Physics Of 9/11 Events

einsteen

22nd June 2007 - 04:06 PM

I agree Arthur, but that model is not applied in Dr Greening's and Bazant's model. And how do you explain that the energy values are around 0.6 GJ in the beginning, even when you apply your pancaking model ? If it is pure pancaking you apply then you also have to admit that that energy value is not really small.

adoucette

22nd June 2007 - 05:22 PM

Because its not a PURE anything.

MOST of the perimeter columns are being shed, but NOT ALL.

MOST of the floors are failing at the truss seats but a great deal of energy is going into smashing the tower contents and floor material along the way.

The majority of the resistance is probably being put up by the Core columns which ARE welded and which have beam braced flooring, but which also rapidly lose the crictical horizontal bracing provided by the floors.

Then there are the periodic maint sections, where the perimeter columns ARE welded and the floors are made of beams.

Etc Etc.

Arthur

einsteen

22nd June 2007 - 06:15 PM

Assuming that only the core provide the 0.6GJ what is the most plausible theory about those welded trusses, is the 0.6GJ due to detaching it from the core columns ? I cannot believe the core itself would break into parts and those welded points should break letting the core intact. But if the upper block falls on the core it is a core on core collision, I think the theory becomes very sophisticated, then the floors should be detached from the core of that upper block first which is absolutely impossible. The tree-trunk idea always made some OCT'ers smile because a building then is 90% air but those cores are 0% air, the initial core on core collision is in fact a tree trunk effect. The homogenized model is also a 0% air situation but I understand it is only a model based on the 90% air one... If everything funnels or wedges the floors should be detached fall in the building on the other floors and the core part from the top block should fall away from the building and the core left in the building should stand. I don't believe this is what we see in the videos.

wcelliott

22nd June 2007 - 06:38 PM

Let's look at a completely different way to collapse a building like the WTC.

Let's say that they were only interested in making the building collapse, but weren't interested in hijacking airplanes or planting explosives.

Step one: Figure out what the maximum load that one floor could support. Let's call that X tons.

Step two: Go to a gravel yard and buy 2X tons of gravel.

Step three: Go buy a bunch of boxes, enough to hold 2X tons of gravel.

Step four: Pack the gravel into boxes and have UPS deliver them to the same floor.

The weight of the gravel delivered by UPS will at some point make that floor collapse.

When that floor collapses, that same gravel (plus the weight of the collapsed floor) will fall onto the next floor down.

That floor, below, will now have more load than it can support, so it collapses, too, onto the floor below.

Etc.

Right down to the basement.

You'll have a progressive collapse, with no explosives needed.

How unrealistic is this model?

How much weight was a floor in the WTC tower designed to hold up?

And how much does a 757 weigh?

Grumpy

22nd June 2007 - 06:50 PM

NEU-FONZE

QUOTE

When you say: "The NIST model, as far as it goes, is indeed the most probable mechanism that can be arrived at given the limits of the evidence..", are you just saying this, or can you prove it?

First, there is no such thing as "proof" in the real world.

Second, NIST has backed up their evaluation in a very robust and well documented fashion, it does not require me to defend itself. If you think you have a better explanation of the available evidence, let's hear it. Otherwise , as adoucette pointed out...

QUOTE (->

QUOTE

When you say: "The NIST model, as far as it goes, is indeed the most probable mechanism that can be arrived at given the limits of the evidence..", are you just saying this, or can you prove it?

First, there is no such thing as "proof" in the real world.

Second, NIST has backed up their evaluation in a very robust and well documented fashion, it does not require me to defend itself. If you think you have a better explanation of the available evidence, let's hear it. Otherwise , as adoucette pointed out...

The NIST report is BY FAR the most extensive investigation to date, yielding a highly verifiable set of impact modeling and fire simulations that has been coupled to the visual evidence and timeline to create a PROBABLE COLLAPSE scenario for both the towers.

UNTIL someone else comes up with a MORE EXTENSIVE investigation, or provides MATERIAL EVIDENCE that NIST left out SOME OTHER SIGNIFICANT FORM OF ENERGY or SOME OTHER SIGNIFICANT PHYSICAL PROCESS then the NIST REPORT remains the MOST PROBABLE COLLAPSE scenario that can be defended SCIENTIFICALLY.

...I could not improve on that analysis and you have not produced anything which comes close to casting doubt on NIST's work(don't feel bad, neither has anyone else).

That's as close to proof as we are likely to come in this world, so, yes, we are justified in calling the NIST scenario the "Most Probable Cause".

QUOTE

NIST did NOT use somthing like a maximum entropy calculation as far as I know... so I fail to see in what sense their model is the "most probable".

Thus sayeth the mathematician, lost in the real world. Or as someone once said(I disremember who)' There are lies, there are damned lies and then there are statistics." NIST started with the evidence and went where it led, I doubt seriously you would be able to assign values(that mean anything) to ALL scenarios with any degree of accuracy, thus GIGO.

QUOTE (->

QUOTE

NIST did NOT use somthing like a maximum entropy calculation as far as I know... so I fail to see in what sense their model is the "most probable".

Thus sayeth the mathematician, lost in the real world. Or as someone once said(I disremember who)' There are lies, there are damned lies and then there are statistics." NIST started with the evidence and went where it led, I doubt seriously you would be able to assign values(that mean anything) to ALL scenarios with any degree of accuracy, thus GIGO.

The NIST model makes many estimates of quantities that have large uncertainties. Most temperatures used by NIST are uncertain to +/- 100 deg C. The loss of thermal insulation is estimated based on an arbitrary criterion concerning damage to furniture/partitions/etc.

NIST has been doing this for years, they are the best at it in the entire world, I think their estimates are well within the ballpark.

QUOTE

There are probably MANY combinations of damage/heating/thermal insulation loss that could possibly trigger a global collapse. The NIST have proposed ONE collapse scenario based on assumptions for which there is NO PHYSICAL EVIDENCE. Meanwhile, NIST ignore chemical effects entirely! Thus I would say that the NIST sees an "effect" and infers a "cause"; scientists prefer to work the other way round.

I would have to say that the big pile of rubble IS evidence of some sort of collapse, the photos and videos ARE evidence, the steel provides lots of EVIDENCE of the types of failure it experienced, so I don't know how you can say NIST had no physical evidence, that is just nonsense. NIST's assumption were very conservative(as were all the methods they employed), not in the least were they wildly speculative, but were well supported by experimentation and previous experience.

As far as the chemical reactions you are speaking of, I have seen no convincing evidence of their importance. That is not saying that they did not occur, but that the role they played was not a major contributor to the outcome. NIST must have a simular opinion. If you feel differently you have a lot of work to do to show it to be important, good luck with that.

You have made plain that in your opinion they reached the wrong conclusions, but you have not convinced me that I should value that opinion over the work of NIST, not even close. And your statements about NIST not having a well supported theory are just rubish and not those I would expect from a serious researcher(or even of an informed layman). Such statements are best left for the CT believers who at least have the excuse of ignorance to fall back on. I've come to expect better of you.

Grumpy

lozenge124

22nd June 2007 - 07:09 PM

QUOTE (einsteen+Jun 22 2007, 01:10 PM)

Lozenge, yes it should be possible to build it then, I've seen one movie that worked but those used pieces of papers between wooden blocks, they were detached from the blocks and didn't crack the blocks. They were also not connected only by frictional force and it didn't have a core and it didn't have trusses. global collapse, forgot it

Yup, I've seen some of these too:

The sad thing is, bad as these models are, these guys have put more effort into scale models than both NIST and the other proponents of gravitational progressive collapse have, combined.

metamars

22nd June 2007 - 07:17 PM

QUOTE (FactCheck+Jun 20 2007, 09:28 PM)

Has any conspiracy theorist written something on:

How much explosives [ = X ] were used [where] to create the seismic data they claim is explosives?

Why would they use [X] in [that] location of the towers to cause the seismic readings? Why was it a needed part of the conspiracy story? Assuming they are smart enough to pull this off, what was the reason they had to risk this part of the conspiracy story? Because any placement of explosives is a risk. It sounds to me this part of the conspiracy story would be a HUGE risk.

I'm looking for quantitative expressions and values.

And who is claiming that seismic activity "is" explosives? IIRC, some posters argued for this many moons ago. But I, for one, never argued that explosives used to achieve CD should have caused seismic activity.

According to BLGB, a certain amount of energy is used to crush each floor (about .6GJ), and as the WTC columns were certainly capable of transferring vibrational energy, the question of seismic activity due to this arises. In BLGB, there are no explosives, hence no "explosive energy" to be transferred.

Hence, above-background seismic activity before "crush up" originating from GZ must be due to the pounding of the lower part of the WTC towers by rubble from the upper section. Of course, BLGB basically avoids such an obvious impliction of their theory, since they assume that energy is dissipated in the crushing front.

Also, NeuFonze claims that there are many ways the buildings could have collapsed. If that were true without explosives, then why would it not be true with explosives?

Hence, a more intelligent question to ask is "Give a CD scenario which generates collapse times as observed and agrees with observations of pulverisation of concrete, rubble distribution, seismic activity, etc."

I fully support such an endeavor, however, it's probably easier to show that either a global collapse would not occur without explosives, or would not have occurred as quickly as observed on 9/11. And that is the thrust of the modelling being done at stj911, i.e., no explosives are included in the modeling.

Furthermore, even if one produces a CD scenario as indicated, the OCT's will simply claim that CD is not a necessary hypothesis, since no explosives models are also show plausibility.

Hence, both efforts are advisable. But, one step at a time. It's not like anybody is giving ae911truth or stj911 $20 million. Indeed, the forum that stj911 uses is a freeby, and we can't even upload files! Having no budget will result in skimping like that, you know.

metamars

22nd June 2007 - 07:32 PM

QUOTE (NEU-FONZE+Jun 22 2007, 01:48 PM)

Grumpy:

When you say: "The NIST model, as far as it goes, is indeed the most probable mechanism that can be arrived at given the limits of the evidence..", are you just saying this, or can you prove it?

NIST did NOT use somthing like a maximum entropy calculation as far as I know... so I fail to see in what sense their model is the "most probable". The NIST model makes many estimates of quantities that have large uncertainties. Most temperatures used by NIST are uncertain to +/- 100 deg C. The loss of thermal insulation is estimated based on an arbitrary criterion concerning damage to furniture/partitions/etc.

There are probably MANY combinations of damage/heating/thermal insulation loss that could possibly trigger a global collapse. The NIST have proposed ONE collapse scenario based on assumptions for which there is NO PHYSICAL EVIDENCE. Meanwhile, NIST ignore chemical effects entirely! Thus I would say that the NIST sees an "effect" and infers a "cause"; scientists prefer to work the other way round.

When I started reading (part of) the NIST reports, I quickly realized that they were making lots of assumptions and judgement calls to make their project tractable. I had falsely assumed that computer power had advanced so much since the 1980's that their analysis would be something like my coursework in numerical methods in the 90's, but more elaborate.

NIST can't be blamed for having to make decisions in order to make their problem tractable. But, by not documenting both their 'pruning processes', as well as work that they did describe in some detail, it's pretty much impossible for anybody to duplicate their work, even if equipped with similar resources, and assuming zero fraud and/or groupthink on the part of NIST scientists and engineers.

