WTC collapses - Layman's terms again

[SpitfireIX]

Originally Posted by Heiwa

Of course fire/heat will affect steel ... but not cause free fall of an upper block. Big difference. Fire/heat does not remove supports allowing sudden free fall. Just softens the supports allowing a very soft movement down. Soon stopped. Happens everytime.

Frankly, this statement demonstrates a gross misunderstanding of the subject of strength of materials. Exactly how far do you believe a column can be compressed before it fails catastrophically? And how is catastrophic failure materially different from the column's having simply disappeared?

Originally Posted by Heiwa

Evidently the lower structure will withstand the upper block falling on it!! The strength of the lower structure occupies only 0.13% of the area of the structure. The upper block misses that ... and gets entangled in some weak floors and the collapse is arrested. Basic.

Each floor can only support the weight of six floors above landing on it, and that's assuming that the supporting floor is undamaged to begin with. Therefore, the collapse will not be arrested. Basic.

Originally Posted by Heiwa

Of course the four perimeter walls on the outside and the core structure on the inside would stand in isolation. Only connected by bolted floors. Easy to show in any structural analysis.

The floor trusses were an important part of the structure. This was one of the novel features of the World Trade Center towers. If it's so easy to demonstrate that neither the core nor the outer walls should have collapsed then please show us your calculations.

Originally Posted by Heiwa

<snip>

Sorry, you are wrong on all accounts. Of course, all OT. As usual. Topic is collapse arrest. Happens every time when steel structures are locally heated.

Even if we were to grant that this is true for the sake of argument, as has been noted many times, the towers didn't just suffer damage from fire. They also each suffered damage from the impact of a 767.

[Myriad]

Originally Posted by Heiwa

Very good - you redid the energy calculations. If your read my home page you find that once we investigated 200+ collisions where oil tankers were stricken by other ships and what happened then. Apart from oil spills in a minority of the collisions (most damage is just above waterline) all collisions were arrested sooner or later. Similar statistics are available for other type of collisions, incl. 33 000 tons ships hitting other ships.

Re WTC 1 the collision energy involved is very small and as soon as it is applied to both parts, it starts to destroy the parts. Both parts. As outlined in my article at http://heiwaco.tripod.com/nist3.htm .

"Small" is meaninglessly subjective. What matters is that the potential energy in each tower was 10,000 times the kinetic energy of a 1,000 ton ship moving at 15 knots, and 300 times the kinetic energy of a 33,000 ton ship moving at 15 knots. This makes your analogies to ship collisions (not to mention tables and bird cages) highly questionable. It strongly suggests that you are failing to consider a major factor in the energy balance. Which I have shown is indeed the case.

Quote:

This means, among many things, that energy is consumed and should result in a deceleration, and that parts may shear off and drop down. The energy of those latter parts do not then contribute to anything (than hitting bystanders in the way).

You're pointing out some areas where energy is consumed while ignoring the much larger amount of energy that is added from the action of gravity. If more energy is added than consumed, the collapse accelerates.

If just the kinetic energy alone of a structure moving at a few meters per second is sufficient to penetrate a similarly composed structure by "a few meters," as your ship collisions demonstrate, then you've proven that collapse will continue. Because by descending those few meters, the falling mass (whether it breaks apart or not) experiences a net gain of kinetic energy, so it speeds up rather than slowing down.

Quote:

The conclusion of my article is that the WTC 1 upper block (mostly air inside the very solid columns and the thin floors) would have been destroyed after falling on the lower structure due many local failures (floors being sliced by columns) and that two of the upper block walls may shear off and drop down while all the floors remain entangled into one another. This is a typical collapse arrest of a steel structure.

The energies involved are consumed in this mess. Quite easy to calculate actually, if you do the effort.

But you have not done the effort to calculate all of the energies involved, and have therefore not supported your paper's conclusion. That conclusion is therefore irrelevant. GergoyUrich's paper on the collapse energy does a much better job. Why don't you explain what he got wrong?

Respectfully,
Myriad

[Apollo20]

Newtons Bit:

Well thank you for that comment!

It is interesting that Heiwa thinks that the upper block of WTC 1 simply disintegrated before it had time to collapse. I have seen no evidence for that. And Heiwa has no proof that such a "disintegration" occurred.

And Heiwa apparently believes there was no tipping of the upper block of WTC 1 when it is in fact clearly visible in many videos (as long as they were not taken from the north!) Thus Heiwa fails to recognize that tipping is very important to collapse initiation and early propagation.

And may I add that it is most regrettable that Heiwa chooses to ignore most of the posts by myself and others that have previously pointed these and other things out to him.

So, before I go over all this stuff again, and get ignored again, I would ask Heiwa to go back and read my posts on all his threads and tell me how many of my posts he has addressed.

Oh, and Heiwa, as to my supposed "hidden agenda", let me tell you that I am a retired scientist living at home with my wife and son trying to live off a small pension. I spend my time writing submissions to the Canadian Nuclear Safety Commission. (In fact if you google on Greening and CNSC or CANDU you can read all about it.)

So Heiwa, what would my " hidden agenda" be? If you can't tell me, I would ask that you retract this comment and stick to talking about things you can back up with evidence.

