9/11 Physics from Non-Experts

[GregoryUrich]

I knew you guys would enjoy those! I was just pointing out how absurd Bazant's sonic booms are when trying to explain phenomena prior to or early in the collapse.

 

[GregoryUrich]

You have failed to prove CD with engineering, so you revert to the CT tactic of flooding the world with this junk. Wow. This means a 9/11 truth minded engineer has no fact or evidence so he follows the 9/11 truth cult of taking stuff and saying it was so. Why would an engineer fall for this junk? What made you a 9/11 truth person?

I haven't tried to prove CD with engineering.

I have tried to establish a necessary input (i.e. the mass) required to prove or disprove gravity driven collapse. I haven't even tried to prove/disprove gravity driven collapse yet. I definitely haven't gotten to trying to prove CD which would be dependent on disproving gravity driven collapse.

If you haven't noticed, I have been pointing out the problems with "physics from experts" (i.e. Bazant et al.) which are significant enough to call his result into question. Did anyone notice that they bumped the total mass up to 566,000 tons? Did anyone notice they have 80% of the mass hitting the bedrock a 47m/s, with 25,000 times more energy (4x10^11 Joules) than is measured seismically? That energy being the same as FEMA predicited for the total PE of the building.

You are supposed to be a truth minded engineer. What about these things?
Or are you getting all "non-truthy" on me?

 

[beachnut]

I knew you guys would enjoy those! I was just pointing out how absurd Bazant's sonic booms are when trying to explain phenomena prior to or early in the collapse.

Engineer or truther asking questions? So you finally found out the WTC will still fall despite a smaller mass, you did the numbers, now you go with sounds like.

I think the sounds at the end were the floors failing and smashing every floor distance as the major mass moved to destroy each floor in turn. I think that last floor failing instantaneously and accelerating for microsecond, instantaneous so to speak to 250 mph was a significant sound event worthy of the sounds like an explosion, but too bad the sound of RDX travel much further with a real cd sound. Sad you have chosen to twist testimony to make up the CD stuff. Good job engineer, super truth investigator.

You have gone CD crazy in just a few post of sounds like. Go ahead show you 9/11 truth stuff, you posted a letter at the 9/11 truth journal, go for it. Tell us what you have.

 

[R.Mackey]

I knew you guys would enjoy those! I was just pointing out how absurd Bazant's sonic booms are when trying to explain phenomena prior to or early in the collapse.

Gregory, Bazant et. al. do not even attempt to explain anything prior to the collapse. Their sonic booms only apply during the collapse.

Some of your observations here are credible and useful, but this one is totally off the wall.

 

[GregoryUrich]

Gregory, Bazant et. al. do not even attempt to explain anything prior to the collapse. Their sonic booms only apply during the collapse.

Some of your observations here are credible and useful, but this one is totally off the wall.

Bazant et al. do try to explain explosive sounds during collapse but fail because the phenomena they are describing do not occur until the "crush down" phase is nearly complete.

I did point out that people thought they heard explosions prior to the onset of collapse, because Bazant is trying to dispell myths but conveniently ignores this.

 

[Kent1]

Bazant et al. do try to explain explosive sounds during collapse but fail because the phenomena they are describing do not occur until the "crush down" phase is nearly complete.

I did point out that people thought they heard explosions prior to the onset of collapse, because Bazant is trying to dispell myths but conveniently ignores this.

Before you create another strawman I would ask Mr. Benson and Greening.

http://forum.physorg.com/index.php?showtopic=12383&st=4290

 

[R.Mackey]

Bazant et al. do try to explain explosive sounds during collapse but fail because the phenomena they are describing do not occur until the "crush down" phase is nearly complete.

Support this assertion, please. I disagree.

I did point out that people thought they heard explosions prior to the onset of collapse, because Bazant is trying to dispell myths but conveniently ignores this.

It's not relevant to the problem they were studying. You're well-poisoning.

 

[rwguinn]

I haven't tried to prove CD with engineering.

I have tried to establish a necessary input (i.e. the mass) required to prove or disprove gravity driven collapse. I haven't even tried to prove/disprove gravity driven collapse yet. I definitely haven't gotten to trying to prove CD which would be dependent on disproving gravity driven collapse.

If you haven't noticed, I have been pointing out the problems with "physics from experts" (i.e. Bazant et al.) which are significant enough to call his result into question. Did anyone notice that they bumped the total mass up to 566,000 tons? Did anyone notice they have 80% of the mass hitting the bedrock a 47m/s, with 25,000 times more energy (4x10^11 Joules) than is measured seismically? That energy being the same as FEMA predicited for the total PE of the building.

