Physics Prof Says Bombs not Planes brought down wtc

Buckling failure

Quite often the buckling of column can lead to sudden and dramatic failure.

www.aeromech.usyd.edu.au...

The behaviour of a compressed shell after buckling is quite different to that of a plate; in this case an unstable ( negative ) stiffness is accompanied by a sudden reduction of load capacity.
Since the displacements are uncontrolled in most practical systems, shells behave in a snap- buckling mode - ie. as an increasing load reaches the bifurcation point, the cylinder must undergo an instantaneous increase in deflection

www.mech.uwa.edu.au...

Non-linear collapse analysis enables successive points on the non-linear primary equilibrium path to be determined until the tangent to the path becomes horizontal at the limit point (Figure 8b). At that stage, assuming weight loading, as is normally the case for engineering structures, non-linear collapse ("snap-through") occurs.

www.kuleuven.ac.be...

I'd like to how you know they fell in an even fashion? I thought we couldn't see properly because of the dust cloud, or did you get a better look?
That bit of the central core that was left standing for a few seconds looked pretty uneven and jagged to me.
When the cap tilited it will have put a lot of stress on the pivot point, when that collapsed it will have driven straight down don't you think?

As for the fires, there will have been countless numbers of boxes of paper, for copiers and printers, books, magazines. Plenty of wood from desks, furniture, doors, etc. All of this won't have just disappeared.
I am well aware of the crucial factor being if the WTC was demolished with explosives or not, but as the discussion branches off into other sub-topics - like what sort of explosives were used if any and what can we find out about them from the fires after - it seems appropiate to discuss them when they come up. All I am interested in along those lines is if the continuing fires are actually relevant to finding out if anything else was used.
I'm not sure why you are so ineager to discuss it, I thought as the topic of this thread is 'Physics prof says bombs not planes brought down wtc' it would be relevant to discuss all aspects of this in as many ways as possible.

Originally posted by AgentSmith
I'd like to how you know they fell in an even fashion? I thought we couldn't see properly because of the dust cloud, or did you get a better look?

Why yes, I did.

Here's one video, taken from below the collapse.

Would you like to argue that that isn't symmetrical?

Notice how far down the building it is by this point, too. I would think, by chaos theory, that a lot of "random" events would have taken their toll by now, but nope. Still trucking along with floors blowing out evenly, and at the same speed, no less.

Or, again, would you like to argue that that isn't even? If you would, I just ask anyone here to watch the video for themself. There really isn't much to argue on that one, Smith, old pal.

That bit of the central core that was left standing for a few seconds looked pretty uneven and jagged to me.

I'm not surprised. It was uneven and jagged. Considering I think explosives were used in the building, do you think it should surprise me? But the fact is that they still stood. That is should trouble you pancake theorists, no?

But I suppose you've a long way to come, from the first pancake theorists, who proposed a core-less WTC.

When the cap tilited it will have put a lot of stress on the pivot point, when that collapsed it will have driven straight down don't you think?

Sure, but how does that make the collapse symmetrical across each floor? Doesn't make sense.

As for the fires, there will have been countless numbers of boxes of paper, for copiers and printers, books, magazines. Plenty of wood from desks, furniture, doors, etc. All of this won't have just disappeared.
I am well aware of the crucial factor being if the WTC was demolished with explosives or not, but as the discussion branches off into other sub-topics - like what sort of explosives were used if any and what can we find out about them from the fires after - it seems appropiate to discuss them when they come up. All I am interested in along those lines is if the continuing fires are actually relevant to finding out if anything else was used.
I'm not sure why you are so ineager to discuss it, I thought as the topic of this thread is 'Physics prof says bombs not planes brought down wtc' it would be relevant to discuss all aspects of this in as many ways as possible.

The topic is, as you yourself indicate, 'Physics prof says bombs not planes brought down wtc'.

So what do you think is more relevant: trying to figure out if the collapses were gravity-driven or if there were additional sources or energy based on observed events, or speculating on what kinds of bombs, without even agreeing on whether or not they were used in the first place.