[tanabear]

Originally Posted by pomeroo

Here is what Mark wrote:

"One of the benefits of my work is that I sometimes get tours behind the scenes in a wide range places: theaters, TV studios, skyscraper mechanical systems, power plants, laboratories, museums, and exhibits.

The pieces of WTC aluminum I handled had characteristics of having cooled while falling in the air (I suppose falling through water is also a possibility). The curator said to me "I bet you can't guess what this is," but I guessed right away. This was before I knew of the conspiracy nonsense or the video of molten material coming from the south tower.

There is a place where the public can handle small debris from Ground Zero: steel, glass, and rubble (which has been cleared for this purpose by investigators and by families). I'm not going to advertise it here because I'm certain that 9/11 deniers would steal these things. People can PM me if they want to visit that place.

At Ground Zero, on Liberty Street next to FDNY 10 House there is a small exhibit that includes large pieces of structural steel, the battered uniform of a fallen firefighter, part of an aircraft fuselage, metal that has melted and cooled (appears to be mostly aluminum), and other artifacts from the towers. Tribute 9/11 WTC Visitor Center (http://www.tributewtc.org/)"


We conclude, then, that Mark told the truth, and--surprise!--the liars were attempting to twist his words. As usual, I am left wondering why you, a fantasist, would call attention to a statement that lends no support whatever to the false claims of your evil movement.

This is a non-answer by Mark. The question posed to you -- and Mark -- was why Mark Roberts didn't provide this sample to NIST or FEMA so that they could definitively conclude that the molten material flowing out of WTC2 was aluminum? Controvery continues to swirl around the issue since there are competing claims that the material was either aluminun, or lead, or iron. NIST would not need to speculate in their FAQ that aluminum glows a certain color if mixed with organics. Why was there no further examination of Mark's stunning revelation?

[Finnegan]

I'm sorry for being ignorant of the context, but is Tanabear and Pomeroo's debate concerning the 80th-81st floor fountain?

What do people think of this? I haven't seen any mention of it beyond Screw Loose Change.

[pomeroo]

Originally Posted by tanabear

This is a non-answer by Mark. The question posed to you -- and Mark -- was why Mark Roberts didn't provide this sample to NIST or FEMA so that they could definitively conclude that the molten material flowing out of WTC2 was aluminum? Controvery continues to swirl around the issue since there are competing claims that the material was either aluminun, or lead, or iron. NIST would not need to speculate in their FAQ that aluminum glows a certain color if mixed with organics. Why was there no further examination of Mark's stunning revelation?

Seriously, do you think that NIST is unaware of the existence of the exhibit Mark visited? Do you think that there was a widepspread feeling among the researchers of, "Damn--we missed something big"? How important do you suppose the "controversy" is?

[DC]

Originally Posted by pomeroo

Seriously, do you think that NIST is unaware of the existence of the exhibit Mark visited? Do you think that there was a widepspread feeling among the researchers of, "Damn--we missed something big"? How important do you suppose the "controversy" is?

Quote:

The pieces of WTC aluminum I handled had characteristics of having cooled while falling in the air

what characteristics are that exactly? and how big was that piece?

[tanabear]

Originally Posted by pomeroo

Seriously, do you think that NIST is unaware of the existence of the exhibit Mark visited? Do you think that there was a widepspread feeling among the researchers of, "Damn--we missed something big"? How important do you suppose the "controversy" is?

This is another non-answer. The question was why didn't Mark Roberts inform NIST or FEMA of this material or provide them with a sample? If NIST is aware of this material then why didn't they reference it in their August 2006 FAQ?

This issue is critically important, which is why NIST had to devote a question to it in their FAQ.

[DC]

well i say Mark based his conclusion on false information, nowadays that is not a lie

[funk de fino]

Originally Posted by tanabear

This is another non-answer. The question was why didn't Mark Roberts inform NIST or FEMA of this material or provide them with a sample?

Why dont you?

Originally Posted by tana

If NIST is aware of this material then why didn't they reference it in their August 2006 FAQ?

Why dont you find out if they are aware of it?

Originally Posted by tana

This issue is critically important, which is why NIST had to devote a question to it in their FAQ.

I do not think you know what critically means. You do realise why the FAQs were issued?

[Heiwa]

Originally Posted by Apollo20

Newtons Bit:

Well thank you for that comment!

It is interesting that Heiwa thinks that the upper block of WTC 1 simply disintegrated before it had time to collapse. I have seen no evidence for that. And Heiwa has no proof that such a "disintegration" occurred.

And Heiwa apparently believes there was no tipping of the upper block of WTC 1 when it is in fact clearly visible in many videos (as long as they were not taken from the north!) Thus Heiwa fails to recognize that tipping is very important to collapse initiation and early propagation.

And may I add that it is most regrettable that Heiwa chooses to ignore most of the posts by myself and others that have previously pointed these and other things out to him.

So, before I go over all this stuff again, and get ignored again, I would ask Heiwa to go back and read my posts on all his threads and tell me how many of my posts he has addressed.