In fairness, I should mention that fully documenting everything would be a major project, perhaps costing a few more $millions. Of course, that is a mere pittance compared to, say, US war expenditures in the Iraq fiasco - a fiasco predicated on taking fictional Iraq-WMD Fairy Tales propagated by the US Government, with a backdrop of 911 Fairy Tales also propagated by the US government, seriously.

Even if Purdue is supposed to have gotten similar results wrt aircraft impact, that sheds little light on whether the rest of NIST's analysis is plausible.

I do not consider the BLGB theory verified, either, even if plausible collapse times are postdicted.

Fortunately, constructing computer models to test BLGB - not by duplicating all their assumptions, but rather just some of them* to make a computational solution easier - is probably within reach, even by non-funded organizations.

Without a state or organizational or enlightened-fat-cat sponsor, showing up errors in NIST's work via a computer modeling which exceeds their level of detail is problematic, to say the least.

* The principal assumption that would have to be maintained is that of symmetry.

lozenge124

22nd June 2007 - 07:52 PM

QUOTE (wcelliott+Jun 22 2007, 06:38 PM)

Let's look at a completely different way to collapse a building like the WTC.

Let's say that they were only interested in making the building collapse, but weren't interested in hijacking airplanes or planting explosives.

Step one: Figure out what the maximum load that one floor could support. Let's call that X tons.

Step two: Go to a gravel yard and buy 2X tons of gravel.

Step three: Go buy a bunch of boxes, enough to hold 2X tons of gravel.

Step four: Pack the gravel into boxes and have UPS deliver them to the same floor.

The weight of the gravel delivered by UPS will at some point make that floor collapse.

When that floor collapses, that same gravel (plus the weight of the collapsed floor) will fall onto the next floor down.

That floor, below, will now have more load than it can support, so it collapses, too, onto the floor below.

Etc.

Right down to the basement.

You'll have a progressive collapse, with no explosives needed.

How unrealistic is this model?

How much weight was a floor in the WTC tower designed to hold up?

And how much does a 757 weigh?

Once the floors have collapsed you will be left with the outside perimeter column structure and the inside core columns still standing in place. The key to understanding how a progressive collapse is possible is to understand how these vertical support structures - that span the distance from the top of the tower to the ground - can fail on a floor by floor basis when subjected to a purely vertical, gravitational force.

If you have trouble understanding what the problem is, try this experiment: take a thin PVC pipe, place it vertically, and whack it with a sledgehammer. Does it fail "progressively"?
User posted image

If you like you can cut the PVC pipe in pieces and glue it back together to get a composite structure made up of sections (no angle cuts allowed!).
user posted image

Can you get this to happen?
user posted image

ie. "floor by floor" progressive collapse, the kinetic energy of the sledge hammer only goes into breaking the glue joints of the sections directly below the impact and into their horizontal kinetic energy as they "blow out". The rest of the sections below are unaffected until they are hit in turn.

If you can, please post a video!

lozenge124

22nd June 2007 - 08:00 PM

metamars:

Has there been any progress with the FEA modeling at stj911.org?

I recently saw a Steven Jones interview where he seemed to imply that Richard Gage's organization - ae911truth.org - would be taking over these FEA efforts, so I am curious. Also, do you know if they were able to use the SAP2000 model of the towers, recently released by NIST under FOIA, in this?

metamars

22nd June 2007 - 08:02 PM

From wikipedia:

QUOTE

In seismology, the Zoeppritz equations describe how seismic waves are transmitted and reflected at media boundaries.

The Zoeppritz equations relate the amplitudes of P-waves and S-waves at each side of an interface.

For practical purposes, various forms of approximations are usually used.

Solutions of reflectance vs. angle of incidence using simplifications is shown at Figure 1 in http://sepwww.stanford.edu/public/docs/sep...tml/node34.html

http://sepwww.stanford.edu/public/docs/sep...f/zoepr-ann.gif
User posted image

For a 'dead on' strike ( angle of incidence = 0 degrees ), most of p waves transmit, and 100% of s waves transmit.

I have no idea how questions of scale come into interpreting this graph, but if we consider scale as of minor concern, in the sense that we could consider reflectance of any portion of a wave, as small as we please, then a random distribution of faults and rock-type layers in bedrock seems consistent with the idea of attenuation via randomized scattering (since reflectances from 0% to 100% seem available), vs. ....

attenuation via rarification due to purely geometric concerns + heat loss.

Also from wikipedia

QUOTE (->

QUOTE

In seismology, the Zoeppritz equations describe how seismic waves are transmitted and reflected at media boundaries.

The Zoeppritz equations relate the amplitudes of P-waves and S-waves at each side of an interface.

For practical purposes, various forms of approximations are usually used.

Solutions of reflectance vs. angle of incidence using simplifications is shown at Figure 1 in http://sepwww.stanford.edu/public/docs/sep...tml/node34.html

http://sepwww.stanford.edu/public/docs/sep...f/zoepr-ann.gif
User posted image

For a 'dead on' strike ( angle of incidence = 0 degrees ), most of p waves transmit, and 100% of s waves transmit.

I have no idea how questions of scale come into interpreting this graph, but if we consider scale as of minor concern, in the sense that we could consider reflectance of any portion of a wave, as small as we please, then a random distribution of faults and rock-type layers in bedrock seems consistent with the idea of attenuation via randomized scattering (since reflectances from 0% to 100% seem available), vs. ....

attenuation via rarification due to purely geometric concerns + heat loss.

Also from wikipedia

The energy, with which an earthquake affects a location, depends from the running distance. The attenuation of ground motion intensity plays an important role in the assessment of possible strong ground shaking. A seismic wave loses energy as it propagates through the earth (attenuation). This phenomenon is tied up to the dispersion of the seismic energy with the distance. There are two types of dissipated energy:

geometric dispersion caused by distribution of the seismic energy to greater volumes
dispersion as heat

If Manhattan behaved like Egypt (a problematic assumption, to be sure

) then an empirically supported equation descrbing intensity as a function of r is

I = 1.143 M - 3.9 log( r ) + 4.37

(from Contribution to Intensity - Distance Relation for Earthquakes in Egypt
By: A. El-Sayed and I. Korrat)

Taking r to be 23 miles or 37 km
and M to be 2.3, we get

I(37) = 1.143 - 3.9 (1.57) + 4.37 = -.61

however,

I(1) = 1.143 + 4.37 = 5.513

I am puzzled as to how to interpret an intensity that tends towards an increasingly negative value. Anybody?

If we assume that I represents an exponent, then we are talking about ~ 10^5 ratio of intensity

In any event, I will guess that, considering the general behavior of the graphs in "Contribution to Intensity - Distance Relation for Earthquakes in Egypt", Figure(2) and observing that I(37) >> I(1), that most of the original seismic energy has been "lost" (not merely rarified), by the time it has reached Columbia's LDEO at Palisades, NY.

If this is so, it doesn't matter whether or not my notion of energy loss through randomization of scattering frequencies, due to inhomogeneity, has any validity, or not. If it does, then such scattering may represent intermediate forms of energy, which themselves degrade to heat.

Capracus

22nd June 2007 - 08:06 PM

QUOTE (metamars+Jun 22 2007, 07:17 PM)

Hence, both efforts are advisable. But, one step at a time. It's not like anybody is giving ae911truth or stj911 $20 million. Indeed, the forum that stj911 uses is a freeby, and we can't even upload files! Having no budget will result in skimping like that, you know.

According to this poll, over 30 million Americans believe that CD brought down the Twin Towers.

QUOTE

The poll also found that 16 percent of Americans speculate that secretly planted explosives, not burning passenger jets, were the real reason the massive twin towers of the World Trade Center collapsed.

http://www.scrippsnews.com/911poll

A one dollar donation from these concerned citizens should be more that enough to fund your investigation. Contact Rosie O'Donnell and have her use her celebrity status to make a plea for donations.

einsteen

22nd June 2007 - 08:13 PM

Lozenge, thanks again for those pics, I was looking for them. I think we can divide the collapse thinkers into two categories, the floor thinkers and the story-thinkers.

Grumpy

22nd June 2007 - 08:45 PM

lozenge124

QUOTE

Once the floors have collapsed you will be left with the outside perimeter column structure and the inside core columns still standing in place.

No, you won't. The outside frame was pushed sideways by the WEDGE(not hammer) of the top block and fell in long sections, popping their bolted connections, and due to the slenderness of the core columns(when compared to their height) they could not stand on their own, bent, fractured their welds and fell. Once the stabilization of the floors was removed, the rest of the structure simply fell over in pieces(and the top block of floors falling on top of them didn't help).

Metamars

QUOTE (->

QUOTE

Once the floors have collapsed you will be left with the outside perimeter column structure and the inside core columns still standing in place.

No, you won't. The outside frame was pushed sideways by the WEDGE(not hammer) of the top block and fell in long sections, popping their bolted connections, and due to the slenderness of the core columns(when compared to their height) they could not stand on their own, bent, fractured their welds and fell. Once the stabilization of the floors was removed, the rest of the structure simply fell over in pieces(and the top block of floors falling on top of them didn't help).

Metamars

If that were true without explosives, then why would it not be true with explosives?

Simple, why should ANY scenario be entertained when there is a complete lack of valid physical evidence supporting that scenario???

A complete lack of substantially elevated radiation levels means it is not scientifically supportable to include nuclear explosions as a valid scenario, wouldn't you say???

The lack of 30 foot footprints, piles of 'zilla poo or huge claw marks probably means Godzilla wasn't the cause.

So why, when there has not been one single solitary scrap of evidence that explosives were used do you people insist that such scenarios be considered???

Of course it is possible to collapse such buildings using explosives, it may(in some blurry, ill defined way) be possible to do it with thermite(or rocket fuel, sulfuric acid, steel eating termites or ray guns from Mars). But IT IS NOT POSSIBLE TO DO EITHER(any) AND NOT LEAVE LARGE AMOUNTS OF PHYSICAL EVIDENCE OF THEIR USE!!!

What we have evidence of is planes full of fuel crashing at high speed and setting huge, multi floor fires causing the slow, gradual deformation of the supporting structure until some critical structure failed and collapse started. We also have mucho evidence that once collapse began there was insufficient remaining strength to STOP that collapse. so...

Nuclear=impossible, no enhanced radiation.

Godzilla=impossible, we're talking about New York, not Tokyo.

Ray gun=impossible, not enough energy in the world.

explosives=impossible,no physical evidence left behind

etc.......

Plane impacts and fire=lots of supporting evidence+within the known laws of physics...

When you have eliminated the impossible...

Grumpy

lozenge124

22nd June 2007 - 09:01 PM

QUOTE (Grumpy+Jun 22 2007, 08:45 PM)

lozenge124

QUOTE

Once the floors have collapsed you will be left with the outside perimeter column structure and the inside core columns still standing in place.

No, you won't. The outside frame was pushed sideways by the WEDGE(not hammer) of the top block and fell in long sections, popping their bolted connections, and due to the slenderness of the core columns(when compared to their height) they could not stand on their own, bent, fractured their welds and fell. Once the stabilization of the floors was removed, the rest of the structure simply fell over in pieces(and the top block of floors falling on top of them didn't help).

You will of course have difficulty getting a wedge by packing gravel on a floor until it collapses as in wcelliott's scenario.

