911myths??

It has been noted that Dr Greening’s report is now available having undergone some alteration.
However there remain serious flaws within the assumptions made and these are having the effect of rendering the conclusions almost worthless.
The main flaw in this report, regarding the collapse is contained within the authors derivation and use of the strain energy requirements to collapse a single floor.

This flaw has as its source the assumptions implied within the bottom paragraph of page 19. The author states, “As noted in Section 4.2 the 236 perimeter and 47 core support columns have an effective cross sectional area of …..10.15 m^2.………we conclude that the supports at a given floor would fail if the downward compressive load exceeded about 4000MN.”
The author then goes on to compute a “collapse safety factor of about 3” for that storey.

The author is stating that the same amount of force would be required to produce failure in any of the storeys. This is plainly wrong since the upper storeys were made of relatively light material section and in some portions, I-section columns, whereas the bottom storeys comprised relatively heavy section box columns.
The author seems to apply a belief that the tower support structures were of the same cross sectional area throughout the height of the tower.

A similar flaw occurs when the author discusses strain energy. Firstly and most importantly he uses the same value, 600MJ, for each of the storeys within the structure. There is no way this can be true and the values would lie over a wide range. For instance the 100th storey normally carries the ten storeys and the hat truss above and would be built with this in mind. The tenth floor would carry 100 upper storeys and the hat truss, so its geometry would reflect this. The author’s use of a constant value for this strain energy requirement does not reflect the situation which actually did exist.

Neither does the author take regard of the elastic strain energy absorbed by storeys other than the topmost storey of the lower section. To be able to cause a failure in those storey columns a force would have to be exerted by the falling upper section and this force would also act on all of the storeys below the impact and also on those above the impact point. The initial impact force exerted and thus the force required to cause buckling failure at the upper levels would not be sufficient to cause these failures at lower levels, but the effect of the force would still be some elastic deflection of all other storeys. The size of the deflection caused would vary from storey to storey and would be in the same ratios as the static load ratios for each storey. The energy requirement for this energy would vary dependent upon the number of storeys remaining but would always be a prerequisite to continued collapse.
The effect of ignoring this phenomenon is to ignore a large energy requirement that has to be satisfied before the collapse can continue. The energy ignored would be the difference between the average of the applied load over one storey’s resultant elastic deflection, and the average of the applied load over all storeys resultant elastic deflection.

The author examines the distance over which the failure load would act and these figures he gives are around 0.11 metres (p31)from a storey height of 3.7m. So he contends that after less than 3% of its length the columns would thereafter offer no further resistance to the falling mass. This contradicts accepted theory most notably contained within BZ that a minimum 3% vertical deflection would be required to even initiate buckling points. BZ show that the required force reduces from that point but it does not at any time fall below 25% of the initial failure value.
The author justifies his use of these small values of deflection by stating that actual failure occurred in the fixings between column sections rather than column failure itself . But this cannot be the case because we know from BZ that buckling points would only appear after 3% vertical deflection. There would be no buckle points at the vertical deflections used by the authors. Buckle points or a horizontal deflection of the column midpoint are necessary for the downward acting mass force to be able to gain a moment through which to apply a force on the fixings.
No buckling=> no moment=> no force=> no failure.
The author at one point suggests he is using compressive failure modes. Again the contention that total and catastrophic failure, resulting in an inability to transmit any force whatsoever, would occur after a deflection of only 3% is contradictory to accepted knowledge of compressive failures, which exhibit deformations of up to 40% with varying load requirements before ultimate failure results in an inability to carry any load whatsoever.

Neither do his own figures tie together
His figure of a failure load for storey 80 was 4000MN.(p19) This force acting over a distance of 0.11 metres would give a maximum energy requirement of 440MJ. But this is in contradiction to his figure for energy requirements to collapse one storey, being 600 MJ.
For these two figures to be satisfied it would be required that the force acted over a distance of a minimum of 0.15metres and in actuality a greater distance than this since the load would be zero at time = 0 rising to a maximum. The author gives no reason for this discrepancy.

