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Paul
Hey look check this out guys this video is great this is flaming fantastic, it is a video of well known 9/11 truther who assembles
some structural steel the way it would have been assembled in the wtc twin towers and other buildings made of structural steel
and he cuts righ through the thick structural steel, well thats kind of a lie he cuts almost all the way through the entire length of
the steel member, using normal thermite using barrium nitrate and sulphur well if this is how it was really done on 911 those cuts even if they dont cut completely all the way still would have weakened the structural steel enough to cause the entire structure to loose alot of it strength enough to bring about a casatrophic global collapse resulting in a gravity driven CD, and watch when he uses the thermite and creates his own charges and the thermite explodes it even creates a hole giving a swiss cheese like appearance, similar to the samples found from the wtc buildings.

Does this video completely destroy the duh bunkers claims that thermite cannot create vertical cuts through steel beams, and also there
claims that you couldnt use normal thermite to demolish a steel framed building?

I have another question why would you use barrium nitrate and sulphur mixed in with normal thermite to cut through structural steel
how would these chemicals improve the thermites cutting power?

9/11 Experiments: The Great Thermate Debate

http://www.youtube.com/watch?v=5d5iIoCiI8g...layer_embedded#!



whistle.gif whistle.gif whistle.gif
BADBURD
Nice find Paul. thumbsup.gif thumbsup.gif
tnemelckram
If our military is anywhere near as competent and equipped as I have repeatedly heard it is today (Veteran's Day) then they have ten zillion ways to blow things up, this one included, and are further able to make it look however they like.
A veritable pyrotechnic smorgasbord. But I guess most people think that's the case on November 11 and all other days except September 11, which must be some kind of annual everything-falls-apart-day.
SanderO
We always knew that thermite can cut steel as can thermate. Jon showed it could blast off bolts and be used to cut through vertical surfaces. Well done Jon.

So we know how steel could be "weakened" and connections made to fail. But most of the steel was not subject to that sort of attack. Most of the steel came apart of the stresses of a gravitational collapse showing no signs of what the few pieces of heat attacked steel show.

We now know conclusively that these materials could have initiated the collapse. Jon showed us. But he didn't show us anything about the actual collapse... such as how thermite/thermate would destroy concrete... of it did.
Paul
QUOTE (SanderO @ Nov 12 2010, 09:32 AM) *
We always knew that thermite can cut steel as can thermate. Jon showed it could blast off bolts and be used to cut through vertical surfaces. Well done Jon.

So we know how steel could be "weakened" and connections made to fail. But most of the steel was not subject to that sort of attack. Most of the steel came apart of the stresses of a gravitational collapse showing no signs of what the few pieces of heat attacked steel show.

We now know conclusively that these materials could have initiated the collapse. Jon showed us. But he didn't show us anything about the actual collapse... such as how thermite/thermate would destroy concrete... of it did.


Ok SanderO why dont we just all throw up our hands and declare that the terrorist did it huh? If we have no
physical evidence of thermite or explosive cuts damage to the steel then what are we doing here i guess the existence of this forum is a waste of time and that rob balsamo should retire it to the dust bin right? I guess we should just all retire from the truth movement is this what you are saying? And also that it very existence is futile and meaningless and a complete waste of time, what you are say points to exactly all of this.

Why are you here doing here on this forum SanderO? It seems to me like you are support the OCT way too much.
onesliceshort
Very interesting find Paul. Cheers.

First time I've actually seen a pretty precise replication of the type of beams in the WTC being exposed to thermite/nanothermite. I'd personally love to see more practical experimentation like this done (especially for those of us who are laymen!).
I think it would be very interesting to see if a smaller replica scale model could be made (cement, weight, structure) and experimented on that way. Only problem is that it's a trial and error method so the closest hypothetical device(s) would have to be found first. The guy in the video made the first step. Here's hoping there's more to come.

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mrmitosis
The other uploads on that guy's YT channel are excellent, as well.

SanderO, I know we've talked about the post-intiation collapse a little bit before, but I'm afraid I'm more convinced by the analyses in physicsandreason's (as he is known) videos. This guy is completely nuts, but his critique of NIST is utterly devastating. I would encourage everyone to take a look.
BADBURD
Paul you just keep up the good work. I learned something from this video that I will share with many people. We all need everything we can to help wake up the masses. That is all we can do at this point. THANK YOU for posting the video!!!! cheers.gif
BADBURD
SanderO you mention "what pulverized the concrete?" The concrete used was a lightweight mix poured on the floors without any reinforcment in it. I doubt it would take much to pulverize it. The fall would do the trick not to mention some explosives going off around it. Lightweight non reinforced concrete is not very strong. It's dense so it makes a great sound deadener which is why they use it instead of something like wood.
SanderO
I agree with the assessment of the destruction of the concrete. I certainly do not support the pack of lies packaged and marketed as the official conspiracy theory. There is more wrong with it than there is correct. Not much makes sense and there are holes big enough to drive a Mack truck through.

My own research into the structure of the twin towers leads me to think that they could collapse by gravity of the tops were first destroyed or broken off and their mass, or a large portion of it descended on the lower section's floors.

The OCT doesn't actually explain the collapse. They explain their initiation and that's all BS. But since they DON'T explain the collapse AFTER initiation, most people assume that they are "hiding" an explosive explanation for the collapse.