Oh, and Heiwa, as to my supposed "hidden agenda", let me tell you that I am a retired scientist living at home with my wife and son trying to live off a small pension. I spend my time writing submissions to the Canadian Nuclear Safety Commission. (In fact if you google on Greening and CNSC or CANDU you can read all about it.)

So Heiwa, what would my " hidden agenda" be? If you can't tell me, I would ask that you retract this comment and stick to talking about things you can back up with evidence.

Hallo Frank!

Evidence that the WTC 1 upper block is disintegrating first before any local failures of the lower structure take place is given in my articles, e.g. that the mast on top of the roof of WTC 1 is falling first, then the roof, etc., when the lower structure is still intact. To suggest that the upper block is intact then is dishonest. In your analysis the mast should be the last part to fail in a push-up on top of the rubble.

Of course the upper blocks of both WTC 1 and 2 are tipping very early - clearly shown in WTC 2 - also described in my articles. And that invalidates the basic assumptions of your recent paper 'What Did and Did not Cause Collapse of WTC Twin Towers in New York' with "Abstract: Previous analysis of progressive collapse showed that gravity alone suffices to explain the overall collapse of the World Trade Center towers". That conclusion is as valid as a three dollars bill! Gravity force does not work like that.

You support many conspiracy theories about the collapse in your paper, e.g.:
1. All supports of WTC 1 suddenly disappear below the upper block.
2. The upper block near free falls 3.7 meters.
3. The upper block impacts a lower structure with perfect alignment.
4. The upper block is still intact.
5. The upper block (mostly air) assisted by gravity only destroys the columns of the lower structure below (the columns break every 10-12 meters like spaghetti).
6. The upper block lands intact on a heap of rubble after a successful push-down of the tower
7. The upper block finally selfdestructs in a push-up of the rubble.

Luckily the paper is not yet published by ASCE so you have time either to withdraw it or at least remove your name as co-writer.

Applying your and Bazant's (and Seffen's) theories to ship collisions it would appear that when a smaller ship hits a big ship, the small ship produces a shock wave, etc. and then slices through the big ship like butter. Ships are of course steel structures. But steel structures do not behave as you assume.

I remind you that ship collisions, or groundings for that matter, are much more frequent than steel tower collapses and that in many of these incidents the energies involved far exceed, e.g. WTC 1 collapse initiation. And they all end with an arrest after only local failures.

Why the WTC 1 local failures should end in a collapse arrest after the columns have locally damaged a few floors is described in my latest article at http://heiwaco.tripod.com/nist3.htm . Evidently the strong columns of the lower structure (only 5-6 m² total crossarea) will slice the upper block - floor area 4000 m² - in two and the walls of the latter on the outside of the lower structure may drop down. The rest of the upper block structure, i.e. the sliced floors and remaining walls, will only get entangled in the lower structure. A thin floor of the upper block can never destroy the columns supported by spandrels of the lower structure.

In view of that and other observations of mine my remark about your agenda remains? Maybe you are only ignorant of basic facts what happens when two steel structures collide? Have you ever studied any ship collisions?

Kind regards

Anders Björkman

[Heiwa]

Originally Posted by Myriad

You're pointing out some areas where energy is consumed while ignoring the much larger amount of energy that is added from the action of gravity. If more energy is added than consumed, the collapse accelerates.

Respectfully,
Myriad

See my previous message to Frank. I do not ignore that gravity (or any force involved) may add energy. Topic is what energy is available at the collision and where it is applied to cause failures and what happens then.

The energy released at the collision will evidently destroy weak parts of both bodies involved - the btm parts of loose upper block, e.g. its lowest floor - and the static lower structure. It means that the upper block starts to disintegrate (even if it seems to have done it long before the collision). To assume that the upper block remains intact after collision contact like a hammer hitting a nail (the lower structure) is wrong.

This destruction of the upper block at collision will slow it down and change its geometry. Example - a hammer hitting a nail very often stops when the nail is only forced down a certain distance ... and you have to hit again to really put the nail down.

Any part that is stopped at this time, failed or not, will not produce or add any energy due to gravity. Actually it will participate in stopping other parts that are still moving. The gravity force will just produce compression of the parts below.

To simplify analysis of local failures of a steel structure assuming that the part above is a solid hammer and the other below is a weak nail is wrong.

And let's face it. The assumption of 'near free fall' over a certain distance of an upper block producing a certain amount of energy to initiate damage to the structure below is very weak. There is no free fall and any potential energy released due to downward displacement of local failures would be consumed just to produce the said downward movement. No energy would be added.

With best regards

Heiwa

[MRC_Hans]

Wow! 16 pages and still at square 1.

Hans

[funk de fino]

I love how Dictator Cheney spat his dummy about Bazant leaving out springiness of the upper block yet says nothing when the fake engineers uses an example of a hammer and nail to simulate the Tower.

[DC]

Originally Posted by funk de fino

I love how Dictator Cheney spat his dummy about Bazant leaving out springiness of the upper block yet says nothing when the fake engineers uses an example of a hammer and nail to simulate the Tower.

what bazant did is more like, crushing a hammer with a nail :/

[funk de fino]

Originally Posted by Dictator Cheney

what bazant did is more like, crushing a hammer with a nail :/

Thats an even worse claim. Hammers and nails made out of many different interconnecting parts are they?

