Moderated Continuation - Why a one-way Crush down is not possible

Tony Szamboti said:
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You need to do a calculation for the central core to try and prove it wasn't self-supporting.

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The core has to have floors and the shell to stand. You fail to grasp reality when it can be researched.

The shell supports virtually all lateral loads and shared the gravity load with the core. Common knowledge to all but conspiracy theorists with failed ideas about physics, and engineering.

So the core can stand if there are virtually no lateral loads of any kind. That condition only exists in the vacuum of Jones thermite riddled mind where delusions take 4 years to erupt and then 3 more years to become "loaded gun" perfect insanity.

The big clue is seeing the WTC towers being built; their great strength and the reason you can't comprehend what happen on 911 is due to their unique design. If you were a structural engineer instead of a failed delusions pusher you would have a better chance of understanding the WTC collapse and distance yourself from the insane conclusions you support.
 
beachnut said:
The core has to have floors and the shell to stand. You fail to grasp reality when it can be researched.

The shell supports virtually all lateral loads and shared the gravity load with the core. Common knowledge to all but conspiracy theorists with failed ideas about physics, and engineering.

So the core can stand if there are virtually no lateral loads of any kind. That condition only exists in the vacuum of Jones thermite riddled mind where delusions take 4 years to erupt and then 3 more years to become "loaded gun" perfect insanity.

The big clue is seeing the WTC towers being built; their great strength and the reason you can't comprehend what happen on 911 is due to their unique design. If you were a structural engineer instead of a failed delusions pusher you would have a better chance of understanding the WTC collapse and distance yourself from the insane conclusions you support.
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Beachnut, you don't ever produce calculations for anything. You have no idea and are obviously just spouting off what you want to think.

The 209 foot x 209 foot x 1368 foot tall building was self-supporting with much more weight than the core had on it. What makes you think a 137 foot x 87 foot x 1368 foot section could not be self-supporting? You have to calculate the moment of inertia to find out.

Although the core was not intended to take the lateral loads that doesn't mean it could not take any. I showed it could have taken a 40 mph wind and it was stable taking it's own weight vertically without external support.
 
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Tony Szamboti said:
The 209 foot x 209 foot x 1368 foot tall building was self-supporting with much more weight than the core had on it. What makes you think a 137 foot x 87 foot x 1368 foot section could not be self-supporting? You have to calculate the moment of inertia to find out.
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Rather pointless to treat the entire core assembly as an individual column without the floor sections providing the lateral stiffness. Not rocket science, once the collapse commenced and the core lost that bracing it was vulnerable to buckling already, and it in fact did it as expected when it lost its structural integrity.
 
Tony Szamboti said:
Why would you compare the moment of inertia and buckling resistance of a single 36" x 60" x 1" wall x 1300 foot column to that of the entire central core?

The difference here is that the moment of inertia of the central core is tens of thousands of times greater than that of the column you calculated it for and the core itself did not weigh even one thousand times more than that column.

You need to do a calculation for the central core to try and prove it wasn't self-supporting.
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The core columns were interconnected by pinned end beams. These do not form a lateral resisting system. Let's look at a basic engineering problem, structures 101 really:

There are two fixed based columns with a beam rigidly attached to the columns. A horizontal force is applied to the top of each column. The beam will develop large moments and act to connect the two columns. The horizontal force is resisted not only by bending in the columns, but also as overturning moment on the frame. One column now develops a tension force and another develops a compression force. For the laypeople: take a chair and push it from the top. The whole chair moves as a body and begins to tip over.

Now take the same problem and change the beam to pinned end connections. What is the force in the beam? ZERO. The horizontal force is completely resisted by bending through the columns and the only axial force in the columns is their own self-weight.

I already did the calculation showing that the core wasn't self-supporting. How? The core doesn't act together. Each column is completely laterally independent when the floor diaphragm and/or perimeter moment frames are removed. And a single column can't stand by itself, which is why the core fell over after the collapse.

This isn't a complicated subject. It's really rather basic engineering.

It was self-supporting and the back of the envelope calculations I did (which you criticized as not being relevant) show that, with more than enough margin to make up for the lack of rigor. The geometry I used was much closer in it's moment of inertia to weight ratio to that of the core than what you have done here.
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The shape you made up doesn't represent anything in reality and the equations you used don't apply to your made up shape if it did exist. You need to read up on compact vs. non-compact shapes.

Out of curiosity last week I did an FEA model of a 10 story lattice structure, like the core, with columns and beams that were 10% the height of a story in the center and perimeter, and a hollow rectangular section of the same outside dimensions with solid walls as thick as the beams and columns of the lattice structure. The lattice structure with interior support from one side to the other had a moment of inertia 3 times greater than the hollow section and the simple hollow section geometry of the same outside plan dimensions as the core shows it to be self-supporting.
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This is completely irrelevant to the WTC.
 
