9/11 Science

[llee]

I just saw this video today and was wondering if there are any structural engineers or architects that would be able to provide insight to the speaker's claims.

Thanks.

 

[Daedalus685]

Well, at least P&N folk barely ever visit highly technical....

So all of the things he says are "possible" in the same sense it is possible that the sky is actually a hologram put there by aliens who conspired with NASA to fake the moon landing in a holodeck buried in Nevada.

Even to avoid the absurd ideas like aliens... It is just poor sense to believe a more complex scenario without any evidence at all in the face of a strongly predictive model that requires no leaps of judgement.

I also should point out that big heavy things tend to fall straight down. Angular momentum does not appear out of nowhere, it would require a tremendous force to tip something like that before it actually hit the ground. People are accustomed to rectangular things that are roughly man sized, things that will twist and turn from air friction alone. A building is remarkably large and the gravitational potential is enough to more than pulverize to dust anything it is made out of as it falls. The building would only tip if the parts below the impact could withstand the impact of the sections above and vice versa while at the same time imparting enough force to increase the angular momentum tremendously. We just don't have materials that can do that, which of course is not proof that the building was not blown up intentionally, but the collapse is not proof that is was, which is my point.

 

[KillerCharlie]

I'm an engineer and it only took about 5 seconds before I determined the speaker is full of shit. This belongs in the tin hat forum, not the highly technical forum.

 

[William Gaatjes]

When they mention nano thermite and so called proof found in concrete(cement) dust, remember that the way that cement, slag cement and concrete are made. A kiln with very high temperatures. And how the raw material of cement is made up of various materials. Especially during the time frame concrete was fabricated for the towers.
Granulated slag is often used for the production of concrete.
Slag comes from smelting ovens for various metals such as copper, aluminium and other metals. Since the processes are not 100% efficient, i think it is save to assume there will always be some trace amounts in the slag. And that is how one can find traces of copper and aluminium (aluminum) in concrete dust.

http://en.wikipedia.org/wiki/Cement_kiln

http://en.wikipedia.org/wiki/Slag
http://en.wikipedia.org/wiki/Concrete

 

[airdata]

I'm an engineer and it only took about 5 seconds before I determined the speaker is full of shit. This belongs in the tin hat forum, not the highly technical forum.

Says a guy w\ the forum handle ' KillerCharlie '.

 

[llee]

What about the free-fall claims? I haven't done the math but it sure looks like the the towers simply 'sank' into the ground.

 

[William Gaatjes]

What about the free-fall claims? I haven't done the math but it sure looks like the the towers simply 'sank' into the ground.

I think that is because of a modification that was done later on in the design.
There where visco elastic dampeners added. These devices dampen the sway of the building. But these devices cannot withstand heat. These dampeners were placed on all higher floors, at least 10,000 were used for each building. When these dampeners lose the strength because of heat like a fire, it is as if a part of the floor has been unbolted. Hanging free in the air. Add the fact that the load distribution because of the impact had been changed as well, it is not that strange.

http://www.designcommunity.com/discussion/7595.html

Viscoelastic (VE) dampers are dependent on both relative velocity and displacement to dissipate energy. VE damping system in Twin Towers is a double-layer shear damper using a 3M material, which is a rubber derivative, glued to steel plate and angle irons. This material will carry some load (which is temperature-dependent and would be less than the two-bolt connection as shown) as it displaces. As installed it has several functions:
1. It develops continuity moment at the end of joist girder, that is, the joist girders will behave as partial continuous members under Dead and Live load. It is partially restrained under Wind load.
2. It restrained the lower chord of the joist girder (in the direction perpendicular to the plane of the joist). Therefore it stabilizes the concrete diaphragm. Note that for a 4-inch thick concrete slab spanning 60 feet, it would buckle if there were no joist girder. It also transfers compression load through bottom chord.
3. Joist girder-column connection is a moment connection.
4. It reduces the energy to be absorbed by the joist girder and the columns under Wind load.