[Apollo20]

Heiwa:

First of all let me tell you that I HAVE looked at ship collisions. I even have a copy of Minorsky’s classic (1959!) paper and I have played around with Minorsky’s KE equation by making various estimates of his resistance factor, Rt, as it might apply to the Twin Towers. If you take Rt to be ~ 18 m^3 you arrive at an energy loss for the impact of a 30,000 tonne “ship” of about 900 MJ which is of similar magnitude to my quantity E1. However, the important difference between ship collisions and the WTC collapse is that GRAVITY is not a factor in ship collisions while it is THE key factor in the collapse of WTC 1, 2 & 7.

But let’s look at your specific points of criticism of my (and other similar) collapse calculations. Here I have to begin by saying that the supports of the upper block did NOT “suddenly disappear” as you claim. How could they? Instead, as many collapse videos and photos show, the perimeter columns first bowed inwards over a vertical height of several floors. Eventually it appears that the A325 bolts at the column splices failed in shear – on the south face of WTC 1, and the east face of WTC 2. This type of failure, although it started along one wall and rapidly spread to other walls, caused the upper block to tilt several degrees from the vertical in the direction of the failed wall. Then, very quickly, the hinged wall also failed allowing the entire upper section to break free and essentially “free fall” onto the lower structure.

Now, because the initial drop involved some tilting motion, the upper section would obviously NOT be perfectly aligned with the lower section at the moment of impact. So, Heiwa, I have never made such an assumption, nor is perfect alignment of the upper and lower sections of the towers critical to my model!

Simple geometrical considerations show that a block that drops by column failure at one face, while remaining hinged at the opposite face, would strike the floor below when the tilt angle reaches about 3.3 degrees. Furthermore, the perimeter columns on the face that is falling would strike the row of columns immediately below the upper block along a line located about 10 cm INSIDE their vertical axis. Such collisions would be more of a series of glancing blows than the “head-on” impact of a drop hammer you imagine. The columns below the upper block would thus be pushed aside like skittles hit by a bowling ball rather than compressed like pistons or springs. Thus the structure below the upper block was destroyed by successive splice (weld or bolt) shear failures all the way down the tower.

Now I admit that none of this detail is explicitly treated in my one-dimensional collapse calculation; but after just a few lower floors were obliterated in the way I have described, the fine detail of each subsequent floor failure has hardly any effect on the overall collapse kinetics which is now dominated by momentum transfer in a gravity field.

So, Heiwa, you are making the same mistake that Ace Baker and others of his ilk have made before; you are assuming that a model must follow every nuance of the process under investigation to be valid. This is simply not true, and is probably not possible for a chaotic event such as the destruction of the Twin Towers. But worse yet, you are also assuming that if a mathematical model of the collapse of a WTC tower has obvious inaccuracies and errors of detail, these flaws somehow PROVE that the collapse was a CD.

I admit my model calculation is very crude, but it shows that a gravity-driven collapse of WTC 1 & 2 was physically possible without the help of explosives! My model may not “see” everything that happened; you, on the other hand, see things that never happened ……

[pomeroo]

Originally Posted by Apollo20

Heiwa:

First of all let me tell you that I HAVE looked at ship collisions. I even have a copy of Minorsky’s classic (1959!) paper and I have played around with Minorsky’s KE equation by making various estimates of his resistance factor, Rt, as it might apply to the Twin Towers. If you take Rt to be ~ 18 m^3 you arrive at an energy loss for the impact of a 30,000 tonne “ship” of about 900 MJ which is of similar magnitude to my quantity E1. However, the important difference between ship collisions and the WTC collapse is that GRAVITY is not a factor in ship collisions while it is THE key factor in the collapse of WTC 1, 2 & 7.

But let’s look at your specific points of criticism of my (and other similar) collapse calculations. Here I have to begin by saying that the supports of the upper block did NOT “suddenly disappear” as you claim. How could they? Instead, as many collapse videos and photos show, the perimeter columns first bowed inwards over a vertical height of several floors. Eventually it appears that the A325 bolts at the column splices failed in shear – on the south face of WTC 1, and the east face of WTC 2. This type of failure, although it started along one wall and rapidly spread to other walls, caused the upper block to tilt several degrees from the vertical in the direction of the failed wall. Then, very quickly, the hinged wall also failed allowing the entire upper section to break free and essentially “free fall” onto the lower structure.

Now, because the initial drop involved some tilting motion, the upper section would obviously NOT be perfectly aligned with the lower section at the moment of impact. So, Heiwa, I have never made such an assumption, nor is perfect alignment of the upper and lower sections of the towers critical to my model!

Simple geometrical considerations show that a block that drops by column failure at one face, while remaining hinged at the opposite face, would strike the floor below when the tilt angle reaches about 3.3 degrees. Furthermore, the perimeter columns on the face that is falling would strike the row of columns immediately below the upper block along a line located about 10 cm INSIDE their vertical axis. Such collisions would be more of a series of glancing blows than the “head-on” impact of a drop hammer you imagine. The columns below the upper block would thus be pushed aside like skittles hit by a bowling ball rather than compressed like pistons or springs. Thus the structure below the upper block was destroyed by successive splice (weld or bolt) shear failures all the way down the tower.