The engineering analysis points to the fact that the towers could and likely did collapse once the floors were sufficiently overloaded.

The initiation certainly could involve the kinds of attacks on the steel structure which Jon's work in this video so well illustrates. And it's likely that the initiation DID involve such things. But once they tops were "released" by destroying or weakening the columns up top, and likely the WF ones which were much more vulnerable to attack the huge mass would crash down through the structure crushing everything in the process. The towers weight 500,000 tons and even subtracting the weight of the steel - 200,000 tons, you have 300,000 tons. That will do a lot of crushing.

What exactly about the OCT do I support? Nothing basically. However, I don't support the idea that the towers were exploded from top to bottom and that gravity was not part of their collapse. If gravity wasn't used.. why weaken any columns?
DoYouEverWonder
QUOTE (SanderO @ Nov 12 2010, 09:17 AM) *
The engineering analysis points to the fact that the towers could and likely did collapse once the floors were sufficiently overloaded.


Really? Please site your sources?


QUOTE
What exactly about the OCT do I support? Nothing basically. However, I don't support the idea that the towers were exploded from top to bottom and that gravity was not part of their collapse. If gravity wasn't used.. why weaken any columns?

No one is claiming that gravity wasn't part of the collapses. Of course it was.

But you want us to believe that it was only gravity and not explosives that destroyed these buildings. That's why the perps used nano-thermite and fuel/air explosives to get the collapses started. There would be very little explosive residue left behind this way and they wouldn't need as many cutter charges, that you can see going off ahead of the debris cloud when the buildings came down.
BADBURD
They had to blow the core columns. Just blowing the top and relying on gravity to do the rest would never work. The top would have taken the path of least resistance. When we see the video of the top starts to fall sideways and then everything comes down. Had they not removed the core columns the top would have fell off to the side. Which is exactly what it started to do. I think they brought the core down just like they any other CD. From the bottom up.The difference is that the outer wall hid what was going on inside. I think they brought the outer wall down from the top a split second behind the core. Since the outer wall was stronger and taller on these buildings they couldn't rely on the core to pull it in and down on it's own. By weakening the outer walls the core was able to pull it down. This is just my opinion!!! I have been wrong before. cool.gif
SanderO
My engineering analysis is the source. You can read a discussion which lays this out quite well here:

http://the911forum.freeforums.org/oos-dest...model-t264.html

If you PM with your email I can send you some the material.

1. There is no evidence in the debris that any of the core columns were "destroyed" at the bottom of the structure. In fact row 500 and 600 - a total of 16 core columns stood to a minimum of 40 stories, some to 50 and column 501 was 72 stories AFTER the floors collapsed and the facade peeled off.

2. The twins were similar to a CD but one initiated above the crash zones. In both towers the mass which came down was more than enough to crash through the floors. Any tenant floor outside the core was designed to support 100#/SF but with the tops crashing down on them (the 92nd to begin with) the loads quickly grew to almost 2000# (or there abouts). This was also a dynamic load as it was dropping down and it was dropping down in a disorganized pattern of debris over the time that the tops descended and broke apart. This force was more than enough to destroy any single tenant floor outside the core. That floor shattered and the same process repeated all the way to the ground growing in mass as it went.

3. The destruction of the twin towers was not caused by plane strikes or office fires. There had to be additional energy inputs to get the tops dislodged from their support so that they could (and did) descend down and impact the FLOORS.

4. The collapse was through the "path of least resistance" which was the floor system which by volume was 98% air. The path of MOST resistance would be crushing through the columns which were increasingly strong as you descend down. No columns in the lower sections were crushed or show signs of being exploded apart. The debris shows THAT sort of damage on the columns and beams ABOVE the strike zone which makes perfect sense as this is how the tops were able to be freed from their supports.

5. The top of WTC 2 was lost support on the South and East side before it did on the North and West. This is like removing two or 4 legs on a table. It will tilt down and fall to the side where the legs were removed. However in the case of tower two the remaining columns were not able to support the mass of the top and they buckled rather quickly. As they did the top which was tilting began to descend. It was both tilting AND descending down. At the plane where it was severed, the core and the floors then began colliding with the standing lower section. The SE lower corner of the tilting top dug into the SE corner of the standing part and these collisions caused mutual destruction of the floors on that side. The collisions of the floors AND the facade columns and the core columns as the tip tilted and dropped sent shocks up through the top and quickly the joints began to break apart. You can see the top 3 floors bend first, just before the entire top breaks apart and disappears into a cloud of dust and debris. The top was a much more rigid part of the structure because of the hat truss with diagonal beams providing that rigidity. Parts of the top did continue over the side, but the virtual hinge was through col 501 and was more than 150' from the East side. For the entire top section to go over the side, it would have to remain rigid and have a hinge on or about the East face. That hinge would have to be supported by the lower section. This is not possible and as it moved both horizontally and vertically the lower East side was destroyed as it collided with the lower section and so it did not only not go outside the foot print but it provided the mass to cause the lower section's floors to collapse.

In all three towers it was not gravity alone which destroyed them.
DoYouEverWonder
QUOTE (SanderO @ Nov 12 2010, 11:44 AM) *
My engineering analysis is the source.


Are you saying you're Major Tom? If you want to quote his work, fine. But that's a bit different then doing you're own engineering analysis, which sorry dear, no can do on the email. Why don't you just post it here for the rest of the world to see?



