Moderated Steel structures cannot globally collapse due to gravity alone

[Heiwa]

Heiwa,
Neither NIST nor Bazant assume that the top section, C, is undamaged or cannot be deformed. This is not what the mechanical term "rigid body" means. If that were the assumption, then Part C would be sitting on top of a rubble pile at the end of the collapse.
tom

You haven't read the BLGB 2008 paper + pictures? Part C, 53 m tall (excl. mast), undamaged, is sitting on top of a 92 m tall rubble part B just hitting ground 22 m below ground in the basement at 70 m/s. Please, to participate in this thread read the back ground papers, incl. mine.
And then? CRUSH UP! POUFF. Part C disappears. Bazant, Lee, Greening & Benson are really crazy!

 

[nicepants]

Thanks for that reply Tom.

So from what you are saying that means that the top portion that fell and caused all that destruction on the lower 96 floors was only 8 floors then, since the 8 floors in-between were the damaged floors that got "crushed" in the beginning.

So how does that jive with the NIST theory? Does the NIST "FINAL" report say it was only 8 floors that crushed the bottom 96 floors? Or does NIST claim it was 16 floors (which according to your theory Tom would be erroneous) that crushed the bottom 96 floors?

Is there enough "energy" in just those 8 floors to do the trick?

The question you should be asking is not "could the energy in 8 floors crush 96?" because the lower floors were not all impacted at once. The question you should be asking is "could the energy in 8 floors crush 1"?

If the answer is yes, now you have 9 floors falling...could those crush 1 floor?

If yes, could the 10 falling floors crush 1 more floor?

 

[Heiwa]

The question you should be asking is not "could the energy in 8 floors crush 96?" because the lower floors were not all impacted at once. The question you should be asking is "could the energy in 8 floors crush 1"?

If the answer is yes, now you have 9 floors falling...could those crush 1 floor?

If yes, could the 10 falling floors crush 1 more floor?

If 8 moving floors really can crush 1 static floor due to gravity alone, then, according BLGB, an 0.9 m thick layer or rubble is formed of this static floor. You would expect this rubble to dampen the movement of 8 floors.
It can also be argued that when 8 moving floors crush 1 static floor, also 1 floor of 8 moving floors gets damaged and becomes rubble. So there are only 7 moving floors left!
When two objects collide it is quite normal that both objects get damaged at the contact area by the energy applied. If the objects are similar the energy is split 50/50 between the objects.
Regardless - plenty of rubble is formed at a collision and it will evidently be affected by gravity and start to drop with the upper floors. The upper floors will actually push the rubble ahead of them ... as a snow plough!
So another question - can this rubble crush further floors below? In my opinion it cannot ... and the destruction should be arrested pretty soon = topic we discuss. At a collision a lot of energy is used to produce rubble. The rubble formed then actually absorbs all the remaining energy as friction/heat.

 

[Gravy]

Hmmm well, are you talking about this video http://www.911research.com/wtc/evidence/videos/docs/north_tower_collapse.mpeg ?

Hi, Steve. Welcome to the forum.

...I look at that video and it is quite clear that the top portion turns nearly completely to dust before the bottom section begins to falls.

I don't want to put words in your mouth, but I'm guessing that you haven't thought through the implications of this truly extraordinary statement. I'm guessing that you don't believe that the whole top section – concrete, glass, furnishings, fixtures, plumbing, wiring, elevator machinery, air conditioning units, computers, paper, carpeting, humans, and especially structural steel – actually turned to dust. (There are a few people who take this idea a step further and claim that the towers were vaporized by high energy "Star Wars" beams.)

One thing I do think is clear about the collapse of the north tower is that the top section doesn't stay essentially intact as it "crushes down" the bottom, as in Bazant's simplified model.

