Offer to the Truth Movement: Let's Settle It

[psikeyhackr]

We have a different take on this since I don't think the top 30 stories could crush the lower 80 anyway. The top of the intact lower portion and the bottom of the falling portion would engage in mutual destruction of crushing each other and the energy required to do that destruction would come from the kinetic energy of the falling mass. It would slow down. If it stayed centered it would eventually stop but the chances of that were infinitesimal so it should have fallen off the side.

So for me the reason for knowing the concrete and steel is try to compute how far down it could come. But this vague information from the NIST it totally unacceptable. We are supposed to wade through whatever BS they dish out. They studied stuff that was irrelevant. Like that report on suspended ceilings which was the only place they used the term "center of mass". They can't tell us the number of each type of perimeter wall panel. The report did not even specify the total quantity of concrete. I think it was set up to dish out BS from the start.

psik

 

[X]

We have a different take on this since I don't think the top 30 stories could crush the lower 80 anyway. The top of the intact lower portion and the bottom of the falling portion would engage in mutual destruction of crushing each other and the energy required to do that destruction would come from the kinetic energy of the falling mass. It would slow down. If it stayed centered it would eventually stop but the chances of that were infinitesimal so it should have fallen off the side.

<snip>

The way I see it, the problem with your idea is gravity.
As the upper section destroys the floors below it (and is destroyed in turn), the mass of the floors from below is added to the overall mass coming down.

Each indivdual floor of the lower section would not pose much resistance to the large mass coming from above, and thus would not slow it by an appreciable amount (appreciable meaning enough that it couldn't regain the speed by the next floor).

So what you have is a lot of mass coming down on a floor, destroying said floor (slowing slightly), and continuing on the next one with the mass of the destroyed floor added to the inital mass and enough space to regain its speed and then some.

So you have a large falling mass that is both gaining mass (from destroyed floors) and speed (courtesy of gravity) as it falls.

Once the collapse began, the structure of the tower below simply didn't have enough strength to resist the mass enough to slow it down.

As for falling off the side, that would have required a lot of unbalanced lateral force that was not present (where would it come from?).

At least, that's my understanding of it. I'm sure more experienced people will be along shortly to correct my mistakes.

I snipped the remainder of your post, because it's basically accusing NIST of peddling nonsense, which is not a debate for this thread, IMHO, nor is it something I feel qualified to answer.

 

[RedIbis]

We know a few things about the collapse. One is that the interior almost certainly failed first, and we know this because the collapse of roof structures preceded motion of the exterior wall. Another is that the collapse initiated low in the structure, which is why a large portion of the perimeter all moved downward as a unit, rather than the progressive mechanism seen in the Towers.


I apologize for the degree of speculation in this post. I look forward to the NIST Report in helping refine the possible space of explanations.

Mackey,
Your patience and thoroughness is commendable. I suspect NIST will agree with you that 7 collapsed due to "single-point failure." In your opinion, was this failure caused by heat from intense fire or from debris, or possibly a combination?

And as it originated low in the structre how did debris impact this point or cause the fire at this location?

Thanks, great thread.

 

[R.Mackey]

Mackey,
Your patience and thoroughness is commendable. I suspect NIST will agree with you that 7 collapsed due to "single-point failure." In your opinion, was this failure caused by heat from intense fire or from debris, or possibly a combination?

And as it originated low in the structre how did debris impact this point or cause the fire at this location?

Again, I'm forced to speculate, and anything I come up with may be replaced by a far superior explanation in the future. However, based on the phenomenology as well as the long delay between the impacts and the collapse, I'm inclined to think the failure was caused almost exclusively by heat.

While the debris impacts were severe, perhaps weakening the structure's stability, nevertheless the failure mode was relatively global, and that suggests there was global connectivity in the structure to the very last.

Additionally, the fires burned for over seven hours. The fireproofing was set to withstand at most two or three in any given location, i.e. steel would have been heated to a "critical temperature" where it would buckle under normal loads in two or three hours. Yet it did not, but took longer. This can be explained in one of three ways:

• Fireproofing greatly exceeded its specification -- I see no evidence of this
• Fires in most locations burned out and cooled before the steel reached its critical temperature, leaving the structure to fail later, after a new area with especially poor fireproofing or a high fuel load ignited
• Fires over a series of floors did not locally defeat the fireproofing completely, but inflicted a small amount of deformation; after spreading over several floors, these locally minor problems contributed to a global catastrophe

Either of the latter two explanations seems reasonable given the vulnerabilities of the design. If impact damage was a significant structural contributor, it would bias us towards the second case over the third. However, I suspect the failure, being low in the structure, was on a floor that was burning pretty much the entire time, and that leads me towards the third explanation. The third case is also bolstered by the relatively early appearance of visible deformations, as reported by the FDNY, several hours before the collapse actually occurred. In this case, the effect of significant impact damage would be to reduce the effective "critical temperature," but had that been so, I would have expected collapse much sooner.