Please spend a little time reading posts in their entirety!

wcelliott

22nd June 2007 - 09:29 PM

QUOTE

The key to understanding how a progressive collapse is possible is to understand how these vertical support structures - that span the distance from the top of the tower to the ground - can fail on a floor by floor basis when subjected to a purely vertical, gravitational force.

I disagree - The key to understanding progressive collapse is recognizing that if one floor fails under load X, that the next floor is subjected to load X+bX, where b<1, and it fails even quicker.

The collapsing floor doesn't sever its ties to its supports simultaneously and without impulse, those brackets weren't held in place with explosive bolts, some failed quicker than others and there had to be a lot of force imparted to the core and perimeter columns by these failing brackets - They were failing from overloads, designed to handle Y amount of force and failing at cY, where c>1. That imparts a lot of displacement forces on the columns, both core and perimeter.

In some cases you might expect that the brackets holding the floor to the core might not have failed as soon as the brackets at the perimeter columns, and that would leave the floors dangling off the core columns until those brackets failed. That's a lot of load that wasn't designed-for.

In any case, when the floors failed, they were what held the perimeter wall columns vertical, and when they were no longer being held vertical they fell over.

And that matches quite well with what we saw in the videos of the WTC collapse(s). Floors collapsing first, wall columns splaying outward and falling off, and (amidst the dust and smoke) the core getting dragged down, reluctantly, last.

As for assuming symmetry, how would you propose to do that when both towers' upper sections tipped over prior to collapsing? It is the non-symmetrical nature of the collapse that subjects individual brackets to overloading conditions one after another. If you start out making symmetry a baseline assumption, you won't find any realistic phenomena coming out of the model. (The airplanes didn't do symmetrical damage to the towers.)

einsteen

22nd June 2007 - 09:35 PM

If the wedging block from the very first moment needs 0.6 GJ per story (independently derived by Bazant and Greening assuming a total crush) then you can wonder how much energy is required for a real crush, but I don't believe in wedging because of the fact that the core columns (also the perimeter) are still attached at the block, like a piece of coax cable. How would that wedge ?

User posted image

the columns become tangled, how will that behave ?

wcelliott

22nd June 2007 - 09:40 PM

QUOTE

You will of course have difficulty getting a wedge by packing gravel on a floor until it collapses as in wcelliott's scenario.

Please spend a little time reading posts in their entirety!

Actually, with gravel you get the equivalent of hydrostatic pressure, so if you had lots of gravel raining down from above, the vertical walls (both perimeter and core) with gravel piling up against them would find significant pressure against them splaying the perimeter walls outwards.

P = rho*g*h
where
P = pressure
rho = density
h = height

The outward force would be the width of the perimeter wall times the integral over h of P*dh.

You do the math.

And this doesn't have to be gravel, specifically, any chunks that fall without stacking in an orderly manner will approximate a liquid with hydrostatic pressure resulting.

And you still get a progressive collapse without explosives.

frater plecticus

22nd June 2007 - 09:53 PM

QUOTE

NEU-FONZE
Thus I would say the NIST "model" is not a scientific THEORY at all since it is not capable of being verified or negated.

frater plecticus

QUOTE (->

QUOTE

NEU-FONZE
Thus I would say the NIST "model" is not a scientific THEORY at all since it is not capable of being verified or negated.

frater plecticus
exactly. i said this months ago

grumpy

QUOTE

And you were wrong then, just as NEU-FONZE is wrong now. NIST provided REAMS of pages of verification for it's conclusions, and can be falsified by evidence, logic or understanding that itself can be verified. I realize NIST has set the bar very high, but noone said it would be easy(or even possible, given the proponderence of the available evidence) to falsify their reports, but it is possible in theory. Maybe the difficulty of falsifying their reports should indicate that they are correct, ever thought of that???

frater plecticus

QUOTE (->

QUOTE

And you were wrong then, just as NEU-FONZE is wrong now. NIST provided REAMS of pages of verification for it's conclusions, and can be falsified by evidence, logic or understanding that itself can be verified. I realize NIST has set the bar very high, but noone said it would be easy(or even possible, given the proponderence of the available evidence) to falsify their reports, but it is possible in theory. Maybe the difficulty of falsifying their reports should indicate that they are correct, ever thought of that???

frater plecticus
I normally don't like to quantify statements, but I really fell this quantifies as "gobbledygook" .

Grumpy

22nd June 2007 - 09:54 PM

einsteen

QUOTE

the columns become tangled, how will that behave ?

Somewhat less stiff than column on column, somewhat more stiff than total bypass.

Some core columns were severed at impact, others snapped as the top block tilted, the rest either buckled or penitrated through the rubble. I would think this provided the majority of the resistence seen by the top block(outer columns were displaced and largely bypassed each other and then were pushed outward and fell over, the floors were largely gone)

QUOTE (->

QUOTE

the columns become tangled, how will that behave ?

Somewhat less stiff than column on column, somewhat more stiff than total bypass.

Some core columns were severed at impact, others snapped as the top block tilted, the rest either buckled or penitrated through the rubble. I would think this provided the majority of the resistence seen by the top block(outer columns were displaced and largely bypassed each other and then were pushed outward and fell over, the floors were largely gone)

but I don't believe in wedging because of the fact that the core columns (also the perimeter) are still attached at the block, like a piece of coax cable.

You need to study the videos of collapse initiation more closely, they clearly show the outer frame beams from the top block passing BEHIND those of the bottom section in both towers BECAUSE the top blocks tilted, creating a wedging action that pushed the beams from the bottom section outward like a banana peel.

Grumpy

Grumpy

22nd June 2007 - 09:59 PM

frater plecticus

QUOTE

I normally don't like to quantify statements, but I really fell this quantifies as "gobbledygook" .

It's a free country(in theory), you have a right to be wrong if you want to.

Grumpy

frater plecticus

22nd June 2007 - 10:02 PM

QUOTE (Grumpy+Jun 22 2007, 09:59 PM)

frater plecticus

It's a free country(in theory), you have a right to be wrong if you want to.

Grumpy

Yeah, I know.

The difference between us is... I don't care if I'm right or wrong.

So it makes no difference to me if what you say is "troof" or not.

wcelliott

22nd June 2007 - 10:10 PM

QUOTE

The difference between us is... I don't care if I'm right or wrong.

I'd say that's a big difference, and a significant admission.

It supports my contention that the "troothers" aren't interested in the Truth, they're motivated entirely by politics.

They're just trolling for idiots who'll buy their bs and march along beside them.

They're counting on the dumbest people being gullible. That's their idea of starting a "grass-roots movement".

David B. Benson

22nd June 2007 - 10:11 PM

wcelliot --- Its called the critical load. Ideally, for any quasi-statically applied load less than the critical load the structure supports it. At the critical load, the structure fails. In terms of the structural engineer's use of DCRs, the critical load will be at a DCR of about 1.35 to 1.67. (DCR design is quite conservative.)

For the towers, before damage, the average DCR of core columns was about 0.5 while the average DCR of exterior wall columns was about 0.2.

Grumpy --- Not quite, even for the simpler case of WTC 1. There, large portions of the north and west walls did not participate the the progressive collapse, only to fall over (by being pushed near the bottom) at the end of crush-down. However, the south and east walls were continually broken apart at the connections and some of the wall sections were thrown for a considerable distance.

Finally, almost none of the core survived the progressive collapse. A small portion provided a temporary spire which then fell down a few seconds later.

einsteen --- Consider the first 0.8 seconds of the collapse of WTC 1. At 0.8- seconds, the first impact of one floor upon another began along the south wall, due to the tilt of the top block. Yet, using NEU-FONZE's measurements, at 0.2, 0.4, 0.6 and 0.8 seconds the center of the top was being accelerated at almost (0.7)g. So energy was being consumed by means other than the impacting of one floor on another, the so-called pancaking or bageling.

It is convenient and reasonable then, to assume, for the first few seconds, a constant energy consumption per unit height. A story is a convenient unit and my calculations, which used the actual masses given in NCSTAR1-6D, give a value of E1 = 510 megajoules. But note that some fraction of this energy was already expended at 0.2, 0.4 and 0.6 seconds.

einsteen

22nd June 2007 - 10:20 PM

DBB, I agree that E is consumed to break everything between two floors and I also agree with your values...

Grumpy,

http://www.google.com/search?q=site%3Awtc....edging+OR+wedge

The NIST pile of papers is almost as high as the wtc was and google is the search engine that finds everything but not much results for your wedge.

newton

22nd June 2007 - 10:24 PM

QUOTE (einsteen+Jun 22 2007, 09:35 PM)

If the wedging block from the very first moment needs 0.6 GJ per story (independently derived by Bazant and Greening assuming a total crush) then you can wonder how much energy is required for a real crush, but I don't believe in wedging because of the fact that the core columns (also the perimeter) are still attached at the block, like a piece of coax cable. How would that wedge ?

User posted image

the columns become tangled, how will that behave ?

thanks for that, einsteen.
your picture illustrates nicely the point that the OCT refuses to acknowledge.

i wonder IF the NIST apologists would need a cray and 20 million for this conundrum....

User posted image

lozenge124

22nd June 2007 - 10:33 PM

QUOTE (wcelliott+Jun 22 2007, 09:29 PM)

In any case, when the floors failed, they were what held the perimeter wall columns vertical, and when they were no longer being held vertical they fell over.

If you believe that without floors the perimeter columns would just collapse and fall over (progressively?), I think I can understand why your posts appear so confused...

QUOTE (wcelliott+)

And that matches quite well with what we saw in the videos of the WTC collapse(s). Floors collapsing first, wall columns splaying outward and falling off, and (amidst the dust and smoke) the core getting dragged down, reluctantly, last.

Again this description, with "floors collapsing first" is in complete contradiction to NIST as they backed away from the pancake collapse for the final report:

QUOTE (NIST faq+)

NIST’s findings do not support the “pancake theory” of collapse, which is premised on a progressive failure of the floor systems in the WTC towers (the composite floor system—that connected the core columns and the perimeter columns—consisted of a grid of steel “trusses” integrated with a concrete slab; see diagram below). Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.

(bold added)
http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm

QUOTE

As for assuming symmetry, how would you propose to do that when both towers' upper sections tipped over prior to collapsing? It is the non-symmetrical nature of the collapse that subjects individual brackets to overloading conditions one after another. If you start out making symmetry a baseline assumption, you won't find any realistic phenomena coming out of the model. (The airplanes didn't do symmetrical damage to the towers.)

You have hit upon an immense problem with the official gravitational collapse scenario. How is it that the 4 WTC sides react in exactly the same way, and at the same speed during the collapse when the upper block is tilting to 1-side? (or in the case of WTC1, a massive block is ejected to the North West)
The problem of symmetry and simultaneity is also there for collapse initiation, where the official story has the perimeter & core columns failing simultaneously across the board at one floor level to initiate the collapse. Symmetry is one of the collapse features that argues against a gravity-driven only collapse.

frater plecticus

22nd June 2007 - 10:35 PM

QUOTE (wcelliott+Jun 22 2007, 10:10 PM)

I'd say that's a big difference, and a significant admission.

It supports my contention that the "troothers" aren't interested in the Truth, they're motivated entirely by politics.