QUOTE
4. The collapse was through the "path of least resistance" which was the floor system which by volume was 98% air. The path of MOST resistance would be crushing through the columns which were increasingly strong as you descend down. No columns in the lower sections were crushed or show signs of being exploded apart. The debris shows THAT sort of damage on the columns and beams ABOVE the strike zone which makes perfect sense as this is how the tops were able to be freed from their supports.


So going through a 100 layers of concrete and steel is the path of least resistance, compared to the empty air that surrounded the buildings. You've got to be kidding?


QUOTE
In all three towers it was not gravity alone which destroyed them.


So if it wasn't gravity alone, what was it?
SanderO
I am not Tom, but I concur with that hypothesis and came upon it myself about 1 year ago. I would upload my slides and so forth, but I can't seem to figure out how to do it in this forum. If you are interested I would email them to anyone who is interested. I am referring others to read Tom's presentation which is basically what I believe accounts for the collapse after initiation.

The destruction of the twins involved several phases which were not distinct but blended one into the other. The last phase was the collapse of the "spire" preceded by the gravity driven collapse of the floors and the peeling off of the facade. The spire broke apart as predicted by Euler's equation for slender columns.

The destruction began with the plane strikes, then fires and then there likely was engineered weakening of the core, perhaps with thermite or similar. This led to the tops collapsing down onto and into the top of the lower section which then collapsed as a result of the large dynamic loads.

The initial damage was not enough to bring the towers down, and the fires from fuel and office contents without sprinklers likely did not weaken the remaining steel enough for it to buckle and set off the collapse of the tops.

Gravity pulls things down. There were 3 structural elements in the towers - the core with its 47 columns, the facade with its 236 columns and the floors suspended between the two. The floors were about 97% air by volume and there were no columns to arrest a floor collapse. The columns however would have to be crushed and buckle or topple over. Crushing them is the path of MOST resistance.
Paul
Hi there i see that you can mix sulphur and barrillium in with thermite to create what i believe is called thermate basically
the same stuff maybe you will want to read this post of mine right NOW there was Barillium at ground zero no doubt about
it just ask first responder Glenn Kleinn if you dont believe me, the only problem is someone suggested that the copper pipes
in the wtc could have been made up of Barrilliium, but my only question would this be enough to poison the ground zero workers
and make them very sick, with this additional piece of evidence of the presence of Barillium at ground zero i am now convinced more
than ever that a form of nanothermite was used with a mixture of Barillium and sulphur the pieces are finally starting to fit together and
i can see them now.

Cheers guys Paul
SanderO
My take away from Jon's video is that thermite could be used to weaken the steel. He doesn't say which steel, how many columns or lateral beams were attacked, but he basically trades on the correct assumption that if the structure is destroy it can no longer carry the loads and gravity will cause it to collapse.

This work completely supports or dovetails into the notion that once initiated from structural weakening or dissociating.. and partial unloading of enough columns so that the remaining ones are overloaded and buckle... the mass once supported will collapse driven by gravity.

The other way to destroy the building is to explode them completely... or attack every structural element. But we did not see that and there is no evidence of this in the debris.
Paul
Barrillium At Ground Zero

http://pilotsfor911truth.org/forum/index.p...mp;pid=10787357

See my post maybe there was a mixture of thermite barillium and sulphur used to demolish the twin towers
combined together into a nanothermite mix the pieces are starting to fit together now more than ever what you
government wont tell you is it just wasnt asbestos that made the ground zero workers soo sick maybe it was
just all the barillium or maybe a mixture of both either way those bastards have to pay one way or another and
that i am sure of they are our enemies not the terrorsists not no citizens the are, they are the greatest threat to
to america and they must be stopped at any cost.
BADBURD
QUOTE (SanderO @ Nov 12 2010, 06:54 PM) *
Gravity pulls things down. There were 3 structural elements in the towers - the core with its 47 columns, the facade with its 236 columns and the floors suspended between the two. The floors were about 97% air by volume and there were no columns to arrest a floor collapse. The columns however would have to be crushed and buckle or topple over. Crushing them is the path of MOST resistance.


So what your saying is that if I wanted to make a huge white elephant fall directly on his belly it would be better to jump up and down on his back instead of pulling all of his legs out at the same time? The strength of the towers are in it legs (columns) just like the elephant. If you want to get something massive on the ground you take it's legs out. Nothing falls in the path of most resistance.
Paul
QUOTE (BADBURD @ Nov 13 2010, 10:54 PM) *
So what your saying is that if I wanted to make a huge white elephant fall directly on his belly it would be better to jump up and down on his back instead of pulling all of his legs out at the same time? The strength of the towers are in it legs (columns) just like the elephant. If you want to get something massive on the ground you take it's legs out. Nothing falls in the path of most resistance.


Actually you are wrong a one way crush down type demolition of the towers would have been entirely possible by initaitaing the collapse
with explosives. It is possible when there is enough energy & weight available to have the top crush the button all the way to freaken ground
which is very unfortunate for the people inside the building at the time what a god damn tradgedy.

Sry for the duh bunker type demolition but they are right on one thing only.

Démolition Balzac Vitry

http://www.youtube.com/watch?v=syzKBBB_THE...feature=related

rolleyes.gif rolleyes.gif rolleyes.gif
amazed!
SanderO

This is the most persuasive iteration of your theory so far, for this layman.