As far as I can see, the only reason why you would be so willing to focus on speculation instead of observable events is simple. It's also something you've accused me of: wanting to avoid facts. Kind of ironic that you should say I want to avoid them, when you yourself favor discussing pure speculation over the observable physics of the collapses.

Originally posted by AgentSmith
I used solid spheres, which works in favour of slower cooling times. I doubt the steel I-beams are 30cm thick and any thermite would have puddled, increasing the surface area and causing it to cool faster.

Size and shape matter, you cannot predict the shape at all, at these temps it would turn concrete into glass, melt it, then 'slip through' (being heavier and all) and bury itself even deeper. any data concerning molten stuff below the towers is UNKNOWN for the time being, because the gov't decided to sell the evidence for scrap to China and kept everyone except their own cronies far away from ground zero, all we have is hearsay.

Your problem can be easily explained: you think of equations as magic items, but they are tools, if you used a drill press to mount nails, you'd soon realise you need the appropriate tool for the task. same here, only difference being, the Internet doesn't necessarly tell you, now does it?

A 100cm Sphere of Steel would still only be 417 deg C after 24 hours from 1200 deg C which would not even be visible let alone molten:

...

A 100cm sphere of Uranium would be 210.21 deg C after 24 hours from 4131 deg C.

So what were you saying about size? As I said molten metals would have a greater surface area to lost heat from and the beams and such were not that thick.

What am i saying about size, well, it matters and you don't know it, because once it's molten it tends to behave unpredictably, especially when buried below a pile of rubble... if you were using a better model, you'd still get wrong results when making that mistake, but since your model is misused, even correcting this deficiency won't help.

it's just the icing on the cake, so to speak, you were calculating heat transfer from a buried object, through radiation, an aspect you might as well ignore, your stuff is in contact with surrounding matter, ok? no radiation models pls.

But again, when you get to use a better model, you will find youself sorely lacking in terms of usable data to feed your equations with, that's why arguing back and forth, claiming that 'qualitative evidence' (courtesy bob2000) doesn't cut it is just deconstructive criticism, because we were purpusefully left out of the loop by the gov't.

wrt charcoal:

Conditions will have changed as things burned and the pile settled, don't forget the actions of recovery and rescue crews will ahve moved stuff around.

Recovery crews don't like to work on top of a lit furnace, do they? furthermore, don't you think that a collapse violent enough to shatter all floors to shards and dust would shred every bit of material in the office spaces as well?

No, as I said I am open to suggestion and I simply seek to find more conventional explanations for different scenarios based on the assumption they are accurately reported.

i'm afraid not, you're actively trying to invalidate anything that's inconsistent with collapse by aircraft, you're not trying to shed any light on the issue, which can be seen nicely when examining the myriad of posts you left in this thread, with nice pics about charcoal generation, subway tunnel entrances (ok, that's news, no?), and so on, and using math as a weapon to silence critical and disagreeing posters.

People, who, unlike you take care in their research, which is geared towards finding answers, not overwhelming the 'opposition', they will take their time for rebuttal, so they can actually answer with something useful, which, to people conditioned by today's faster-is-better mentality, will sometimes look like weakness (appeal to primordial instincts, not your fault, though)


perhaps my thoughts are too muddled to completely understand your motivation -

..
Maybe the words you hear in your head are different to the ones you read or something, I can't explain it. You seem rather muddled in your thoughts anyway. Where's your scientific rebuttel to everyting I said?
..

- but i can certainly tell when something's amiss, which is the case, not because you're wrong, but due to the amazing tenaciousness with which you're pursuing your crusade.

So can you do some workings with that amazing brain of yours and come up with some figures relating to how long these materials will have been able to sustain such high temperatures? If I can't expect people to just take my word for it without showing proof, nor can you I'm afraid.

i don't expect ANYONE to take ANYONE's word for ANYTHING.

see the divergent worldview? the only reason i post is to give people reading this an alternaive view, so they don't get sucked into the world of magic simplicity, where they're not unable to feel the mayhem their narrow-minded beliefs continously inflict upon them, and others.


