Explosives Found in World Trade Center Dust

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Green Lemon
Posts: 392
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Re: Explosives Found in World Trade Center Dust

Post by Green Lemon » Mon Apr 13, 2009 2:11 pm

I'm not telling you that the *way* it collapsed is normal- I'm not sure how to answer that question. (Although I find it at least plausible that it would just go straight down. But twice? Hmmm. Maybe, I really cant say.)

I am telling you that the *fact* that steel loses strength due to heat- in ordinary building fires, leading to structural failure - is known, and we are specifically taught how to design for that. Its a very small point. The building I posted a pic of was maybe 5 stories high, and you could see the sagging steel structure- it obviously at least partly melted. Put another hundred stories on that- I think it'd be flat, what do you think?

I agree that the incredibly uniform demolition of both towers strikes me as bizarre- but I have seen many bizarre things in the real world. In fact, a skyscraper is itself something of a defiance of the laws of physics, so maybe that holds in both erection and spontaneous demolition.

Here's a cool video of a 13 story steel building collapsing due to fire:

http://video.aol.com/video-detail/delft ... 3741771392


Another steel building destroyed by fire:

http://newsimg.bbc.co.uk/media/images/4 ... ire203.jpg

http://news.bbc.co.uk/2/hi/uk_news/engl ... 105942.stm
A spokesman for the fire service said the blaze had resulted in a black smoke cloud which could be seen for miles.

He added: "Intense heat buckled the steel girders holding the roof."

Here's a nice picture of a test subjecting a steel beam and a wooden glulam (timber) beam to 30 min of fire. Guess what? As you can see, wood (big, thick pieces) is more structurally sound for longer times in a fire than steel! (File under crazy but true...and things you learn in architecture school.)

http://farm4.static.flickr.com/3542/336 ... 0319_o.jpg

Theres unfortunately tons more examples- which is why they invented steel fireproofing. Its that stuff that looks like cottage cheese. Flocking, they call it. Theres also intumescent paint, which is basically paint which foams up in the presence of heat, turning into fire retardant insulation. Another technique used is to fill steel structural tubes with water.

Amazing how widespread this misconception is.

Why then heck cant I post pictures anymore? Is it the new forum?
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Emissary
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Re: Explosives Found in World Trade Center Dust

Post by Emissary » Mon Apr 13, 2009 2:47 pm

Thats an interesting video, its only a partial collapse, but i can see what your getting at. If you look at the undamaged section of the building bellow the burning section it does seem to take a good hit before it begins to collapse. But you can see that there is definite resistance to the falling building. The WTC collapsed at virtually free fall speed, which means that each floor gave no resistance to the floors above it. The opposite of what should happen. The WTC should have collapsed much like your video up to a point and then stopped maybe 1/3 or 1/2 of the way down due to the resistance of the undamaged parts of the building. At this point sections would have begun to topple off sideways. You have to think that the WTC was built to easily hold its own weight and so no extra weight apart from gravity would have been applied to the core columns, in a real collapse these should have been left standing. So why the free fall speed with no resistance? We have to remember that only a few floors of the WTC buidlings were actually damaged, the rest were still functioning and had no fire.

On first impressions it seems to make sense that each floor would build up momentum as the collapse proceeded but the opposite is true, with each floor more resistance and more resistance. The collapse should have slowed not sped up. We cant really tell from the video you supplied as to how far that building would have continued to fall if it had 30 or 40 more undamaged floors underneath it.

Also watching your video again you may notice is took that 13 story building about 10 seconds to collapse from start to finish, WTC 1 took 9 seconds. And i think it was a tad bigger

Green Lemon
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Re: Explosives Found in World Trade Center Dust

Post by Green Lemon » Mon Apr 13, 2009 3:06 pm

I do see what you're saying, I think the fact that there were 30 or 40 floors above the damaged floors, as well as below, is important to remember. Its hard to believe that it would just freefall straight down, I agree- but the one in the video did just kind of melt away (only the burning part of course, it definitely hit resistance that the WTC didn't seem to). I am not qualified to know what "should" happen in the WTC collapse, but I agree it looks quite controlled. Just remember that steel often fails in a building fire and I will consider my mission accomplished :wink:
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Imaulle
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Re: Explosives Found in World Trade Center Dust