It does raise several points for me. The floors might indeed have been 'shattered', but by all appearances they were actually pulverized, and I still cannot see how a natural collapse could give that result.

Yes, as you have stated before, additional energy in the form of explosives of some sort was required. And this additional energy also was sufficient to create a fairly symmetrical debris field, and to launch several large pieces of the exoskeleton/skin outwards about 400 feet.

I think I understand your use of the term "path of least resistance", but I'm not sure I agree with it. As another poster pointed out, it was actually the path of most resistance. Without the assistance of other 'additional energy' further down the structure, how can we end up with what is for all practical purposes, a free fall rate of natural collapse?
BADBURD
If it is indeed true that the buildings came down in the 10 second range. Which I admit we don't know that is a fact because me or you were not there to see and time it with our own eyes. But if that is the number. There would be some type a resistance on the way down. You are talking roughly 8 floors a second. Think about that. I'm not disputing any of the explosives or Thermite. I'm not disputing that something was going on high up in the towers. I'm just saying to get that to the ground in it's own footprint at that speed the resistance has to be addressed. Floor by floor we should have seen some change in speed of the collapse do to the mass under it. Remember the columns get much bigger and stronger when get to the lower 2/3rds of the building.
So what your telling me Paul is that you would use the method of jumping on the elephants back to get it on it's belly? eek2.gif
SanderO
The increasing strength of the columns as you go down has nothing to do with the floor collapse. The columns were larger at the base because they supported the columns above them. Floors were attached to the SIDE of the columns so each column which was 36' tall carried 3 floors and added the weight of 3 floors to the load it carried from above. Since each floor had the same strength and the same connection to the columns regardless of what floor it was, if the load was too large for THAT floor it would collapse and then the one below and so on.

The issue is how long this would take and it would only take about a second to bust through 10 floors or so. But this was definitely not a pancake collapse. The floor top floor was not "attacked" by falling debris evenly overloading the truss seats uniformly. Rather it was a chaotic assault compressed into a fraction of a second... like buck shot. The collapse floors became a chaotic avalanche which grew as it descended. It ground and pulverized everything which was not compressible or tearable into find grained debris and dust, The collapsing floors and their contents weighed north of 300,000 tons. It pressed against the facade from the inside pushing it away and it spilled into the core destroying the shaft walls and many of the lateral beams. None of the connections or components of the floor system could support or arrest the immense dynamic loads of the hundreds of thousands of tons of falling debris.
BADBURD
I would be with this all the way except your not explaning what brought the core down. What you explain is the floor sections that fasten to the core like you state. 10 floors a second? You can't drop a rock 80 feet in a second. How does something with floors bolted to steel drop faster than that? Now if you did blow the truss bolts like in Paul's video here. That would remove the resistance. But what about the core? The core size getting bigger doesn't effect the floor system like you said. But it does effect the cores strength.
SanderO
The floor collapse can be timed at about 100 feet per second which is about 63 mph. The collapse accelerated from 0 mph to 63mph which was its terminal velocity if you drop a rock

sec / ft traveled
0 / 0
0.5 / 5
1 / 16
1.5 / 36
2 / 64
2.5 / 100
3 / 145
3.5 / 197


This is at free fall with no resistance. So if the acceleration was 60% of free fall it would reach ~63 mph in about 3 seconds.

The columns collapsed from several causes and mechanisms. There were 47 and all of rows 500 and 600 survived the collapse of the floors as high 40, 50 and even 72 floors. Row 500 and 600 were still joined by the lateral beams up to about the 40th floor. A few of the columns stood with no bracing left. One of the topples over to the east. 501-601 wobbles back and forth. It was too tall slender and unstable for its height. Even without any explosives a 600' tall column made up of sections 36' long could not stand without guys and or lateral support. See Euler's formula about column buckling related to slenderness.

Most of the columns in the core cam apart with the avalanche which destroyed the lateral support between them and the debris falling chaotically broke them apart. The splices were not meant to resist that kind of movement and they were only welded at the edges of the splice plates.

The columns above the strike zone which likely were attacked by thermite or similar might have not only destroyed the splices, but destroyed the bearing so the columns buckled or translated laterally. The steel frame broke apart at the joints. This is seen throughout the debris. Have a look see.
DoYouEverWonder
QUOTE (SanderO @ Nov 13 2010, 07:03 AM) *
My take away from Jon's video is that thermite could be used to weaken the steel. He doesn't say which steel, how many columns or lateral beams were attacked, but he basically trades on the correct assumption that if the structure is destroy it can no longer carry the loads and gravity will cause it to collapse.

This work completely supports or dovetails into the notion that once initiated from structural weakening or dissociating.. and partial unloading of enough columns so that the remaining ones are overloaded and buckle... the mass once supported will collapse driven by gravity.

The other way to destroy the building is to explode them completely... or attack every structural element. But we did not see that and there is no evidence of this in the debris.


