What are the most glaring flaws in the Popular Mechanics "debunking" of 9/11?

reply to post by ANOK


Shudder...I think of all my years on a motorcycle and picture bugs blowing my head off.

reply to post by ANOK


www.civil.northwestern.edu...

So then why are these people saying it is what happened to the WTC, and that you are wrong?

reply to post by GenRadek


They're paid.

reply to post by Yankee451


Seriously? That's your rebuttal? You didn't even see if it made sense or not. Did you notice that it has a bibliography of sources for their data and a lot of math? Or is every non-truther a paid government disinfo agent? Because that must mean there are a lot of disinfo agents.

reply to post by Varemia


Seriously?

This is the point you choose to argue?

Also more info for ANOK as to the response of long span trusses under fire conditions:

Effect of fire on composite long span truss floor systems

More interesting info showing how wrong ANOK is in his assumption that a sagging truss does not exter lateral force, causing the exterior columns to bend in

fire-research.group.shef.ac.uk...

Originally posted by GenRadek
reply to post by ANOK

 

www.civil.northwestern.edu...

So then why are these people saying it is what happened to the WTC, and that you are wrong?

You keep appealing to authority every time the discussion goes over your head.

I don't care what they say, I am showing you KNOWN excepted physics, why can't you except it? Do you not realise we are saying that the OS is a lie? So why would you think they'd NOT lie to cover up their other lies?

If you think I'm wrong then show me where I'm wrong, you explain how Newtons laws of motion work.

Do you really think the crush down crush up model can work? It's nonsense. How would the upper block stay as a whole block? And how would it crush when it hit the ground, and not during the collapse?

This is the silly hypothesis that treats the top block of floors as one whole block falling on just ONE floor of the lower block which again is nonsense. You have to treat it as one whole block falling on one whole block , or one floor falling on one floor, for correct analysis. If the top block is crushing lower floors then the upper block is not going to stay undamaged until it's finished crushing the lower floors. This is what I've been trying to explain to you for many posts now, NEWTONS laws of motion is all you need to prove you wrong. The top CAN NOT crush the bottom without being crushed itself, even if only partly. If the top did manage to crush all the way through to the bottom it would not crush itself when it hit the ground. Classic pancake collapse, or progressive collapse, always has intact floors still left.

Originally posted by GenRadek
Effect of fire on composite long span truss floor systems

Why would you link me to something I have to pay for?

fire-research.group.shef.ac.uk...

Can't you find something that makes your point that isn't connected to the 911 events? I look at anything that makes claims as to how the towers fell as suspect. You should be able to prove your point about trusses without referring to 911 connected literature, if it is true. If it claims sagging trusses can put a force greater than they were already creating on the columns they were connected to then it is not factual.

For you to have any credibility here you need to explain using known physics, in your own words, how sagging trusses can put more force on the columns, and prove that the columns could not hold that force if it was present.
Can you do that without linking to someone else's work that I don't agree with? I'm not interested in appeals to authority, I am debating you no one else. If you want me to wade through someone else's paper you need to do more than just link to it. Notice I don't do that? I don't give out homework. Make your point, don't point me to someone else's.

reply to post by ANOK


How about rather than either side talking about blocks, we should treat every single one as sets of individual floors. If you think about it that way, then you have the first impact of collapse being 1 floor versus 1 floor with the weight of the section above. Both floors would be destroyed and turned into a mass of debris within the tower. Then, the second floor from above drops down without any supports to hold it up. It impact the debris of two floors and makes it crash down into the floor below, essentially creating an additional floor of impact below for every single floor on the above collapsing section until the majority of the tower (say, 60 floors or more) has been destroyed simply by the merit of the initial energy of the falling section of building. Then, the rest would naturally fail from the weight and acceleration by gravity, allowing the collapse to continue downward to the ground, with every space between floors acting as a debris dropping mechanism.

One might be able to see this with x-ray vision and slow motion replay, but that's not quite possible, so we'll have to deal with the visualization for now and see if it fits the outward behavior that was perceived.

Edit: as for sagging, consider a string between two objects. If you put your finger anywhere on the string and push down, it will tug on one or both objects connected to it. This is the same idea with the sagging steel, since there's no way it was hot enough to allow the steel to stretch. With the weight on the steel, the weakening made it prone to sagging.

reply to post by Varemia


That is simply reiteration of the OS's pancake explanation. For starters we have 101 stories + 6 stories of foundation below ground.

Statics or the Physics of structures, if you recall uses a Free Body Diagram which depicts the forces in which a structure is subjected to. You have the forces of gravity pushing downward opposed by the cumulative forces pushing upwards called the Normal.

