9/11 Discussion Thread

#21
The thing about 9/11 that got me was how the towers fell. The manner in which they collapsed was unlike anything I've ever seen. There is simply nothing to compare it to. How does a 100 story high rise shatter like that so evenly from the top down? Not even controlled demolition can do that.
Yeah, even if the entire structural support gave way where the planes hit, how in the world would that produce the implosion of the buildings? Wouldn't one expect that portion of the building above the impact site to topple over? It makes absolutely no sense. Nonetheless, it's fascinating.

From what I've heard from the experts, apparently a controlled demolition can indeed do that. That's what it looks like to me from the videos I've seen of controlled demolitions.
 
#22
Here is an explanation for why they fell straight down (from Thomas W. Eagar and Christopher Musso, MIT, in the Journal of Minerals, Metals and Materials):

http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html#authors

"Nearly every large building has a redundant design that allows for loss of one primary structural member, such as a column. However, when multiple members fail, the shifting loads eventually overstress the adjacent members and the collapse occurs like a row of dominoes falling down.

The perimeter tube design of the WTC was highly redundant. It survived the loss of several exterior columns due to aircraft impact, but the ensuing fire led to other steel failures. Many structural engineers believe that the weak points—the limiting factors on design allowables—were the angle clips that held the floor joists between the columns on the perimeter wall and the core structure (see Figure 5). With a 700 Pa floor design allowable, each floor should have been able to support approximately 1,300 t beyond its own weight. The total weight of each tower was about 500,000 t.

As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell. The floor below (with its 1,300 t design capacity) could not support the roughly 45,000 t of ten floors (or more) above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h.1 It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself. Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down."
It's not like I haven't looked into the arguments on both sides. The above makes no sense to me.

The way one gets away from near free fall speed is to skew the exact starting point of collapse. Apparently, that's what he's doing here. The way to measure whether or not free fall is occurring is to measure points within the collapse itself, I'd suspect. Additional, the support of WTC was internal, through the elevator shafts-- I'd think this would even more so work against any sort of implosion like we see. Lateral is exactly what one should expect. Think about it. All the strength resides at the center of the structure. Nonetheless, what the hell happened to the steel? Why would it twist and bend... and melt?!
 
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#23
Here is an explanation for why they fell straight down (from Thomas W. Eagar and Christopher Musso, MIT, in the Journal of Minerals, Metals and Materials):

http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html#authors

"Nearly every large building has a redundant design that allows for loss of one primary structural member, such as a column. However, when multiple members fail, the shifting loads eventually overstress the adjacent members and the collapse occurs like a row of dominoes falling down.

The perimeter tube design of the WTC was highly redundant. It survived the loss of several exterior columns due to aircraft impact, but the ensuing fire led to other steel failures. Many structural engineers believe that the weak points—the limiting factors on design allowables—were the angle clips that held the floor joists between the columns on the perimeter wall and the core structure (see Figure 5). With a 700 Pa floor design allowable, each floor should have been able to support approximately 1,300 t beyond its own weight. The total weight of each tower was about 500,000 t.

As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell. The floor below (with its 1,300 t design capacity) could not support the roughly 45,000 t of ten floors (or more) above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h.1

It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself. Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down."
I'm familiar with this explanation and you really have to be a builder to understand how jaw droppingly stupid it is. That's why about 2,000 structural engineers and architects have disagreed with this explanation. It requires a great deal of pretending and suspension of disbelief to swallow it if you understand buildings. Here's the thing: the only structural steel that could possibly fail under normal conditions was the place where it was hit by the planes. That was the only spot. We know the fire wasn't especially hot because the smoke was black and there was no super intense fire coming out the windows. That's to be expected because you need a whole lot of oxygen to get jet fuel to its maximum temperature, in which case it will burn a lot cleaner.

In order for the upper stories to inflict maximum 500k tons of pressure on the floors below, as is being suggested, they have to be completely intact. Here's a way to visualize it. If we drop a ten pound weight and a ten pound spring next to each other, the weight will do the most damage because its stiffness ensures that all of the weight will be transferred to the point of impact immediately. A spring of the same weight will do far less damage because the force isn't completely applied at the moment of impact. Rather, it might spread that force out over an entire second to create, let's say, 1/10 of the total force of the weight at the initial moment of impact.

In the case of the towers, the upper stories disintegrated, meaning that the total initial impact force was more like dropping a spring rather than a weight, meaning that there was far far less force on the lower stories than they're making it out to be.

Also, in order for the orderly collapse that actually happened to take place, all that force has to come down nearly perfectly evenly so that every section of the building collapses together. If you don't hit that structural steel with enough initial force, If it's even slightly off, it's never going to fail and one part of the building will stay up and the debris will start sliding off of the more damaged side. There are plenty of examples of this in controlled demolitions.