They're just trolling for idiots who'll buy their bs and march along beside them.

They're counting on the dumbest people being gullible. That's their idea of starting a "grass-roots movement".

Politics is inseparable from 9-11.

David B. Benson

22nd June 2007 - 10:49 PM

QUOTE (lozenge124+Jun 22 2007, 10:33 PM)

If you believe that without floors the perimeter columns would just collapse and fall over (progressively?), ...

How is it that the 4 WTC sides react in exactly the same way, and at the same speed during the collapse when the upper block is tilting to 1-side? (or in the case of WTC1, a massive block is ejected to the North West)

The problem of symmetry and simultaneity is also there for collapse initiation, where the official story has the perimeter & core columns failing simultaneously across the board at one floor level to initiate the collapse.

Symmetry is one of the collapse features that argues against a gravity-driven only collapse.

Geez, I just finished explaining much of this in a post towards the bottom of the previous page.

(1) The north wall and separately the west wall of WTC 1 did not participate in the progressive collapse. Poster shagster says one can see the north wall oscillating back and forth before it falls over. Seeing is believing, in this case...

(2) So the four walls do not all behave in the same way. And no, no massive block was ejected to the northwest.

(3) And you are wrong once again about collapse initiation. For WTC 1, first the south wall buckles, immediately followed by the east and west walls. Hinged upon the still intact north wall, the top blocks begins tilting to the south.

(4) So it is not entirely symmetric, even for the more nearly so case of WTC 1. In any case, an argument based on symmetry or its lack is specious here.

FactCheck

22nd June 2007 - 10:49 PM

QUOTE (frater plecticus+Jun 22 2007, 10:35 PM)

Politics is inseparable from 9-11.

But not from the collapse.

frater plecticus

22nd June 2007 - 10:51 PM

QUOTE (FactCheck+Jun 22 2007, 10:49 PM)

But not from the collapse.

Really?

I beg to differ.

David B. Benson

22nd June 2007 - 10:51 PM

QUOTE (newton+Jun 22 2007, 10:24 PM)

your picture illustrates nicely the point that the OCT refuses to acknowledge.

Sorry, I must have missed the point.

adoucette

22nd June 2007 - 10:56 PM

QUOTE (lozenge124+)

Again this description, with "floors collapsing first" is in complete contradiction to NIST as they backed away from the pancake collapse for the final report:

QUOTE (NIST faq)

QUOTE

NIST’s findings do not support the “pancake theory” of collapse, which is premised on a progressive failure of the floor systems in the WTC towers (the composite floor system—that connected the core columns and the perimeter columns—consisted of a grid of steel “trusses” integrated with a concrete slab; see diagram below). Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.

(bold added)
http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm

How many times do we have to go over this?

I wish we had material for radiation protection this DENSE.

NIST is talking about COLLAPSE INITIATION.

As they point out in their other report, the floors, ONCE THE COLLAPSE STARTED, did indeed PANCAKE.

Arthur

frater plecticus

22nd June 2007 - 11:01 PM

QUOTE (adoucette+Jun 22 2007, 10:56 PM)

(bold added)
http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm[/QUOTE]

How many times do we have to go over this?

I wish we had material for radiation protection this DENSE.

NIST is talking about COLLAPSE INITIATION.

As they point out in their other report, the floors, ONCE THE COLLAPSE STARTED, did indeed PANCAKE.

Arthur

But NIST doesn't say what caused the initiation.

David B. Benson

22nd June 2007 - 11:07 PM

QUOTE (frater plecticus+Jun 22 2007, 11:01 PM)

But NIST doesn't say what caused the initiation.

Yes, they do.

(1) Walls bow-in, over many minutes.

(2) Walls buckle.

(3) Collapse has commenced.

David B. Benson

22nd June 2007 - 11:15 PM

QUOTE (einsteen+Jun 22 2007, 04:06 PM)

And how do you explain that the energy values are around 0.6 GJ in the beginning, ... ?

Other than qualitatively, the only explanation is that is (about) the observed model. I leave to RealityCheck, Grumpy, wcelliot and others to offer qualitative descriptions of potential energy sinks. They do that much better than I.

frater plecticus

22nd June 2007 - 11:18 PM

QUOTE (David B. Benson+Jun 22 2007, 11:07 PM)

Yes, they do.

(1) Walls bow-in, over many minutes.

(2) Walls buckle.

(3) Collapse has commenced.

How much did this cost?

David B. Benson

22nd June 2007 - 11:25 PM

QUOTE (metamars+Jun 22 2007, 07:32 PM)

I do not consider the BLGB theory verified, either, even if plausible collapse times are postdicted.

I suppose everyone is still entitled to their own opinion, but with regard to this I have repeatedly asked you to bring forth objections to the simplifying assumptions so that I could defend the crush-down equation's use of the four. You continue to fail to do so.

I pointed out a way the test the crush-down equation on a lab bench. You poo-pooed that, obviously not having thought the matter through. (By the way, possibly a toy train setup would work as well as a physics lab rail car and is likely to be much less costly.)

Pierre-Normand has recently pointed out that the crush-down equation is nothing but a time-reversed rocket equation. You ignored that.

So I'll have to state that I find you biased and irrational in your so-called considerations.

As the tired phrase goes, put up or shut up.

David B. Benson

22nd June 2007 - 11:30 PM

QUOTE (frater plecticus+Jun 22 2007, 11:18 PM)

How much did this cost?

About as much as is spent each 100 minutes in Iraq.

Grumpy

22nd June 2007 - 11:31 PM

David B. Benson

QUOTE

Grumpy --- Not quite, even for the simpler case of WTC 1. There, large portions of the north and west walls did not participate the the progressive collapse, only to fall over (by being pushed near the bottom) at the end of crush-down. However, the south and east walls were continually broken apart at the connections and some of the wall sections were thrown for a considerable distance.

Finally, almost none of the core survived the progressive collapse. A small portion provided a temporary spire which then fell down a few seconds later.

In WTC 1 the banana peel analogy is even more apt, rather than being thrown the frames layed out nearly intact, draping across WTC 6 and hitting 7(the North wall) and this occured long before crush down(a poor name because almost none of the outer frame WAS crushed, the floor was well on the way to the basement and the only thing crushed by the top block WAS the core) reached the ground. Your point about the core is true, I believe the core provided most of the resistive force against the top block and suffered thereby.

User posted image

http://www.studyof911.com/gallery/albums/u...l_GJS-WTC28.jpg

lozenge124

QUOTE (->

QUOTE

Grumpy --- Not quite, even for the simpler case of WTC 1. There, large portions of the north and west walls did not participate the the progressive collapse, only to fall over (by being pushed near the bottom) at the end of crush-down. However, the south and east walls were continually broken apart at the connections and some of the wall sections were thrown for a considerable distance.

Finally, almost none of the core survived the progressive collapse. A small portion provided a temporary spire which then fell down a few seconds later.

In WTC 1 the banana peel analogy is even more apt, rather than being thrown the frames layed out nearly intact, draping across WTC 6 and hitting 7(the North wall) and this occured long before crush down(a poor name because almost none of the outer frame WAS crushed, the floor was well on the way to the basement and the only thing crushed by the top block WAS the core) reached the ground. Your point about the core is true, I believe the core provided most of the resistive force against the top block and suffered thereby.

User posted image

http://www.studyof911.com/gallery/albums/u...l_GJS-WTC28.jpg

lozenge124

Again this description, with "floors collapsing first" is in complete contradiction to NIST as they backed away from the pancake collapse for the final report:

NIST only pointed out that the pancaking of the floors was not the INITIATING event, they too recognize that the floors did pancake after the initiation. That pancaking left the outer frames and the core unsupported, a condition they could not survive intact.

QUOTE

If you believe that without floors the perimeter columns would just collapse and fall over (progressively?),

There is no "IF" to it, the outer frame and core were designed to be connected and braced by the floor. Neither could stand without it.

QUOTE (->

QUOTE

If you believe that without floors the perimeter columns would just collapse and fall over (progressively?),

There is no "IF" to it, the outer frame and core were designed to be connected and braced by the floor. Neither could stand without it.

The problem of symmetry and simultaneity is also there for collapse initiation, where the official story has the perimeter & core columns failing simultaneously across the board at one floor level to initiate the collapse. Symmetry is one of the collapse features that argues against a gravity-driven only collapse.

Actually ASYMMETRY was required for collapse initiation. If all the beams had failed at the same time the collapse is less likely. The collapse initiated after one critical column failed, transfering a load to it's neighbors that was too great, causing them to fail, etc. This lead to a PROGRESSIVE failure(one thing failing after another)

einsteen

QUOTE

The NIST pile of papers is almost as high as the wtc was and google is the search engine that finds everything but not much results for your wedge.

Here, try this one.

http://www.google.com/search?hl=en&safe=ac...ing&btnG=Search

Grumpy

lozenge124

22nd June 2007 - 11:33 PM

QUOTE (adoucette+Jun 22 2007, 10:56 PM)

(bold added)
http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm[/QUOTE]

How many times do we have to go over this?

I wish we had material for radiation protection this DENSE.

NIST is talking about COLLAPSE INITIATION.

As they point out in their other report, the floors, ONCE THE COLLAPSE STARTED, did indeed PANCAKE.

Arthur

QUOTE

NIST’s findings do not support the “pancake theory” of collapse, which is premised on a progressive failure of the floor systems in the WTC towers. (...) the floors did not fail progressively to cause a pancaking phenomenon.

If you cannot parse a simple paragraph, there is not much point in arguing about more complex physical phenomena.

This faq quote will keep coming back as many times as necessary.

Miragememories

22nd June 2007 - 11:38 PM

QUOTE (David B. Benson+Jun 22 2007, 11:07 PM)

Yes, they do.

(1) Walls bow-in, over many minutes.

(2) Walls buckle.

(3) Collapse has commenced.

Some perimeter columns bow in.

Timed core demolitions occur in upper section.

Floors collapse inwards following the descending core while demolitions project debris and perimeter columns outwards.

Rapid implosion ensues, as a combination of inwardly collapsing floors and outwardly blasted perimeter columns combined with various debris, constitute the actual collapse scenario.

Observed on TV by armchair intellectuals, the obvious demolition process is ignored and the phenomenon is analyzed as just another math puzzle, supposedly solvable without the need of a 20 million dollar plus investigation.

These experts claim "we know what caused it dammit, we just have to work backwards and make the numbers work!"

CIA says the "good job, the cheques are in the mail!"

MM

lozenge124

22nd June 2007 - 11:38 PM

QUOTE (David B. Benson+Jun 22 2007, 11:25 PM)

I suppose everyone is still entitled to their own opinion, but with regard to this I have repeatedly asked you to bring forth objections to the simplifying assumptions so that I could defend the crush-down equation's use of the four. You continue to fail to do so.

I have repeatedly pointed out that there is no good reason to assume B&V simplifying hypothesis (ii) "Energy is dissipated only at the crushing front."

If you would care to defend this assumption with more than "well, that is what was observed" please do.

David B. Benson

22nd June 2007 - 11:45 PM

QUOTE (lozenge124+Jun 22 2007, 11:38 PM)

I have repeatedly pointed out that there is no good reason to assume B&V simplifying hypothesis (ii) "Energy is dissipated only at the crushing front."