Now I admit that none of this detail is explicitly treated in my one-dimensional collapse calculation; but after just a few lower floors were obliterated in the way I have described, the fine detail of each subsequent floor failure has hardly any effect on the overall collapse kinetics which is now dominated by momentum transfer in a gravity field.

So, Heiwa, you are making the same mistake that Ace Baker and others of his ilk have made before; you are assuming that a model must follow every nuance of the process under investigation to be valid. This is simply not true, and is probably not possible for a chaotic event such as the destruction of the Twin Towers. But worse yet, you are also assuming that if a mathematical model of the collapse of a WTC tower has obvious inaccuracies and errors of detail, these flaws somehow PROVE that the collapse was a CD.

I admit my model calculation is very crude, but it shows that a gravity-driven collapse of WTC 1 & 2 was physically possible without the help of explosives! My model may not “see” everything that happened; you, on the other hand, see things that never happened ……

A splendid post, Frank! You've illustrated with crystal clarity the difference between a genuine scientist such as yourself and an ineducable, agenda-driven fraud.

[pomeroo]

Originally Posted by MRC_Hans

Wow! 16 pages and still at square 1.

Hans

Heiwa has reached a near-Kirkmanic level of imperviousness to correction. He calls to mind Ace Baker at his worst.

[SpitfireIX]

Originally Posted by pomeroo

Heiwa has reached a near-Kirkmanic level of imperviousness to correction. He calls to mind Ace Baker at his worst.

Kirkmanic--I like it.

[DGM]

Any guesses as to how long it will be before Heiwa spits in Dr. Greenings face with his usual hand wave?

Dr. Greening:
I just want to say that I appreciated your post and I am also sure that many interested lurkers questions were addressed. Heiwa on the other hand is a conspiracy theorist first, engineer second that will not give your effort a second look (if he reads it at all).

[Apollo20]

Pomeroo and DGM:

Thank you!

I agree, Heiwa will probably press on regardless ....

Why should I care?

I write mainly to convince myself, the toughest, most sceptical critic I know.

Hidden agenda, my foot!

[ElMondoHummus]

Originally Posted by Apollo20

My model may not “see” everything that happened; you, on the other hand, see things that never happened ……

I am stealing this for my signature.

[rwguinn]

Dr Greening:
Excellent summary of what modeling actually is and does. Thank you

[tanabear]

From the answers I've received, I think it's safe to conclude that Mark Roberts wasn't telling the truth about holding the molten material flowing out of WTC2 in his hands.

[pomeroo]

Originally Posted by tanabear

From the answers I've received, I think it's safe to conclude that Mark Roberts wasn't telling the truth about holding the molten material flowing out of WTC2 in his hands.

I, on the other hand, think it's safe to assume that everything Mark Roberts says about the events of 9/11/01 is completely accurate. He, like the fantasy movement, has a track record.

[DC]

Sagging floors and bowing perimeter columns, that speaks pretty hard against 3.7m free fall.

[Heiwa]

Apollo20:

Thanks for reply in message #617

Apollo20:

First of all let me tell you that I HAVE looked at ship collisions. I even have a copy of Minorsky’s classic (1959!) paper and I have played around with Minorsky’s KE equation by making various estimates of his resistance factor, Rt, as it might apply to the Twin Towers. If you take Rt to be ~ 18 m^3 you arrive at an energy loss for the impact of a 30,000 tonne “ship” of about 900 MJ which is of similar magnitude to my quantity E1. However, the important difference between ship collisions and the WTC collapse is that GRAVITY is not a factor in ship collisions while it is THE key factor in the collapse of WTC 1, 2 & 7.

Very good! In a ship collision or grounding we have initial momentum + forces that produce structural damage. The forces involved are the propulsive force of the striking ship and of course the reaction forces incl. friction. In grounding gravity is an important factor. In the WTC 1 case gravity force, reaction forces when parts contact and fail and friction between various parts are the key factors.

Apollo20:

But let’s look at your specific points of criticism of my (and other similar) collapse calculations. Here I have to begin by saying that the supports of the upper block did NOT “suddenly disappear” as you claim. How could they? Instead, as many collapse videos and photos show, the perimeter columns first bowed inwards over a vertical height of several floors. Eventually it appears that the A325 bolts at the column splices failed in shear – on the south face of WTC 1, and the east face of WTC 2. This type of failure, although it started along one wall and rapidly spread to other walls, caused the upper block to tilt several degrees from the vertical in the direction of the failed wall. Then, very quickly, the hinged wall also failed allowing the entire upper section to break free and essentially “free fall” onto the lower structure.

The specific points of criticism regarding the initiation of global collapse are:

1. All supports of WTC 1 suddenly disappear below the upper block.
2. The upper block near free falls 3.7 meters.
3. The upper block impacts a lower structure with perfect alignment.
4. The upper block is still intact.

