Hardfire: Physics of 9/11

[ozeco41]

Why would they get entangled? There are no columns under the flors to keep them up, and there is a limit to how much weight the brackets can hold at the ends of the trusses....

Exactly leftysergeant.

This is the bit that failed:

And (Courtesy Heiwa for the base diagram) this is how the first few floors of the outer office space started the global collapse.

(So leftysergeant's words and my picture.)

NOTE the accumulating floors. No "one for one" BUT the Top Block would progressively yield to other forces and mostly collapse.

And, disclaimer, this only explains the outer office space. See earlier post for the core.

 

[Heiwa]

Exactly leftysergeant.

This is the bit that failed:
[qimg]http://conleys.com.au/webstuff/003.jpg[/qimg]

And (Courtesy Heiwa for the base diagram) this is how the first few floors of the outer office space started the global collapse.

(So leftysergeant's words and my picture.)
[qimg]http://conleys.com.au/webstuff/globalstart.jpg[/qimg]

NOTE the accumulating floors. No "one for one" BUT the Top Block would progressively yield to other forces and mostly collapse.

And, disclaimer, this only explains the outer office space. See earlier post for the core.

Thanks for reply and visiting http://heiwaco.tripod.com/mac5.htm .

Pls visit the The Heiwa Challenge thread about how to proceed.

 

[Newtons Bit]

.
What is exact? How would we know what was within 2%?

The only weight I have heard of any perimeter wall panels is 22 tons and that did not come from the NIST. The NIST said there were 12 types though the original building design called for 14. They tell that us the manufacturer asked for two to be upgraded and was granted permission. The NIST tells us that one plane had 5 tons of cargo and the other had 9.

Now if they can tell us such details what is so difficult about the numbers and weights of ALL 12 OF THE PERIMETER WALL PANELS? And what is your problem with wanting the information? They only had THREE YEARS and $20,000,000. Wouldn't that information fit anywhere in the 10,000 pages they gave us that don't specify the total amount of concrete? They could do it for the steel.

psik

You didn't answer my question: why is it necessary. Why MUST you know the weight of something that even if your ballpark is off by 100% it only affects the entire mass of the structure by 0.01%?

 

[ozeco41]

Thanks for reply and visiting http://heiwaco.tripod.com/mac5.htm .

Pls visit the The Heiwa Challenge thread about how to proceed.

I have read your challenge and the thread.

There is nothing to debate AFAICS. You are right in the scenario you propose. Your specification of the challenge shows that you are capable of clear thought. You do misrepresent posters who like me do not claim

It is assumed at JREF 9/11 Conspiracy Theories Forum that a structure will be crushed, if you drop a piece (1/10th) of the same structure on it and that it is quite normal - no conspiracy.

...with the inference that your model represents WTC on 9/11.

Your challenge scenario does not parallel or relate to the collapses which happened at WTC on 9/11

Given your clarity of thinking I do not comprehend why you seem to persist in innuendo that it somehow represents WTC on 9/11 and why you seem to evade any consideration of what really happened.

So - yes you are right with the sort of things that will happen in the scenario you set for the challenge and wrong in inferring that it somehow relates to WTC 9/11. It doesn't. And I have now posted several explanations as to how WTC 9/11 collapses really did happen.

So there is no need for me to take the "Challenge"

 

[psikeyhackr]

You didn't answer my question: why is it necessary. Why MUST you know the weight of something that even if your ballpark is off by 100% it only affects the entire mass of the structure by 0.01%?

.
You CLAIM my ballpark is off by 100% all you want.

I demonstrated in my second video that mass slows a top down gravity driven collapse.

http://www.youtube.com/watch?v=LXAerZUw4Wc

I demonstrated in my first video that mass and ist distribution affects the response of a flexible tower therefore it would have affected how much energy did structural damage to the towers.

http://www.youtube.com/watch?v=z0kUICwO93Q

I showed how the distribution of mass affected the potential energy of the building and how Frank Greening's paper HAD TO BE wrong.

http://www.internationalskeptics.com/forums/showpost.php?p=3667265&postcount=316

I find it totally absurd that people claiming to understand the subject weren't demanding it long ago. I say the problem cannot be solved without it and the buildings never should have collapsed. If that is not a satisfactory answer so be it.

psik

 

[Furcifer]

.
You CLAIM my ballpark is off by 100% all you want.