If you would care to defend this assumption with more than "well, that is what was observed" please do.

Gosh, I'm only a scientist applying the scientific method. Yuno, try to understand what was observed?

So there is every good reason for simplifying hypothesis (ii). And no reason whatsoever to do otherwise. Finally, it is an accounting method. Suppose some energy leaves, going into making seismic waves. Obviously this could only happen in the bottom of the Bathtub. Fine. We'll just add this minuscule amount to the crushing front energy.

Happy now?

Grumpy

22nd June 2007 - 11:51 PM

lozenge124

QUOTE

If you cannot parse a simple paragraph, there is not much point in arguing about more complex physical phenomena.

This faq quote will keep coming back as many times as necessary.

Failure of the gusset plate welded to the top of the truss chord was again almost exclusively observed regardless of location. This may be a result of overloading the lower floors as the floors above were "pan-caking".

NIST NCSTAR 1-3C Sect 3.5.3

Since you don't care if you are right or wrong, then you won't be suprised if we think everything you say is CRAP and treat it accordingly.

Grumpy

David B. Benson

23rd June 2007 - 12:00 AM

Grumpy --- Thanks for the useful link! An I'll agree to the banana peel analogy if you'll include some Japanese cooks to immediate slice up the peel parts which represent the east and south walls of WTC 1.

einsteen --- If you are having trouble with wedging, think about the tilting.

adoucette

23rd June 2007 - 12:04 AM

QUOTE (lozenge124+Jun 22 2007, 06:33 PM)

QUOTE (adoucette+)

How many times do we have to go over this?

I wish we had material for radiation protection this DENSE.

NIST is talking about COLLAPSE INITIATION.

As they point out in their other report, the floors, ONCE THE COLLAPSE STARTED, did indeed PANCAKE.

Arthur

If you cannot parse a simple paragraph, there is not much point in arguing about more complex physical phenomena.

This faq quote will keep coming back as many times as necessary.

lozenge124, it is YOU who can not read or parse.

NIST did NOT study how the collapse progressed.

As they pointed out their study was about

"the sequence of events from the instant of the aircraft impact until the initiation of the collapse"

See NIST FINAL REPORT Exec Summary pg xxxvii

Thus the FAQ can't POSSIBLY be about what happened AFTER collapse initiation since that was NOT something they studied.

Arthur

Miragememories

23rd June 2007 - 12:04 AM

QUOTE (David B. Benson+Jun 22 2007, 11:45 PM)

Gosh, I'm only a scientist applying the scientific method. Yuno, try to understand what was observed?

So there is every good reason for simplifying hypothesis (ii). And no reason whatsoever to do otherwise. Finally, it is an accounting method. Suppose some energy leaves, going into making seismic waves. Obviously this could only happen in the bottom of the Bathtub. Fine. We'll just add this minuscule amount to the crushing front energy.

Happy now?

The rub lies in converting the PE to KE.

Your pretty theory all hangs on an assumption that is not proven by the observables.

You dogmatically believe impact and fire had to be the cause, therefore that validates your mechanism for the required KE being allowed to develop.

Controlled demolition allows it to develop as well and does a better job of matching the observables.

MM

David B. Benson

23rd June 2007 - 12:08 AM

QUOTE (Miragememories+Jun 22 2007, 11:38 PM)

Observed on TV by armchair intellectuals, ...

who don't understand even high school physics, much less structural stability theory and practice, haven't studied fires other than the camp kind, and in general who are know-nothings, come to fairly bizzaro opinions.

adoucette

23rd June 2007 - 12:09 AM

QUOTE (Miragememories+Jun 22 2007, 07:04 PM)

The rub lies in converting the PE to KE.

Your pretty theory all hangs on an assumption that is not proven by the observables.

You dogmatically believe impact and fire had to be the cause, therefore that validates your mechanism for the required KE being allowed to develop.

Controlled demolition allows it to develop as well and does a better job of matching the observables.

MM

NOPE

Controlled demolition does not explain how the collapse begins in each tower at the collision floors.

Controlled demolition does not explain how the exterior walls bowed in over time.

Controlled demolition does not explain how no evidence of high explosives were found.

Etc etc ad nauseum

Arthur

David B. Benson

23rd June 2007 - 12:14 AM

QUOTE (Miragememories+Jun 23 2007, 12:04 AM)

Your pretty theory all hangs on an assumption that is not proven by the observables.

Your stating this is so doesn't make it so. What assumption? Fires? Observed. Walls bowing-in and buckling? Observed.

wcelliott

23rd June 2007 - 12:29 AM

Does anyone have the figure for how much floor-load the WTC towers were designed for?

In other words, what's the maximum amount of weight that you could've put on the floor of a WTC tower before it was considered "in imminent danger of collapse"?

I'm guessing that it would be something less than what a 757 weighs, but that's just a guess on my part.

adoucette

23rd June 2007 - 12:40 AM

Not offhand, but you can use 100 pounds per sq ft as the design live load and figure that it could have handled probably at least 100 lbs more, or roughly 4 million lbs, if evenly distributed, which the plane wasn't.

But also consider that the planes hit the towers tilted and at angles such that the remains of the planes ended up on multiple floors and a significant amount of the fuel weight burnt up rather quickly.

Arthur

lozenge124

23rd June 2007 - 12:42 AM

QUOTE (David B. Benson+Jun 22 2007, 11:45 PM)

Gosh, I'm only a scientist applying the scientific method. Yuno, try to understand what was observed?

So there is every good reason for simplifying hypothesis (ii). And no reason whatsoever to do otherwise. Finally, it is an accounting method. Suppose some energy leaves, going into making seismic waves. Obviously this could only happen in the bottom of the Bathtub. Fine. We'll just add this minuscule amount to the crushing front energy.

Happy now?

Truly pathetic, that's really all you've got?

Your paper is entitled "Collapse of World Trade Center Towers: What Did and Did Not Cause It", yet you ignore one of the most compelling reasons to hypothesize explosives or cutter charges - the progressive nature of the collapse - by simply assuming off the bat that "Energy is dissipated only at the crushing front."

In a true scientific approach to the problem of "What Did and Did Not Cause" the collapse, scale models or FEA models would be developed of various structures to see if they can be made to collapse progressively and under what conditions/parameters this happens. Then the WTC structures would be analyzed/modeled to see if they satisfy these conditions. If they do, and the study indicates that a progressive collapse is not only possible, but likely, then you could roll in hypothesis (ii) with some confidence that the model applies. As it is the assumption is made based on nothing more than that it seems "reasonable", even though "total progressive collapses" are apparently so rare that nobody can replicate anything like it either through FEA, or scale modeling.

Furthermore, it floors me that the paper tries to prove that explosives were not used by energetic considerations alone (ie. there was sufficient potential energy in the upper block and tower to account for all observed phenomena)

Consider this example:

I show you a video of a pool "break" in a 9-ball game.

user posted image

The cue ball has velocity V (all velocities are vectors in the following) just before impact.
user posted image

The cue ball halts completely, only 2 balls move with velocities V1 (the 4 ball) & V2 (the 5 ball).
user posted image

Now I call shenanigans yes? Surely there is something wrong here, why did no other balls move?

On a frame by frame analysis of the video however, it appears that there is a relationship between V, V1 & V2. Namely, if you make the "reasonable" assumption that the balls are of the same mass, it turns out that kinetic energy is conserved:
(1/2)m(V)^2 = (1/2)m(V1)^2 + (1/2)m(V2)^2!

Using the same "logic" as in the BGLB paper, I make the "perfectly reasonable" assumption that "all the impact energy was dissipated in balls 4 & 5" (after all that is what we all observed, right?) and hey presto! I have proven that everything is in order, there is no reason to doubt that this was a perfectly ordinary pool table, because the energy going into the break is the same as afterwards. QED.
What kind of nonsense is this? Yet this is the BGLB argument in a nutshell.

If the BGLB were entitled something like "A linearized equation and some energetic considerations of the WTC collapses" it would be more accurate. By calling it "Collapse of World Trade Center Towers:What Did and Did Not Cause It?" and attempting to draw conclusions about the use explosives in the collapses - when it was assumed from the outset that explosives were not used - it completely overstates its case.

David B. Benson

23rd June 2007 - 12:43 AM

QUOTE (wcelliott+Jun 23 2007, 12:29 AM)

I'm guessing that it would be something less than what a 757 weighs, but that's just a guess on my part.

From NCSTAR1-2, page lxxv (77 ordinal):

"The downward trajectory of the aircraft structures transfered sufficient vertical load such that the truss floor structures on the 95th and 96th floors collapsed in the impact zone."

David B. Benson

23rd June 2007 - 12:53 AM

lozenge124 --- You haven't developed a rational argument against using the crushing front as an accounting method.

The BLGB paper compares two hypotheses: (1) Gravity-driven collapse with resistance as given by the crush-down equation together with other known energetics; (2) Free fall without resistance, occasioned by planned destruction of all elements capable of resistance.

The evidence overwhelmingly supports (1). I have even measured just how overwhelmingly it does.

But feel free to propose another equation for the collapses for me to compare against the crush-down equation. metamars won't take me up on it, but he wrote that he passed the challenge on the the troofers. So far, no reply...

lozenge124

23rd June 2007 - 01:12 AM

QUOTE (David B. Benson+Jun 23 2007, 12:53 AM)

lozenge124 --- You haven't developed a rational argument against using the crushing front as an accounting method.

The BLGB paper compares two hypotheses: (1) Gravity-driven collapse with resistance as given by the crush-down equation together with other known energetics; (2) Free fall without resistance, occasioned by planned destruction of all elements capable of resistance.

The evidence overwhelmingly supports (1). I have even measured just how overwhelmingly it does.

But feel free to propose another equation for the collapses for me to compare against the crush-down equation. metamars won't take me up on it, but he wrote that he passed the challenge on the the troofers. So far, no reply...

I have just shown you that it is not sufficient to use observations of the WTC to make the claim the "energy is dissipated only at the crushing front". You need to provide some backing for this hypothesis - in your own words: "put up or shut up"

David B. Benson

23rd June 2007 - 01:15 AM

QUOTE (lozenge124+Jun 23 2007, 01:12 AM)

I have just shown you that it is not sufficient to use observations of the WTC to make the claim the "energy is dissipated only at the crushing front".

You need to provide some backing for this hypothesis - in your own words: "put up or shut up"

No, you have failed to do so. Utterly.

What about using it as an accounting method do you fail to understand?

RealityCheck

23rd June 2007 - 01:27 AM

QUOTE (lozenge124+Jun 23 2007, 12:42 AM)

Truly pathetic, that's really all you've got?

Your paper is entitled "Collapse of World Trade Center Towers: What Did and Did Not Cause It", yet you ignore one of the most compelling reasons to hypothesize explosives or cutter charges - the progressive nature of the collapse - by simply assuming off the bat that "Energy is dissipated only at the crushing front."

In a true scientific approach to the problem of "What Did and Did Not Cause" the collapse, scale models or FEA models would be developed of various structures to see if they can be made to collapse progressively and under what conditions/parameters this happens. Then the WTC structures would be analyzed/modeled to see if they satisfy these conditions. If they do, and the study indicates that a progressive collapse is not only possible, but likely, then you could roll in hypothesis (ii) with some confidence that the model applies. As it is the assumption is made based on nothing more than that it seems "reasonable", even though "total progressive collapses" are apparently so rare that nobody can replicate anything like it either through FEA, or scale modeling.