Post by Imaulle » Mon Apr 13, 2009 10:28 pm

fire would not cause the steel beams to look like this

Image


and fire would not cause countless beams to be found looking as if they were cut with explosive charges/thermite


Image

ThrowAway
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Re: Explosives Found in World Trade Center Dust

Post by ThrowAway » Tue Apr 14, 2009 4:51 am

I have no idea what steel cut by explosives would look like but I would assume they would be very clean cuts. Figure 18 looks like a typical oxidized cut with low pressure( Ive made hundreds of cuts with the metal being in the normal temp range of what the building fire temps would have been that looked similar) Actually that cut looked like what would happen from the air pressure from the building coming down. The fact that there is so much slag on would leave me to believe theres no way the air pressure that would come from a blast cut that. Give me the measurements and I can give you the psi of air it would take to do something like that.

Also ,Come to think of it in the 60s thermite might have been used to weld those beams together.

So to respond to your statement fire plus a gust of air focused on the beam would make the beam look like that.
Last edited by ThrowAway on Tue Apr 14, 2009 3:58 pm, edited 2 times in total.

ThrowAway
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Re: Explosives Found in World Trade Center Dust

Post by ThrowAway » Tue Apr 14, 2009 4:55 am

Coming from a metal worker, all those cuts(except fig 18) are typical of an arc-gouging machine. When were those pictures taken? Could you even reliably give a time frame?


ThrowAway
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Re: Explosives Found in World Trade Center Dust

Post by ThrowAway » Tue Apr 14, 2009 5:44 am

I could believe something like that happened but these fucking bomb theories are toilet fodder.

Green Lemon
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Re: Explosives Found in World Trade Center Dust

Post by Green Lemon » Tue Apr 14, 2009 8:29 am


you just expect me to click without any explanation of what its about....or why its relevant :roll:

lazy tsk tsk
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Green Lemon
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Re: Explosives Found in World Trade Center Dust

Post by Green Lemon » Tue Apr 14, 2009 8:31 am

ThrowAway wrote:I have no idea what steel cut by explosives would look like but I would assume they would be very clean cuts. Figure 18 looks like a typical oxidized cut with low pressure( Ive made hundreds of cuts with the metal being in the normal temp range of what the building fire temps would have been that looked similar) Actually that cut looked like what would happen from the air pressure from the building coming down. The fact that there is so much slag on would leave me to believe theres no way the air pressure that would come from a blast cut that. Give me the measurements and I can give you the psi of air it would take to do something like that.

Also ,Come to think of it it the 60s thermite might have been used to weld those beams together.

So to respond to your statement fire plus a gust of air focused on the beam would make the beam look like that.

oh man, I love a construction tech! can I join your fan club?

OK just kidding, but props for a post based on actual personal experience.
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Green Lemon
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Re: Explosives Found in World Trade Center Dust

Post by Green Lemon » Tue Apr 14, 2009 8:37 am

Imaulle wrote:fire would not cause the steel beams to look like this

Do you have any actual experience in judging what steel beams "should" look like after a plane impacts a skyscraper?

Not trying to be rude- if you have it, let it be known. If not, quote someone who does and who supports your conclusion.

This is like trying to decide if its normal that the towers impacted straight down or not. Laypeople simple cannot make that judgment reliably, even professionals will disagree I imagine. The best we can say is that something looks amiss.
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Machinesworking
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Re: Explosives Found in World Trade Center Dust

Post by Machinesworking » Tue Apr 14, 2009 8:42 am

Emissary wrote: On first impressions it seems to make sense that each floor would build up momentum as the collapse proceeded but the opposite is true, with each floor more resistance and more resistance. The collapse should have slowed not sped up. We cant really tell from the video you supplied as to how far that building would have continued to fall if it had 30 or 40 more undamaged floors underneath it.

Also watching your video again you may notice is took that 13 story building about 10 seconds to collapse from start to finish, WTC 1 took 9 seconds. And i think it was a tad bigger
I think you're missing a huge and simple fact though, the more floors collapsed the less resistance would be an issue, as the weight was coming straight down, so each floor added tons of pressure. This would make the fall speed up to free fall speed, not slow down.