The impacts, of course, were still no doubt significant in terms of starting the fires in the first place, opening ventilation paths in the exterior, and possibly knocking down interior partitions that could have acted as firebreaks. But it's my guess that the structural damage caused by the impacts had little contribution to the failure mode we saw in the collapse.

Thanks, great thread.

I've enjoyed it myself, and it's exceeded my expectations.

 

[R.Mackey]

We have a different take on this since I don't think the top 30 stories could crush the lower 80 anyway. The top of the intact lower portion and the bottom of the falling portion would engage in mutual destruction of crushing each other and the energy required to do that destruction would come from the kinetic energy of the falling mass. It would slow down. If it stayed centered it would eventually stop but the chances of that were infinitesimal so it should have fallen off the side.

There is absolutely no question that the top 30 floors could crush the bottom 80. Not even Gordon Ross has claimed this is impossible.

You are correct that there is some slowing with each impact, but not nearly enough. Again, instead of energy, you should think in terms of momentum. Momentum is conserved whether energy is expended in material destruction or not.

As Dr. Bazant, Dr. Greening, Dr. Seffen, and Gregory Urich have all shown independently, the collapse mechanics are driven primarily by momentum. The lower floors simply do not have enough strength to counteract all of this momentum before they fail. And if the collapse is to be arrested, it must happen at the first contact, or not at all. The second contact will be faster than the first (at worst, the same speed), more massive than the first (unless losses on contact are severe, and this is not expected or observed early in collapse), and the lower floors will already have been weakened both by transmission of the first shock and loss of bracing above.

It is because of this dependence on momentum that other incident energy costs, such as the total amount absorbed in destruction of materials, has very little effect on the overall timing of collapse. This has been shown several times in simple models. There is no countervailing opinion.

 

[Hokulele]

It is because of this dependence on momentum that other incident energy costs, such as the total amount absorbed in destruction of materials, has very little effect on the overall timing of collapse. This has been shown several times in simple models. There is no countervailing opinion.

Other than Heiwa's.

 

[LastChild]

So has this been settled yet?

What's taking so long? shhheeez

 

[e^n]

A series of excellent points

Ryan (I hope I can call you Ryan).

I am doing a cursory inspection of various threads to see if there is anything I have the knowledge to respond to and I just wanted to post and say how constantly impressed I am with the quality of your posting. You say everything I would like to and more besides.

 

[psikeyhackr]

There is absolutely no question that the top 30 floors could crush the bottom 80. Not even Gordon Ross has claimed this is impossible.

I don't give a damn who claimed what. I haven't seen what I regard as reliable data on the distribution of concrete and steel yet. It is totally ridiculous that the NIST can't even tell us the number of each type of 12 different perimeter wall panels. But they can tell us the original design called for 14. What matters is what was there when the plane struck not the original design.

The nation that put man on the moon can't tell the entire world the tons of steel and concrete on every level of buildings designed before the moon landing. HILARIOUS

psik

 

[Confuseling]

There is absolutely no question that the top 30 floors could crush the bottom 80. Not even Gordon Ross has claimed this is impossible.

You are correct that there is some slowing with each impact, but not nearly enough. Again, instead of energy, you should think in terms of momentum. Momentum is conserved whether energy is expended in material destruction or not.

As Dr. Bazant, Dr. Greening, Dr. Seffen, and Gregory Urich have all shown independently, the collapse mechanics are driven primarily by momentum. The lower floors simply do not have enough strength to counteract all of this momentum before they fail. And if the collapse is to be arrested, it must happen at the first contact, or not at all. The second contact will be faster than the first (at worst, the same speed), more massive than the first (unless losses on contact are severe, and this is not expected or observed early in collapse), and the lower floors will already have been weakened both by transmission of the first shock and loss of bracing above.