Furthermore, it floors me that the paper tries to prove that explosives were not used by energetic considerations alone (ie. there was sufficient potential energy in the upper block and tower to account for all observed phenomena)

Consider this example:

I show you a video of a pool "break" in a 9-ball game.

user posted image

The cue ball has velocity V (all velocities are vectors in the following) just before impact.
user posted image

The cue ball halts completely, only 2 balls move with velocities V1 (the 4 ball) & V2 (the 5 ball).
user posted image

Now I call shenanigans yes? Surely there is something wrong here, why did no other balls move?

On a frame by frame analysis of the video however, it appears that there is a relationship between V, V1 & V2. Namely, if you make the "reasonable" assumption that the balls are of the same mass, it turns out that kinetic energy is conserved:
(1/2)m(V)^2 = (1/2)m(V1)^2 + (1/2)m(V2)^2!

Using the same "logic" as in the BGLB paper, I make the "perfectly reasonable" assumption that "all the impact energy was dissipated in balls 4 & 5" (after all that is what we all observed, right?) and hey presto! I have proven that everything is in order, there is no reason to doubt that this was a perfectly ordinary pool table, because the energy going into the break is the same as afterwards. QED.
What kind of nonsense is this? Yet this is the BGLB argument in a nutshell.

If the BGLB were entitled something like "A linearized equation and some energetic considerations of the WTC collapses" it would be more accurate. By calling it "Collapse of World Trade Center Towers:What Did and Did Not Cause It?" and attempting to draw conclusions about the use explosives in the collapses - when it was assumed from the outset that explosives were not used - it completely overstates its case.

Hi Lozenge124.

Your example to David B Benson just confirmed that an axial force can result in radial forces which affect the 'sidewalls' of the pool table (ie, downwards impacts affected WTC outer tube walls...both as debris and compressed-air front impacts/pressures). Which explains for the troofer how NO explosives were necessary for assisting the outward peel of the outer walls.

But your analogy does not factor in the relentless presence of the initial source of acceleration (gravity), so that CUE BALL actually is NOT STOPPED if it is contantly and continuingly being repeatedly struck by the player....so those intially dispersed balls continue to be JOINED/PUSHED by further expulsions/movements from the ball mass that is ITSELF ALTOGETHER ALREADY UNDER ACCELERATION BY GRAVITY IN THE REAL WORLD (just imaging that table being suddenly put on edge...and see that the whole mass tends too already be 'accelerating' even before any cue stick strikes the cue ball).

And no amount of speculation will actually quantify the enormous amount of floor-connector damage done by the plane impact and disintegration forces, vibrations, undulations and loadshifting stresses EVEN BEFORE THE WEIGHT of the plane itself and other higher-floor 'FALLEN-THROUGH' debris accumulates on any one floor at the lower extent of the impact zone.

However, the videos through some windows show that SOME edges of SOME floors were HANGING LOOSE....and if a 'zipper oveload' floor-to-wall progeressive DICONNECTION effect (both serial and parallel depending on actual locations/forces) ensues as the fires etc further overload the floor-to-wall connectors, then the situation can only get worse from there.

By the way, anyone:

I can just imagine that the organic materials of viscoelastic dampers at the outer edges of the floors in and around the impact/fire zones would have started burning fiercely like high energy fuel in a blast furnace as the airflows induced by the 'stack effect' up from below to the upper reaches along the floor/wall gaps at the connection line. More differential heating cooling and 'softening/tempering' of the steel's initial specs? What was the organic material, and how much per damper unit...and what would be the energy/heat produced by its combustion?

Cheers all!

RC.
.

lozenge124

23rd June 2007 - 01:30 AM

QUOTE (David B. Benson+Jun 23 2007, 01:15 AM)

No, you have failed to do so. Utterly.

What about using it as an accounting method do you fail to understand?

You crack me up!

Your equations are totally worthless if you cannot prove that the "energy is only dissipated at the collapse front" hypothesis is valid. You cannot use the progressive features of the WTC collapse as a reason, because at that point of the paper you are still trying to determine if explosives were used or not - the presence of explosives in the WTC is an unknown. What do you not comprehend here?

As to your comparison between "(1) Gravity-driven collapse with resistance as given by the crush-down equation together with other known energetics; (2) Free fall without resistance, occasioned by planned destruction of all elements capable of resistance." it is totally idiotic, because you forgot one option

(3) Free fall with some resistance, occasioned by planned destruction of some of the elements capable of resistance.

Who are you trying to fool with your "science"?

David B. Benson

23rd June 2007 - 01:38 AM

QUOTE (lozenge124+Jun 23 2007, 01:30 AM)

(3) Free fall with some resistance, occasioned by planned destruction of some of the elements capable of resistance.

Propose an equation. I'll be happy to use my Bayesian factor program which will determine, measured in units called bans how much the evidence favors (1) versus your (3) or vice versa.

By the way, the Bayesian factor method is probably the sharpest statistical test of competing hypotheses available.

lozenge124

23rd June 2007 - 01:38 AM

QUOTE (RealityCheck+Jun 23 2007, 01:27 AM)

Hi Lozenge124.

Your example to David B Benson just confirmed that an axial force can result in radial forces which affect the 'sidewalls' of the pool table (ie, downwards impacts affected WTC outer tube walls...both as debris and compressed-air front impacts/pressures).

But your analogy does not factor in the relentless presence of the initial source of acceleration (gravity), so that CUE BALL actually is NOT STOPPED if it is contantly and continuingly being repeatedly struck by the player....so those intially dispersed balls continue to be JOINED/PUSHED by further expulsions/movements from the ball mass that is ITSELF ALTOGETHER ALREADY UNDER ACCELERATION BY GRAVITY IN THE REAL WORLD (just imaging that table being suddenly put on edge...and see that the whole mass tends too already be 'accelerating' even before any cue stick strikes the cue ball).

And no amount of speculation will actually quantify the enormous amount of floor-connector damage done by the plane impact and disintegration forces, vibrations, undulations and loadshifting stresses EVEN BEFORE THE WEIGHT of the plane itself and other higher-floor 'FALLEN-THROUGH' debris accumulates on any one floor at the lower extent of the impact zone.

However, the videos through some windows show that SOME edges of SOME floors were HANGING LOOSE....and if a 'zipper oveload' floor-to-wall progeressive DICONNECTION effect (both serial and parallel depending on actual locations/forces) ensues as the fires etc further overload the floor-to-wall connectors, then the situation can only get worse from there.

By the way, anyone:

I can just imagine that the organic materials of viscoelastic dampers at the outer edges of the floors in and around the impact/fire zones would have started burning fiercely like high energy fuel in a blast furnace as the airflows induced by the 'stack effect' up from below to the upper reaches along the floor/wall gaps at the connection line. More differential heating cooling and 'softening/tempering' of the steel's initial specs?

Cheers all!

RC.
.

Hi RC,

The pool table example was not meant to be a precise analogy of the WTC collapse, with the cue ball representing the upper block, the 2 balls a floor etc...

I was just pointing out that energy considerations are necessary - but not sufficient - to prove that a phenomena is possible. So even though energy here is conserved, it is impossible to break like that in a 9 ball game.

Similarly, it has not been proven that a progressive collapse is possible (or that "Energy is dissipated only at the crushing front." as Bazant & Verdure put it) under gravity alone,even though the upper block surely has enough energy to crush one floor (including perimeter and core columns) at a time.

David B. Benson

23rd June 2007 - 01:53 AM

QUOTE (lozenge124+Jun 23 2007, 01:38 AM)

Similarly, it has not been proven that a progressive collapse is possible (or that "Energy is dissipated only at the crushing front." as Bazant & Verdure put it) under gravity alone,even though the upper block surely has enough energy to crush one floor (including perimeter and core columns) at a time.

Well, the crush-down equation is just the one dimensional version of Newton's laws, applied to a time-reversed rocket. What more empirical evidence do you need?

You could experiment with the horizontal version using rail cars, a pulley and some weights. Then you'd actually see a horizontal crush-down (really, a crush-sideways) in action.

RealityCheck

23rd June 2007 - 01:58 AM

QUOTE (lozenge124+Jun 23 2007, 01:38 AM)

Hi RC,

The pool table example was not meant to be a precise analogy of the WTC collapse, with the cue ball representing the upper block, the 2 balls a floor etc...

I was just pointing out that energy considerations are necessary - but not sufficient - to prove that a phenomena is possible. So even though energy here is conserved, it is impossible to break like that in a 9 ball game.

Similarly, it has not been proven that a progressive collapse is possible (or that "Energy is dissipated only at the crushing front." as Bazant & Verdure put it) under gravity alone,even though the upper block surely has enough energy to crush one floor (including perimeter and core columns) at a time.

Hi lozenge124.

Who said it was any type of game 'setup'. It was chaotic at best...with multiple 'game setups' being 'played out' by nature under physics/chemistry as 'directed' from moment to moment by random and unknown factors withoin the range of possible factors that were present without needing explosives for their presence in the normal course of known physical/chemical processes.

I suggest that you both study the PATHWAYS by which the energy that WAS present NATURALLY (given the gravity, plane impact/fire loads etc) could actually BE dispersed to its immediate structural, air and ground environment.

I think you will both find that the energies 'PEAKED' and 'EBBED' and REFLECTED and ABSORBED and CONVERTED etc here and there RANDOMLY in the immediate vicinity (crush zone) BEFORE being 'dissipated' from there. The DURATIOBN/DWELL time for these 'pre-dissipation' forces/effects and their damaging potential would depend on various factors at various sub-locations/times within the continuous process which the 'crush zone' represented due to the relentless gravity acceleration despite what may happen TRANSIENTLY here or there in any one or other location/conditions in that tumult over a LARGE area of damage/accelerations/impacts INTERPLAY.

Cheers and good luck with the analysis!

RC.
.

lozenge124

23rd June 2007 - 02:04 AM

QUOTE (RealityCheck+Jun 23 2007, 01:58 AM)

Hi lozenge124.

Who said it was any type of game 'setup'. It was chaotic at best...with multiple 'game setups' being 'played out' by nature under physics/chemistry as 'directed' from moment to moment by random and unknown factors withoin the range of possible factors that were present without needing explosives for their presence in the normal course of known physical/chemical processes.

I suggest that you both study the PATHWAYS by which the energy that WAS present NATURALLY (given the gravity, plane impact/fire loads etc) could actually BE dispersed to its immediate structural, air and ground environment.

I think you will both find that the energies 'PEAKED' and 'EBBED' and REFLECTED and ABSORBED and CONVERTED etc here and there RANDOMLY in the immediate vicinity (crush zone) BEFORE being 'dissipated' from there. The DURATIOBN/DWELL time for these 'pre-dissipation' forces/effects and their damaging potential would depend on various factors at various sub-locations/times within the continuous process which the 'crush zone' represented due to the relentless gravity acceleration despite what may happen TRANSIENTLY here or there in any one or other location/conditions in that tumult over a LARGE area of damage/accelerations/impacts INTERPLAY.

Cheers and good luck with the analysis!

RC.
.