PS: what will you do if molten steel is indeed confirmed ?

[edit on 23-12-2005 by Long Lance]

Fair enough, are there any mathematical models which we can use to try and get a good idea if it would be possible for the materials to stay hot that long unaided, or are there too many parameters to consider?

Originally posted by AgentSmith
Fair enough, are there any mathematical models which we can use to try and get a good idea if it would be possible for the materials to stay hot that long unaided, or are there too many parameters to consider?

here's a logical model.

ever hear of insulation? do you think, say, 50, 000 tons of debris would provide any? or do you need to see a mathematical formula before you put coffee in your thermos?
ever hear of acceleration? because, when you drive slowly, for example, you get more miles to the gallon. if you're all jackrabbit starts and burning rubber, your fuel bill goes up, up, up! that is because it requires greater energy to cause the same amount of change over a short period of time.
so, any molten STEEL in the sublevels was VERY well insulated, and also, the important bit, had to have been turned molten in SECONDS. the energy required is staggering, i'm sure(without getting all mathy).
in order for the steel to be heated by ambient temperature, the air temperature has to be much greater than the temperature of the steel and for extended periods of TIME(the biggest hole in the pancake fairy-tale. i think of it as more of a doughnut hole theory.....ie. no substance).
even well insulated molten steel would cool in the ground if it was a small amount. because, as pointed out by some of our thinking meme-burrs, heat release is a function of surface area to volume, the volume must have been HUGE to stay molten for weeks.

of course, once again, smith and roark, you guys are way too smart not to know this.
very telling.

I just thought I'd also throw out here that thermite would be able to keep burning and keep temperatures up for as they would've needed to.

"How?," you may ask?

1. Thermite requires aluminum and iron oxide to burn.

2. Iron oxide is created as a byproduct of steel that's exposed to fire.

Obviously, immense amounts of steel would've been available, as well as all the aluminum from the facades that covered the perimeter columns. Thermite would just be feeding itself from the massive amount of steel it was burning.

Btw, the subways weren't that deep underground,

The towers have six basement levels (B1 to B6) that extend beyond the subway system and are 65 feet (20 m) deep.

(Source)

so the air that would've had to have been coming from those shafts to reach the bottom of the pile.... It just wouldn't happen. The bottom of the smoldering debris pit would've been too far down for the subway to fan.

In fact, you can find a picture of the subway tunnel here, and aside from not being a big charcoal pit, or having one anyone near it, it's also filled with debris. Not paper and plastic, either, so much as metals and concrete.

Also, the air would not've been compressed in the pile, as it was in a diagram AgentSmith provided. Compressed air: higher temperatures. The WTC debris pile wouldn't have had this advantage.

Etc., I could go on in greater detail with more problems with a charcoal fire if anyone wishes. Basically, for it to work, a bunch of things would have had to have lined up that would create great improbabilities. The amount of fuel required, for one thing, would've had to have been enormous, and yet how much paper was down there? Would gas bottles have been the source of fuel? Check how many gas bottles were recovered from Ground Zero. The cars were only on the upper levels. For there to have been much jet fuel left over after burning out in the first 10-15 minutes of building fire, let alone fall 98 floors and still be in good shape to fuel an even longer fire, of even higher temperatures, doesn't even make sense.

And remember that charcoal fires also burn faster at higher temps, unlike thermite. So the extremely high temps created by any theoretical charcoal fire would have the same problem AgentSmith asserts the thermite would've had: it would've cooled very quickly. But, again, the thermite would've provided its own fuel amongst all that steel.

Just some additional thoughts on the charcoal fire theory, or what remains of it now.