Simply put, in order for anything to stand statically, including ourselves, the Normal Forces must exceed the Forces (F=ma) pushing downwards. And why we need leg muscles in order to stand upright.

So back to the 911 scenario. Now we have the top of the tower falling and is no longer a static mass but is now creating Kinetic Energy which IS adding to the overall Forces pushing downwards now. OK.

This now Kinetic Energy can be calculated as one half times the mass of the 15 or so floors x 9.8 meters/sec squared which is the acceleration of gravity.


In order for the entire structure to collapse as it did. Especially as quickly as it did. The energy created by the 15 floors would have to exceed the forces of the 90 floors below or 6 times the undamaged supporting structure of 90 or so floors of structural steel below. Structural steel also designed to support an additional 20% share of it's load for safety.


Underwriters Laboratory aka (UL), a nationally recognised testing firm, had performed tests on model replicas of the WTC towers's girders/trusses and heated them well beyond the temperatures in which the WTC structures were exposed to.

We did test the floor models in August 2004,” Ryan said, “and those tests disproved the primary theory behind the collapse of the buildings.”

“The floor models didn’t collapse in the tests,” Ryan said, “and these (models) were in furnaces in much hotter temperatures, for a longer period of time (as compared with the temperature and endurance of the fires on 9-11). Yet, they still did not collapse.”

NIST manipulated the test data in order to achieve the results in which they were seeking by doubling the time their computer model exposed the columns to fire – 90 minutes, as opposed to 50 minutes.

In summary:

Eventually, NIST was forced to substitute the “pancake theory” (which wrongly hypothesized that the combined force of the upper floors began a domino effect downward) for the “inward bowing theory,” which argues that the floors and walls of the WTC buildings buckled to the point where they could no longer support the weight of the structure – an equally implausible explanation for the collapses, given the low temperatures inside the structures.

Kevin Ryan was fired from his job with Underwriters Laboratory one week after he challenged the results of the NIST report, the US government’s official version of the reasons for the WTC collapses.

rt.com...

Originally posted by ANOK

Originally posted by FDNY343
But, again, you still do not understand what my point was. The MASS part is not as important to KE as the SPEED part is! GD!! Why is this so hard for you to understand?

You are wrong once again.

If a fly hits a car windshield, remember Newtons 3rd law equal opposite reactions, the force on the windshield is the SAME as on the bug. What makes the bug go splat, KE or MASS?

It's the mass mate. Both objects are putting the same force on each other, the only difference is the mass.

Consider this question...

3. Miles Tugo and Ben Travlun are riding in a bus at highway speed on a nice summer day when an unlucky bug splatters onto the windshield. Miles and Ben begin discussing the physics of the situation. Miles suggests that the momentum change of the bug is much greater than that of the bus. After all, argues Miles, there was no noticeable change in the speed of the bus compared to the obvious change in the speed of the bug. Ben disagrees entirely, arguing that that both bug and bus encounter the same force, momentum change, and impulse. Who do you agree with? Support your answer.

www.physicsclassroom.com...

Ben Travlun is correct.

The bug and bus experience the same force, the same impulse, and the same momentum change (as discussed in this lesson). This is contrary to the popular (though false) belief which resembles Miles' statement. The bug has less mass and therefore more acceleration; occupants of the very massive bus do not feel the extremely small acceleration. Furthermore, the bug is composed of a less hardy material and thus splatters all over the windshield. Yet the greater "splatterability" of the bug and the greater acceleration do not mean the bug has a greater force, impulse, or momentum change.

Answer

Yes, I understand that a bug is not going to do anything to the windshield, I unserstand that. The bug also is not a rigid body comparable to the windshield.

However, when you compare two rigid structures, the analysis is much more accurate.

Originally posted by nh_ee
Underwriters Laboratory aka (UL), a nationally recognised testing firm, had performed tests on model replicas of the WTC towers's girders/trusses and heated them well beyond the temperatures in which the WTC structures were exposed to.

We did test the floor models in August 2004,” Ryan said, “and those tests disproved the primary theory behind the collapse of the buildings.”

“The floor models didn’t collapse in the tests,” Ryan said, “and these (models) were in furnaces in much hotter temperatures, for a longer period of time (as compared with the temperature and endurance of the fires on 9-11). Yet, they still did not collapse.”

Where are these tests? UL has not published these tests at all.

Originally posted by nh_ee
Kevin Ryan was fired from his job with Underwriters Laboratory one week after he challenged the results of the NIST report, the US government’s official version of the reasons for the WTC collapses.

rt.com...