However,

there is much that truthers miss in their analysis of these north tower collapse videos and images. While focusing on what they believe to be anomalies, they conveniently ignore the forest and the trees. I'm not claiming that you hold any of the views below, but just in case, a few points:

1) There are, of course, no detonations preceding the collapse. That doesn't preclude the involvement of some hidden and extraordinarily robust system of incendiaries invisibly planted by fiendish invisible technological geniuses and working in concert with the building fires for a reason that no one can explain while leaving no trace of their effects that ordinary fires wouldn't leave, but it does preclude the use of explosives. Proponents of the explosive demolition hypothesis cannot rationally confront the absence of detonations and their unmistakable secondary effects. Richard Gage's brain broke when I challenged him to do that during our Hardfire debate.

2) The clearest views of the north tower collapse are from the north. I'm not aware of any video or photo sequences that document the collapse sequence in detail from the south. The reason for the lack of such visual evidence should be obvious. The views from the north may be a bit deceptive, for these reasons:
A) The collapse started on the south side.
B) The top of the tower, including the antenna, leaned to the south as the collapse began. We don't know what damage to the south wall is being done.
C) The photo below shows the north tower after the top has fallen about one story. The lowest line of fire is at the 92nd floor. However, it is believed that the collapse began where the severe inward bowing of the south wall was, from about the 95th to the 98th floors, particularly around 97-98. Therefore, destructive events may be happening above, opposite, and slightly before the downward movement we first see on the north side.

3) It is clear that large structural sections are not shed (pushed away/rebounded/peeled away, or even blasted away by gigantic yet undetectable detonations as some truthers would have it) from the north tower as the top descends several floors, at least from the sides that are visible, as they are shed shortly after. To learn more about the effect of mass "shedding" on the collapse progression, please see page 13 of this paper by Bazant, Le, et. al. You may be surprised by what the calculations reveal.

4) It is necessary that the first things to be pushed from the tower as the top falls will be the lightest and most friable materials: smoke, dust and pulverized debris from the aircraft impacts, fires, and internal collapses; gypsum wallboard, fireproofing insulation, ceiling tiles, etc.

5) In light of (3 and 4), and accepting that we cannot invoke magic to make several thousand tons of descending steel, concrete, furnishings, etc. disappear, a question:

What happens to the first intact floor – let's say it's 93 or 92 – when that several thousand tons of descending mass hits it? If you have trouble answering this, please review NIST's FAQ of December, 2007, in particular the answers to questions 1, 2, and 10.

6) Whenever truthers make a structural claim about one – and only one – tower, it's always a good idea to ask, "Why are they not mentioning the other tower?" After all, the towers were of nearly identical construction and sustained broadly similar damage and fires on 9/11.

In fact, when we look at the collapse sequence of the south tower, we clearly see that the collapse front propagates well into the lower section while significant intact structure remains in the descending mass above:

​

I drew the red lines as reference marks. The top line is extended to approximately where the south tower collapse began, at the 81st floor (actually, I see that it's off by about half a floor between the left and right: no biggie). In both images the bottom mark is aligned with the 75th floor mechanical level of the north tower (not the south: keep in mind that the south tower is closer to the camera than the north. The lines aren't meant to denote the same floor numbers for both towers).

In the left image, the collapse has just begun at about the top red line. In the right image, the collapse front has proceeded from the top line to well below the bottom line. A significant portion of the top has fallen many stories, is accelerating, and clearly has not "turned to dust." If you want a laugh, ask Heiwa to explain how the remaining bottom portion of the building is going to arrest the collapse of the top from this point forward.

The photo below, taken from the southeast later in the collapse, may show that although most of the upper section is shrouded in smoke and dust, at least part of it (circled) is still intact. With its increasing momentum, the collapse front has become extraordinarily violent.

​

It is amazing that 16 people inside the north tower survived its collapse. FDNY Captain Jay Jonas:

The entire collapse of this 110-story building took 13 seconds. So it sounded like boom, boom, boom, boom, boom, boom, boom, you know, like that. And every time that happened, it shook the entire building. It shook the whole floor. So every time a floor would hit another floor, we’d be literally bouncing off the floor. We were being thrown around the stairway.