[edit on 23-12-2005 by bsbray11]

Originally posted by AgentSmith
Fair enough, are there any mathematical models which we can use to try and get a good idea if it would be possible for the materials to stay hot that long unaided, or are there too many parameters to consider?

i'd really love to give a useful answer, but there's no way for me to come even remotely close to the conditions and material mix at GZ, posting something based on a model of a sphere buried at infite depth in homogenous material would be misleading and basically useless, even without taking dousing water into account.

Originally posted by bsbray11
I just thought I'd also throw out here that thermite would be able to keep burning and keep temperatures up for as they would've needed to.

"How?," you may ask?

1. Thermite requires aluminum and iron oxide to burn.

2. Iron oxide is created as a byproduct of steel that's exposed to fire.

Obviously, immense amounts of steel would've been available, as well as all the aluminum from the facades that covered the perimeter columns. Thermite would just be feeding itself from the massive amount of steel it was burning.

...

minor issues: (quickly) creating iron oxide takes more than 'steel exposed to fire' you could use steel wool, which burns easily (due to large surface) or simply let it rust - even if you had the iron oxide, simply tossing it together with aluminium parts will not work well if at all, because thermite works best with fine powders, shards are not enough.

neither the Al facade nor the comumns were ground to powder upon collapse, were they?


----------

PS: final note wrt the equation i used 2 pages ago, which has a built in flaw, can you spot the error?

Ta = Te + (Ta-Te)*exp[-t/(Ct)]

Hint: it should be obvious to anyone and has nothing to do with the exponential function itself.

Originally posted by Long Lance
Ta = Te + (Ta-Te)*exp[-t/(Ct)]

Hint: it should be obvious to anyone and has nothing to do with the exponential function itself.

Is it that the answer is one of the parameters in the equation?

[edit on 24-12-2005 by AgentSmith]

Originally posted by AgentSmith

Originally posted by Long Lance
Ta = Te + (Ta-Te)*exp[-t/(Ct)]

Hint: it should be obvious to anyone and has nothing to do with the exponential function itself.

Is it that the answer is one of the parameters in the equation?

yes, of course!

edit:

Ta(t) = Te + [Ta(t=0) - Te]*exp[-t/(Ct)]

[edit on 24-12-2005 by Long Lance]

Originally posted by Long Lance
minor issues: (quickly) creating iron oxide takes more than 'steel exposed to fire' you could use steel wool, which burns easily (due to large surface) or simply let it rust - even if you had the iron oxide, simply tossing it together with aluminium parts will not work well if at all, because thermite works best with fine powders, shards are not enough.

neither the Al facade nor the comumns were ground to powder upon collapse, were they?

No, I don't suppose they were.

I may be mistaken, and so correct me if I'm wrong, but will molten aluminum and steel not do the job just the same as powders? The Wikipedia article on thermite says that thermite reactions can occur with aluminum being melted, but the only thing it says about steel or iron is that "molten iron is useful for welding." I'm not sure what the article is implying with that, but it directly says of aluminum that "[a] low melting point means that [aluminum] is easy to melt the metal, so that the reaction can occur mainly in the liquid phase (or rather, where the solid oxide particles meet the liquid metal) and thus proceeds fairly quickly." I would assume molten steel would work too, then, though I wouldn't really know.

Just some thoughts. Thanks for pointing that out, though.

Originally posted by bsbray11
...
I may be mistaken, and so correct me if I'm wrong, but will molten aluminum and steel not do the job just the same as powders?
..

well, perhaps.

if you poured molten aluminium onto rust, it would burn instantly (although inefficently, due to incorrect mix). Now the question is how much iron rust (not steel) and molten Al were available after the collapse.

Originally posted by Long Lance

Originally posted by bsbray11
Now the question is how much iron rust (not steel) and molten Al were available after the collapse.

Here is an actual picture of the "iron rust" on an actual steel column of the WTC taken back in the '90's

This scale adversely affected the adhesion of the critical fireproofing.

Several stories of missing fireproofing discovered in the early 1990's.

Missing fireproofing on a beam in the elevator shaft. Note also what appears to be an opening in the wall.