Prior to this it is suggested that some perimeter columns bowed inwards over a height of several storeys, i.e. serious local failures. What would have caused that in WTC 1 south wall? Heat, fire? Anyway, bowing inward and, I assume, followed by bending/buckling would produce a layer of failed structural parts that would dampen any following downwards displacements of parts above. As the failures apparently spread to the east and west walls, same failures would happen there assuming that 100's of bolts sheared off at the floors connections. In my view such a scenario is very unlikely and not seen on any videos; no floors are seen falling down at this point. But let's assume two or three floors fall down and that the east and west walls also bow and buckle bend inwards. The result would be 2000 m² of buckle bent south, east and west walls (columns) would form a layer of failed parts between the upper block and the lower structure. Those failed parts would definitely arrest any further failures. I will include that in the picture in my article! Thanks for the idea.

You on the other hand suggest that the entire upper section breaks free! How? From the failed columns below that has buckle bent?

I my opinion the upper block would still be connected to the failed columns all the time and there would never be any free fall or impact. All potential energy released at this time would be consumed to produce the layer of failed parts between the upper block and the lower structure. The upper block should therefore have remained on top of the lower structure.

Apollo20:

Now, because the initial drop involved some tilting motion, the upper section would obviously NOT be perfectly aligned with the lower section at the moment of impact. So, Heiwa, I have never made such an assumption, nor is perfect alignment of the upper and lower sections of the towers critical to my model!

The figures in your latest paper to be published in the ASCE journal show perfect alignment.

Apollo20:

Simple geometrical considerations show that a block that drops by column failure at one face, while remaining hinged at the opposite face, would strike the floor below when the tilt angle reaches about 3.3 degrees. Furthermore, the perimeter columns on the face that is falling would strike the row of columns immediately below the upper block along a line located about 10 cm INSIDE their vertical axis. Such collisions would be more of a series of glancing blows than the “head-on” impact of a drop hammer you imagine. The columns below the upper block would thus be pushed aside like skittles hit by a bowling ball rather than compressed like pistons or springs. Thus the structure below the upper block was destroyed by successive splice (weld or bolt) shear failures all the way down the tower.

You conveniently forget the enormous amounts of failed perimeter wall columns inside the initiation zone + a couple of failed floors that act as an effective damping device. The forces and momentum now applied from above must evidently pass through these failed parts and then down to the uppermost intact floor of the lower structure, through the 500+ bolts there to be applied to the columns below.

You cannot assume that the forces/momentum from above are directly applied to the columns of the structure below; they have to pass the damping device, the intact top floor of the lower structure and the bolts.

If this unlikely event would take place, I would assume the bolts would shear off and there would be no bowling ball hitting the intact columns below like skittles.

When the bolts of the uppermost floor shear off more failed parts are added to the damping device already formed above.

Apollo20:

Now I admit that none of this detail is explicitly treated in my one-dimensional collapse calculation; but after just a few lower floors were obliterated in the way I have described, the fine detail of each subsequent floor failure has hardly any effect on the overall collapse kinetics which is now dominated by momentum transfer in a gravity field.

So you assume that the upper block remains intact and that failed parts in the initiation zone do not produce any resistance or consume any energy! In my opinion the local collapse would have been arrested at this time, many times over. But now the following is supposed to happen:

5. The upper block (mostly air) assisted by gravity only destroys the columns of the lower structure below (the columns break every 10-12 meters like spaghetti).
6. The upper block lands intact on a heap of rubble after a successful push-down of the tower
7. The upper block finally selfdestructs in a push-up of the rubble.

Apollo20:

So, Heiwa, you are making the same mistake that Ace Baker and others of his ilk have made before; you are assuming that a model must follow every nuance of the process under investigation to be valid. This is simply not true, and is probably not possible for a chaotic event such as the destruction of the Twin Towers. But worse yet, you are also assuming that if a mathematical model of the collapse of a WTC tower has obvious inaccuracies and errors of detail, these flaws somehow PROVE that the collapse was a CD.

I admit my model calculation is very crude, but it shows that a gravity-driven collapse of WTC 1 & 2 was physically possible without the help of explosives! My model may not “see” everything that happened; you, on the other hand, see things that never happened ……

Mistake? I quote your latest article (to be published?) in the ASCE journal (June?, July?) and query some basic assumptions in it, e.g. points 1-7 above. Your mathematical model is another matter. It doesn't prove anything. I just propose that collapse arrest is the most likely outcome of local structural failures due heat/fire in a steel structure. No free fall, no impact.

Your model and mathematical calculations are very crude and do not show that a gravity only driven collapse is physically possible unless you make fancy assumptions that cannot be supported by real observations and physics and, of course, experience gained from analysing ship collisions/groundings where much bigger energies and forces are involved.

I suggest again that you do not publish the article or at least take away your name as co-author.

kind regards

Heiwa

[Heiwa]

Originally Posted by MRC_Hans

Wow! 16 pages and still at square 1.

Hans

Of course thanks to DC but now Apollo20 has taken off so it starts to get interesting. Maybe I should start another thread just with Apollo20:s highflying ideas?