There was also this very loud sound of twisting steel all around our heads. These massive steel beams and girders were just being twisted around our heads just like they were twist ties on a loaf of bread. And a very loud, like a steel screeching sound, almost like a lot of trains coming into a subway station at the same time and all of them hitting their brakes at the same time.

There was tremendous air movement with the building coming down. The air movement was so strong that one of my fireman was standing on the fourth floor. You’ve got to figure with his gear and everything on, he’s well over 200 pounds. He’s about 180 pounds and with his gear, you gotta figure he’s about 250 pounds. This wind kind of picked him up and threw him down two fights of stairs.

We were getting hit with all kinds of debris. Thank God it was nothing that was going to really hurt us, but after it was all over, it was almost like we kind of got mugged. We were all bruised up and small cuts and things like that. Source

Truthers should take a lesson from those stairwell survivors, who do not invoke explosives, thermite, nukes, space beams, or other absurdities to explain what happened to them.

 

[tfk]

Heiwa,

You haven't read the BLGB 2008 paper + pictures? Part C, 53 m tall (excl. mast), undamaged, is sitting on top of a 92 m tall rubble part B just hitting ground 22 m below ground in the basement at 70 m/s. Please, to participate in this thread read the back ground papers, incl. mine.
And then? CRUSH UP! POUFF. Part C disappears. Bazant, Lee, Greening & Benson are really crazy!

I'd suggest that YOU take the - for you, unheard of - step of actually reading these papers. You might learn something.

Not the least of which is how to publish something somewhere OTHER than JREF & ae911.

In "What Did and Did not Cause Collapse of WTC Twin Towers in New York", Bazant, Jia-Liang Le, Frank R. Greening and David B. Benson, J. Engineering Mechanics ASCE , Vol. 134 (2008)

the authors say: "During the crush-down, the falling upper part of tower (C in Fig. 2 bottom), having a compacted layer of debris at its bottom (zone B), is crushing the lower part (zone A) with negligible damage to itself."

Do you know what the term "negligible damage" means? It doesn't mean "no damage".

It goes on to say:

"The fact that the crush-up of entire stories cannot occur simultaneously with the crush-down is demonstrated by the condition of dynamic equilibrium of compacted layer B, along with an estimate of the inertia force of this layer due to vertical deceleration or acceleration; see Eq. 10 and Fig. 2(f ) of Bazant and Verdure (2007). This previous demonstration, however, was only approximate since it did not take into account the variation of crushing forces Fc and F ′ c during the collapse of a story. An accurate analysis of simultaneous (deterministic) crush-up and crush-down is reported in Bazant and Le (2008) and is reviewed in the Appendix, where the differential equations and the initial conditions for a two-way crush are formulated. It is found that, immediately after the first critical story collapses, crush fronts will propagate both downwards and upwards. However, the crush-up front will advance into the overlying story only by about 1% of its original height h and then stop. Consequently, the effect of the initial two-way crush is imperceptible and the hypothesis that the crush-down and crush-up cannot occur simultaneously is almost exact."

In other words, UNLIKE YOU, these guys do not resort to monotonous, unsubstantiated assertions. They actually take the extra step of analyzing the process and presenting their results. You know, like REAL engineers do.

I'd seriously recommend that you take your own advice and read the papers. If you can't understand them, you can ask, and I'll try to explain it to you. As time permits, of course...

tom

 

[Heiwa]

Heiwa,



I'd suggest that YOU take the - for you, unheard of - step of actually reading these papers. You might learn something.

Not the least of which is how to publish something somewhere OTHER than JREF & ae911.

In "What Did and Did not Cause Collapse of WTC Twin Towers in New York", Bazant, Jia-Liang Le, Frank R. Greening and David B. Benson, J. Engineering Mechanics ASCE , Vol. 134 (2008)

the authors say: "During the crush-down, the falling upper part of tower (C in Fig. 2 bottom), having a compacted layer of debris at its bottom (zone B), is crushing the lower part (zone A) with negligible damage to itself."