Here's another problem. Even assuming that there was enough force, which itself is absurd, there was certainly never that kind of force applied to the very top ten stories, which would have been practically weightless until they hit bottom. They should have been destroyed by the ground and nothing else, yet they had come completely apart in a matter of a few seconds. Why? Assuming that the towers were destroyed as described, this amounts to pure magic.
 
#24
I'm familiar with this explanation and you really have to be a builder to understand how jaw droppingly stupid it is.
There's the rub. Those involved in these sort of shenanigans know that much of the public doesn't have the background to know when something is amiss nor the inclination to spend time studying the issue.
 
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#25
Here is an explanation for why they fell straight down (from Thomas W. Eagar and Christopher Musso, MIT, in the Journal of Minerals, Metals and Materials):

http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html#authors

"Nearly every large building has a redundant design that allows for loss of one primary structural member, such as a column. However, when multiple members fail, the shifting loads eventually overstress the adjacent members and the collapse occurs like a row of dominoes falling down.

The perimeter tube design of the WTC was highly redundant. It survived the loss of several exterior columns due to aircraft impact, but the ensuing fire led to other steel failures. Many structural engineers believe that the weak points—the limiting factors on design allowables—were the angle clips that held the floor joists between the columns on the perimeter wall and the core structure (see Figure 5). With a 700 Pa floor design allowable, each floor should have been able to support approximately 1,300 t beyond its own weight. The total weight of each tower was about 500,000 t.

As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell. The floor below (with its 1,300 t design capacity) could not support the roughly 45,000 t of ten floors (or more) above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h.1 It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself. Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down."
I forgot to add the above theory was rejected by NIST. (I suspect the government wanted to go with the most plausible incorrect explanation :))
 
#26
I forgot to add the above theory was rejected by NIST. (I suspect the government wanted to go with the most plausible incorrect explanation :))
I included the paper only because of the final sentence, which I bolded: "a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down." NIST rejected that idea?
 

Bart V

straw materialist
Member
#27
I'm familiar with this explanation and you really have to be a builder to understand how jaw droppingly stupid it is. That's why about 2,000 structural engineers and architects have disagreed with this explanation.
What i find stupid is that so many people claim expertise in something that has ever happened only once.
Nobody is an expert in what happens to buildings that are deliberately hit by planes.
 
#28
What i find stupid is that so many people claim expertise in something that has ever happened only once.
Nobody is an expert in what happens to buildings that are deliberately hit by planes.
Thanks for bringing up this argument Bart. I think it's important to get this stuff on the table for it to be addressed. There are absolutely experts on buildings being hit by planes. It's a whole field of structural engineering called failure analysis. It's totally a thing and there are companies that specialize in it. This is the industry leader. No one hired either them or their competitors:

http://www.failureanalysisco.com

This was never properly done for 9/11. A real failure analysis looks nothing like what has come out. Instead we have a whole range of bullshit opinions "explaining" the collapse of the towers ranging from the one cited above to "fire went through ventilation shafts and burned the whole building." The mere fact that these far fetched opinions are all we have is troubling in itself.

It's important to understand that everything that happened on 9/11 has to conform to known physics. Fire and structural collapse, which is all this is, is probably the most well understood type of disaster known to man. We know exactly how all these materials perform under intense heat, we know how much weight steel can bear under various temperatures, the structural load capacity of sheetrock, how long it takes to burn. We know absolutely everything we would need to know about planes hitting buildings for a proper failure analysis. It's just math and physics at this point.
 

Bart V

straw materialist
Member
#29
Thanks for bringing up this argument Bart. I think it's important to get this stuff on the table for it to be addressed. There are absolutely experts on buildings being hit by planes. It's a whole field of structural engineering called failure analysis. It's totally a thing and there are companies that specialize in it. This is the industry leader. No one hired either them or their competitors:

http://www.failureanalysisco.com
How is this in any way relevant to being an expert in something that happened only once?

This was never properly done for 9/11. A real failure analysis looks nothing like what has come out. Instead we have a whole range of bullshit opinions "explaining" the collapse of the towers ranging from the one cited above to "fire went through ventilation shafts and burned the whole building." The mere fact that these far fetched opinions are all we have is troubling in itself.
Now you are confusing me, do you want to say these 2000 structural engineers and architects can claim expertise because a proper analysis was never performed?
I think you just strengthened my argument.
It's important to understand that everything that happened on 9/11 has to conform to known physics.
Obviously.
Fire and structural collapse, which is all this is, is probably the most well understood type of disaster known to man. We know exactly how all these materials perform under intense heat, we know how much weight steel can bear under various temperatures, the structural load capacity of sheetrock, how long it takes to burn. We know absolutely everything we would need to know about planes hitting buildings for a proper failure analysis. It's just math and physics at this point.
This is simply not true, the understanding we have is for circumstances and parameters we are used to work with. The events of 9/11 are so far outside these that we would have to start from scratch to understand certain things.