Kevin Ryan was fired because he claimed things that UL did not support. He also did NOT work for UL, he worked for Environmental Health Laboratories Inc., a subsidiary of UL. He worked at Environmental Health Laboratories, which is responsible for water testing, and has NOTHING to do with their Fire Protection department.

www.mindfully.org...

screwloosechange.blogspot.com...
You should read the entire article here. It's got some interesting information.

reply to post by ANOK


Because according to physics, the way the WTC collapsed is acceptable. YOU just dont accept it because it does not fit with your "Its gotta be a controlled demolition" fantasy. Its that simple.

I am very well aware of how Newton's laws work. I am also aware that it is a lot more complicated than your simplistic version of "it cant happen according to Newton's 3rd law." Well I posted to you a paper that describes in detail of how it can happen and DOES happen. Did you read it? It is only 12 pages.

You just throwing out there "Newton's 3rd Law" means diddly squat if you dont bother to do some more research into how the mechanism works in something like the collapse of the WTC. The very first paper shows how it happened. It's not an appeal to authority when I use a paper written by someone who is very knowledgeable in this field, and can explain the entire physics side of it, that adds everything YOU like to leave out (ie momentum, mechanics, potential energy, kinetic energy, force, gravity, energy absorption, accretion of mass, etc)
www.civil.northwestern.edu...

The kinetic energy of the top part of the tower impacting the
floor below was found to be about 8.4X larger than the plastic
energy absorption capability of the underlying story, and considerably
higher than that if fracturing were taken into account
(Bažant and Zhou 2002a). This fact, along with the fact that
during the progressive collapse of underlying stories [Figs. 1(d)
and 2] the loss of gravitational potential per story is much greater
than the energy dissipated per story, was sufficient for Bažant and
Zhou (2002a) to conclude, purely on energy grounds, that the
tower was doomed once the top part of the tower dropped through
the height of one story (or even 0.5 m). It was also observed that
this conclusion made any calculations of the dynamics of progressive
collapse after the first single-story drop of upper part superfluous.

But hey, rather than brag to me and everyone about how well you know Newton's Third Law and how it makes the collapse impossible according to you, explain how the conclusions and calculations done in this paper are all wrong according to your precious N3rdL. You have all the calculations in the paper that explain in detail exactly how the mechanisms work, and how it collapsed the way it did. According to this data, you are wrong horribly. Newton's 3rd Law is just drop in the bucket and is much much much too simplistic to apply to this scenario. Was N3rdL in play at the WTC? Yes it was, of course. Was there a lot more to it than just N3rdL? Oh yes. Did you miss a lot? Yes. Just throwing out N3rdL does nothing in the debate, other than trying to use fancy words to impress the uninformed. I can do that too. According to the laws of thermodynamics, the WTCs collapsed properly. See? I can say fluffy techno-jargon too. Sounds impressive. Does it mean anything here? Not really. But for this scenario, the biggest physics "buzzwords" are "kinetic energy". Not N3rdL.

Also, just because two objects meet does not mean they are exerting equal and opposite forces on each other. I thought you would have at least realized this fact. When forces are unequal, acceleration occurs. Did you forget that fact, ANOK, in your beloved N3rdL? Best example is pushing a car in neutral. You are pushing on the car, and as the velocity is increasing, you are exerting more force than the car is on you. Once the car is rolling at constant speed, the forces are now equal.

And by the way, this is my favorite part of understanding Newton's Laws and their misconceptions:

* Newton's third law is frequently stated in a simplistic but incomplete or incorrect manner through statements such as

Action and reaction are equal and opposite
To every action there is an equal and opposite reaction

These statements fail to make it clear that the action and reaction apply to different bodies. Also, it is not because two forces happen to be equal in magnitude and opposite in direction that they automatically form an action-reaction pair in the sense of Newton's Third Law.

en.wikipedia.org...

Sorry ANOK, but it looks like you just got a whole heapin helpin of crow. Dig in!

So who here again knows something about Newton's Laws? Well it sure isnt you. Newton's Laws cannot be so simplified. I guess this is where 99% of the mistakes in the Truther world occur. Oversimplification. Better luck next time ANOK.

Here is an interesting article on the common misconceptions of Newtons Third Law:
www.eric.ed.gov... Page 16 and 17 of the paper are most important.

Oh, here are some pictures of pancaked floors at WTC:

What are the most glaring flaws in the Popular Mechanics "debunking" of 9/11

Hard to say, all their flaws are equally as flawed as each other. The one about the collapse perhaps... Major flaw there! The whole article was just plain wrong in my opinion, I don't think it's worth the time or energy to debate, it's simply a cesspit pit of professional disinformation to me.

reply to post by GenRadek

Here is an interesting article on the common misconceptions of Newtons Third Law: www.eric.ed.gov... Page 16 and 17 of the paper are most important.