It is because of this dependence on momentum that other incident energy costs, such as the total amount absorbed in destruction of materials, has very little effect on the overall timing of collapse. This has been shown several times in simple models. There is no countervailing opinion.

On this note have you or Gregory Urich perhaps done any calculations to show how overengineered the structures would have had to have been in order to arrest collapse using the proposed failure mechanism? It might make an interesting paper, more for the purposes of debunking I suspect than for anybody else, but still interesting.

I've heard (I think in this very thread ) that NIST estimate that the energy released in the collapse was orders of magnitude larger than what was strictly required. What does that translate to in structure?

 

[DC]

think the failure was caused almost exclusively by heat.

im suprised you did not include the more stress the remaining columns had because of the prolly destroyed columns from impacting debris.

only heat seems to me very unlikely, column 81 and the columns next to it was afaik not damaged from impacting debris. so the fireprotecting was prolly not damaged. sure 7 hours are prolly alot more than the fireprotection was designed for. while i would expect that a building that contains a command center / bunker will have a bit better fireprotection.

for me its not so strange the building fell, its more the way it fell.

 

[DC]

And if the collapse is to be arrested, it must happen at the first contact, or not at all

i disagree, the lower part of the building was alot lot stringer than the upper part, also there was the alot stronger mechanical floors and lobbys that would have delivered more resistance than other floors.

i also would not say it is not possible to have a global collapse, but i would say it is possible a bazantsche collapse could be arrested.

also i am supriced by the symetry of the collapses. they are so "systematic"
but the construction was very special.

 

[uk_dave]

for me its not so strange the building fell, its more the way it fell.

Because every other 47 storey steel framed structure built partially over a pre-existing structure, suffering severe structural damage and prolonged un-fought fires, has fallen differently?

 

[DC]

Because every other 47 storey steel framed structure built partially over a pre-existing structure, suffering severe structural damage and prolonged un-fought fires, has fallen differently?

the Bolded things and the column pattern is the main points why i would expect it to collapse to the damaged side and not almost straight down (yes i know its the direction of gravity)

and that the collapse was initiated by the columns that was prolly not damaged makes it strange for me and alot others.

 

[uk_dave]

and that the collapse was initiated by the columns that was prolly not damaged makes it strange for me and alot others.

And the documentary evidence showing the building collapse is available........where?

I would imagine you have quite a library of clear, close up video footage, taken from many angles, along with extensive stills photographs showing the collapse for you to be so very certain that the building collapsed in a particular way which makes it 'strange'....yes?

C'mon DC, you have a preconceived notion that 9-11 was an 'inside job' and you're desperately trying to find anomalies to back up that notion. But your anomalies are based upon scant information from a couple of videos available for download in compressed form from various websites. It's not really good data to base a belief on, now is it?

 

[Confuseling]

...
only heat seems to me very unlikely, column 81 and the columns next to it was afaik not damaged from impacting debris. so the fireprotecting was prolly not damaged. sure 7 hours are prolly alot more than the fireprotection was designed for. while i would expect that a building that contains a command center / bunker will have a bit better fireprotection.

for me its not so strange the building fell, its more the way it fell.

Two points. The debris impact was immensely forceful. Wouldn't you expect fireproofing to be dislodged throughout the building? Secondly, 7 hours would be vastly longer than designed for. It seems that the bunker / command part was not in the original design specification, but was retrofitted later. Besides which, I just don't think it's often realistically practicable to design buildings, whether bunkers or not, to survive unfought fires.

 

[Confuseling]

DDP

(darn double post!)

 

[DC]

i think i have seen all public availbe videos of 7. but i also readed FEMA and the "drafts" from NIST. to get informed about the construction of the building. also the damage can not really been seen in those videos, nor the inferno.

 

[uk_dave]

also the damage can not really been seen in those videos, nor the inferno.

So how can you conclude that the collapse was 'strange' when you haven't seen the extent of the damage or the extent of the fires?

I trust that you will agree that wtc7 on 9-11 was not in the same condition as wtc7 on 9-10, yes?

 

[DC]

So how can you conclude that the collapse was 'strange' when you haven't seen the extent of the damage or the extent of the fires?

I trust that you will agree that wtc7 on 9-11 was not in the same condition as wtc7 on 9-10, yes?

how can you conclude that it was not strange?

afaik non of the WTC buildings was on fire nor heavy damaged on 9/10.