You're a very all or nothing guy. You try to convince us that gravity alone was enough to the job, but the only other way to bring the buildings down would be to 'attack every structural element.' No CD requires attacking every structural element. I can't believe a real engineer would even make such an ridiculous claim. Especially, in regards to a building where they didn't even bother to weld the steel columns that made up the perimeter walls. I don't think it would be hard to blow those out, if you destroyed the cores with fuel air explosives. Wouldn't leave much for evidence either.
tnemelckram
I hope people do not mis-understand SanderO. He is not saying explosives were not involved. He just questions the relative degree of explosives versus gravity. I think his thoughts are sound, but think explosives were relied on by the plotters more than he does.
onesliceshort
QUOTE (tnemelckram @ Nov 14 2010, 02:36 AM) *
I hope people do not mis-understand SanderO. He is not saying explosives were not involved. He just questions the relative degree of explosives versus gravity. I think his thoughts are sound, but think explosives were relied on by the plotters more than he does.


I personally don't believe that the perps would rely solely on the laws of physics to collapse the lower portion of the towers.
What intrigues me is that the experiment in the video shows how exotic explosives, if properly harnessed, would massively reduce the need for "tonnes" of the stuff and would greatly reduce the visual effects one would expect to see from a proposed demolition job.
The cores could very well have been rigged with these types of charges.

I know it's only speculation at this point but it's food for thought.
SanderO
Do You recognizes that a commercial CD does not attack every structural connection. Most of the ones attacked are at the lower part and in the center to have the static loads cause the overloaded structure to collapse inward. The twins were very different from the strike zones down. The tops actually DO resemble a CD, but the bottom's destruction does not. No CDs have figured out a way to break some structural elements at the top and have the roof and a few floors take the whole building down.

What essentially happened with the twins is that the engineered destruction of the top section DID deliver the required overload which would crash through all the floors, strip off the facade and destroy the core so that it was absent enough lateral support to stand.

If the plane or explosive start was at the 105th floors the building would not have collapsed even if there was explosive CD on the top 5 floors. The released mass is less than the safety factor and there would be an arrest of the collapse. You'd be left with a tower with 5 floors of debris piled up on the 105th floor more or less.
Paul
QUOTE (SanderO @ Nov 14 2010, 01:01 PM) *
Do You recognizes that a commercial CD does not attack every structural connection. Most of the ones attacked are at the lower part and in the center to have the static loads cause the overloaded structure to collapse inward. The twins were very different from the strike zones down. The tops actually DO resemble a CD, but the bottom's destruction does not. No CDs have figured out a way to break some structural elements at the top and have the roof and a few floors take the whole building down.

What essentially happened with the twins is that the engineered destruction of the top section DID deliver the required overload which would crash through all the floors, strip off the facade and destroy the core so that it was absent enough lateral support to stand.

If the plane or explosive start was at the 105th floors the building would not have collapsed even if there was explosive CD on the top 5 floors. The released mass is less than the safety factor and there would be an arrest of the collapse. You'd be left with a tower with 5 floors of debris piled up on the 105th floor more or less.


Oh really is that so is it? Taking the crazy heiwa approach to thing now are we? I wish someone could prove that the collapse could be arrested
but that is never going to happen as we all know.

rolleyes.gif rolleyes.gif rolleyes.gif
SanderO
Not at all. The idea presented is that to cause a progressive collapse which does not arrest, you need to provide the suffient conditions for each floor to collapse. Since there is a safety factor of about 5, a single floors could support about 4 floors without it failing. This is very much like the local collapse of a few floors from the plane strike. That mass was insufficient to meet to minimum condition to fail the floor areas it descended on to this local collapse was arrested.

In both towers the minimum conditions were met and it applied to each floor below 92 for wtc 1 and below 77 for wtc 2. This explanation has nothing to do with small block crushing larger blocks as Bjorkmen and others try to reduce this to. That argument is true but not applicable. If you don't examine the event on a more micro level - that of structure and the composite floors in particular the are not looking at what failed.
amazed!
Because of Willy's testimony I too believe that the lower regions were prepared for the imminent destruction.

Sander

Since the first time I saw the buildings coming down, it seemed that there was some sort of "cascading" dynamic at work there.

But it is true that in order to turn solids into dust, one needs both a hammer and a proper surface--a surface that will not give way. Because of the relative free fall collapse, there was no resistance at all. What happens if you swing a hammer against the air?

It won't make dust, is the answer. blink.gif
SanderO
The floor collapse included all the collisions of the avalanche front with each successive floor. It was a chaotic highly energetic event where the material in the avalanche acted up itself much like the way a tumbler or rick crusher works.

There was an enormous roar when the collapse was taking place. That was the sound of millions of collisions or the materials in the building grinding, crushing, tearing apart and pulverizing everything in the towers. That sound was part of the energy released by the avalanche.
amazed!
Poor answer, unpersuasive.

Energy is required to pulverize solid objects including concrete floors.

For all practical purposes, the bottom two thirds of the tower offered the falling upper third the same resistance as air. Falling concrete cannot pulverize itself.
SanderO
Falling concrete did not pulverize itself. Collisions of concrete with tens of thousands of tons of falling debris pulverized it.

If you take any floor in the lower section... say 52... Falling on this floor was the mass of 58 floors or about 150,000 tons, less the material which went outside the footprint and into the core. The facade "tried" to contained the avalanche but it was pushed away. You don't think even 2/3's or 100,000 tons crashing down on a 4" slab wouldn't pulverize it to pretty fine material? What do you expect from such an onslaught?