Good paper. It helps clear up some misconceptions of physics I've had.

Sure page 16 and 17 are important...since the author is lamenting the poor understanding of the third law by physics students after they've been taught the subject, much of this article focuses on those misconceptions, and they enumerate the difficulties in understanding at the top of page 16:

A possible solution to students' difficulties with the concept of force as an innate or acquired property of objects is to simply re-label their naive concept of force by calling it, for example, "momentum" or "kinetic energy"

you feel me FDNY343?

He goes on:

1) Momentum or kinetic energy do not cause motion (as students view force causing motion), they are simply properties of a moving object arising as a result of the motion of that object.

2) Momentum and kinetic energy vary with the fame of reference. If a student were to simply re-label his conception of force to be, for example, momentum, she might well ask how an object could have a lot of force (or strength of forcefulness) in one frame of reference, and none from another perspective.

3) If a student is encouraged to equate momentum with her naive conception of force, she is likely to add momentum to force in problem solving, or be confused about why it is improper to do so.

For the above reasons, re-labeling the student's naive concept of force is not a satisfactory solution to the problem of the naive view of force as a property and may lead to an even greater confusion (how many times have the students used the words "the force of momentum" in a physics class)...

How many times have the OSers used the words "kinetic energy" on these forums?

As good as page 16 is, I like page two and three the best:

A number of studies conducted in recent years have demonstrated a wide range of beliefs about physical phenomena which students have apparently formed on their own without the benefit of formal instruction. Particularly well documented have been student beliefs which are in contradiction with the ideas of Newtonian mechanics. For example, many students hold the belief that there is a force on or in an object in the direction of the object's motion, when in fact no force is necessary to keep an object moving at constant velocity...

...Thus some students view objects as inherently more "force-full" by virtue of their mass, speed, activity, etc.

reply to post by Yankee451


The point was, Yankee451, that though its true that there are always forces acting in the collapse of the event, that is just the tip of the iceberg. There are far more things to talk about rather than just saying: Equal and opposite reaction".

You have to deal with energy, momentum, mechanics, etc. Just saying something won't happen because of a simplistic view of N3rdL, (like how ANOK is so apt at doing), is a very bad misconception that opens up more erroneous assumptions.

NrdL deals with force. But just saying "N3rdL says it cant happen" is ignoring all aspects of classical mechanics, acceleration, velocity, kinetic energy, etc. Plus it means nothing when you cannot show how it doesnt work. ANOK's simplistic view of "equal-action equal-reaction" is meaningless. That is what I was conveying.

Originally posted by Varemia
reply to post by ANOK

 

How about rather than either side talking about blocks, we should treat every single one as sets of individual floors.

This is what I'm saying. You have to treat the top AND bottom as individual floors, or both as complete blocks. Either way works.

If you think about it that way, then you have the first impact of collapse being 1 floor versus 1 floor with the weight of the section above.

Now you have just contradicted yourself. I floor vs 1 floor does not include the weight above, that would be one block falling on one floor. It doesn't work like that because of NEWTONS 3rd LAW, opposite and equal reactions. If you want to consider the top as one block, with all that weight, then you have to consider the mass of the block its falling on, not just one floor, and the fact that it will put as much force on the falling section, as the falling section puts on it. Equal opposite reactions.

Conservation of momentum, the top will want to continue falling down, the bottom will want to continue pushing up equally. Mass is what decided which object wins that battle.

The bottom is going to put the SAME force on the top, as the top puts on the bottom. If you take it by one floor landing on one floor you have more or less equal masses, we KNOW the floors were destroyed, so this MUST be when they were destroyed, so you would run out of floors before the collapse was complete. If you take it by blocks you have a 30 floor block falling on an 80 floor block (not just one floor, you have to consider the bottom is the same as the top, one block). This means you have a smaller mass, 30 flrs, overcoming a larger mass of 80 flrs, it won't work either.

Both floors would be destroyed and turned into a mass of debris within the tower.

Exactly, so if both floors are destroyed you would run out of falling floors before all the bottom floors are destroyed, right?

Then, the second floor from above drops down without any supports to hold it up.

To make this claim you have to explain how the supports holding them up failed in the first place.

It impact the debris of two floors and makes it crash down into the floor below, essentially creating an additional floor of impact below for every single floor on the above collapsing section until the majority of the tower (say, 60 floors or more) has been destroyed simply by the merit of the initial energy of the falling section of building. Then, the rest would naturally fail from the weight and acceleration by gravity, allowing the collapse to continue downward to the ground, with every space between floors acting as a debris dropping mechanism.