You are supposed to be a truth minded engineer. What about these things?
Or are you getting all "non-truthy" on me?

So a person who's demonstrated knowledge of both physics and structural analysis is minisucle is explaining how those who do know them are wrong, wrong, wrong!
The seismic data is a give-away--you don't understand it in the least. You also don't understand that transformers, and other common items can explode when exposed to heat or short-circuit (ever see a film of a tornado hitting a sub-station?). Explosions=explosives=Controlled Demolition! 11!! pwned!
Please refrain from design work on anything that will be used by the public--for all our sakes.

 

[GregoryUrich]

Support this assertion, please. I disagree.

It's not relevant to the problem they were studying. You're well-poisoning.

Regarding the first assertion, Bazant et al. themselves say:

Since the velocity of the crushing front near the end of North Tower crush-down is, according to the solution of Eq. (2), z = 47.49 m/s (110 mph), the velocity of escaping air near the end of crush-down is...

where they then give estimates of expelled air velocity at 206-340m/s, the latter being the speed of sound at around ground level.

Regarding the "well-poisening", I think the scope they set for the paper:

Universally though has the foregoing explanation of collapse been accepted by the communities of structural engineers and structural mechanics researchers, some outside critics have nevertheless exploited various unexplained observations to disseminate claims of controlled demolition
by planted explosives. The objective of this paper is to examine whether these claims are technically and mathematically justifiable. Is the explanation of collapse unique? Do alternative explanations have any scientific merit?

is not handled fairly or convincingly. They cherry pick a few ideas which are easy to discredit and misrepresent "free-fall" as being a claim rather than the ubiquitous "near free-fall" claim presented by the majority of gravity driven collapse critics.

 

[GregoryUrich]

Question regarding sturctural design

Bazant et. al. claim the specific density (as a function of height) varies from 1.02x10^6 kg/m at the top to 1.05x10 kg/m at the 81st floor. They give an exponential function for this part of the building with a number of constants which are not explained. They use a linear approximation from that point downward which I think it makes because the supported mass increases nearly linearly.

Here one thing I just don't get. To simplify this I am ignoring the hat truss and the antenna.

The supporting structure for the second to top floor (109) carries approx twice as much weight as the supporting structure for the top floor (110). The supporting structure for the next floor (108) needs to support 50% more weight than the supporting structure for floor 109. It would seem that the greatest variation in steel strength (and weight) would be on these uppermost floors but Bazant et al. have a variation of 0.00103 kg/m in the highest part while in the lower part the variation is 0.00471 kg/m.

Is there some structural design concept involved here that I as a layman may be unaware of?

Rwguinn, I may ease your worries regarding public safety, as I do not design anything other than software applications.

 

[R.Mackey]

Regarding the first assertion, Bazant et al. themselves say:

where they then give estimates of expelled air velocity at 206-340m/s, the latter being the speed of sound at around ground level.

I think you miss my question. You haven't adequately described exactly what phenomenon you think they "fail" to explain. I think you're continuing to extrapolate their findings beyond the scope for which they were intended.

Regarding the "well-poisening", I think the scope they set for the paper:

is not handled fairly or convincingly. They cherry pick a few ideas which are easy to discredit and misrepresent "free-fall" as being a claim rather than the ubiquitous "near free-fall" claim presented by the majority of gravity driven collapse critics.

And here you're avoiding my point. Bazant et. al. are not studying reports of noises well before the collapse. Nor are they required to, nor does any rational thinker care. Your insistence that they are "avoiding" such a question, perhaps for a nefarious purpose, is well-poisoning. There are a multitude of WTC Tower phenomena that are not covered by the paper. Their paper is only about 20 pages long, whereas if we use NIST as a guideline, a proper treatment of everything takes thousands of pages.

Just criticize the paper as written, if that's your aim. Stop trying to make it something that it isn't.

 

[TruthSeeker1234]

By the way... a bit off topic... but check out this photo taken during the construction of the Twin Towers:

http://i207.photobucket.com/albums/bb98/visibility911/wtc4small.jpg

I think the diagonal bracing explains the infamous "diagonal cut" so beloved by the CTers!

Frank, I've been trying to convince Ryan Mackey that the core sections were abundantly cross braced. I thought that, in addition to the diagonal bracing shown in your picture, the cores also had independent flooring systems.

Ryan has told us that the cores were only braced by the main floor assemblies, so that once those broke away, the core structure lacked bracing. He says that the diagonal bracing shown in your picture was actually only part of the kangaroo crane assemblies, and were removed after construction.

Who's right?

 

[R.Mackey]

Liar.