If you look at WTC 7 you will observe the same absence of concrete and the same sort of pulverization and we all saw it collapse DOWN with a destruction zone in the lower part of the tower. The falling mass of the top pulverized almost everything which was not crushable... created a huge dust cloud and left a small pile. We did not see that tower collapse from the top down. but we say a similar fate to the walls, concrete and contents - crushed and turned to dust. This is what one would expect from have such huge mass with so much kinetic energy.

The engineering in all three cases involved releasing the gravitational energy which would destroy everything which could not be crushed or torn to shreds - heavy steel etc.
trimble
QUOTE (amazed! @ Nov 14 2010, 10:26 PM) *
For all practical purposes, the bottom two thirds of the tower offered the falling upper third the same resistance as air.


Quite incorrect. You are overlooking that the floors have a large inertia. The effect of a floor's resistance on the velocity of the falling debris is indeed minimal (due to the massive momentum of the falling debris), but the resistance of the individual rigid floors against acceleration (aka 'Inertia') is high because they have a high effective mass, and the acceleration will occur over a tiny fraction of a second (the collision is highly inelastic). The first debris to hit will be pulverised by what follows. Due to the chaotic nature of the collapse, these massive forces will be applied unevenly to the concrete slab resulting in further shattering and pulverisation of the slab.

Your rhetorical question, "What happens if you swing a hammer against the air?" is therefore based on a mischaracterisation of the system. The floor being hit might as well have been an anvil.

I came to a similar conclusion to SanderO on collapse propagation some time ago, although I put a lot less thought into the details smile.gif The question in my mind since has not been, "How did the building end up as a pile of rubble?" (it seems to me inevitable, once a lot of mass starts to descend) but "Why did the building start to collapse?". And this is a good video that dispels some of the anti-thermite myths.

*goes back to lurking*
onesliceshort
QUOTE (trimble)
Due to the chaotic nature of the collapse, these massive forces will be applied unevenly to the concrete slab resulting in further shattering and pulverisation of the slab.


That's fine on an individual floor by floor basis, but what we saw of the collapses were far from "chaotic". If 7-8 floors were collapsing per second, you're suggesting that every eighth of a second there was a chaotic event which lead to the pulverization of each floor.
I know it's a simplistic way of putting it but you get my point?
amazed!
Welcome to the forum Trimble, but I do not find your post to be particularly persuasive.

Considering the nearly free fall rates of collapse, I see nothing whatsoever, including your random chaos theory, that would act as anvil to the hammer.

The concrete was not broke into smaller pieces, it was pulverized into a pyroclastic flow. An anvil of large proportions would have been required. The dust was so fine that it drifted for blocks in the air.
onesliceshort
The characteristics of the massive spray of sparks seen in this clip..

http://www.youtube.com/watch?v=M6f9Jpfz1Vo...feature=related

..coupled with its proximity to the point of initial collapse plus the video in the OP is uncanny.
SanderO
You can't pulverize concrete or stone for that matter without "collisions" as far as I know. So the process of turning concrete into granules and even dust would require grinding of some sort which is used in commercial rock crushing. You might want to read this:

http://en.wikipedia.org/wiki/Crusher

which discusses how rock is crushed into smaller aggregates and powder. The concrete of the WTC floors was not especially strong, and had little or not stone aggregate and likely had something like light weight fly ash or crushed lava with lots of entrained air to make it light. This sort of concrete (no large aggregate) with little or no reinforcing was not structural and intended to resist tension. It was basically just a grout over the trusses and supported by the metal pans and would break up very easily.

The metal pans would have to be shredded to small pieces in the process and this is clearly less understood. But we've never see the kinds of forces that the floor avalanche contained before and how thin metal would respond to that.
trimble
QUOTE (amazed! @ Nov 15 2010, 10:32 AM) *
Considering the nearly free fall rates of collapse, I see nothing whatsoever, including your random chaos theory, that would act as anvil to the hammer.

I make no theory. I am merely stating basic mechanics.

To change the velocity of an object (ie apply an acceleration to it) requires a force. The resistance to that force is the object's inertia. The force is proportional to the object's mass and acceleration being applied. In the case of a floor slab, this inertial force is huge. An object travelling at 60mph is moving at around 30ms-1. A rigid floor is accelerated to this,despite a large safety factor, after what ... a 10cm drop? If you plug that into the standard motion equations (which is to make all sorts of invalid assumptions -- yes, yes, I am aware of this, but the purpose is to illustrate, not provide accurate numbers), you will get an acceleration of around 3000ms-2 over a hundredth of a second. Inertia = m.dv/dt . Once there is no more acceleration, there is no more inertial force -- ie the "anvil" is in existence for only as long as the debris from above is accelerating it. But for that fraction of a second, it is one hell of an anvil (and indeed one that in turn shatters) for the lower layer of debris and the slab itself.

QUOTE (amazed! @ Nov 15 2010, 10:32 AM) *
The concrete was not broke into smaller pieces, it was pulverized into a pyroclastic flow. An anvil of large proportions would have been required. The dust was so fine that it drifted for blocks in the air.


Concrete is a brittle aggregate material susceptible to fractures. If you hit a block of concrete, shock waves will travel throughout the material, and there will be localised stresses resulting in shattering and dust. Hit it hard enough, and vigorously tumble your small pieces together, and you are going to get more dust than chunks. Comparable to a giant commercial VSI crusher, I suppose.