Indeed, I am still waiting for the FEA model of the collapse.

RealityCheck

23rd June 2007 - 02:15 AM

QUOTE (lozenge124+Jun 23 2007, 02:04 AM)

Indeed, I am still waiting for the FEA model of the collapse.

Any suggestions for the 'games setup' for that modeling? hehehe. The troofers before you had plenty of suugestions for which they could not find TENABLE evidence/probabilities in support.

What would you posit as 'man-made explosives' inputs to the model?

Cheers and again, good luck to you all!

RC.
.

lozenge124

23rd June 2007 - 02:20 AM

QUOTE (RealityCheck+Jun 23 2007, 02:15 AM)

Any suggestions for the 'games setup' for that modeling? hehehe. The troofers before you had plenty of suugestions for which they could not find TENABLE evidence/probabilities in support.

What would you posit as 'man-made explosives' inputs to the model?

Cheers and again, good luck to you all!

RC.
.

I would be very happy to see a simple upper block dropped onto a lower block that results in "total progressive collapse" - no explosives, no thermate, just gravity.

RealityCheck

23rd June 2007 - 02:37 AM

QUOTE (lozenge124+Jun 23 2007, 02:20 AM)

I would be very happy to see a simple upper block dropped onto a lower block that results in "total progressive collapse" - no explosives, no thermate, just gravity.

Hi Loz!

That would be OK ...IF that was what you were actually studying, hehehe.

You are actually studying a 'concentric square tube' structure whose upper section has been taken out of all as-designed STATIC/DYNAMIC specifications.

And that top section is HEAVIER than would be expected if it was just the SUM of the upper floors in between...simply because of the HEAVY hat truss structure tying together the upper 10? floors and roof and 'core' & perimeter walls.

And on top of all that, the TOP did not fall ONTO the BOTTOM...but INSIDE the OUTER tube....which FUNNELED most of the damaging forces ONTO only the INNER tube and the floors....with the outer tube being merely 'collateral damage to the main 'straight down' collapse process which mostly progressed through each floor inside.

So your suggestion should perhaps be modified to read:

"....simple upper block dropped INTO a lower block"

..... to see if it results in "total progressive collapse" AS THE OUTER WALLS FALL AWAY AFTER THEY HAVE FUNNELED AND CONCENTRATED THE COLLAPSE ENERGIES onto a smaller inner tube and the attached floors which by design were necessary for the overall stability/integrity of the design...which integrity was thus COMPROMISED/OVERWHELMED at each stage of the collapse ALL THE WAY TO THE GROUND.

Would that be more 'real' BOUNDS for the modeling?

Cheers!

RC.
.

lozenge124

23rd June 2007 - 02:57 AM

QUOTE (RealityCheck+Jun 23 2007, 02:37 AM)

Hi Loz!

That would be OK ...IF that was what you were actually studying, hehehe.

You are actually studying a 'concentric square tube' structure whose upper section has been taken out of all as-designed STATIC/DYNAMIC specifications.

And that top section is HEAVIER than would be expected if it was just the SUM of the upper floors in between...simply because of the HEAVY hat truss structure tying together the upper 10? floors and roof and 'core' & perimeter walls.

And on top of all that, the TOP did not fall ONTO the BOTTOM...but INSIDE the OUTER tube....which FUNNELED most of the damaging forces ONTO only the INNER tube and the floors....with the outer tube being merely 'collateral damage to the main 'straight down' collapse process which mostly progressed through each floor inside.

So your suggestion should perhaps be modified to read:

"....simple upper block dropped INTO a lower block"

..... to see if it results in "total progressive collapse" AS THE OUTER WALLS FALL AWAY AFTER THEY HAVE FUNNELED AND CONCENTRATED THE COLLAPSE ENERGIES onto a smaller inner tube and the attached floors which by design were necessary for the overall stability/integrity of the design...which integrity was thus COMPROMISED/OVERWHELMED at each stage of the collapse ALL THE WAY TO THE GROUND.

Would that be more 'real' BOUNDS for the modeling?

Cheers!

RC.
.

Hi RC,

Yes, it's all very complicated isn't it? I say take the NIST WTC model (or the Purdue one for that matter) to collapse initiation and let it rip, see what happens. Alternatively, because collapse initiation is a bit of a contentious issue, lift the WTC upper block up a floor or two and drop it to get things kicked off.

Then we can drop the idle speculation about "inner tubes" and "funneling" and actually study something concrete (even if just a simulation).

RealityCheck

23rd June 2007 - 03:36 AM

QUOTE (lozenge124+Jun 23 2007, 02:57 AM)

Hi RC,

Yes, it's all very complicated isn't it? I say take the NIST WTC model (or the Purdue one for that matter) to collapse initiation and let it rip, see what happens. Alternatively, because collapse initiation is a bit of a contentious issue, lift the WTC upper block up a floor or two and drop it to get things kicked off.

Then we can drop the idle speculation about "inner tubes" and "funneling" and actually study something concrete (even if just a simulation).

Hi Loz.

In that case, studies of WEDGES and the INITIAL mechanical advantage/damage attendant to their uses/occurrences in everyday life should answer your questions of what is POSSIBLE 'initially'.

And the ever-present force of gravity to effectively keep that wedge 'in use' so as to EFFECTIVELY CONTINUE THROUGH its initial impact REPEATEDLY should answer your question of what would keep the process going 'progressively' until ground.

In short, the NATURAL processes/principles that would explain what happened to the towers AS DESIGNED and AS AFFECTED by planes/fires are all available in text books. Just use a wedge yourself on something that is both 'hollow' AND 'constructed piecemeal' with its basic integrity depending on its WEAKEST/MOST VULNERABLE structural element/form/function in the event.

RC.
.

metamars

23rd June 2007 - 03:48 AM

QUOTE (David B. Benson+Jun 23 2007, 12:53 AM)

lozenge124 --- You haven't developed a rational argument against using the crushing front as an accounting method.

I suppose by "accounting method", you merely mean an abstraction which, you hope, gives the right answer.

Unfortunately for BLGB, such an abstraction seems thoroughly un-physical. It may turn out (though I doubt it), that considering energy transport beyond the crushing front requires only minor corrections to your theory.

There is not much point in going over objections which have been repeated many times. Perhaps someday you might figure out the implications of, e.g., Calladine and English and explain to us what little difference that would make to your theory. But I'm not going to hold my breath.

As for more recent objections, namely energy transport through the bottom of the columns and into the earth, I hope to find additional information. However, I don't see how you can have a warm, fuzzy feeling about this effect being neglible, either, as BLGB seem to have produced not a scintilla of theory or experiment showing that this is the case.

Frankly, it wouldn't surprise me if it is neglible ito of the explicit predictions of your theory. However, even relatively minor amounts of energy leakage may still spell the doom of your theory via what it tell us about E1.

QUOTE

The BLGB paper compares two hypotheses: (1) Gravity-driven collapse with resistance as given by the crush-down equation together with other known energetics; (2) Free fall without resistance, occasioned by planned destruction of all elements capable of resistance.

The evidence overwhelmingly supports (1). I have even measured just how overwhelmingly it does.

(2) is actually a straw man, since, CT misapprehensions and mistatements aside, the buildings didn't fall at free fall speed.

QUOTE (->

QUOTE

The BLGB paper compares two hypotheses: (1) Gravity-driven collapse with resistance as given by the crush-down equation together with other known energetics; (2) Free fall without resistance, occasioned by planned destruction of all elements capable of resistance.

The evidence overwhelmingly supports (1). I have even measured just how overwhelmingly it does.

(2) is actually a straw man, since, CT misapprehensions and mistatements aside, the buildings didn't fall at free fall speed.

But feel free to propose another equation for the collapses for me to compare against the crush-down equation. metamars won't take me up on it, but he wrote that he passed the challenge on the the troofers. So far, no reply...

I hadn't done so, but just did at stj911.

Now if the ae911truth forum ever gets restarted, and if I'm given access as promised.....

wcelliott

23rd June 2007 - 03:55 AM

QUOTE

it has not been proven that a progressive collapse is possible (or that "Energy is dissipated only at the crushing front." as Bazant & Verdure put it) under gravity alone,even though the upper block surely has enough energy to crush one floor (including perimeter and core columns) at a time

I think I showed how delivering gravel via UPS would cause a progressive collapse via gravity alone.

Did you miss that?

metamars

23rd June 2007 - 03:58 AM

An idea occurred to me recently, while thinking about columns getting pounded into the bedrock by impacting rubble. Would not such impacts cause the windows to deform and vibrate? Furthermore, even if not visible to the naked eye, could careful study of the films give us bounds for refraction due to such vibrations?

If we could be positive about how much refractions should occur in a true gravitational collapse, we might be able to support this notion or cast more doubt upon it.

Capracus

23rd June 2007 - 07:49 AM

QUOTE (wcelliott+Jun 23 2007, 03:55 AM)

I think I showed how delivering gravel via UPS would cause a progressive collapse via gravity alone.

Did you miss that?

I wonder if the FBI checked out the number of UPS and other delivery service drops on the morning of 9/11? The 1300 tons of gravel needed in the deliveries would be indistinguishable from the rest of the rubble after the collapse, and would go unnoticed as a potential cause. It's a brilliant plan. I really think you're on to something, or were in league with the evil doers.

On the subject of overloading a floor system, here is an article that posits one of the upper floors in WTC 1 being heavily loaded by water from the sprinkler system.

QUOTE

A third possibility as to the initial trigger for the Tower 1 collapse is sprinkler system water overloading one floor. For instance if the restaurant on the 107th floor were sprinklered and the heated smoke set off some or all of the heads, after a time, the water buildup over a large floor area could initiate the sequential bar-joist failure. "From the video footage this collapse appeared to occur (begin) uniformly around the building ("at or near the top of the building") and spread rapidly down to the floor above the impact region. That region than pancaked…" (Clifton, p8).

http://www.ericdarton.net/afterwords/fireandair.html

metamars

23rd June 2007 - 10:41 AM

QUOTE (wcelliott+Jun 23 2007, 03:55 AM)

I think I showed how delivering gravel via UPS would cause a progressive collapse via gravity alone.

Did you miss that?

In the spirit of Benson's proposed rail car/velcro/pulley test of BLGB, why don't you test your wonderful proposal, blessed as it is by your wonderful physical intuition, as follows:

Construct the infamous 'chicken wire WTC model' ( see http://www.democraticunderground.com/discu...6&mesg_id=56836 )

http://i18.photobucket.com/albums/b108/jan...oked/4_fire.jpg
User posted image

However, cut strips of aluminum foil and string them across horizontal wire segments, thus simulating floor panels. You have to make sure that you use enough layers of aluminum foil, and afix them firmly enough, such that the aluminum foil collapses at about 4% of the maximum load that the vertical wire segments can handle. (The 4% is from memory, from a Benson post; on intuitive grounds, I had postulated 10%, but if 4% is more realistic, who am I to argue?)

Now, pre-load your aluminum foil 'floors' with gravel, simulating a normal load. Finally, pick a 'floor' and add enough to collapse it.

I believe that, if saying 'boo' will cause not only the foil to rupture, but also, simultaneously the columns as the foil ruptures, then you will get "global collapse" if you rapidly say "boo! boo! boo! boo! boo! boo!" with just the right timing.

