Common Sense

[babazaroni]

28th, you do know that buildings are supposed to stand up right? If the top section began to tilt and collapse, what do you think is going to happen to the rest of the building?

Dude, don't you get it. The rest of the building was supposed to tip over to. Since it didn't, explosives must have been used.

 

[aggle-rithm]

What do I say to that? What part of please address exactly what I said and tell me how it doesn't make sense don't you understand?

If the upper mass isn't touching the lower floors... can it still apply pressure to the lower floors?

The upper mass tilted, because it was simply off balance...from the uneven failure of the impact floors... please don't interject some magical super force of energy...that counter reflected to the lower floors...

What is your trip? We are talking common sense here. I am asking utterly simple questions, and you are all scared to answer them. Now... if the upper mass isn't touching the lower floors can it still apply pressure to the lower floors? That is a common sense question... can you answer it?

I think 28Personality's problem is in having an overly simplistic mental model of the collapse.

In his mind, the upper section of the building was a monolithic entity that stayed in one piece until it hit the ground.

In his mind, each floor collapsed with perfect symmetry, so that if the monolithic upper section was tilted, only one corner could touching the lower floors at any given time.

In his mind, as each floor collapsed, it exploded and was expelled to the side, reducing its mass to zero.

Clearly, his thinking is strictly algebraic, so he has no appreciation for the dynamic changes taking place during the collapse.

You have now taken a tour of 28K's mind. Feel free to take a shower now.

 

[beachnut]

at near free fall speeds

What speed would that be 28th? State the speed of the core collapse!

Gee I saw core falling over 30 seconds after the fall began. What free fall speed do CT guys have that takes 30 seconds?

What speed would that be 28th? State the speed of the core collapse!

Gee I saw core falling over 30 seconds after the fall began. What free fall speed do CT guys have that takes 30 seconds?

 

[Pardalis]

I think 28Personality's problem is in having an overly simplistic mental model of the collapse.

In his mind, the upper section of the building was a monolithic entity that stayed in one piece until it hit the ground.

You mean... like a tree?

 

[28th Kingdom]

When you severely and suddenly overload a structural system it collapses violently. Thats the answer! Anyone with the slightest amount of common sense would know that.

Okay, so where is the proof that the WTC were overloaded? What because they collapsed? You are blinded because you automatically eliminate the possibility of explosives... which makes all of your theories warped.

There is absolutely no proof that the towers could have fell the way they did from the damage that was done. The speed at which the buildings fell defies the laws of physics... and that is a fact. It really is that simple.

Common sense tells us... given the knowledge of free falls speeds... that these towers could not have collapsed as fast as they did without a synthetic catalyst like explosives.

Otherwise... you're saying that this marvel in structure engineering and design, provided virtually no resistance to the falling upper mass. You're basically saying this steel structured building provided no more resistance than if it were made of cardboard.

I was watching a History Channel special last night about the collapses... and they even claim the towers fell in 10 seconds... so how long do you all think it took for the towers to fall? And, if you give exact numbers... please tell me how you calculated them? I mean.. video footage has to be involved, right? If so... please link to it.

 

[Pardalis]

28th, the towers start to collapse: what should have happened according to your common sense?

ETA: forget about explosives, forget about the NIST, what should have happened according to you?

 

[aggle-rithm]

Common sense tells us... given the knowledge of free falls speeds... that these towers could not have collapsed as fast as they did without a synthetic catalyst like explosives.

A PERFECT example of how common sense is not a valid tool to analyze uncommon occurances. Which, of course, is the point of this thread. Which, of course, is the very point that has eluded 28IQ from the beginning.

Sheesh!

 

[aggle-rithm]

You mean... like a tree?

Yes, containing elves hard at work manufacturing comestibles.

 

[28th Kingdom]

28th, the towers start to collapse: what should have happened according to your common sense?

ETA: forget about explosives, forget about the NIST, what should have happened according to you?

Firstly...when the impact floors supposedly gave out...at this point, the lower floors hadn't collapsed... if there weren't any explosives, and this happened... the upper mass of floors would have (if the core columns all failed) toppled over and fallen off of the building.

Maybe you need to tell this building...that it was suppose to completely collapse, since half of it is missing.

http://img144.imageshack.us/img144/4847/ntp10ini8.jpg

 

[Pardalis]

BTW Firestone, your avatar is so beautiful, from what artist is it?

 

[Architect]

Someone ask the idiot if he understands the middle third rule.