BadBoy said:
so, are you saying the whole structure wouldn't move (sway) with wind load, because if they did then the floors would get pushed into the inner core wouldnt they?:confused:
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The core consists of 46 vertical columns interconnected by horizontal beams at regular intervals. This assembly of structural elements, connected to ground, is self-supporting and quite elastic.

The perimeter consists of 4 walls about 60 m square (and 410 m tall). The 4 walls are connected at the corners. A wall consists of pre-fab 3columns/3 spandrels assemblies bolted together. It is also self-supporting. It is like a big cage! Is is also quite flexible and will deflect laterally due to wind, etc.

The floors are just installed hanging between perimetere and core. All explained in my papers. When core/perimeter deflect laterally the floors just follow.

All vertical elements, i.e. columns, get stronger towards bottom. Apart from carrying their own weights, minimal, they can also carry the weight/load of all floors attached to them. With a Factor of Safety of at least 3. The core and the perimeter are thus very strong. To suggest that they can collapse like a house of cards dropping some sections on them up top is ridiculous.
 
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Tony,
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quote=Tony Szamboti;4979186]
You need to do a calculation for the central core to try and prove it wasn't self-supporting.
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I've been watching this discussion with a fair amount of bemusement, Tony.

Who gives a rat's butt if the core, as built in a nice pristine condition would, or would not be, self supporting?

This whole silly conversation grew out of a discussion as to whether or not the core would stand after the rest of the building collapsed around it. Do you really think that the columns would be nice & straight, everything as originally built, after all the trusses connected to those beams were ripped away??

Here are the only two significant questions here (IMO, of course):

1. Heiwa offered the, uh, "interesting" opinion that the floor system outside the core did NOT contribute lateral support to the columns.
Do you agree with this statement?

2. When the building began to collapse, video shows clearly that the outer columns formed 3 knuckle "Vees", pivoting inward or outward at the top, middle & bottom of 2 full 3-story units.

This failure mode would cause
a. the instantaneous doubling of all loads on the core columns as the peripheral columns gave way
b. the instantaneous application of 5x moment loading on core columns, probably 20x their design bending loads
c. the instantaneous unloading of 6 - 10 stories of all core columns (as the outer columns peeled away, dropping the floor assemblies),
d. the instantaneous loss of 6 to 10 stories worth of lateral support, and
e. about a second later, as the suddenly unsupported floors swung down, the simultaneous application of around 500 to 800 metric tonnes (floor assy weight) of dead weight pulling down and outward, spread over 6 to 10 successive floor to each outer row of core columns.

My question to you is "Do you think that sudden change in loading, sudden addition of moment loads, sudden loss of lateral support over 6 - 10 successive stories, and sudden addition of that magnitude of abnormal dead weight pulling outward on the columns ...

... do you think that all that might have destabilized the core columns enough that they buckled??
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quote=Tony Szamboti;4979186]
Out of curiosity last week I did an FEA model of a 10 story lattice structure, like the core, with columns and beams that were 10% the height of a story in the center and perimeter, and a hollow rectangular section of the same outside dimensions with solid walls as thick as the beams and columns of the lattice structure. The lattice structure with interior support from one side to the other had a moment of inertia 3 times greater than the hollow section and the simple hollow section geometry of the same outside plan dimensions as the core shows it to be self-supporting.
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Just out of curiosity, if you're going thru the trouble of creating an FEA model, why the heck are you making it 10 stories high?? With columns that are 1 story high?? If you were looking to answer the silly question regarding "were the cores self-supporting?" why the heck didn't you model it at the dimensions & height that they actually were??

You put in the effort to produce a model. Why did you produce such an unrepresentative one?

Tom
 
bill smith said:
Repost of post #1465. How does this slot in ?

' Look at it this way. Take just one outer core column and picture the floors runnng to at at about 12 foot intervals for 110 floors up to a height of 1300 feet.Do you think that puts a fair amount of vertical stress on the column ?

It still stands though. Now remove all the floors. Will the column now collapse under it's own weight ? (I'm not talking about stability here, only the fact that the column is strong enough to remain standing) '
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Bill. Are the floors attached to your column attached to anything else? If they aren't then your column will obviously collapse. You miss the point that the support for the weight of the floors is distributed between all the other columns. Also, throgh the trusses and floor frame your column is being supported via the other columns the floors are attached to. As tfl says it's the geometery of the whole structure not a single column. have you ever seen those Spanish human towers ? Rings of guys bracing each other, rings standing on the sholders of the others. What would happen if they tried to go 8 people tall as a single column of guys. The top guy would probably hurt himself the worst as he hits the floor.