[Minadin]

Maybe you should attempt to answer just one technical question in relation to any of the various ridiculous statements you've made in your attempt to support your "theory".

[Architect]

Reading comprehension does not appear to be one of Heiwa's strong points.

[Heiwa]

Originally Posted by Apollo20

Heiwa:

Instead, as many collapse videos and photos show, the perimeter columns first bowed inwards over a vertical height of several floors. Eventually it appears that the A325 bolts at the column splices failed in shear – on the south face of WTC 1, and the east face of WTC 2. This type of failure, although it started along one wall and rapidly spread to other walls, caused the upper block to tilt several degrees from the vertical in the direction of the failed wall. Then, very quickly, the hinged wall also failed allowing the entire upper section to break free and essentially “free fall” onto the lower structure.

Assume the WTC1 south wall fails due to all bolts shearing off at three floors and that the wall locally bucklebends inwards and breaks in one location(not seen on any videos of course). Very bad local failure.

I would then assume that the south wall above drops down a little, all the bolts of the floors above shear off, and that the complete south wall of the upper block drops to the ground. Serious local failure - but not global collapse.
The floors previously attached to the south wall above would be hanging on the core. No tilting.

Same goes for the east and west wall if the floor bolts shear off and their is local buckling. The walls would drop down and the floors would be hanging on the core. No tilting.

Now of course someone will suggest that the outer walls didn't fall down because they were hanging on the roof hat trusses and that all the loads of the walls (not supported by the columns below) and all the floors attached to them above the buckle area were transmitted via the hat trusses to the core that in turn was overloaded.

So the hat trusses could transfer the load of 60 metres of walls/floors. Any evidence for that?

But let's assume it. Now also the core bucklebends if it is overstressed. Where? apparently at the top just below the hat trusses, where the core columns were weakest.

So now the core buckles up at the top just below the roof. The walls are still hanging on the roof. What happens then? Tilting? Maybe.

Free fall and impact? No.

Well - we would see the roof moving down. And we see that. We should then focus what happens 60 metres down. Are the walls in the initiation zone bowing and bucklebending inwards? Maybe.

So we have two areas of local failures - one is the floors 94, 95 and 96 that have dropped down and the walls there are bowing inwards and another is up top the core is collapsing just below the hat trusses on which the outer walls of the upper block are hanging.

What happens then? Well it would appear that any further collapse would continue up in the core just below the hat trusses. By gravity. But the core gets stronger further down. It is possible that local failures are arrested where the core gets stronger. There is neither free fall or impacts in the scenario. Just transfer of loads to the core where the parts are deformed.

But let's assume the core fails completely in the upper block.

So in this scenario the upper block disintegrates in the core starting from top. That is why the upper block is getting shorter. It telescopes down into itself. No further local failures at the other failed area.

When the parts of the upper block now is mowing down due to local failures in the core starting up top, two walls of the upper block would surely be outside the lower structure and shear off and drop down to ground.

Many things may happen. But one thing is certain. The upper block is partly destroyed in this phase. Any theory assuming that the upper block remains solid, rigid, intact, indestructible in any later phase of failures is WRONG.

[Architect]

Originally Posted by Heiwa

Assume the WTC1 south wall fails due to all bolts shearing off at three floors and that the wall locally bucklebends inwards and breaks in one location(not seen on any videos of course). Very bad local failure.

I would then assume that the south wall above drops down a little, all the bolts of the floors above shear off, and that the complete south wall of the upper block drops to the ground. Serious local failure - but not global collapse.
The floors previously attached to the south wall above would be hanging on the core. No tilting.

Wrong wrong wrong.

The outer walls are the loadbearing element. The floors are not capable of a cantilever such as you describe, indeed DC has a seperate thread going at the moment regarding the connections from which it is abundantly clear that such a scenario is wholly impossible.

Quote:

Same goes for the east and west wall if the floor bolts shear off and their is local buckling. The walls would drop down and the floors would be hanging on the core. No tilting.

Previously we had a garden table analogy. Now you're moving on to a Christmas tree, as far as I can tell.

Quote:

Now of course someone will suggest that the outer walls didn't fall down because they were hanging on the roof hat trusses and that all the loads of the walls (not supported by the columns below) and all the floors attached to them above the buckle area were transmitted via the hat trusses to the core that in turn was overloaded.

The accepted hypothesis based on the evidence is that initially localised failures were transmitted to adjacent panels but that, as the failure progressed, these significantly exceeded their capacity and instead loads were transmitted via the hat trusses to the core. These were not designed to carry such loads and consequently failure occurred.

Quote:

So the hat trusses could transfer the load of 60 metres of walls/floors. Any evidence for that?

As I said, reading comprehension.

Quote:

But let's assume it. Now also the core bucklebends if it is overstressed. Where? apparently at the top just below the hat trusses, where the core columns were weakest.

So now the core buckles up at the top just below the roof. The walls are still hanging on the roof. What happens then? Tilting? Maybe.

Incomplete technical appraisal based upon a strawman argument. No change in your usual MO, Heiwa. The rest of your post is similarly error-ridden.