Do you know what the term "negligible damage" means? It doesn't mean "no damage".

It goes on to say:

"The fact that the crush-up of entire stories cannot occur simultaneously with the crush-down is demonstrated by the condition of dynamic equilibrium of compacted layer B, along with an estimate of the inertia force of this layer due to vertical deceleration or acceleration; see Eq. 10 and Fig. 2(f ) of Bazant and Verdure (2007). This previous demonstration, however, was only approximate since it did not take into account the variation of crushing forces Fc and F ′ c during the collapse of a story. An accurate analysis of simultaneous (deterministic) crush-up and crush-down is reported in Bazant and Le (2008) and is reviewed in the Appendix, where the differential equations and the initial conditions for a two-way crush are formulated. It is found that, immediately after the first critical story collapses, crush fronts will propagate both downwards and upwards. However, the crush-up front will advance into the overlying story only by about 1% of its original height h and then stop. Consequently, the effect of the initial two-way crush is imperceptible and the hypothesis that the crush-down and crush-up cannot occur simultaneously is almost exact."

In other words, UNLIKE YOU, these guys do not resort to monotonous, unsubstantiated assertions. They actually take the extra step of analyzing the process and presenting their results. You know, like REAL engineers do.

I'd seriously recommend that you take your own advice and read the papers. If you can't understand them, you can ask, and I'll try to explain it to you. As time permits, of course...

tom

"Negligible damage" is unscientific. Actually, by just watching any video (many links in my paper) you see how upper part C first shortens itself 50% and then blows up in smoke and dust prior to contacting part A. According BLGB that is "negligible damage". I would suggest it is an unsubstantiated assertion of the worst kind.

I have pointed this out to the authors and Benson's reply was that he cannot see any videos at all, as his PC is too slow.

 

[tfk]

Steve,

Thanks for that reply Tom.

You're welcome.

So from what you are saying that means that the top portion that fell and caused all that destruction on the lower 96 floors was only 8 floors then, since the 8 floors in-between were the damaged floors that got "crushed" in the beginning.

Not quite. It was 16 stories. When the floors get crushed, they don't lose their mass, except for the portion that gets ejected, of course.

So how does that jive with the NIST theory? Does the NIST "FINAL" report say it was only 8 floors that crushed the bottom 96 floors? Or does NIST claim it was 16 floors (which according to your theory Tom would be erroneous) that crushed the bottom 96 floors?

It jives just fine. It is exactly what those experienced engineers expected to happen from their ENORMOUS amounts of hard experience.

Steve, I'll jump to a conclusions here, from your attack quotes around "final report", that your are skeptical of those engineers' conclusions. That's fine. But you should know about whom & about what you're being skeptical.

First, the guys & gals. Go look up their credentials. You'll find no one on the NIST panel that has a degree in religious studies or politics. They are absolutely first rate engineers. Do you realize the extent of the honor it means to be a fellow of the American College of Engineering? Think "Hall of Fame".

Second, you've got to appreciate that engineering is NOT a soft, subjective field like psychiatry, medicine, philosophy. You can NOT falsify results & get away with it. Because everything is laid out in public, the methods are well understood, and if you fake your results, you're gonna get caught. Do you remember Fleischman & Pons & "cold fusion"?

Finally, these guys KNOW, with absolute certainty, that this is the absolute pinnacle work of their professional lives. This work will be scrutinized in the engineering community (if not the public) for decades. Just as they have been ever since they came out. No highly respected professional is going to give anything less than their best effort under these circumstances. And they certainly will not compromise their integrity. Those suggestions are seriously brain-dead stupid. (I'm not suggesting that you've made them.)

Is there enough "energy" in just those 8 floors to do the trick?

There is absolutely enough energy to do this trick. Specifically because it was NOT 8 or 16 floors against 94 floors.