That should puzzle him.





For the rest of you, it's not hugely relevant but will show his ignorance. Essentially what is says is that the moment the centre of gravity moves outside the middle third of the structure's width, then it will be unable to take the loads and collapse.

Such collapses are invariably straight downwards. Why? Because the change in the centre of gravity and thus the joints/connections/whatever means they exceed design capacity and fail.

Generally.

 

[Pardalis]

Firstly...when the impact floors supposedly gave out...at this point, the lower floors hadn't collapsed... if there weren't any explosives, and this happened... the upper mass of floors would have (if the core columns all failed) toppled over and fallen off of the building.

So the building would have withstood the weight of the falling top section?

How?

 

[R.Mackey]

Everyone knows what? That the upper mass was increasing in size? How do they know this? We can't even see the upper mass for the majority of the collapse, so what tells us it's increasing in size?

Because more and more of the building is involved in the collapse over time.

The additional parts of building have mass, therefore, the mass increases over time.

Anticipating your pathetic objection, it is true that some would and did fall over the sides. However, remember that the Towers were over 200 feet across. What magical force would explain the bulk of material moving sideways up to 100 feet? None. Thus, the losses over the side are understood to be fairly minor.

And it doesn't really matter, anyway. From Greening, page 17:

Because uncertainties also exist in our knowledge of the precise mass of the WTC, M, it is worth noting that the momentum transfer calculations of t_c are also relatively insensitive to the value used for M. To show this, collapse time calculations were run using a fixed value of E1 of 1 x 10⁹ J and a mass, M, varied in increments of 50,000,000 kg between 510,000,000 kg and 300,000,000 kg. The resulting collapse times varied by less than 0.8 seconds confirming that the collapse time is indeed quite insensitive to M over a wide range. Upon reflection, this is not so surprising since this result is precisely what Galileo showed in his famous experiment at Pisa.

Put another way, the collapse times -- indeed, the whole visible phenomenon -- doesn't change much if you vary the amount of mass present. Or simpler still, losses over the side don't change the nature of the collapse.

So if the lower floors collapsed as a result of the energy released from the falling mass - than wouldn't the upper mass have to be touching the lower floors in order to release this energy onto the lower floors? Wouldn't the upper mass have to continually touch the lower floors all the way to the ground... or could the upper mass fall off at some point... with the momentum causing the remaining floors to collapse?

Wow.

Your mind is an empty vessel, 28^th Kingdom. The student is prepared. I will now attempt to teach.

YES, the upper mass has to touch the lower floors to "release" (actually transfer) its kinetic energy. It does so. It hits the lower floors. That's because gravity pulls the upper block straight down, and the lower floors are directly beneath them. Naturally, the collapse doesn't initiate in earnest until the upper block hits the lower floors.

NO, this does not mean the upper mass has to continually touch the lower floors. Momentary collision is plenty of time. But since it's all pretty much a vertical phenomenon, the process is self-regulating. The longer the lower floors resist, the longer the upper block stays in contact. The two masses only drift away from each other while both are in free-fall, i.e. when both are already irrevocably collapsing.

So you are saying that you reached your conclusion through pure speculation and opinion, right? Because that was all there in my statement.

Your inability to understand my comments does not make them wrong. I initially speculated, then made some calculations. I give my opinion. All three of these also just happen to be consistent with the NIST report. It is therefore incorrect to say that I reached my conclusion through "pure" speculation and opinion.

So you just admitted, that the upper mass may of only been touching the lower floors on one side. What twisting... you say after the initial tilt of the upper mass it stopped tilting... so which is it? Did it continue to twist and tilt all the way to the bottom or did it stopped twisting and tilting right after the collapse began?

It's not an admission, it's fact. After the aircraft impact but prior to collapse, several columns were severed. That's "upper mass touching lower floors on one side." No surprises here.

The twisting occurred while the upper block rotated. Rotation == twist. Capiche?

After the impact floor was completely destroyed, the force couple created by asymmetric loading no longer existed. The upper floors had already tilted to some degree, and retained some angular momentum. But the tilted corner would fall on the lower block first, and the upper block would gain some opposite angular momentum. After the collapse started for real, the upper block would probably neither gain nor lose angular momentum through the essentially random impacts floor after floor. Thus, it didn't stop tilting or twisting, but its rate of tilt became essentially negligible.

Even if the upper mass is only touching on one side of the lower floors? Do you not equate that into the calculations?