[Myriad]

Originally Posted by Heiwa

See my previous message to Frank. I do not ignore that gravity (or any force involved) may add energy. Topic is what energy is available at the collision and where it is applied to cause failures and what happens then.

You say that you do not ignore the gravitational potential energy, then you proceed to ignore it.

Limiting your analysis only to the energy that is "available at the collision" by which you apparently mean only the kinetic energy generated after a drop of one floor, is like declaring how far a car can go based on ignoring the energy of the fuel in the gas tank.

The energy readily available, released by the simple process of mass dropping (whether or not it drops in "free fall" and whether or not it's structurally intact at the time), is hundreds to thousands of times the energy of the ship collisions you're familiar with.

Respectfully,
Myriad

[Heiwa]

Originally Posted by Minadin

Maybe you should attempt to answer just one technical question in relation to any of the various ridiculous statements you've made in your attempt to support your "theory".

Which one?

[applecorped]

All of them.

[Heiwa]

Originally Posted by Myriad

You say that you do not ignore the gravitational potential energy, then you proceed to ignore it.

Limiting your analysis only to the energy that is "available at the collision" by which you apparently mean only the kinetic energy generated after a drop of one floor, is like declaring how far a car can go based on ignoring the energy of the fuel in the gas tank.

The energy readily available, released by the simple process of mass dropping (whether or not it drops in "free fall" and whether or not it's structurally intact at the time), is hundreds to thousands of times the energy of the ship collisions you're familiar with.

Respectfully,
Myriad

Sorry, I do not ignore gravity and its effects. I just focus on what gravitational energy is available at every step of the incident.

When the structure is intact the energy is stored in the parts (including the Earth) and only produces forces that produce stresses in the structure. You agree?

When local failures of parts occur and no displacement of attached parts occur no energy is released. Only forces are redirected to other parts, where stresses may be increased. You agree?

When any failed part is displaced downwards due to gravity it releases energy. In local failures, parts still attached to other parts, that energy is normally consumed causing local deformation of the failed part! You agree?

Of course, if a big loose weight on a failed part starts to drop free fall there is energy involved/released ... but then we have to analyse that;

What weight is it?
Why does it free fall?
Where does it start from and where does it end?
Etc.

A loose weight dropping outside the structure will evidently not damage the structure.

I have not been able to identify any loose weights in the WTC1 except for furniture, decorations and humans. Everything else, i.e. the structural parts, were connected to one another. Nothing free falls! Only local parts fail and all energy released is consumed to deform the parts. No free fall, no impact. Not even floor bolts sheared off at the walls, so that the walls could hinge down on the loose end. But even if some floor bolts shear off and the floor hinges down the energy involved is known and will be absorbed by the floor below. No ship collision where the momentums and forces are 100 times bigger than at WTC 1.

Sorry - you are 100% wrong in your analysis. Try again. I always look forward to your comments.

Kind regards

Heiwa

[Heiwa]

Originally Posted by applecorped

All of them.

Minadin just asked for one. Let's start with that one. Take a difficult one. I want to impress my audience that I can answer it.

[DGM]

Originally Posted by Heiwa

Minadin just asked for one. Let's start with that one. Take a difficult one. I want to impress my audience that I can answer it.

How about the resistance of the floor structure to the gravitational acceleration of the top mass. You told me before you don't deal with this because you like to keep it simple. Impress us with your calculations!

[Heiwa]

Originally Posted by Architect

The accepted hypothesis based on the evidence is that initially localised failures were transmitted to adjacent panels but that, as the failure progressed, these significantly exceeded their capacity and instead loads were transmitted via the hat trusses to the core. These were not designed to carry such loads and consequently failure occurred.

I have difficulty to follow:

What localised failures are you talking about? The outer walls bucklebending inwards at around floor 96? Reason? The floor bolts sheared off at the walls and that the floors dropped down a little - still attached at the core, I assume. Ok, I can follow that.

But what adjacent panels are you talking about? The wall columns bucklebend locally and that means that the wall above will displace downwards. As the wall above is connected to the core via floors, the wall will try to pull the floors with it. The weakest link is the floor bolt but it will not shear off at this step because the wall is now hanging on the hat truss.

Is that what you mean? I cannot see any panels here - and failures transmitted to them.

So the wall is hanging on the hat truss and the hat truss transmits the load to the core. Very well.

If the hat truss doesn't fail and the wall drops down (and a piece of the hat truss), the forces involved will be transmitted to the core. No energy has been released so far. Only forces have been shifted around. You agree? This is what happens due local failures. Forces are shifted around.

So now extra forces are carried by the core and the stresses there increase.
You agree?

How much? So that the core columns start to buckle. Why not? Where? Of course where they are weakest = just below the hat truss.

So let's assume the core columns up top deform and the structure attached displace downwards and any potential energy released is consumed by the deformations in the core.

No free fall. No impact!

Actually it is very frequent when local failures occur for any reason (a columns is heated and buckles!) and forces are shifted about (the force in the column must move somewhere else!) that local failures occur at other locations (where the force is now applied).

Free falls and impacts are very rare. Never occur, actually (apart from loose furniture that slides to the side and out of a window).

Pls clarify what you actually mean. Adjacent panel?