please.

    Finally, the trusses that failed were the ones that held up the floor, allowing the floors to sag, so that’s why NIST’s theory is all about failed trusses.

    When you speak of trusses “failing” here, you don’t mean that the trusses broke, just that they sagged, right?

    Comment by Diane — December 1, 2007 @ 5:39 am | Reply

  3. For now, I would be interested to see any substantive critiques of any of his points. (If you overwhelm me with too many papers to read, then I’ll ask your help in narrowing the list down a little.)

    Comment by Diane — December 1, 2007 @ 5:39 am

    I’m not aware of any critiques, It seems that Ryans key technical point (also mentioned by Hoffman) was that fires in the towers could not have heated the steel beyond 500 degree F. This is true and is based on the samples taken from the WTC. They apparently did not find any steel from within the fire itself, but there is strong evidence that office fires can quickly heat unprotected steel over to 800 C. This has been known through tests going back many decades. See for example the data here, where unprotected steel can be heated to 800 C or higher in as little of 15 minutes. http://www.mace.manchester.ac.uk/project/research/structures/strucfire/DataBase/TestData/default1.htm. Steel component tests go back to the early 20th century and see similar results. While it would be nice in the scientific sense to find the actually steel that was heated in the WTC fire, in engineering, this is usually about as good as gets, you rarely have all the data you really need, so you have to rely on test data, theory and inference. So if unprotected steel in test fires gets heated over the acceptable limit of 1000 F, and you can see that there was a heavy fire in the WTC, you can (and definitely should) assume that any unprotected steel in the WTC would also be overheated. The question remains “was the steel unprotected?”

    Ryan also critized the WTC tests that showed the fire proetctive coating was knocked off the beams. I will review his criticism and the test and get back to you. May take me a little time. The “12 page document” he linked to, turned out to be about 100 pages.

    Comment by anonanonanon — December 1, 2007 @ 1:54 pm | Reply

  4. Diane, I have issued an update to my post, based on a comment by Mark (Gravy) Roberts, who says that he does not believe the columns on the West face were severed. Looking very closely at the photographs it appears that at least some of what I saw was an optical illusion caused by the blackening of the columns exposed to the fire. I’m not entirely positive that none of the columns have severed but I’m certainly less confident that a substantial number of them have been severed.

    Comment by patslc — December 1, 2007 @ 3:20 pm | Reply

  5. “I’m not aware of any critiques, It seems that Ryans key technical point (also mentioned by Hoffman) was that fires in the towers could not have heated the steel beyond 500 degree F. This is true and is based on the samples taken from the WTC.”
    Comment by anonanonanon — December 1, 2007 @ 1:54 pm

    I need to clarify that what I meant was that it is true they did not find any pieces of steel that had been heated over 500 degrees, there was strong indirect evidence that the fires probably did (and unquestionably could have) heated some of the steel to over 1000 F, (the temperature. at which steel begins to lose strength rapidly)

    Comment by anonanonanon — December 1, 2007 @ 7:40 pm | Reply

  6. When you speak of trusses “failing” here, you don’t mean that the trusses broke, just that they sagged, right?

    Comment by Diane — December 1, 2007 @ 5:39 am

    Yes, sagging would be considered a type of failure.

    Comment by anonanonanon — December 1, 2007 @ 7:43 pm | Reply

  7. Whew! Lots of comments here, I see. I’m not sure when I’ll have a chance to reply. Possibly tomorrow, possibly not until Tuesday or Wednesday. Busy weekend.

    Among other things, I’ve been asked for feedback on a paper someone is writing critiquing Bazant. I’m no structural engineer, but at least I’m reasonably good at catching math errors and misapplications of basic laws of physics.

    In other news, I got a brief email today from someone who is working with Richard Gage on his presentation, so it would appear that things are moving along on that front.

    Anyhow, until I have a chance to reply to the latest bunch of comments, I would appreciate it very much if you guys could wait with posting very many more comments for me to reply to although, if you come across any very important information you feel that I should look at, do feel free to let me know about it here.

    To Pat: The comment you posted in the thread WTC 7: FEMA report and NIST prelim report: What about pre-collapse leaning and the transit??? did eventually go through. Posts containing two or more links are automatically put in the moderation queue, but for some reason I didn’t see it there until quite a while after you apparently posted it. Anyhow, I hope soon to reply to that comment, too.

    Comment by Diane — December 1, 2007 @ 9:56 pm | Reply

  8. anonanonanon wrote:

    See for example the data here, where unprotected steel can be heated to 800 C or higher in as little of 15 minutes. http://www.mace.manchester.ac.uk/project/research/structures/strucfire/DataBase/TestData/default1.htm.