It is 16 floors destroying 1/3rd of the supports for one floor, then 17 floors destroying 1/3rd of the supports for one floor, then 18 floors destroying 1/3rd of the supports for one floor, etc.

The progressive collapse did it one floor at a time.

Why "1/3rd of a floor"? Because the core & peripheral columns are 3 story high units. And they are staggered. You can see the stagger in these images:
http://911research.wtc7.net/talks/towers/docs/site1099.jpg
http://911research.wtc7.net/wtc/arch/perimeter.html

Think about the crush down reaching, for example, the 90th floor. 1/3rd of the supports (both core & peripheral) on the 90th floor reach up to the 91st. Another 1/3rd reach up to the 92nd floor. Those 2/3rd of the supports for the 90th floor were destroyed (i.e., the support columns were pried out of alignment & their supports shredded) when the crush was passing thru the 92nd & 91st stories. By the time the crush gets to the 90th floor, 2/3rds are already gone.

The last point that you must understand is what kept the towers standings. It was the GEOMETRY (i.e., the vertical alignment) of the supports and the loads. As soon as the cross supports are gone, the geometry is gone. As soon as the geometry is gone, the strength of the STRUCTURE is gone. Those stub ends of the columns are NOT 1/3rd as strong as they were before the top supports were gone. They are (on the order of) 1/10th to 1/100th as strong.

Second, as soon as the DIRECTIONS of force on the columns moves from strictly compressive to bending stresses, then these long, slender columns get incredibly weak (at least, in comparison to their strength with purely axial loads).

Was there enough energy? It wasn't even close. You bet there was enough energy.

tom

 

[tfk]

heiwa,

If 8 moving floors really can crush 1 static floor due to gravity alone, then, according BLGB, an 0.9 m thick layer or rubble is formed of this static floor. You would expect this rubble to dampen the movement of 8 floors.
It can also be argued that when 8 moving floors crush 1 static floor, also 1 floor of 8 moving floors gets damaged and becomes rubble. So there are only 7 moving floors left!

Ah, I see. You think that a pile of material that is organized has weight somehow becomes weightless once disorganized. How, uh, interesting.

When two objects collide it is quite normal that both objects get damaged at the contact area by the energy applied. If the objects are similar the energy is split 50/50 between the objects.

I know that this is a pretty subtle concept for a mechanical engineer to grasp, but if two objects collide horizontally, then the forces between them are equal & opposite.

However, if one objects falls onto another, then the upper one crushes the bottom one. The bottom one doesn't crush the upper one.

Edited by Gaspode: 

Edited for civility

It's a little thing called gravity. It makes the situation asymmetric.

Regardless - plenty of rubble is formed at a collision and it will evidently be affected by gravity and start to drop with the upper floors. The upper floors will actually push the rubble ahead of them ... as a snow plough!

"... evidently ..."

No, it is not in the slightest "like snow". You see, snow needs to be pushed. Snow "wants" to stop if the plow stops pushing it.

When you have a couple tens of thousands of tons of a building structure that has it supports kicked out from under it, it "wants" to rush to the ground.

When you have a couple tens of thousands of tons of rubble (that used to be a building structure) that has been crushed and its supports have also been kicked out from under it, it ALSO wants to rush to the ground.

That would be different than snow on the ground.

So another question - can this rubble crush further floors below? In my opinion it cannot ...

Sure thing. twenty thousands of tons of steel, concrete, wood, paper, etc. wants to simply hang in the air...

and the destruction should be arrested pretty soon = topic we discuss.

"... should be arrested ..." And I don't suppose the 150th suggestion that your support this rather silly notion in some formal, you know, "engineer-y" way will make any more of an impression on you than the previous 149.

For a demonstration of how this is done, you might review Bazant, et al, "What Did and Did not Cause Collapse of WTC Twin Towers in New York", Journal of Engineering Mechanics ASCE , Vol. 134 (2008)

At a collision a lot of energy is used to produce rubble.The rubble formed then actually absorbs all the remaining energy as friction/heat.