Let us now examine the actual value of strain energy requirement for collapse. The author has identified the strain energy requirement for the first 3% of the vertical deflection of the buckling columns. We know from BZ that the remaining 97% of the vertical deflection will require a further energy input of some ten times this amount. So using a very rough approximation we can argue that the energy requirement is of the order of some ten times greater than the value used by the author. Even if we included a factor to allow a pessimistic view of early fracture and did this by allowing that only half of this additional requirement has to be met, we can see that the new value would still be of the order of some five times greater than the value used by the author.
To demonstrate the relative size of the energies involved let us assume for the moment that the aircraft was travelling slightly faster than the author has assumed, and let that assumption be that the velocity was 240ms^-1 rather than the 220ms^-1. This is not an absurd suggestion since it reflects the velocity given by the NIST report. We now see that the aircraft impact energy would be increased from the 3.0 x 10^9 J which the author uses to about 3.6 x 10^9 J. Thus an additional 600MJ would be available and according to the authors figures this would be sufficient to take out all of the perimeter columns and all the core columns on one entire storey. This would be in addition to the damage which we did witness being caused. Is this realistic? The aircraft velocity increased by a mere 20ms^-1, now has the energy to destroy an additional entire storey? This in itself casts doubt upon the relative size of these figures.

So what can be salvaged from this report? The author has demonstrated that the collapse times which were actually observed on the day, were consistent with a value of strain energy requirement to collapse each floor of around 600 - 800 MJ. Thus it can be shown that only by application of strain energy requirements of this order could the observed collapse times have been achieved. Since the values of strain energy were demonstrably higher than those used by the author we must conclude that since the observed collapse times were achieved then some mechanism must have applied in order for the energy requirements to be reduced to the levels used by the author. Without the removal of that ability the collapse times could not have been achieved.

Greetings Fellow Believers,

I cannot and will not subscribe to conspiracy theories about 9/11. However, I do follow legitimate investigations. I thank you for your posting.

Science and physics have been lacking in the mainstream press regarding 9/11. I suspect that Americans are mind-numb about that day. Imagine the attention span required for the market potential of this tragedy: 4 seconds.

You have voted gordonross for the Way Above Top Secret award. You have two more votes this month.

Good work. If you haven't already, think about forwarding this to ST911. Using a constant for the floors' strain energy, regardless of reality, does not favor Greening's theory per se - however, using ~600MJ clearly does. And it's a highly unsubstantiated value, backed only by rather obscure references. I think the +20m/s airplane KE example illustrates this brilliantly.

Originally posted by Jack of Scythes
Greetings Fellow Believers,

I cannot and will not subscribe to conspiracy theories about 9/11. However, I do follow legitimate investigations. I thank you for your posting.

Science and physics have been lacking in the mainstream press regarding 9/11. I suspect that Americans are mind-numb about that day. Imagine the attention span required for the market potential of this tragedy: 4 seconds.

the plaines crashed half way up the tower but they was a explosen at the bottom of the tower moments later why

Great work gordonross! Definitely send that to st911.org.

In fact send it to greening himself to see what he has to say about it!
[email protected]

He is really good at responding to emails.

A friend of mine determined that Greening was way off to begin with because his figures for mass are entirely incorrect. When we confronted Greening with it he didn't deny it! Here is my friends hypothesis along with Greening's reply:

Dr. Greenings paper did provide a scientific look into the collapse of the buildings by providing detailed calculations and referenceces. However here's where he went wrong....Those of you that may not understand chemistry nor physics or math for that matter would take his word as bond due to his qualifications. And that is normal as this is the man's life and it is what he does. However having carefully looked over his paper on the collapses, I noticed a fundemental flaw...He made a major assumtion that bascially ended up with missrepresented results.

Searching for the actual values of the twin tower masses, you'll get 500, 000, 000Kg from many sites. However, none of these sites tell you where this figure was taken from. If you were to read the 2002 fema and nist reports, you would get 200, 000, 000kg for each tower. So I ask the question...where does Greening and others that support his position get this figure from?

Before i go into the more acurate figures I wanna point something out to each of you. There are buildings taller than wtc....made of concrete and steel that do not even weigh in 500, 000 tonnes.


Empire State Building, NYC = 365, 000, 000 kg


Woolworth Building, NYC = 223, 000, 000 kg


John Hancock Tower, Chicago = 384, 000, 000 kg


Sears Tower Chicago = 440, 000, 000 kg.


Taipei 101 = 700, 000, 000 kg.


Petronas Twin Towers = 350, 000, 000 kg. (each)

Both twin towers were built to be as light yet rigid as possible so as to withstand the extreme forces of the 100 + mphs. The buildings load was carried 60% by it's core and 40% by it's perimiter steel columns. The perimiter carried the lateral load to resist the wind whereas the core carried the gravity load.


Now check this....the weight of structural steel used in each Tower is generally reported to be 96, 000, 000 kg and the weight of concrete is said to be 48, 000, 000 kg per Tower.

The Aluminium panels were reported at 2 million kg

The wallboards were at 8 million kg


Adding those together the skeletal structure clocked in at 154 million kg per tower.