    This link doesn’t work. Could you please provide a working link, if one is available?

    Comment by Diane — December 3, 2007 @ 2:22 am | Reply

  9. SOrry for the bad link. I used a period at the end of the sentence and it became part of the URL. Try this one.

    http://www.mace.manchester.ac.uk/project/research/structures/strucfire/DataBase/TestData/default1.htm

    Comment by anonanonanon — December 3, 2007 @ 7:58 am | Reply

  10. To anonanonanon:

    I’ll reply later today, or perhaps tomorrow, about fire temperatures and steel temperatures.

    To Pat:

    I’ve replied in the thread WTC 7: FEMA report and NIST prelim report: What about pre-collapse leaning and the transit??? to your comment above, here in this thread, about WTC 7, since this thread here is about the Twin Towers, not WTC 7. In the meantime I’ve replied to your other comment there.

    To all:

    I’ve added the following to my Comment policy:

    Please post all comments after posts to which they are relevant, not necessarily the most recent post. If your comment is not directly in reply to a post, please try to find the most relevant post using the “Categories” list on the sidebar. The “recent comments” list in the sidebar is there to enable readers to find all recent comments, on older posts as well as recent ones.

    Comment by Diane — December 3, 2007 @ 12:37 pm | Reply

  11. diane wrote:
    To anonanonanon:

    I’ll reply later today, or perhaps tomorrow, about fire temperatures and steel temperatures.
    Comment by Diane — December 3, 2007 @ 12:37 pm

    Please wait until I’ve got my discussion of the fire protection up, because it may answer some of your questions.

    Comment by anonanonanon — December 3, 2007 @ 2:26 pm | Reply

  12. To anonanonanon:

    I would actually prefer to devote a separate thread to the topic of fire temperatures and steel temperatures. I would prefer to have our subsequent discussion on this topic there rather than here, reserving this thread for challenges to my hypothesis on other grounds.

    So I’ll go ahead and post on this topic. I should be able to post something in 2 or 3 hours, I hope.

    Comment by Diane — December 4, 2007 @ 1:31 am | Reply

  13. (This comment is an edited pingback.)

    To anonanonanon:

    I just now posted a brief reply, as a new post. Please post your promised “discussion of the fire protection” as a reply to that post, linked below.

    -Diane

    Pingback by Fire temperatures and steel temperatures « New York City activist — December 4, 2007 @ 3:08 am | Reply

  14. Diane, I put it here as a courtesy since it was specifically linked in this post.

    Comment by patslc — December 4, 2007 @ 3:32 pm | Reply

  15. Pat, I certainly don’t blame you for not following a rule that I hadn’t even announced yet.

    Comment by Diane — December 5, 2007 @ 1:02 am | Reply

  16. (This comment is an edited pingback.)

    The post linked below reviews a website which features a thermite arson hypothesis similar to what I suggested above, in that it involves the use of thermite just to weaken steel, not cut it.

    – Diane

    Pingback by “The Adventures of Max Photon” - a review « New York City activist — December 17, 2007 @ 5:24 am | Reply

  17. In comments in the thread following my post about Fire temperatures and steel temperatures, “anonanonanon” called my attention to this photo on this page of an official-story defender’s site. The photo, which shows a sagging floor in the South Tower, is said to have been taken from NIST’s Media and Public Briefing of April 5, 2005 (PDF). I haven’t had time to look at the latter paper yet, so I still don’t know which side of WTC 2 that photo is said to portray. In the meantime, I’ll note the following:

    Gordon Ross’s page about his hypothesis on How the Towers were Demolished contains a link to NIST’s conference, September 15, 2005, Session VI (PDF) which contains, on page 12, a similar photo of a “Hanging Floor 83 Slab in Windows of Floor 82,” said to be on the east side of WTC 2. Note that this sagging floor is disconnected from the columns on the east side, so it can’t pull the east side columns inward, though perhaps it could pull on the north and south columns near the corners.

    But Gordon Ross says the following:

    Note that the bowing identified by Nist was only on one side of each tower. It was not generalised across all of the tower. For the example of WTC1, Nist report bowing only on the South face, storeys 94 – 100. For WTC2 bowing only on the East face, storeys 77 – 83. Note that for both Towers only the MID-WALL perimeter columns were bowed. The corners were not visibly bowed.

    Further doubt is thrown on the Nist theory that the bowing was caused by sagging floors by examination of the photographs contained in their own report on WTC2, which shows floors sagging in a direction perpendicular to that which would be required to cause the bowing.

    Sometime later, I’ll need to study the relevant sections of the NIST report to verify Gordon Ross’s claims.

    Comment by Diane — December 23, 2007 @ 7:22 pm | Reply


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