As the temperature rises, 3M materials would loose its load carrying capacity, i.e. its energy-dissipating capacity. This is equivalent as loosing the two-bolt connection because it will act as though there is gaps between the steel plate and the angle irons. As a result, several things would occur:
1. The joist girder is no longer a continuous member. Therefore, even under Dead and Live load, its top chord would rotate more relatively to its supporting column.
2. All the compression or tension force to the diaphragm would go through the top chords only.
3. More rotation between the top chord and its respective column under Wind load.
4. No more lateral restraint for the bottom chord and the joist girder could buckle laterally and the slab diaphragm would follow.

And the result is a tremendous demand on the connection between the top chord and its supporting column.
Let be clear that the VE damping system is a novelty design. First of its kind in the World. First of its kind implemented in a skyscraper. The reason I still think it is a design flaw is that:
In the 60’s and beginning 70’s there are many literatures about plastic design in steel including ASCE manual No 41. From J Heyman to Beedle, they all emphasize the importance of collapse mechanism in Limit Analysis. And in dealing with inelastic behavior such as VE damping system is engaging in Limit Analysis whether you want it or not because you have to think what will happen beyond the device limit.

http://science.howstuffworks.com/engineering/structural/wtc2.htm

World Trade Center Elevators

To stand up to the horizontal force of wind, skyscrapers need the right combination of stability and flexibility. They have to be rigid enough that the wind can't push them too far from side to side, but flexible enough that they can give a little, absorbing some of the wind energy.

The WTC crew ran extensive tests to find out just how much sway they could allow without disturbing the building occupants. They put structural models in wind tunnels and even lured unsuspecting test subjects to movable rooms hooked up to heavy hydraulics.

In the end, they designed the towers so they could sway about 3 feet in either direction. To minimize the sway sensation, they installed about 10,000 visco-elastic dampers between support columns and floor trusses throughout the building. The special visco-elastic material in these dampers could move somewhat, but it would snap back to its original shape. In other words, it could give a little and then return to its initial position, absorbing much of the shock of the building's swaying motion.

 

[Mark R]

What about the free-fall claims? I haven't done the math but it sure looks like the the towers simply 'sank' into the ground.

This would be the expected behavior of large towers.

Air resistance is more relevant at small scales, and gravity is more relevant at large scales. This is why tiny insects can jump so far and glide/float on water, etc. - whereas elephants can't. As you scale up, the familiar human-scale balance of forces changes. By the time you get to WTC scale, gravity is everything, air resistance is a rounding error.

The other issue that scuppers the air resistance braking claim is that, this would be most relevant, at the start when you have only a single floor collapsing and being braked by the air resistance. Once more floors join the fall, the effect disappears, as the effect of air resistance stays constant, but the weight increases. In fact, when the towers did collapse, the collapse didn't begin from the top, but from a good way down, so that the amount of weight falling was enormous.

Similarly, at these scales, the angular momentum needed to push the fall off axis is huge. It's not like at the normal human scale where you can rotate things, and push them off axis; the "moment of inertia" is proportional to length times mass (and mass is proportional to side length cubed) - so in effect, if you make a cube building twice as long on each side, it becomes 16x more difficult to rotate. 3x as long on each side -> 81x as difficult to rotate. The effect is that the bigger a structure, the straighter it falls.

 

[alkemyst]

I'm an engineer and it only took about 5 seconds before I determined the speaker is full of shit. This belongs in the tin hat forum, not the highly technical forum.

Well saying your are an engineer and debunking someone without stating your field of expertise or even experience is laughable.

 

[William Gaatjes]

To put some oil on the fire :twisted:
I give plausible explanations only. I did not do any research on any material. But before i call out a conspiracy, i give all more logical and probable options. It could have been the case that real thermite bombs where used, and that the perpetrators knew of the composition of the concrete and to use that as a plausible explanation for copper and aluminium traces... But the whole problem is the organization of such an event such as a controlled demolition of not only 1 but 2 huge buildings. Controlled demolition takes such an amount of preparation that even together with a plane crashing in, people would have noticed. There would have been to much people involved for an inside job. There would have someone spilled his or her guts. Or there would have been a killing wave of people all connected to the controlled demolition of the WTC towers. It is just impossible. It is unfortunate, but be thankful the buildings dropped as they did, or the death toll would have been much higher if they had not.