Not relevant for the full collapse. This situation only occured for the < 1 second between the upper block beginning to move, and the total failure of the impact floor. It's a minor footnote to the overall mechanics of collapse.

 

[babazaroni]

Okay, so where is the proof that the WTC were overloaded?

The inward bowing columns. Sorry, I know you don't want to talk about them.

What because they collapsed? You are blinded because you automatically eliminate the possibility of explosives...

No ejecting debris was seen at the moment of collapse.

Common sense tells us... given the knowledge of free falls speeds... that these towers could not have collapsed as fast as they did without a synthetic catalyst like explosives.

Try dropping a brick on a balsa model. The model will collapse at very near free fall speeds.

Otherwise... you're saying that this marvel in structure engineering and design, provided virtually no resistance to the falling upper mass. You're basically saying this steel structured building provided no more resistance than if it were made of cardboard.

This tube-in-tube design with lightweight trusses as a key structural element will not be built again, for obvious reasons.

 

[Architect]

After the impact floor was completely destroyed, the force couple created by asymmetric loading no longer existed. The upper floors had already tilted to some degree, and retained some angular momentum. But the tilted corner would fall on the lower block first, and the upper block would gain some opposite angular momentum. After the collapse started for real, the upper block would probably neither gain nor lose angular momentum through the essentially random impacts floor after floor. Thus, it didn't stop tilting or twisting, but its rate of tilt became essentially negligible.

Correct, and well put.

The tilt itself will also have resulted in structural failure within the mobile tilted section, removing it's integrity, at which poin the seperate sub sections would be even more inclined to proceed in an orderly vertical direction.

 

[Firestone]

BTW Firestone, your avatar is so beautiful, from what artist is it?

From Tamara de Lempicka.

It is the portrait of Marjorie Ferry.

 

[Architect]

This tube-in-tube design with lightweight trusses as a key structural element will not be built agian, for obvious reasons.

I wouldn't bet on that, to be honest. It would be perfectly possible to build a more robust version of it.

But today we tend to do it differently anyway.

 

[aggle-rithm]

Otherwise... you're saying that this marvel in structure engineering and design, provided virtually no resistance to the falling upper mass. You're basically saying this steel structured building provided no more resistance than if it were made of cardboard.

I was watching a History Channel special last night about the collapses... and they even claim the towers fell in 10 seconds... so how long do you all think it took for the towers to fall? And, if you give exact numbers... please tell me how you calculated them? I mean.. video footage has to be involved, right? If so... please link to it.

Since he watches the History Channel, he knows that structures DO exist that can provide resistance to a large chunk of itself dropping downwards -- they're called the pyramids.

Given that only about 1% of these structures is open space, I don't think this would be a very pragmatic design for an office building.

 

[babazaroni]

I wouldn't bet on that, to be honest. It would be perfectly possible to build a more robust version of it.

But today we tend to do it differently anyway.

While you are at it Architect, do you have any comments on the new Freedom Tower?

I've heard it will have a concrete core and the exterior will have a cable mesh. Sounds intriguing.

 

[ConspiRaider]

There is absolutely no proof that the towers could have fell the way they did from the damage that was done. The speed at which the buildings fell defies the laws of physics... and that is a fact. It really is that simple.

The speed at which the buildings fell IS the speed at which they fell, Doctor 28IQ. Which law of physics is being defied?

Common sense tells us... given the knowledge of free falls speeds... that these towers could not have collapsed as fast as they did without a synthetic catalyst like explosives.

Free fall speeds are NOT common sense, Doctor 28IQ. The vast vast vast majority of common folk - keepers of common sense - have no clue concerning freefall speeds of ANYTHING. Let alone giant skyscrapers.

The only way the buildings could have fallen "faster than freefall speed" is if a force other than gravity was acting upon them, from the top down. Little directional explosive rockets, for example, increasing DOWNWARD momentum. Everything has to be aimed DOWN.

Therefore, Doctor 28IQ, you are now required to explain how many of these directionally explosive rockets were used, per floor, how they were delivered to the WTC complex, how smuggled into the building, who installed them and how many, time to install, how much material required for triggering devices, how that was installed - and of course why security didn't tumble to any of this, nor did any of those tens of thousands of people swarming in and around the WTC complex in the middle of the downtown section of the most populous city in the 3rd most populous country on the planet Earth.

Thank you Doctor. Oh here, you dropped your IQ...