I am not, however, going to make any argument or point of how concrete is turned to dust. I am not a materials scientist (my field is far removed from anything related to 9/11). The sole point I am making (and that SanderO is making) is that there is no *need* for anything additional to help the building on its way, after collapse is initiated. Whether additional help is required to explain other observations (ie. the dust) is a completely different matter.

Unrelated niggle : do please avoid inaccurate terms like "pyroclastic flow" and "chaos theory". You dont mean either, thus its inaccurate and lazy language that may confuse another reader (probably fall into laziness myself sometimes, but I hope not over such specific terms).
Paul
QUOTE (trimble @ Nov 16 2010, 02:32 AM) *
I make no theory. I am merely stating basic mechanics.

To change the velocity of an object (ie apply an acceleration to it) requires a force. The resistance to that force is the object's inertia. The force is proportional to the object's mass and acceleration being applied. In the case of a floor slab, this inertial force is huge. An object travelling at 60mph is moving at around 30ms-1. A rigid floor is accelerated to this,despite a large safety factor, after what ... a 10cm drop? If you plug that into the standard motion equations (which is to make all sorts of invalid assumptions -- yes, yes, I am aware of this, but the purpose is to illustrate, not provide accurate numbers), you will get an acceleration of around 3000ms-2 over a hundredth of a second. Inertia = m.dv/dt . Once there is no more acceleration, there is no more inertial force -- ie the "anvil" is in existence for only as long as the debris from above is accelerating it. But for that fraction of a second, it is one hell of an anvil (and indeed one that in turn shatters) for the lower layer of debris and the slab itself.



Concrete is a brittle aggregate material susceptible to fractures. If you hit a block of concrete, shock waves will travel throughout the material, and there will be localised stresses resulting in shattering and dust. Hit it hard enough, and vigorously tumble your small pieces together, and you are going to get more dust than chunks. Comparable to a giant commercial VSI crusher, I suppose.

I am not, however, going to make any argument or point of how concrete is turned to dust. I am not a materials scientist (my field is far removed from anything related to 9/11). The sole point I am making (and that SanderO is making) is that there is no *need* for anything additional to help the building on its way, after collapse is initiated. Whether additional help is required to explain other observations (ie. the dust) is a completely different matter.

Unrelated niggle : do please avoid inaccurate terms like "pyroclastic flow" and "chaos theory". You dont mean either, thus its inaccurate and lazy language that may confuse another reader (probably fall into laziness myself sometimes, but I hope not over such specific terms).


I think a building would have to be very strong to arrest it's own collapse if you where to remove say ten or so floors cut of
the top lift it up and drop down on the remaining floors i think the case of a steel skyscraper you would have to have very thick
out core columns you would have to have very thick floor trussed more like thick long metal beams supporting the underneath of
the floors you would have to have very strong bolted connections you probably even have to have very strong welds as well just think
about like in the case of the wtc you have like 100 tonnes or probaly even more than that maybe like 300 tonnes of upper floors
suddenly dropping and hitting the floors below i think in order to arrest such a collapse you would have to have a building that
can support more than it's static load i think you would have to have a building that could support 1.5 times it's static load or maybe even
almost twice it's actual static load because when you take the top of a building and drop it you have a tremendous amount of energy
and weight that want to go only one way the way the gravity is pulling it and that is straight down, and in order to have a building that could areest it's own collapse it would have be strong enough to catch and hold the entire weight of the upper floors all without buckling having and bolts shear
come out due to the entire weigh of the upper floors that have just been dropped on it, and for a building to arrest it's own collapse in this
manner would be an incredible feat and i dont think most buildings could do it, anyway just an interesting though if the wtc twin towers where
built of a much tough stronger desighn and supposing the top section still did manage to drop give way fail buckle i wouldnt not be suprise if
if the top went straight over the side and crashing down into the streets below, this is what i would suspect would have happened if the wtc twin towers where of such a tough desighn that they could arrest themselves.

Anyway that's just a few thoughts of mine from a non engineer pretty good huh?

thumbsup.gif welcome.gif welcome.gif
Paul
QUOTE (Paul @ Nov 16 2010, 05:56 AM) *
I think a building would have to be very strong to arrest it's own collapse if you where to remove say ten or so floors cut of
the top lift it up and drop down on the remaining floors i think the case of a steel skyscraper you would have to have very thick
out core columns you would have to have very thick floor trussed more like thick long metal beams supporting the underneath of
the floors you would have to have very strong bolted connections you probably even have to have very strong welds as well just think
about like in the case of the wtc you have like 100 tonnes or probaly even more than that maybe like 300 tonnes of upper floors
suddenly dropping and hitting the floors below i think in order to arrest such a collapse you would have to have a building that
can support more than it's static load i think you would have to have a building that could support 1.5 times it's static load or maybe even
almost twice it's actual static load because when you take the top of a building and drop it you have a tremendous amount of energy
and weight that want to go only one way the way the gravity is pulling it and that is straight down, and in order to have a building that could areest it's own collapse it would have be strong enough to catch and hold the entire weight of the upper floors all without buckling having and bolts shear
come out due to the entire weigh of the upper floors that have just been dropped on it, and for a building to arrest it's own collapse in this
manner would be an incredible feat and i dont think most buildings could do it, anyway just an interesting though if the wtc twin towers where
built of a much tough stronger desighn and supposing the top section still did manage to drop give way fail buckle i wouldnt not be suprise if
if the top went straight over the side and crashing down into the streets below, this is what i would suspect would have happened if the wtc twin towers where of such a tough desighn that they could arrest themselves.