I demonstrated in my second video that mass slows a top down gravity driven collapse.

http://www.youtube.com/watch?v=LXAerZUw4Wc

I demonstrated in my first video that mass and ist distribution affects the response of a flexible tower therefore it would have affected how much energy did structural damage to the towers.

http://www.youtube.com/watch?v=z0kUICwO93Q

I showed how the distribution of mass affected the potential energy of the building and how Frank Greening's paper HAD TO BE wrong.

http://www.internationalskeptics.com/forums/showpost.php?p=3667265&postcount=316

I find it totally absurd that people claiming to understand the subject weren't demanding it long ago. I say the problem cannot be solved without it and the buildings never should have collapsed. If that is not a satisfactory answer so be it.

psik

Could somebody translate what this guy is saying into english? I have no idea how the mass distibution would have any effect on the collapse given that it was increasing linearly. He seems to think it is very important so I wish to understand it like he does.

 

[Newtons Bit]

.
You CLAIM my ballpark is off by 100% all you want.

I demonstrated in my second video that mass slows a top down gravity driven collapse.

http://www.youtube.com/watch?v=LXAerZUw4Wc

I demonstrated in my first video that mass and ist distribution affects the response of a flexible tower therefore it would have affected how much energy did structural damage to the towers.

http://www.youtube.com/watch?v=z0kUICwO93Q

I showed how the distribution of mass affected the potential energy of the building and how Frank Greening's paper HAD TO BE wrong.

http://www.internationalskeptics.com/forums/showpost.php?p=3667265&postcount=316

I find it totally absurd that people claiming to understand the subject weren't demanding it long ago. I say the problem cannot be solved without it and the buildings never should have collapsed. If that is not a satisfactory answer so be it.

psik

Could you explain why being off by a few kips from the perimeter panels would matter. I've asked this many times and you still haven't given an explanation.

 

[ozeco41]

Could somebody translate what this guy is saying into english? ......

..sorry, no, I have tried in another life and another place.

...I have no idea how the mass distibution would have any effect on the collapse given that it was increasing linearly.

..it has no effect ... it is irrelevant in the collapses which actually occurred on 9/11

.. He seems to think it is very important so I wish to understand it like he does.

...I don't think you could or would want to "understand it like he does"

 

[Furcifer]

..sorry, no, I have tried in another life and another place

You must be one of those experts that just doesn't get it

 

[ozeco41]

You must be one of those experts that just doesn't get it

I must be special - I rarely miss out on a ROFLMAO

 

[bardamu]

So, given that mini lecture in Structures 101, you should see why I cannot answer your question at this stage.

How the connections join beam to column changes the simple example for bending. And both bending and shear strength would depend on how the joins were made.

For my example earlier - ie the bending beam pulling a bend into the columns the column would be relatively weak in bending would be pulled sideways by a force much smaller than the column could take as its axial load.

To apply that pull on the columns the joint of beam to column would almost certainly be similar to the axial strength of the beam. Explanation if needed.

I pause there - you should have enough to see what details I would need before I can better answer your original inquiry.

Thanks for such a thorough reply. I asked the question because your model/theory seems to depend on the assumption that the joins between the horizontal beams and the vertical core columns would have held up. I was wondering if the beams were part of the primary structure of the building, or if their main purpose was to hold the floor trusses up. That would give some indication of how securely they had to be connected to the core columns.

Your explanation is a big improvement on the vague 'layer of rubble' theory, in that it describes which parts of the structure came into contact with each other. That means it should be possible to work out the forces involved, even though the calculations would be complex.

Assuming for now that the joins would not fail, have you roughly estimated the energy that would be needed to bend all the horizontal beams and pull in the core columns?

 

[ozeco41]

Thanks for such a thorough reply. I asked the question because your model/theory seems to depend on the assumption that the joins between the horizontal beams and the vertical core columns would have held up.⁽¹⁾ I was wondering if the beams were part of the primary structure of the building,⁽²⁾ or if their main purpose was to hold the floor trusses up.⁽³⁾ That would give some indication of how securely they had to be connected to the core columns.⁽⁴⁾ ...