 

[VI3L]

To put some oil on the fire :twisted:
I give plausible explanations only. I did not do any research on any material. But before i call out a conspiracy, i give all more logical and probable options. It could have been the case that real thermite bombs where used, and that the perpetrators knew of the composition of the concrete and to use that as a plausible explanation for copper and aluminium traces... But the whole problem is the organization of such an event such as a controlled demolition of not only 1 but 2 huge buildings. Controlled demolition takes such an amount of preparation that even together with a plane crashing in, people would have noticed. There would have been to much people involved for an inside job. There would have someone spilled his or her guts. Or there would have been a killing wave of people all connected to the controlled demolition of the WTC towers. It is just impossible. It is unfortunate, but be thankful the buildings dropped as they did, or the death toll would have been much higher if they had not.

Obviously you haven't seen the World Trade Center Building 7 COLLAPSE, no plane hit it.

http://www.youtube.com/watch?v=LD06SAf0p9A

 

[William Gaatjes]

Obviously you haven't seen the World Trade Center Building 7 COLLAPSE, no plane hit it.

http://www.youtube.com/watch?v=LD06SAf0p9A

Of course i have seen it. I also know that the building that was WTC7 was larger and heavier then the original foundation was designed for. There was a novel cantilever construction created. A part of the building WTC7 was actually from a certain point of view suspended in the air. If i recall correctly, WTC7 was build also over a electrical transformer station. WTC7 also carried storage tankers with diesel fuel. I recall that WTC7 was hit by debri from WTC1 (but i am not sure). WTC7 was burning and a part of the cantilever contstruction was damaged. The building was unstable. And if my memories about the foundation is correct i can promise you that if a plain would have struck WTC7, WTC7 would have never withstand any plain crash at all the way WTC1 and WTC2 and would have collapsed immediately.

http://911research.wtc7.net/mirrors/guardian2/wtc/WTC_ch5.htm

I am sure that you will be able to verify that the building had been build this way.

 

[William Gaatjes]

It seems the website i posted has been altered. And the added red comments are particularly misleading.

 

[Matt1970]

The 9/11 truthers are always good for a laugh. Every scenario they come up with is always easily debunked. Everything from the ghost planes to the missiles all get debunked. Yet they continue to look and look, hell bent of finding anything they can use to further their cause. One thing that will always deflate any conspiracy theory is for any of them to actually work, means that well over a thousand people would have had to be involved. Everyone from the President himself, to the air traffic controllers, to the rescue workers on the ground, to even the families of the people who had to sacrifice loved ones all had to be in on it. You tell me how the US Government, who can’t even keep anything quiet, kept them ALL quiet for over 10 years. Not one single email, taped phone conversation, or even a document has ever surfaced discussing the plan.

 

[alkemyst]

Everyone from the President himself, to the air traffic controllers, to the rescue workers on the ground, to even the families of the people who had to sacrifice loved ones all had to be in on it. You tell me how the US Government, who can’t even keep anything quiet, kept them ALL quiet for over 10 years. Not one single email, taped phone conversation, or even a document has ever surfaced discussing the plan.

I don't think ALL those people had to be involved should this have been a conspiracy...however; it's naive to think we as the public know all the secrets our government holds.

 

[Matt1970]

I don't think ALL those people had to be involved should this have been a conspiracy...however; it's naive to think we as the public know all the secrets our government holds.

Maybe not all, but it would have to be well over 500. Just take WTC7 demolition theory. It would take a small army of demolition experts a week to set that building for demolition. All of this would have to go unnoticed. Now you have to get rid of the evidence. Beams that were cut in half by explosives are easily identifiable so they need to be removed. There was not enough time between the building falling and the fire fighters arriving so now all the rescue workers have to be involved since they clearly would have found some of them, not to mention all the det cord. There was just about every news organization on the planet there with cameras so they have to be involved and instructed not to film any of the evidence. You see what I am getting at? That was just a single building. There were 3 building hit that day, a plane that went down in PA and a whole slew of phone calls from the people on the planes to loved ones and to 911. It would have taken our government years of planning, a thousand people and tons or resources to pull of a hoax like that. Meanwhile all done in secrecy and 10 years later to not have one single person involved have an attack of conscience and come clean.