 

[Newtons Bit]

Frank, I've been trying to convince Ryan Mackey that the core sections were abundantly cross braced. I thought that, in addition to the diagonal bracing shown in your picture, the cores also had independent flooring systems.

Ryan has told us that the cores were only braced by the main floor assemblies, so that once those broke away, the core structure lacked bracing. He says that the diagonal bracing shown in your picture was actually only part of the kangaroo crane assemblies, and were removed after construction.

Who's right?

This has got to be one of the least-informed assertions I have ever heard in regards to structures. We know that the exterior columns were MOMENT FRAMES. These frames are not that stiff in resisting lateral forces compared to braced frames (cross-bracing). If there were intricate layers of braced frames in the core, than the vast majority of the lateral load (say from wind) would be delivered to the core, rather than the moment frames. These moment frames, which are exceedingly expensive to make, would be rendered useless and the load path would never be through them.

 

[TruthSeeker1234]

Here is the post where Mackey says the the cores were cross braced by the floor assemblies.

Ryan, I've asked you directly, and you've never answered.

Did the cores have their own independent flooring systems?

Were the cross braces, as shown in Frank's picture, removed after construction?

Those are both yes/no questions.

 

[TruthSeeker1234]

This has got to be one of the least-informed assertions I have ever heard in regards to structures. We know that the exterior columns were MOMENT FRAMES. These frames are not that stiff in resisting lateral forces compared to braced frames (cross-bracing). If there were intricate layers of braced frames in the core, than the vast majority of the lateral load (say from wind) would be delivered to the core, rather than the moment frames. These moment frames, which are exceedingly expensive to make, would be rendered useless and the load path would never be through them.

I thought that the perimeter had to transfer lateral load to the core, via the floor assemblies, so that the whole building flexes as a whole.

In any case, perhaps you have the intellectual honesty and courage to answer direct questions, ones that Ryan Mackey has steadfastly avoided for many months.

Newton'sBit:

Were the diagonal braces, as shown in Apollo's picture, removed after construction, or were they part of the final core structure?

Did the core have its own independent flooring system?

 

[rwguinn]

You know your case is in trouble and your arguments are specious when Ace finds it necessary to start butting in to confuse the issue...

 

[Newtons Bit]

I thought that the perimeter had to transfer lateral load to the core, via the floor assemblies, so that the whole building flexes as a whole.

In any case, perhaps you have the intellectual honesty and courage to answer direct questions, ones that Ryan Mackey has steadfastly avoided for many months.

Newton'sBit:

Were the diagonal braces, as shown in Apollo's picture, removed after construction, or were they part of the final core structure?

Did the core have its own independent flooring system?

The diaphragm of the building (in this case, the concrete floor slab) transfers lateral loads to the various different lateral elements in the structure. This is a very rigid element and will deliver the loads in proportion to the stiffness of lateral resisting elements. Moment frames are no where near as stiff as braced frames. The core area was sitting on a 5"+1 1/2" slab and the other areas on a 4" + 1 1/2" slab. These will act continuously.

You can find out information on this by reading the fema report (chapter 2). Just do a search for "brace". The lower seven floors of the core were "cross-braced". This was likely done for a number of reasons which I'll not get into here, but there was NO cross-bracing of core members at or near the impact. Though I think I read somewhere that there was cross-bracing at mechanical floors, but I can't remember where that was at.

 

[TruthSeeker1234]

You know your case is in trouble and your arguments are specious when Ace finds it necessary to start butting in to confuse the issue...

Guinn, another engineer, jumps jumps in to avoid the question. RW, sir, please answer these very direct, very simple questions:

Were the diagonal braces, as shown in Apollo20's picture, removed or left in the cores?

Did the cores have independent flooring systems?


Thank You.

(pssst. When you government guys avoid questions, it tells us where to keep digging)

 

[TruthSeeker1234]

The diaphragm of the building (in this case, the concrete floor slab) transfers lateral loads to the various different lateral elements in the structure. This is a very rigid element and will deliver the loads in proportion to the stiffness of lateral resisting elements. Moment frames are no where near as stiff as braced frames. The core area was sitting on a 5"+1 1/2" slab and the other areas on a 4" + 1 1/2" slab. These will act continuously.

You can find out information on this by reading the fema report (chapter 2). Just do a search for "brace". The lower seven floors of the core were "cross-braced". This was likely done for a number of reasons which I'll not get into here, but there was NO cross-bracing of core members at or near the impact. Though I think I read somewhere that there was cross-bracing at mechanical floors, but I can't remember where that was at.

Great stuff. Can you attempt to answer my questions now? If you don't know, or are not qualified, just say so.