"... a lot of energy ..." You know, engineers frequently use numbers.
"... then absorbs all the remaining energy ..."?? Don't be silly.

tk

 

[Heiwa]

heiwa,

... if one objects falls onto another, then the upper one crushes the bottom one. The bottom one doesn't crush the upper one.

Edited by Gaspode: 

Edited for civility

It's a little thing called gravity. It makes the situation asymmetric.

I thought that when you drop a glass on a floor or similar, the glass is crushed by the floor and not vice versa. What you suggest seems paranormal! Pls, enter the JREF contest.

I know that gravity ensures the drop of the glass, but what has gravity to do with the contact glass/floor? If gravity decided, glass would just continue through the floor! Pls clarify.

 

[tfk]

Heiwa,

"Negligible damage" is unscientific. Actually, by just watching any video (many links in my paper) you see how upper part C first shortens itself 50% and then blows up in smoke and dust prior to contacting part A. According BLGB that is "negligible damage". I would suggest it is an unsubstantiated assertion of the worst kind.

Sorry, Anders, wrong again. The meaning of the term "negligible" is perfectly clear to engineers & scientists.

"... many links in my paper ..." You are embarrassingly enamored with that one flawed paper. If you were to expand your source of reference material, perhaps your understanding would improve. Regardless of your personal comprehension, if you were to quote other qualified experts, you'd come across as less self-promoting and, frankly, hucksterish.

I've pointed out to you a half dozen times that the ONLY reason that you assert that "upper part C first shortens itself 50%" is that you have arbitrarily and erroneously included all of the damaged floors in part C.

If you happened to have divided up the tower in a different, arbitrary, erroneous fashion and included those same floors in lower Part A, then all of the initial collapse would have happened in Part A.

If you had done it right, then none of the initial collapse would have happened in Part C. It all would have happened in Part D, the damaged floors.

What is your explanation for the undeniable fact that, as Gravy points out above, none of your claims holds true in the other tower. The upper segment is NOT destroyed, blown apart, etc. and successfully and obviously crushes down the entire lower segment, one floor at a time.

And now, of course, you will continue to ignore the obvious...

I have pointed this out to the authors and Benson's reply was that he cannot see any videos at all, as his PC is too slow.

Sure, Heiwa. I am CERTAIN that this is the ONLY issue that a competent engineer would argue with you.

We have seen the same thing repeatedly here. Nobody attempts to cross factual swords with you. Everyone is overly concerned with trivia, style, and presentation. Folks are pointlessly argumentative. No one will discuss the substantive issues. And each time you bring up the hard facts, all those others (like me) ignore your comments and simply reassert our unsupported claims.

Oh, wait a second. Perhaps I've got that backwards...

tom

 

[tfk]

Heiwa,

I thought that when you drop a glass on a floor or similar, the glass is crushed by the floor and not vice versa. What you suggest seems paranormal! Pls, enter the JREF contest.

Perhaps English isn't your first language. The principle meanings of "crush" are squash, squeeze, press, compress, flatten. They all connotate something being squeezed, usually by something from above.

No, the glass is NOT "crushed" by the floor.

Once again, you seem to have a problem with difference between static forces and dynamic inertial forces due to sudden acceleration.

More germane to the issue, the situation is not symmetric. As proven by the following:

I can sit the glass on top of a block that is sitting on the floor. The block can be small, big or huge. And the glass does not get crushed.

If I sit a small block on top of the glass, it survives. If I put the heavy block on top of the glass, the glass gets crushed.

And what causes the asymmetry? Gravity.

Perhaps, if you ponder this situation carefully, you'll begin to understand how rubble can help crush the towers.

I know that gravity ensures the drop of the glass, but what has gravity to do with the contact glass/floor? If gravity decided, glass would just continue through the floor! Pls clarify.

Go look up electromagnetism. Perhaps you'll come to understand.

tom

 

[Heiwa]

Heiwa,



Sorry, Anders, wrong again. The meaning of the term "negligible" is perfectly clear to engineers & scientists.