Of course we do not need any new math and physics, we just can not apply it in the same way we are used to do with current structural engineering rules.

I do not think we have enough data to build an accurate simulation, we would need to do some experimental work to get to that.

To me that means that these 2000 "experts" have spoken to fast, they are 2000 very smart people who acted stupid once in overestimating their expertise.
 
#30
It will not be very helpful at all to conduct experiments and simulations. They did that on the Estonia disaster. They made a model and simulated the event. In this they could make it flip around, but they could not make it sink; So they simply put in an air valve in the bottom of the model, that they operated by remote control, and down she went. Science fraud to defend the official story.
 
#31
How is this in any way relevant to being an expert in something that happened only once?


Now you are confusing me, do you want to say these 2000 structural engineers and architects can claim expertise because a proper analysis was never performed?
I think you just strengthened my argument.
Obviously.

This is simply not true, the understanding we have is for circumstances and parameters we are used to work with. The events of 9/11 are so far outside these that we would have to start from scratch to understand certain things.

Of course we do not need any new math and physics, we just can not apply it in the same way we are used to do with current structural engineering rules.

I do not think we have enough data to build an accurate simulation, we would need to do some experimental work to get to that.

To me that means that these 2000 "experts" have spoken to fast, they are 2000 very smart people who acted stupid once in overestimating their expertise.
The area I've bolded in your statement is unfalsifiable. You've moved into the area of magic. You might want to rethink this.
 
#32
It will not be very helpful at all to conduct experiments and simulations. They did that on the Estonia disaster. They made a model and simulated the event. In this they could make it flip around, but they could not make it sink; So they simply put in an air valve in the bottom of the model, that they operated by remote control, and down she went. Science fraud to defend the official story.
It wouldn't work for the towers anyway. Small things have different stress points than big things. For example, an exoskeleton works fine for bugs and crabs, but above a certain size is no longer practical.
 
#33
I included the paper only because of the final sentence, which I bolded: "a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down." NIST rejected that idea?


Tower one not falling straight down. Of course, the upper stories completely disintegrated before it could fall, but that's a different anomaly.
 

Bart V

straw materialist
Member
#34
The area I've bolded in your statement is unfalsifiable. You've moved into the area of magic. You might want to rethink this.
No it's not, show me the structural engineering handbook that describes building code to make a building safe for impact of two fully fueled airliners, and my statement is falsified.
 
#35
The area I've bolded in your statement is unfalsifiable. You've moved into the area of magic. You might want to rethink this.
Unless one believes that Popper's viewpoint is the actuality of all knowledge, falsifiability is irrelevant. To claim the absence of it as being magic (whatever you think that is) is silly.
 

Bart V

straw materialist
Member
#36
It will not be very helpful at all to conduct experiments and simulations. They did that on the Estonia disaster. They made a model and simulated the event. In this they could make it flip around, but they could not make it sink; So they simply put in an air valve in the bottom of the model, that they operated by remote control, and down she went. Science fraud to defend the official story.
So, you think it is more helpful to do no experimental work at all, an then claim something is completely impossible.
The 2000 "experts" rely on an expertise that simply does not cover the events that happened at 9/11
 
#37
#38
No it's not, show me the structural engineering handbook that describes building code to make a building safe for impact of two fully fueled airliners, and my statement is falsified.
The vid that super sex posted interviews the builders and they talk about the buildings being hit by planes. Did you watch it?

Also, as for them being "fully fueled," the same vid goes through example after example after example of buildings burning for hours and none of the structures are ever damaged. I believe every single one of them got rebuilt using the same structure and is still in use! But a few simple office fires in building 7 - what would be the tallest building in 30 some odd states - completely disintegrated the entire structure in one sixth of a minute? First time to happen so no one can understand it? Surely you jest
 
#39
Unless one believes that Popper's viewpoint is the actuality of all knowledge, falsifiability is irrelevant. To claim the absence of it as being magic (whatever you think that is) is silly.
I disagree. Bart's statement, "no one can really know because this is special" can be applied to absolutely any explanation anyone can come up with. An unfalsifiable statement is just belief dressed in a white lab coat. For this disaster to be unknowable, given that we know everything important about every material involved in the crash, it would have to defy present construction knowledge and physics to be unknowable. i.e. magic.
 
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