So, being the swell guy I am, you hereby have my permission to say "boo" all you want, in any manner you want, as you conduct your wonderful experiment.

Please be sure to post a video, and don't neglect the accompanying soundtrack!

Personally, I have little doubt that if you perform such an experiment, you will, in the end, say "boo hoo", but I welcome you to prove me wrong.

metamars

23rd June 2007 - 10:44 AM

QUOTE (metamars+Jun 23 2007, 03:58 AM)

An idea occurred to me recently, while thinking about columns getting pounded into the bedrock by impacting rubble.

More accurately, as per, e.g., a Benson post, columns gettting pounded into the bathtub, in turn getting pounded into the bedrock.

wcelliott

23rd June 2007 - 11:04 AM

QUOTE

In the spirit of Benson's proposed rail car/velcro/pulley test of BLGB, why don't you test your wonderful proposal, blessed as it is by your wonderful physical intuition, as follows:

My wonderful physical intuition is the result of many years of education (BS/EE and MS/ECE) plus many more years as an engineer (30).

I don't need any chickenwire nonsense to figure out failure modes in systems, that's part of my job. I get paid to recognize failure modes and prevent them in the systems I design.

I've simplified the "progressive collapse" scenario as much as humanly possible.

Too much weight on floor X causes floor X to collapse. That drops that weight onto the floor below. It's too much weight for that floor, too, so it falls next.

And so on.

I can't think of a simpler way to explain it.

Maybe you're just stupid.

metamars

23rd June 2007 - 11:22 AM

QUOTE (wcelliott+Jun 23 2007, 11:04 AM)

My wonderful physical intuition is the result of many years of education (BS/EE and MS/ECE) plus many more years as an engineer (30).

I don't need any chickenwire nonsense to figure out failure modes in systems, that's part of my job. I get paid to recognize failure modes and prevent them in the systems I design.

I've simplified the "progressive collapse" scenario as much as humanly possible.

Too much weight on floor X causes floor X to collapse. That drops that weight onto the floor below. It's too much weight for that floor, too, so it falls next.

And so on.

I can't think of a simpler way to explain it.

Maybe you're just stupid.

And I can't think of a simpler way to explain my objections. By using imprecise language, such as "floor X to collapse", you obscure the argument. You pre-suppose that collapse of floor panels is automatically accompanied by collapse of the perimeter and core columnar sections associated with that floor.

The chicken wire/aluminum foil setup is meant to make that clear, but you have resorted to ducking, appeal to authority, and innuendo when confronted with, what to me, is a rather obvious and rational objection.

Since you don't want to rationally discuss the issue, can you explain to us why the structural, civil, and mechanical engineers at ae911truth.org ( http://ae911truth.org/joinus.php ) didn't also realize that they are simply looking at an expected failure mode, when viewing the collapses?

FactCheck

23rd June 2007 - 12:33 PM

I'd like to know what NEU-FONZE thinks of this...

http://11-settembre.blogspot.com/2007/02/u...or-of-wtc2.html

FactCheck

23rd June 2007 - 01:06 PM

http://www.debunking911.com/collapseview.jpg

user posted image

A picture is worth a thousand conspiracy theories.

FactCheck

23rd June 2007 - 01:18 PM

QUOTE (wcelliott+Jun 23 2007, 11:04 AM)

Maybe you're just stupid.

He's even more dangerous than that. He thinks he's smart. His ignorance is by design. He's a libertarian who thinks it's easy to convince the simple minded masses to hate government. Unfortunately for him they aren't that simple minded.

Chainsaw,

23rd June 2007 - 01:35 PM

What about looking at the actual collapse front as an increasing fluidic flow, similar to a stone dropping down a water fall onto another stone.
The cushion of fluid can make all the difference between the rocks shattering or not.
The rubble proceeding the top block down the outer funnel should be what is doing the damage to the floors below and that should protect the top block until crush up phase occurs.

We also must remember that the whole building not just the columns are tapered, that adds to the accumulating mass.
The pool table analogy is really not that relevant as it does not include the Shielding effects of the rubble ahead of the top block, that helps to separate the floors connections before the top block hits.
The rubble ahead of the falling top block is what shields the top block and causes the accumulating mass, it also explains a lot of the Fluidic flow effects.
It would however be a more complicated equation.

Grumpy

23rd June 2007 - 04:07 PM

metamars

QUOTE

You pre-suppose that collapse of floor panels is automatically accompanied by collapse of the perimeter and core columnar sections associated with that floor.

Actually they are two very different, discrete processes, though the floors being gone sets the core and outer columns up to be vulnerable to other forces(wedging and crush).

Grumpy

3bodyproblem

23rd June 2007 - 04:07 PM

Hey guys, just looking back at the thread I've seen some debate as to the possibility of progressive collapse. From my building experience the issue progressive collapse is factored into the buildings design. In fact the NBCC directly addresses this. Don't you think this acknowledgment is sufficient to skip the "can it happen?" directly to the "how did it happen?". It can happen and it can happen to just about any building, the WTC were no exception. Long story short, it is a known failure mode.

I think Mr. Benson has pointed out that the reverse time, variable mass rocket analogy is appropriate. I would concur on this, however I would be careful trying to explain this to twoofers as a rocket in reverse time is actually very similar to a Controlled Demo, perhaps even more so than a progressive collapse. A rocket is an exogenic collision of sorts due to the nature of the combustion process

I've tried unsuccessfully to analogize the collapse to many a twoofer, they always seem to get hung up on the particulars and not see the physical principle you are trying to convey.

That's my 2 cents for today. Oh, and NeuFonze I must apologize, you have certainly shown that it was I being the Nit Pick in regards to the sway. I had no intention of suggesting you were being a Nit Pick, merely stating that the process of Nit Picking is an exhausting process in many regards. Greg does have a tendency to do this, then justify a total disregard for the overall body of work based in the minutiae.

wcelliott

23rd June 2007 - 04:47 PM

QUOTE

You pre-suppose that collapse of floor panels is automatically accompanied by collapse of the perimeter and core columnar sections associated with that floor.

No, I just say that when the floor has too much weight on it, it collapses, and when it collapses, it drops the load that made *it* collapse onto the floor below it.

By whatever mechanism/definition of "collapse" you feel reasonable, floors do *collapse*, and when they do, they drop their load to the next-lower floor.

Which itself collapses, in turn.

QUOTE (->

QUOTE

You pre-suppose that collapse of floor panels is automatically accompanied by collapse of the perimeter and core columnar sections associated with that floor.

No, I just say that when the floor has too much weight on it, it collapses, and when it collapses, it drops the load that made *it* collapse onto the floor below it.

By whatever mechanism/definition of "collapse" you feel reasonable, floors do *collapse*, and when they do, they drop their load to the next-lower floor.

Which itself collapses, in turn.

can you explain to us why the structural, civil, and mechanical engineers at ae911truth.org ( http://ae911truth.org/joinus.php ) didn't also realize that they are simply looking at an expected failure mode, when viewing the collapses?

Maybe they're stupid, too.

NEU-FONZE

23rd June 2007 - 05:38 PM

FactCheck:

Yes, I have read about the UPS on the 81st floor of WTC 2. I think the scenario described in the link you gave is quite likely. Even without an electrical short of those batteries, lead melts at a mere 328 deg C. Lead acid batteries may have been used throughout the Towers, but were highly concentrated in UPSs for mainframe computeres in data centers. I think this particular use of lead explains why lead was highly enriched in the WTC dust (~100 mg/kg).

And remember, all those batteries contain concentrated SULFURIC ACID.

3bodyproblem:

No need to apologize, compared to some JREFers, you are a SAINT!

wcelliott

23rd June 2007 - 06:54 PM

QUOTE

I think this particular use of lead explains why lead was highly enriched in the WTC dust (~100 mg/kg).

I think it could also explain that glowing-hot molten metal pouring out of the side of the WTC tower that Dr. Jones insists *must* be thermate.

Maybe molten aluminum doesn't glow, I'm pretty sure molten lead does.

David B. Benson

23rd June 2007 - 07:20 PM

lozenge124 --- In a one dimensional world, all quantities are scalars. In particular, one dimensional billiards is called Newton's cradle. So, one dimensionally, there seems to be no rational objection to accounting for all energy consumption at the crushing front.

Obviously, this is only an approximation. The zone B crushed mass would have, in fact, consumed some energy by be re-crushed at every impact. Towards the end of crush-down, the air pressure would be so high that it alone could begin pre-destroying the floor below, not yet actually impacted. But both of these effects are close to the crushing front and easily accounted for there. Any energy loss to seismic effects take only about 0.2 seconds or less for the pressure waves to travel down the columns. Hence we can account for this at the time that the pressure wave is formed at the crushing front.

metamars --- By my calculations, the energy consumed per undamaged, truss floored, story for the first few seconds was 510 megajoules. Of this stupendous consumption, so far only about 20 megajoules is accounted for in breaking the truss seats. Nobody seems ready to supply figures for breaking connections in the core or breaking the bolts holding wall sections together. Nobody seems ready to estimate the energy required to crush the trusses. But qualitatively only, I'm having difficulty finding ways to expend the remaining 490 megajoules. Some small portion goes to air movement, but for the first few seconds this is negligible. The initial speeds seem a bit low for much concrete comminutiion.

However, the columns resting on the bottom of the Bathtub obviously provide a very poor means of producing seismic waves. They weren't pile-drivers. Look again at the LDEO seismograph trace, a better quality one than in the BLGB paper. Notice the very small amplitude at the beginning. So I'm not at all concerned with the small amount of energy consumed seismically. There seems to be an embarrassingly large amount to find ways to consume...

FactCheck

23rd June 2007 - 08:19 PM

QUOTE (Chainsaw,+Jun 23 2007, 01:35 PM)

What about looking at the actual collapse front as an increasing fluidic flow, similar to a stone dropping down a water fall onto another stone.
The cushion of fluid can make all the difference between the rocks shattering or not.
The rubble proceeding the top block down the outer funnel should be what is doing the damage to the floors below and that should protect the top block until crush up phase occurs.

We also must remember that the whole building not just the columns are tapered, that adds to the accumulating mass.
The pool table analogy is really not that relevant as it does not include the Shielding effects of the rubble ahead of the top block, that helps to separate the floors connections before the top block hits.
The rubble ahead of the falling top block is what shields the top block and causes the accumulating mass, it also explains a lot of the Fluidic flow effects.
It would however be a more complicated equation.

I believe this is a very important part of the collapse and I'm waiting for one of physorgs greats like NEU-FONZE and DBB to depict this in a paper.

(I know, don't hold your breath.

)

I think this is important because of the lives which may be lost in the future and the billions of dollars in collateral damage created by the peel open effect. There must be a way to design tall buildings which fall apart and straight down instead of opening like a flower.

David B. Benson

23rd June 2007 - 09:40 PM

QUOTE (lozenge124+Jun 23 2007, 02:20 AM)

I would be very happy to see a simple upper block dropped onto a lower block that results in "total progressive collapse" - no explosives, no thermate, just gravity.

Well, try the rail car setup. The rail car on the left is attached via a line over a pulley at the right to a pan with weights. Somewhat to its right is another rail car to which it will couple. Repeat with as many rail cars as will appropriately fit of the rail. Let go of the line and observe.

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