Disclaimer here engineers:- appologies if this doesn't make sense or is a bad example. Please correct me if I'm off track here
 
BadBoy said:
Bill. Are the floors attached to your column attached to anything else? If they aren't then your column will obviously collapse. You miss the point that the support for the weight of the floors is distributed between all the other columns. Also, throgh the trusses and floor frame your column is being supported via the other columns the floors are attached to. As tfl says it's the geometery of the whole structure not a single column. have you ever seen those Spanish human towers ? Rings of guys bracing each other, rings standing on the sholders of the others. What would happen if they tried to go 8 people tall as a single column of guys. The top guy would probably hurt himself the worst as he hits the floor.

Disclaimer here engineers:- appologies if this doesn't make sense or is a bad example. Please correct me if I'm off track here
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Every column takes it's share of the static weight of the floor through it's connectors. An accumulation of these forces over 110 floors will place some vertical compressive stress on the column.

If the column did not deform vertically under this added weight then when that weight is completely removed I doubt that the column will then buckle under it's own weight.

As I said I am not talking about stability here. only that the column will not collapse under it's own weight.
 
Ignore Bill. He's an idiot. Either posing as one or the real article I wouldn't like to say. But with his posts on this board the word idiot is the only correct one.

I sort of hope he's just winding people up. The alternative is a little more worrying.

As I said, ignore him.
 
Heiwa said:
The core consists of 46 vertical columns interconnected by horizontal beams at regular intervals. This assembly of structural elements, connected to ground, is self-supporting and quite elastic.

The perimeter consists of 4 walls about 60 m square (and 410 m tall). The 4 walls are connected at the corners. A wall consists of pre-fab 3columns/3 spandrels assemblies bolted together. It is also self-supporting. It is like a big cage! Is is also quite flexible and will deflect laterally due to wind, etc.

The floors are just installed hanging between perimetere and core. All explained in my papers. When core/perimeter deflect laterally the floors just follow.

All vertical elements, i.e. columns, get stronger towards bottom. Apart from carrying their own weights, minimal, they can also carry the weight/load of all floors attached to them. With a Factor of Safety of at least 3. The core and the perimeter are thus very strong. To suggest that they can collapse like a house of cards dropping some sections on them up top is ridiculous.
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from what I've been reading here its not nearly as simple as that billyboy.

1. You have removed lateral support for the column.
2. The building was crashing down around it.
3. All the previous posts proving otherwise.
 
Heiwa, on the other hand, is completely insane.

The sooner he gets to a hospital and has professional help the better.
 
BadBoy said:
from what I've been reading here its not nearly as simple as that billyboy.

1. You have removed lateral support for the column.
2. The building was crashing down around it.
3. All the previous posts proving otherwise.
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The core columns do not depend on the external floors for lateral support. The complete core assembly is self-supporting.

The perimeter walls do not depend on the internal floors for lateral support; the walls support one another via the corner connections. The four walls are thus self-supporting (like a bird cage).

Removing floors (and associated loads) between perimeter walls and core do not produce any critical local failures that cannot be arrested.

Quite easy to show with a 3-D beam or FEM model. It is one reason Why a one-way Crush down is not possible of a structure like WTC 1 ... or any structure for that matter!

Try to design a structure that can self-destruct! See The Heiwa Challenge thread for details!
 
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heiwa: To suggest that they can collapse like a house of cards dropping some sections on them up top is ridiculous.
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but they did (collapse)! We have all watched it.

IF, we were discussing this BEFORE the buildings had been attacked as a "what if", I personally wouldnt have been so convinced, though Im afraid the excellent posts from the likes of Tom, Newtons Bit etc etc, for me at least, compared with the opposing arguments, appear much better informed would still have convinced me it was possible in the end Im sure.

However, we are not talking what if. We have all seen what actually happened and Im afraid for me, the alternative that is being postulated is by an order of magnitude more ridiculous.

BTW, Im not American. I think the USA is a great place, though I'm not a big fan of US foriegn policy and I find some Americans i've met a little insular/ignorant in terms of their understanding of the world. Im definitely NOT a bush supporter, what a complete tosser. I dont disagree with you because I LOVE America. I disagree with you because there is absolutely no evidence that proves the truthers theory, not because I believe the gov loves its people and would never do such a thing (though I dont think they would).

To go along with CD we are expect to take for granted, go on faith, far far far too many assumptions. Tell me this, why would CD have to be an inside job? why not the work of terrorists? Even if evidence of a Bomb were found, i'd be more willing to believe that an outside organization were responsible.
 