.... Thank you. Obviously I cannot give such a lengthy reply to every enquiry and the effort cam soon be lost as the thread rapidly moves on.
So indexed comments follow:
⁽¹⁾ Understood - because of how the Towers were designed and how they fell we don't need to be sure of much of the detail. The key word is "overwhelming" - many parts were hit by descending forces that were "overwhelming" to THAT PART. So I will need to focus some parts of your understanding where you appear to be "globalising" - i.e. taking a broader implication than is needed or than is appropriate.

^{(point "X")}So for this point whether I hold that assumption or not is not critical. That is not evasion it is because either option would not change the outcome. Take the beam on beam "collision". If the connections held up the beam would bend - the primary point I made AND the columns attached would be bent inwards - the secondary point I made. Both those would be moves towards collapse. HOWEVER if the end connections of the beam failed the beam would immediately cease to be a part of the structure and would join the falling mass of debris - still heading towards collapse.
⁽²⁾ The "beams" fall into two clear categories.
1) The "beams" of the outer office space area were the floor joists ONLY although in about four slightly different versions. I always refer to them as "Floor Joists" or such.
2)The beams I am focussed on at present were those in the core. So they were "part of the primary structure of the building CORE". See what I mean about narrowing to a focus some of your more "globalising" statements.
⁽³⁾ So the beams I refer to were in the core. Some of then served as the inside end attachment points for the floor trusses/joists of the outer office space. HOWEVER in thinking about the collapse I draw the line that the outer floor joists fell mostly due to being hit by the descending overwhelming mass which sheared off the end connections. See this:

From there the collapse of the beam itself I see as part of the core structure collapse. No simple picture sorry.
⁽⁴⁾ Understood BUT "how securely they had to be connected to the core columns" doesn't matter in the overall picture see previous comments flagged as ^{(point "X")}

...Your explanation is a big improvement on the vague 'layer of rubble' theory,⁽⁵⁾ in that it describes which parts of the structure came into contact with each other. ⁽⁶⁾ That means it should be possible to work out the forces involved,⁽⁷⁾ even though the calculations would be complex....⁽⁸⁾

⁽⁵⁾Thanks again
⁽⁶⁾ Just knowing that gets past the big problem with many "explanations" which presume that the two blocks impacted as if they were single solid entities. They didn't collide like that. The overall collision was made up of lots of little "one element on one element" sort of mini collisions which sequenced and overlapped in a very complicated total mess.
⁽⁷⁾...working out the forces is a trap - it is too complicated to work out all the bits and add them up in the time and space of the overall event. Stay with me and see if my reasoning becomes clearer.
⁽⁸⁾.. yes - "Complicated" is an understatement. see previous comment and lets continue.

...Assuming for now that the joins would not fail, have you roughly estimated the energy that would be needed to bend all the horizontal beams and pull in the core columns?⁽⁹⁾

⁽⁹⁾ ... no .. because I cannot, I doubt anyone could add up all the bits. But I can legitimately move to an acceptance that each one and the sum of them would be "overwhelming".

I suspect that may be not satisfying for you YET - can you see where I am heading?
Does it help?

 

[psikeyhackr]

Could you explain why being off by a few kips from the perimeter panels would matter. I've asked this many times and you still haven't given an explanation.

.
So provide a link to where I said something about kips on the perimeter panels.

psik

 

[Newtons Bit]

.
So provide a link to where I said something about kips on the perimeter panels.

psik

kips is a unit of measurement for WEIGHT. Again. Why do you have to know the exact weight of the exterior panel? Why can't you be off by a few kips.

I've asked this question FIVE TIMES now.

 

[nicepants]

How much of section A could be crushed by section C?

Interestingly if you dropped the 13 floors of part C the 3.7 metres onto the 97 floors of part A then part A would also be crushed flat almost at freefall speed.

Only on 9/11.lol

I'm interested in your answer:

How much of section A could be crushed by section C?

2 floors? 8 floors? 30 floors? 0 floors?