The condition of the fireproofing on the floor trusses where they were attached to the exterior spandrel plate.

source

Originally posted by bsbray11

Obviously, immense amounts of steel would've been available, as well as all the aluminum from the facades that covered the perimeter columns.

Not to mention the aluminum from the burning airplane.

The total weight of an empty 767 is 175,400lbs.

Oh, BTW, For those of you who are claiming that all of the jet fuel burned within 5 minutes of the crash, can you please calculate how much heat the combustion of 5,000 gallons of jet A would be released (in BTUs) if it all burned up in 5 minutes? Where did all of this heat go?

Originally posted by HowardRoark

Originally posted by bsbray11

Obviously, immense amounts of steel would've been available, as well as all the aluminum from the facades that covered the perimeter columns.

Not to mention the aluminum from the burning airplane.

The total weight of an empty 767 is 175,400lbs.

So, what's the deal with agreeing that there were resources for thermite? 'Cause, you know, if that's the next official line, there would still be the same physics problems with the collapses themselves.

Oh, BTW, For those of you who are claiming that all of the jet fuel burned within 5 minutes of the crash, can you please calculate how much heat the combustion of 5,000 gallons of jet A would be released (in BTUs) if it all burned up in 5 minutes? Where did all of this heat go?

More between 10 and 15 minutes, I think, if you watch the smoke output. I think government reports even put it around those times, but I don't remember any being so low as 5 minutes.

At any rate, the steel in those buildings would have been excellent heat sinks, and after the jet fuel fire was over (unless you are suggesting that it was the cooler period, and I don't think you are), the rest of the times before the collapses would've seen cooler fires and cooling steel, regaining what little strength was lost.

Edit, and PS: Thermite requires an ignition temperature of about 2000 degrees Farenheit.

[edit on 27-12-2005 by bsbray11]

Originally posted by HowardRoark
This scale adversely affected the adhesion of the critical fireproofing.

The fireproofing is not critical. Arup Fire engineering, the Cardington fire tests, and a host of other fire engineering institutes and tests on structures with unprotected steel have repeatedly stated and shown this. The only ones who cling to the limp fireproofing argument are NIST and shills like yourself.

HowardRoark wrote:
Not to mention the aluminum from the burning airplane.

I thought you said what was left of the planes was melted in those awesome computer simulated 1100C fires... But please explain for the class your theory of how bits of the planes made it from 1200 feet up in the air through 500,000 tonnes of structure and ended up in the basements. Did it travel down the elevators with the all-purpose jet fuel? Or did it fly out into the Manhattan sky and onto the street, before taking a shortcut back through the subway entrance? I look forward to reading your hypothesis.

HowardRoark wrote:
Oh, BTW, For those of you who are claiming that all of the jet fuel burned within 5 minutes of the crash...

Nobody stated 5 minutes. Nice strawman, though. Was that one straight out of the manual, or did you come up with that all by yourself?

...can you please calculate how much heat the combustion of 5,000 gallons of jet A would be released (in BTUs)...

Here ya go => www.uscrusade.com...

And that calculation makes outrageous, fantastical assumptions in favor of the official story...a bit like you really.

...Where did all of this heat go?

Here's your new word for the day: Convection. Do a wiki search for it and you should find a simplified explanation there for you. Then search through your image files at Shill Central and look at the massive holes in the buildings, the broken windows, and all that hot smoke pouring out everywhere. Think about the new word you learnt and how it relates to what you see. Then when you come back, we can discuss another term called "specific heat". We'll also look at some real-world examples of steel recovered from the fire-exposed areas.


And while you're on that job, here's a little riddle to think about:

"If the force of the falling building is strong enough to pulverize concrete then the bolts and rivets would have to hold while that force is being applied in order for the concrete to be pulverized, and then give way. Yet the force to pulverize concrete into fine powder is greater than the force that sheers or stretches steel bolts and rivets. It cannot be both ways."