Tony Szamboti said:
Why would you compare the moment of inertia and buckling resistance of a single 36" x 60" x 1" wall x 1300 foot column to that of the entire central core?

The difference here is that the moment of inertia of the central core is tens of thousands of times greater than that of the column you calculated it for and the core itself did not weigh even one thousand times more than that column.

You need to do a calculation for the central core to try and prove it wasn't self-supporting.

It was self-supporting and the back of the envelope calculations I did (which you criticized as not being relevant) show that, with more than enough margin to make up for the lack of rigor. The geometry I used was much closer in it's moment of inertia to weight ratio to that of the core than what you have done here.

Out of curiosity last week I did an FEA model of a 10 story lattice structure, like the core, with columns and beams that were 10% the height of a story in the center and perimeter, and a hollow rectangular section of the same outside dimensions with solid walls as thick as the beams and columns of the lattice structure. The lattice structure with interior support from one side to the other had a moment of inertia 3 times greater than the hollow section and the simple hollow section geometry of the same outside plan dimensions as the core shows it to be self-supporting.
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I cannot believe you have the nerve to show up again. How about some more imaginary doumentaries Tony? Found it yet?

Or some more false claims about NIST evidence?
 
BadBoy:
I find some Americans i've met a little insular/ignorant in terms of their understanding of the world.
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I don't think it's their fault. I noticed this ignorance too when I first visited America. For a start their media thinks the rest of the world is somewhere outside Pluto. And secondly, being in America, miles away from anywhere else, you do feel apart. It's a very strange feeling for someone who grew up in Britain and is used to the hurly-burly of European arguments on the telly news every 5 minutes, and worrying about them.

Is America insular? Yes.

Should the American people know more about the outside world? My God, YES.

Are the majority of Americans bad for not realising this? NO. They're just like you and me. They just live on a different continent and eat different food and watch different movies. (Well, probably the same films and food, but you get what I'm driving at.)

We're all the same, just different. Ahem, if you see what I mean.

OK, back to the point:

The multicoloured , multicultured population of the USA is fab. It would just help if they didn't live thousands of miles away from the rest of the world
 
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BadBoy said:
but they did (collapse)! We have all watched it.

IF, we were discussing this BEFORE the buildings had been attacked as a "what if", I personally wouldnt have been so convinced, though Im afraid the excellent posts from the likes of Tom, Newtons Bit etc etc, for me at least, compared with the opposing arguments, appear much better informed would still have convinced me it was possible in the end Im sure.

However, we are not talking what if. We have all seen what actually happened and Im afraid for me, the alternative that is being postulated is by an order of magnitude more ridiculous.

BTW, Im not American. I think the USA is a great place, though I'm not a big fan of US foriegn policy and I find some Americans i've met a little insular/ignorant in terms of their understanding of the world. Im definitely NOT a bush supporter, what a complete tosser. I dont disagree with you because I LOVE America. I disagree with you because there is absolutely no evidence that proves the truthers theory, not because I believe the gov loves its people and would never do such a thing (though I dont think they would).

To go along with CD we are expect to take for granted, go on faith, far far far too many assumptions. Tell me this, why would CD have to be an inside job? why not the work of terrorists? Even if evidence of a Bomb were found, i'd be more willing to believe that an outside organization were responsible.
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Yes, they got destroyed, but let's face it; The upper part (C), a weak structure, mostly air, cannot crush the lower part (A) due to local failures (plane impact, fire) and with C displacing down on A. The latter displacement will produce and apply too little energy - locally - and it would only produce some further local, structural failures in both parts where the energy/forces are applied. You cannot destroy a building by dropping a little part of it on the rest!

So what is the alternative cause of total destruction? In my view CD from top down is quite obvious as explained by David Chandler & Co. It is a pity that US authorities do not investigate that cause properly.
 
Attack the argument not the poster is fine normally.

But Heiwa is an exception.

Mods, please ban him. He's just an idiot.
 
Oscar: Are the majority of Americans bad for not realising this? NO.
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ya, I know. I wasnt wanting to bash Americans and I agree with you completely. I also think its not just because America is isolated geographically, I think its also because the country itself is so vast and diverse, I think it would be easy to forget that other places exist.

I was just trying to illustrate to Heiwa where my motivation was coming from because some posts on this thread appear to assume that people are truthers because they hate the USA (not sure how you can hate a whole country anyway, thats just stupido). My motivation for my point of view are the facts, not my love of the north American government. Basically Im trying to get him to see that his alternative is completely nuts. I guess though thats never gonna happen.
 
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