Sorry, wouldn’t buy it in a million years.

 

[alkemyst]

Maybe not all, but it would have to be well over 500. Just take WTC7 demolition theory. It would take a small army of demolition experts a week to set that building for demolition. All of this would have to go unnoticed. Now you have to get rid of the evidence. Beams that were cut in half by explosives are easily identifiable so they need to be removed. There was not enough time between the building falling and the fire fighters arriving so now all the rescue workers have to be involved since they clearly would have found some of them, not to mention all the det cord. There was just about every news organization on the planet there with cameras so they have to be involved and instructed not to film any of the evidence. You see what I am getting at? That was just a single building. There were 3 building hit that day, a plane that went down in PA and a whole slew of phone calls from the people on the planes to loved ones and to 911. It would have taken our government years of planning, a thousand people and tons or resources to pull of a hoax like that. Meanwhile all done in secrecy and 10 years later to not have one single person involved have an attack of conscience and come clean.

Sorry, wouldn’t buy it in a million years.

Those calling loved ones from a doomed plane I doubt would have been 'in on it'.

Not saying what or what not happened, but I doubt most would know what was going on in the infrastructure of a building anyway. You wouldn't need 500 people to pull this off.

Has Seal Team 6's identies been leaked? More than 500 people know about them.

 

[Matt1970]

Those calling loved ones from a doomed plane I doubt would have been 'in on it'.

Not saying what or what not happened, but I doubt most would know what was going on in the infrastructure of a building anyway. You wouldn't need 500 people to pull this off.

Has Seal Team 6's identies been leaked? More than 500 people know about them.

I highly doubt a team of demolition experts are going to be allowed in WTC with cases of explosives. Now you have to pull drywall and expose beams, cut holes in the beams and insert the explosives. Now run miles of det cord and have nobody find any of it.

 

[wirednuts]

i like how we dont question some historic events much because we know they were well documented at the time, so how is it that 9/11 is such a mystery when IT PLAYED OUT ON LIVE FUCKING TELEVISION!?!?

plane hit buildings. buildings impressively hold for about an hour then fall down because unlike all other building fires, there were massive amounts of accellerants packed inside. all you need is 1 floor to collapse. the weight of the dozens above will not be stopped by even god himself.

 

[pandemonium]

i like how we dont question some historic events much because we know they were well documented at the time...

Which events would those be? Because there's a conspiracy flavor for anything out there now. On the flipside, people are more and more willing to question face value of news reports and accepted knowledge of known events and we're "discovering" the truth, as it were, is never as it was simply portrayed the first time around.

 

[beginner99]

You tell me how the US Government, who can’t even keep anything quiet, kept them ALL quiet for over 10 years. Not one single email, taped phone conversation, or even a document has ever surfaced discussing the plan.

And if it did? How would you proof it is legitimate and not a hoax? The thing about such conspiracy theories is that most people think believers are nuts. The fact that we read and write about here would actually confirm what you said. it could not be kept quiet.

And all the weird stuff about ghost planes and controlled demolition that makes it sound ridiculous could just be to make a more simple plan sound ridiculous.


1. Religious nuts fly into skyscraper for the holly war
OR
2. Religious Nut of a President orders such a mission to be able to go to war with Iraq.

Viewed like this the differences to the probable truth (1.) to the conspiracy theory (2.) isn't that great anymore is it?

 

[William Gaatjes]

And if it did? How would you proof it is legitimate and not a hoax? The thing about such conspiracy theories is that most people think believers are nuts. The fact that we read and write about here would actually confirm what you said. it could not be kept quiet.

And all the weird stuff about ghost planes and controlled demolition that makes it sound ridiculous could just be to make a more simple plan sound ridiculous.


1. Religious nuts fly into skyscraper for the holly war
OR
2. Religious Nut of a President orders such a mission to be able to go to war with Iraq.