Oh, and BTW, the concrete floors were steel-reinforced, set on metal floor pans, and hardened over shear studs connected through the pans to the joists themselves, all of which kind of crushes your silly potato chip analogy into greasy little crumbs.

Merry Christmas to you and all the other Initiates.


[edit on 2005-12-27 by wecomeinpeace]

Originally posted by wecomeinpeace

Originally posted by HowardRoark
This scale adversely affected the adhesion of the critical fireproofing.

The fireproofing is not critical. Arup Fire engineering, the Cardington fire tests, and a host of other fire engineering institutes and tests on structures with unprotected steel have repeatedly stated and shown this. The only ones who cling to the limp fireproofing argument are NIST and shills like yourself.

Ohh, a quote!

So why does every building code in this country and in the rest of the civilized world require buildings to be fireproofed in the first place?

The Cardington tests were conducted on a structure that was nothing like the WTC buildings. They have no applicability to the WTC structures.

Originally posted by wecomeinpeace
I thought you said what was left of the planes was melted in those awesome computer simulated 1100C fires... But please explain for the class your theory of how bits of the planes made it from 1200 feet up in the air through 500,000 tonnes of structure and ended up in the basements. Did it travel down the elevators with the all-purpose jet fuel? Or did it fly out into the Manhattan sky and onto the street, before taking a shortcut back through the subway entrance? I look forward to reading your hypothesis.

The same way that the rest of the building wound up in the basement, it fell down when the building collapsed.

HowardRoark wrote:
Oh, BTW, For those of you who are claiming that all of the jet fuel burned within 5 minutes of the crash...

Nobody stated 5 minutes. Nice strawman, though. Was that one straight out of the manual, or did you come up with that all by yourself?

...can you please calculate how much heat the combustion of 5,000 gallons of jet A would be released (in BTUs)...

Here ya go => www.uscrusade.com...

From your link:

Each story had a floor slab and a ceiling slab. These slabs were 207 feet wide, 207 feet deep and 4 (in parts 5) inches thick and were constructed from lightweight concrete. So each slab contained 207 x 207 x 1/3 = 14,283 cubic feet of concrete. Now a cubic foot of lightweight concrete weighs 50kg, hence each slab weighed 714,150 ? 700,000 kgs. Together, the floor and ceiling slabs weighed some 1,400,000 kgs

Does anyone see the errors in this part?

There are three major errors actually.

First is the assumption that the lightweight concrete used in 1969 had the same density as that used now. Generally Lightweight concrete has a density that ranges from 40 to 54 lbs/ft3 so I’ll ignore this one.

The second is that both the floor slab and the ceiling slab were heated to the same degree. I guess he forgot that heat rises, huh?

The biggest and most obvious is that he overestimates the area of concrete present on each floor by assuming that there were no openings or penetrations in the floor (i.e no elevator shafts, etc.) (also his dimensions are off slightly. The outer edge of the concrete slab would have been about 206 x 206. )

If we assume that 25% of the core area had floor slabs, then the total concrete drops down about 21 per cent.

That link also states:

Because oxygen comes mixed with nitrogen, we have to include it in the equations. Even though it does not react, it is "along for the ride" and will absorb heat, affecting the overall heat balance.

The problem here is that the author of this particular bit of bad science is conveniently ignoring the fact that the majority of the heat will be released as radiant heat. This it will heat up the solid objects on the floor at a much faster rate then the air.

In addition, while he insists that some of the heat releases be used to heat up the surrounding air, he then conveniently forgets to use that preheated air in his combustion equation.

Finally, he uses a value for the specific heat of concrete that I have not been able to find anywhere. The values that I have found are about 4 times less then the values that he uses (880j/kgC). Even if we go with 1000 j.kgC, we would still have a number that is three times lower then the number he used (3300j/kgC).



That site is Bad Science all the way around. But I have to give the guy credit, he uses enough technical terms to fool some people into believing that he knows what he is talking about.

Mod Edit: Fixed Quote Tag.


[edit on 27/12/2005 by Mirthful Me]