I know what negligible means (of little or of no importance). But 'negligible damages' to only one object when two similar objects collide is simply wrong and nefarious. Both objects are affected to the same extent. Denying that is negligence and makes the BLGB paper worthless. It is not negotiable!

 

[tfk]

Heiwa,

I know what negligible means (of little or of no importance). But 'negligible damages' to only one object when two similar objects collide is simply wrong and nefarious. Both objects are affected to the same extent. Denying that is negligence and makes the BLGB paper worthless. It is not negotiable!

You know what "negligible" means. Good for you. So do scientists & engineers. Thank you for acknowledging that the term is not "unscientific".

baby steps... baby steps...

And you're right about something else. When two similar objects collide, then damage will get done to both objects. Thank you for acknowledging that lower Part A does NOT just sit there, intact, while upper Part C slices itself in half. Or simply sits impaled on the top of Part A.

So we agree that the damage goes BOTH upwards and downwards from the floor that originally collapses.

more baby steps...

And as I've said before, the initial collapse did NOT happen in intact, undamaged Part C. Nor did it happen in intact, undamaged Part A. And since Part B did not exist yet, it certainly didn't happen there. So it had to happen in its own Part D - the damaged, weakened 6 floors.

Can we agree on that??

baby steps...

We can get there. Maybe.

tom

 

[Shalamar]

What was the load capacity of one of the floors?

How much did one of the floors weigh?

 

[Heiwa]

Heiwa,



You know what "negligible" means. Good for you. So do scientists & engineers. Thank you for acknowledging that the term is not "unscientific".

baby steps... baby steps...

And you're right about something else. When two similar objects collide, then damage will get done to both objects. Thank you for acknowledging that lower Part A does NOT just sit there, intact, while upper Part C slices itself in half. Or simply sits impaled on the top of Part A.

So we agree that the damage goes BOTH upwards and downwards from the floor that originally collapses.

more baby steps...

And as I've said before, the initial collapse did NOT happen in intact, undamaged Part C. Nor did it happen in intact, undamaged Part A. And since Part B did not exist yet, it certainly didn't happen there. So it had to happen in its own Part D - the damaged, weakened 6 floors.

Can we agree on that??

baby steps...

We can get there. Maybe.

tom

Yes, that's my point - parts C and A get damaged at the contact interface (and that's it - only local failures of parts C and A take place, no further collapses of any kind)!
NIST, Bazant & Co disagree. Part A is crushed by part C and part C is only subject to 'negligible damages'. Crushed parts of part A become part B (rubble). Part B is then compressed and accelerated by part C. Part B then crushes part A assisted by part C, &c. All NWO physics nonsense, of course. It has never happened before 9/11, when it was invented and US media reported it as some sort of new phenomenon where common sense doesn't apply. Luckily it is easy to show with basic physics that this phenomenon doesn't exist.

 

[Gravy]

Yes, that's my point - parts C and A get damaged at the contact interface (and that's it - only local failures of parts C and A take place, no further collapses of any kind)!

Your point is nonsensical. Repeating it will never make it true. You continue to ignore the reality of progressive collapse. Once again, here is a video of structural steel failing due to fire, leading to a progressive collapse that propagates to the ground:



Some reminders:
1) This building was intact when the fire started.
2) The collapse was caused by fire alone. No explosives or thermite or even jet fuel was involved. Heat + gravity did this.

So, Heiwa, why wasn't the damage limited to "local failures" that led to "no further collapses"?

 

[Heiwa]

Your point is nonsensical. Repeating it will never make it true. You continue to ignore the reality of progressive collapse. Once again, here is a video of structural steel failing due to fire, leading to a progressive collapse that propagates to the ground:



Some reminders:
1) This building was intact when the fire started.
2) The collapse was caused by fire alone. No explosives or thermite or even jet fuel was involved. Heat + gravity did this.