Anyway that's just a few thoughts of mine from a non engineer pretty good huh?

thumbsup.gif welcome.gif welcome.gif


What are they talking about when they mention buildings and elastoplastics is that like how much strain a particular piece of steel like
steel beam or column can take before it begins to bend buckle fail? Just interested that's all.
amazed!
I guess WTC 7 must have used the same grout, eh?
SanderO
I don't know for sure the floor specs, but the concept was to not use shoring and to create a composite system and the concrete was lightweight and the trusses resisted deflection (concrete in compression).

I don't know what the system used in 7 was, haven't looked into it. The structural system was similar though with a core whose perimeter columns support the outside the core floors with a series of columns just inside the curtain wall. I believe there were girders and beams and perhaps trusses as well. But it likely used metal pans since shoring is too expensive and the underside appearance of the slab was not critical. Open web joists facilitate placement of ducts / services etc which are concealed inside suspended ceilings.
trimble
QUOTE
I guess WTC 7 must have used the same grout, eh?

WTC7 collapsed in a totally different manner, so is (potentially) a different beast. But yes, any concrete floors in any building are generally going to be lightweight and unreinforced: there is no reason for anything else.

But really, why make the question? Who cares? The big point here is that if it is not necessary to "help along" the collapse, anyone trying to achieve total collapse would have done some sums and been sure of this. This was not an operation worked out over lunch. They wouldn't bother chopping the entirety of the towers up into nice 30' sections (the logistics of which are ridiculous, and are often cited in favour of a full CD being 'impossible'), so why look for it when it (probably) isn't there? If initiation is all that is required, and that initiation cannot be explained from the plane and fires (I can't see how it can be), let's expend effort investigating something odd, rather than something obvious (though, in truth, I think there is sufficient evidence already that has not been countered in support of thermite involvement).

QUOTE
if the top went straight over the side and crashing down into the streets below, this is what i would suspect would have happened if the wtc twin towers where of such a tough desighn that they could arrest themselves.

Toppling is only ever possible if the centre of gravity of an object lies outside its vertical projection. A pivot is also required. A building would surely need to be extremely strong to survive significant symmetrical collapse if there is no toppling (think 'pile-driver'). Or rather less strong to survive a collapse if there is toppling (the KE of the upper section no longer has to be absorbed by the lower), but this would necessitate an asymmetrical collapse (either by design or accident) AND a pivot capable of withstanding enough force for the falling block to obtain sufficient angular velocity to clear the lower section.
trimble
I mean horizontal projection, ofc wink.gif
BADBURD
[quote name='Paul' date='Nov 15 2010, 02:26 PM' post='10791123']
just an interesting though if the wtc twin towers where
built of a much tough stronger desighn and supposing the top section still did manage to drop give way fail buckle i wouldnt not be suprise if
if the top went straight over the side and crashing down into the streets below, this is what i would suspect would have happened if the wtc twin towers where of such a tough desighn that they could arrest themselves.


Paul that is exactly what should have happened. When you see the video the top starts to fall over right before something pulls it's legs out from under it. But really this is all just something to talk and nit pick about. We can talk for eternity about how and why. I'm sure everyone on this forum is in agreement they were brought down by something other than jet fuel. What we need to be doing is deciding if and what we are going to do about it.

I'm going to save you all a lot of trouble of asking me. I don't know what. But I can tell you voting is not going to fix it. Greed will just replace one with another. Think about this. Who the hell in there right mind would want to be in politics? We are losing OUR country to these crooks and pysco's more and more as everyday goes by.
SanderO
The entire top could not have tipped over the side... certainly not as integrated mass. When the SE support was destroyed the NW columns were taking all the load for a bit as the SE side came down. Still connected to the core and the floors the entire top hung together for a few seconds and it tilted and dropped. But the load buckled the NW columns and there was no longer any support for the top and it had no resistance to drop vertically. The CG was well within the footprint and ther was not enough momentum nor a strong enough hinge to sustain continued rotation.

The SE corner of the top dug into the SE corner or the bottom and the collisions of the two sent shockwaves through the top and the joints broke apart and it seemed to turn to dust. Most of it had descended into into the debris cloud created as the SE corners collided and gave the illusion that it simply turned to dust when in fact it was hidden in the dust and debris created a few moments earlier.

Bit the material which had made it over the side... the top SE section did continue to drop down and landed outside the footprint.

Claiming the top should have continued over the side is incorrect and shows no understanding of the force distribution of collision of the two masses.
mrmitosis
SanderO -

I've just watched a video presentation by Gordon Ross (whose work I am otherwise not familiar with), who makes the observation that the antannae sitting at the top of the North Tower drops before any other part of the structure, making it the first visible phase of the collapse. In other words, no other damage to the corners of the buildings was evident prior to the downward movement of the antannae.

He then makes the startling claim that "all 47 core columns had to be severed - had to be disassociated - in order for the antennae to begin to move downwards."

At least, it struck ME as being somewhat controversial, given that these columns are presumably quite fundamental to the overall structure.

I was just wondering if you have any thoughts on that particular statement. I'm not in a position to make any qualified comment myself, but I was interested in whether or not it conflicts with your own theory.
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