Also, people are amazed that it fell straight down, but consider this, a HUGE jet hit it, slightly ripping all the steel beams loose from the concrete around it, at least for a few floors above and bellow impact. So once these start crumbling, which wouldn't necessarily be visible from outside, it would start pancaking, that weight alone would take out any remaining beams. Also, in many ways the larger an object gets in sheer size, the more it's going to be pulled down, instead of responding to horizontal pressure. We're talking about two of the largest buildings in existence, with ten times more support beams than an average building, not a couple major ones, and supporting smaller beams. On impact, those beams hold on the concrete floors was compromised. It doesn't to me seem feasible that such huge slabs of concrete would swerve off a course straight down because of dozens of support beams that have been busted slightly off of the surrounding concrete?

I'm all for catching the government on things that you can, and I really wish the people in office who could have acted to prevent this were found out, (I do suspect that to be the case), but I really doubt any explosives and that level of conspiracy. What makes more sense is as I said before, a planned negligence on the part of those in power who would benefit from this sort of attack. Plus it really is building 7 we should be worrying about IMO.
Last edited by Machinesworking on Tue Apr 14, 2009 8:51 am, edited 1 time in total.

UKRuss
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Re: Explosives Found in World Trade Center Dust

Post by UKRuss » Tue Apr 14, 2009 8:46 am

Still giving me my LOLZ! :lol:

It utterly amazes me that there seems to be some kind of debate about the collapse of large structures when we have no structural or demolition engineers in the room, just usual pseudo-intellectual forum nonsense.

My starting point would be: Planes hit buildings, buildings fell down.

I think even as a layman I would be happy to accept that that thousands of tonnes of material falling at speed would cause vertical collapse of a building of that size. Childhood physics would show us that much.

Come on. Sometimes things are just what they are, even in the USA.

Green Lemon
Posts: 392
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Re: Explosives Found in World Trade Center Dust

Post by Green Lemon » Tue Apr 14, 2009 8:52 am

UKRuss wrote:Still giving me my LOLZ! :lol:

It utterly amazes me that there seems to be some kind of debate about the collapse of large structures when we have no structural or demolition engineers in the room, just usual pseudo-intellectual forum nonsense.

My starting point would be: Planes hit buildings, buildings fell down.

I think even as a layman I would be happy to accept that that thousands of tonnes of material falling at speed would cause vertical collapse of a building of that size. Childhood physics would show us that much.

Come on. Sometimes things are just what they are, even in the USA.

Ahem...we at least have one architect, and one structural welder. No, we're not demo engineers, but we do have some relevant experience.
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Green Lemon
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Re: Explosives Found in World Trade Center Dust

Post by Green Lemon » Tue Apr 14, 2009 8:53 am

Machinesworking wrote:
Emissary wrote: On first impressions it seems to make sense that each floor would build up momentum as the collapse proceeded but the opposite is true, with each floor more resistance and more resistance. The collapse should have slowed not sped up. We cant really tell from the video you supplied as to how far that building would have continued to fall if it had 30 or 40 more undamaged floors underneath it.

Also watching your video again you may notice is took that 13 story building about 10 seconds to collapse from start to finish, WTC 1 took 9 seconds. And i think it was a tad bigger
I think you're missing a huge and simple fact though, the more floors collapsed the less resistance would be an issue, as the weight was coming straight down, so each floor added tons of pressure. This would make the fall speed up to free fall speed, not slow down.

Also, people are amazed that it fell straight down, but consider this, a HUGE jet hit it, slightly ripping all the steel beams loose from the concrete around it, at least for a few floors above and bellow impact. So once these start crumbling, which wouldn't necessarily be visible from outside, it would start pancaking, that weight alone would take out any remaining beams. Also, in many ways the larger an object gets in sheer size, the more it's going to be pulled down, instead of responding to horizontal pressure. We're talking about two of the largest buildings in existence, with ten times more support beams than an average building, not a couple major ones, and supporting smaller beams. On impact, those beams hold on the concrete floors was compromised. It doesn't to me seem feasible that such huge slabs of concrete would swerve off a course straight down because of dozens of support beams that have been busted slightly off of the surrounding concrete?

I'm all for catching the government on things that you can, and I really wish the people in office who could have acted to prevent this were found out, (I do suspect that to be the case), but I really doubt any explosives and that level of conspiracy. What makes more sense is as I said before, a planned negligence on the part of those in power who would benefit from this sort of attack. Plus it really is building 7 we should be worrying about IMO.
That nicely sums up my opinion as well.
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