So, Heiwa, why wasn't the damage limited to "local failures" that led to "no further collapses"?

This video proves (if you can see through the smoke) my point. Upper part C is pretty big though, compared with lower part A.
There are thus local failures due to fire at abt. half height of building and some part of upper part C displaces downwards, elements of both C and A get in contact and fail, so that damaged part C continues down, while getting further damaged. Evidently the complete building is not crushed down at 0.7 g by part C remaining intact, &c.

 

[RedIbis]

. Once again, here is a video of structural steel failing due to fire, leading to a progressive collapse that propagates to the ground

Look really closely. It does not collapse all the way to the ground.

http://bp0.blogger.com/_fSEfCn8PW5s/SCylFNc26_I/AAAAAAAAAuc/hpLLbYMfdz8/s1600-h/Delft04.jpg

 

[tfk]

Heiwa,

Yes, that's my point - parts C and A get damaged at the contact interface

Nah, this is completely wrong.

Why do you consistently, deceptively group the damaged & weakened 6 floors in with the undamaged upper Part C? This is simply wrong.

The initial collapse happens within part D, the weakened floors. Not in Part A OR in Part C.
The crush damage in Part D DOES happen both upwards & downwards.

(and that's it - only local failures of parts C and A take place, no further collapses of any kind)!

Nah, you're completely wrong here, too.

Part D is about 6 floors thick. By the time that it has almost crushed, Part A & Part C are still ALMOST untouched. And by the time upper Part C has descended say 3 stories, gathering up 3 stories of rubble, the bottom portion of Part C is completely packed in with debris of Part D.

By the time upper Part C with Part D debris packed in reaches the top of Part A, it is essentially solid on the bottom surface. As a direct result of this, ONLY lower Part A will be destroyed.

JUST LIKE we saw on 9/11.

NIST, Bazant & Co disagree. Part A is crushed by part C and part C is only subject to 'negligible damages'.

Nah, this is all wrong. I've explained it above.

Crushed parts of part A become part B (rubble).

Nope. See above.

Part B is then compressed and accelerated by part C. Part B then crushes part A assisted by part C, &c.

Well, almost. Part B is accelerated by BOTH gravity & Part C.

All NWO physics nonsense, of course.

Nah, the NWO are like you. They don't know physics either. By the way, this has very little to do with physics. (This is why Steven Jones is stumbling around so helplessly.) It is engineering.

It has never happened before 9/11,

That's true. No fully laden passenger jets had been intentionally flown into 110 story skyscrapers prior to 9/11.

when it was invented and US media reported it as some sort of new phenomenon where common sense doesn't apply. Luckily it is easy to show with basic physics that this phenomenon doesn't exist.

Common sense will actually go a long way to understanding what is going on. You should try it some time.

Rather than resorting to unsupported assertions, and flawed papers over at Heiwaco, why don't you address my simple assertions in this post?

tom

 

[Newtons Bit]

Part D is about 6 floors thick. By the time that it has almost crushed, Part A & Part C are still ALMOST untouched. And by the time upper Part C has descended say 3 stories, gathering up 3 stories of rubble, the bottom portion of Part C is completely packed in with debris of Part D.

By the time upper Part C with Part D debris packed in reaches the top of Part A, it is essentially solid on the bottom surface. As a direct result of this, ONLY lower Part A will be destroyed.

JUST LIKE we saw on 9/11.

This is more or less Bazant's reasoning for why the upper block was intact for so long. Once the rubble has formed and is collapsing floor after floor of the lower block, the only force on the upper block is decelerating from moving slightly faster than the rubble. This rubble is likely tearing the upper block apart as it's acting on components other than columns. The point though, is that the upper block is only moving into the rubble at about 0.2m/s^s or so. The lower block crushes down much faster than the upper block crushes up.

In Heiwa's world, the floors will eventually stop collapsing due to FRICTION, thus stopping the rubble from continuing.

Edited by chillzero: 

Edited for moderated thread