More mass is added to the figure when you factor in the utilities, and other fixtures.


Because there is no actual report that fema nor nist gave for these figures the only thing we can really do is take a guess at it.

Plumbing, electrical and telecom would each add about 5 million kg giving us additional 15 million kg. Adding that to our structure we get a figure of 169 million kg which constitutes as the buildings dead load.


When we populate the buildign with office furniture, supplies and people then more mass is added.

As you can see this 169 million is only a 1/3 of the reported total weight of the building. Factoring the live load of people, office furniture and other objects in the buildings...the live load will rise dramatically and the building could top out to over 300 million kg. but it's still 200 million shy of the 500 million.

The sears tower was larger and taller than either tower and it is also a tube within a tube steel building yet it weighs less?

John Hancock is 100 stories and is built as tube within a tube just like the twin towers composing, of steel, aluminium and glass, yet it clocks in at 384, 000, 000kg. (live load included). And the building was not built of light weight steel like the twin towers so it was in fact heavier.

WTC is similar to John Hancock in terms of it's concept so it's fair to consider the two buildigns will be close in mass value. In any mathematicaly equation if one variable is off by just a mere fraction this throws ur result off. Greening was off by 200 million kgs....so his values for the k.e. and g.p.e. would undoubtedly give us those high values with such a large mass.

What upsets me guys is not enough detailed information on the towers construction is widely distributed....and the only figures we can really work from are fema and nist....bc the buildings plans and structural elements are deamed national security. If they have nothing to hide then why cacn't independent scientists get copies of the buildings designs? They are already destroyed and they won't be used again so why the secrecy?


here is greenings reply:

"You make some very good points and I will try to address them as best I can. First let me say that the article you are quoting was written a while back and I have done some other stuff since then that adds and expands on my original work. That original work was therefore a first attempt to see if the Towers could theoretically have fallen by a pancake collapse. The answer appeared to be YES! But as I looked at more videos and read some of the stuff I am sure you have also read, I now say that the collapse of both Towers was more complex than my simple model, as I will explain in a moment. First, on the mass of the Twin Towers, I have recently done some checking into that and I see quite a spread in values.... Some references simply give the potential energy, which implies a mass through the equation 1/2Mgh, (factor of 1/2 because average height fallen is h/2)...... For example, FEMA give the PE of one Tower as 4 x 10^11 J which implies a mass of 196, 000, 000 kg, but the May 2002 issue of Civil Engineering Magazine to be found at ASCE.ORG gives the PE as 3 x 10^12 J implying a mass of 1, 472, 000, 000 kg! The figure I used, and I think it was similar to the value quoted by Profs Eager, Bazant and Kausel ( all engineering profs who have written articles on 9-11) is somewhere between the FEMA and the ASCE.ORG number, let's say about 500, 000, 000 kg....... But I would really like to see a detailed breakdown of the mass, because I am not sure if any of these numbers are correct!"

so he is clearly backing away from his own work and he admits the values he used could be incorrect! furthermore he admits that he is "adding" to this orginal work based on faulty numbers rather than revise it with more accurate numbers!

is this really a scientist?

You have voted gordonross for the Way Above Top Secret award. You have used all of your votes for this month.

the most excellent post i've seen in a long time.

and that seems to be the only kind of post anyone's making these days!

it's too quiet. i don't here any birds or crickets.

gordon you rock. the real cincher for me is the deformation of steel. that's what steel does. it doesn't just go *poof*. also, the way the 'plunger' disintegrates(with about half or more of it being ejected to the side) before the lower part even budges. there's no reasonable way you can just suddenly apply a 12 foot freefall of the entire falling mass of upper floors as a physical possibility.
the official lie would have you believe that a small wind would blow these huge steel cages down. i think maybe too much mail(read, secret service investigation into terror connections and drug running connections, hard evidence documents), made it into 'the shredder'(a massive conflagration which turned all adjacent buildings black, flipped cars, blew out the windows of cars and burned all the paint off, speared the banker's trust building with a huge 'tree' of perimeter columns and spandrels in the upper stories, threw aluminum cladding up and over buildings, leaving them scattered on upper tiers), to 'renew' the 'opportunities' available in the 'transporation and energy industry', as protected by the (bad guy)'military and police and secret police' forces, while keeping a stranglehold on the (good guy)'military and police and secret police' forces through 'propoganda' and 'media complicity' and 'assassination'.

what do you think of 'janedoe''s billiard ball experiment? here

A great post indeed. Wish I had cut and pasted it first!

lofi.forum.physorg.com...

Well, and the name of the poster on physorg.com is...wait for it

GORDON

So, what's your point?