 

[GlennB]

kips is a unit of measurement for WEIGHT. Again. Why do you have to know the exact weight of the exterior panel? Why can't you be off by a few kips.

I've asked this question FIVE TIMES now.

Because by demanding unrealistic (and maybe even unavailable) levels of precision he gains an excuse to cling on to his delusions?

Sorry to butt in ...

 

[Newtons Bit]

Because by demanding unrealistic (and maybe even unavailable) levels of precision he gains an excuse to cling on to his delusions?

Sorry to butt in ...

That much is obvious. I'm just trying to figure out what his rationalization is. Why is an approximate not good enough?

 

[tfk]

Oz,

Howdy & welcome. Excuse me for missing it, if you mentioned it before, but what is your background. You sound like an engineer to me. I'm mechanical.

Exactly leftysergeant.

This is the bit that failed:
http://conleys.com.au/webstuff/003.jpg

And (Courtesy Heiwa for the base diagram) this is how the first few floors of the outer office space started the global collapse.

(So leftysergeant's words and my picture.)
http://conleys.com.au/webstuff/globalstart.jpg

NOTE the accumulating floors. No "one for one" BUT the Top Block would progressively yield to other forces and mostly collapse.

And, disclaimer, this only explains the outer office space. See earlier post for the core.

A couple of points, but ones that are significant.

In your rework of Heiwa's sketches, I believe that it is important to NOT include the damaged 6 floors or so in either section A or C. A & C are basically intact & not weakened by damage, distortion or fire. Those weakened floors (93 - 98 in WTC1) are likely the ones that collapsed first. By the time that any collapse got to an intact section of the towers (A or C), it had already gathered 6 stories worth of momentum.

Second in your last sketch, you show the debris collecting predominantly in the part A, the lower section. This is wrong. Think about any floor that is hit by debris and begins to fall. It is starting from a standing start, as a fast descending hammer comes down from above. For the first 2-5 stories (my SWAG), the faster descending upper block is going to sweep the debris into its open structure and pack in there. After a couple of stories, the bottom surface of the upper block C will be so impacted with debris, that it'll approximate a solid surface.

Thrid point. Think about the effect that the stagger of the peripheral & core columns had on the destruction of any give floor. By the time that the descending upper block arrives at some given floor (say the 80th), fully 2/3rds of the columns supporting the 80th floor have already been destroyed. This is because 1/3 of all those columns reached up to the 82nd floor and another 1/3 reached up to the 81st floor. These have been ripped away BEFORE the descending block even arrives at the 80th floor. There ain't that much more work to do to snap the 1/3rd connections that are left supporting that floor.

And I feel strongly that Bazant goes off course in calculating work required to buckle columns. This is an important calculation in the collapse initiation, but not after that point.

AFTER the collapse had initiated, the failure mode was snapped connections, gross breakup of the concrete floors and deformation of the cross trusses. This it the calculation that should have been used in calculating the work of disassembly.

Your correction to Heiwa's sketch, that the unsupported columns become immediately unstable & snap off, is right on the money. I would tend to think, tho, that the impacting of debris at the bottom of the upper block will give those bottom columns of the upper block some lateral support. The top "stubs" of broken off columns in the lower section have approximately zero ability to resist side loads, however.

This is one (of many) of Heiwa's fundamental errors. He distributes the strain energy of the of the lower (larger) section uniformly over its entire structure. And he ignores the stress concentrations and side loads that are applied to the non-braced column in the top floor that is being crushed.

Just a couple of points.

tom

 

[Furcifer]

Because by demanding unrealistic (and maybe even unavailable) levels of precision he gains an excuse to cling on to his delusions?

Sorry to butt in ...

It's tough to move the goal posts if you don't know exactly where they need to go.

 

[beachnut]

.... ...
I suspect that may be not satisfying for you YET - can you see where I am heading?
Does it help?

You are using facts and evidence and these are lost to the delusion believers who use fantasy, lies and hearsay. They will not recognize logic and evidence.

To explain the unique design of the WTC is lost on those not looking for truth but saying they are. They are interested in the anti-intellectual poppycock to feed their delusions, not reality based explanations involving research, math and physics. They are political trolls who have religious based faith in some elusive 911Truth delusion.