Viewed like this the differences to the probable truth (1.) to the conspiracy theory (2.) isn't that great anymore is it?

It is also possible that some people knew about the coming terrorist attack. There have been rumors that the German intelligence agency had notified the US embassy about the WTC attack. There have also been rumors that the CIA knew about it prior before the attack.

Here is a brain fart :
The worst possibility is a true conspiracy that certain individuals (not Bush jr Cheney or Rumsfeld : All are very US patriotic in a way and would not allow such a thing if they had known) knew about it and kept it in the dark. Thus it was prepared by terrorists but kept in the dark by politicians with influence who had a lot to gain by letting the US going to war in the Middle East. The advantage is that the US would be the general scapegoat. I mean who is going to attack a nation with the most powerful army in the world ? A nation build on technologically advancing it's army for the last 70 years ?

 

[DrPizza]

Which events would those be? Because there's a conspiracy flavor for anything out there now. On the flipside, people are more and more willing to question face value of news reports and accepted knowledge of known events and we're "discovering" the truth, as it were, is never as it was simply portrayed the first time around.

Part of the problem is "fair and balanced" reporting. By balanced, they mean 50% of the time to each side. When that happens, it lends credibility to things that have zero credibility to begin with. Likewise all the other dumbed down crap on television - ghost hunters, etc.

 

[TastesLikeChicken]

The simple fact is that until truthers come up with a viable explanation of their own for what happened on 9/11, one that passes scientific scrutiny, all of their claims don't mean squat because without a better theory than the official one all of their attempts to poke holes and point fingers amount to a hill of beans.

 

[Anarchist420]

The 9/11 truthers are always good for a laugh. Every scenario they come up with is always easily debunked. Everything from the ghost planes to the missiles all get debunked. Yet they continue to look and look, hell bent of finding anything they can use to further their cause. One thing that will always deflate any conspiracy theory is for any of them to actually work, means that well over a thousand people would have had to be involved. Everyone from the President himself, to the air traffic controllers, to the rescue workers on the ground, to even the families of the people who had to sacrifice loved ones all had to be in on it. You tell me how the US Government, who can’t even keep anything quiet, kept them ALL quiet for over 10 years. Not one single email, taped phone conversation, or even a document has ever surfaced discussing the plan.

I don't know whether there were no taped phone conversations, but the government documents that lie about it are phony.

i like how we dont question some historic events much because we know they were well documented at the time, so how is it that 9/11 is such a mystery when IT PLAYED OUT ON LIVE FUCKING TELEVISION!?!?

plane hit buildings. buildings impressively hold for about an hour then fall down because unlike all other building fires, there were massive amounts of accellerants packed inside. all you need is 1 floor to collapse. the weight of the dozens above will not be stopped by even god himself.

They can always use special effects and lie so that people won't believe it. Don't believe anything you hear and believe nothing that you see.

It is also possible that some people knew about the coming terrorist attack. There have been rumors that the German intelligence agency had notified the US embassy about the WTC attack. There have also been rumors that the CIA knew about it prior before the attack.

Here is a brain fart :
The worst possibility is a true conspiracy that certain individuals (not Bush jr Cheney or Rumsfeld : All are very US patriotic in a way and would not allow such a thing if they had known) knew about it and kept it in the dark. Thus it was prepared by terrorists but kept in the dark by politicians with influence who had a lot to gain by letting the US going to war in the Middle East. The advantage is that the US would be the general scapegoat. I mean who is going to attack a nation with the most powerful army in the world ? A nation build on technologically advancing it's army for the last 70 years ?

Brian fart indeed. There are timelines with links to MSM stories detailing that something bad was about to happen before it happened. Since when did the Federal U.S. government defend itself rather than aggress against someone else?

I think that a plane hit it and there was definitely an internal demolition, but I could never be convinced that Bush didn't want it to happen. That man didn't believe a damn thing he said and it's insulting to myself and many other people that he expects anyone to believe it (from saying blatantly false stuff like democracies never attack each other, to saying that he did what he did to protect the American people). Tyrants aren't capable of protecting people and Obama may not be smart enough to know that, but Bush is.