You're contradicting yourself again, you have already admitted floors were destroying each other as they fell, so as each floor is destroyed it is no longer available to cause any more crushing of other floors.

One might be able to see this with x-ray vision and slow motion replay, but that's not quite possible, so we'll have to deal with the visualization for now and see if it fits the outward behavior that was perceived.

This is true, but we know Newtons laws apply, you don't have to actually see it to know those laws would not be ignored. The only away they could be ignored is if there was another energy acting on the towers other than gravity.

Edit: as for sagging, consider a string between two objects. If you put your finger anywhere on the string and push down, it will tug on one or both objects connected to it.

Oh dear another lame analogy. Your piece of string is NOT malleable, it will not sag, it has a fixed length once you take up the slack. If you were to push down on a piece of malleable steel it will just keep sagging. Not the same thing at all.

But regardless again there was no one pushing down on the trusses, no extra force was added that they did not already hold up.

Originally posted by GenRadek
reply to post by Yankee451

 

The point was, Yankee451, that though its true that there are always forces acting in the collapse of the event, that is just the tip of the iceberg. There are far more things to talk about rather than just saying: Equal and opposite reaction".

Actually no there isn't, it proves the OS wrong all by itself. You just don't like that fact, and no amount of your opinions will change that fact.

You have to deal with energy, momentum, mechanics, etc. Just saying something won't happen because of a simplistic view of N3rdL, (like how ANOK is so apt at doing), is a very bad misconception that opens up more erroneous assumptions.

Newtons laws apply to ALL things in motion and can not be ignored. No one is ignoring energy, moments, mechanics etc, you are misunderstanding them as I have shown. They ALL come into play but if you ignore Laws of motion then you will be lost. It's hilarious you don't even realize MOMENTUM is NEWTONS 2nd law, very important to understand if you want to understand the 3rd law. The law of conservation of energy is what Newtons laws explain.

NrdL deals with force. But just saying "N3rdL says it cant happen" is ignoring all aspects of classical mechanics, acceleration, velocity, kinetic energy, etc. Plus it means nothing when you cannot show how it doesnt work. ANOK's simplistic view of "equal-action equal-reaction" is meaningless. That is what I was conveying.

No it's not. Simplistic? You have proven you don't even understand simplistic physics. You want us to believe it's far more complicated than it is because you fail to understand basic physics and how to put them into context.

reply to post by ANOK


And yet, AGAIN, you ignore the paper that talks about the mechanics in detail which talkas exclusively about just how it was possible and did happen, all in accordance with the laws of physics.

For the fourth time:
www.civil.northwestern.edu...

I understand very well how Newton's laws work. And with my understanding that there is more to the WTC collapses, than you just saying, N3rdL forbids it because YOU say so. Come now ANOK, I gave a paper, very simple 12 page paper, that goes into detail about the collapses of the WTC. Are you going to address it at all or are you going run and hide behind your simple grade school views of Newton's Laws? You keep tossing out Newton's Laws as if by just saying them, it means something. Yeah And I can say, the laws of thermodynamics agree with the events on 9/11.

Now you have just contradicted yourself. I floor vs 1 floor does not include the weight above, that would be one block falling on one floor. It doesn't work like that because of NEWTONS 3rd LAW, opposite and equal reactions. If you want to consider the top as one block, with all that weight, then you have to consider the mass of the block its falling on, not just one floor, and the fact that it will put as much force on the falling section, as the falling section puts on it. Equal opposite reactions.

Conservation of momentum, the top will want to continue falling down, the bottom will want to continue pushing up equally. Mass is what decided which object wins that battle.

The bottom is going to put the SAME force on the top, as the top puts on the bottom. If you take it by one floor landing on one floor you have more or less equal masses, we KNOW the floors were destroyed, so this MUST be when they were destroyed, so you would run out of floors before the collapse was complete. If you take it by blocks you have a 30 floor block falling on an 80 floor block (not just one floor, you have to consider the bottom is the same as the top, one block). This means you have a smaller mass, 30 flrs, overcoming a larger mass of 80 flrs, it won't work either.

I just have to chime in here, as this is horribly wrong. The way the WTC was designed, each floor was a separate section which had the only connections on either end to the exterior and interior. No other forms of support (ie vertical columns in between floors and columns, etc) held up the floors. They were only held up on each end of the truss in seats connected with two 1" bolts. That was it. When the top 30 floors started to move down as one unit, they only had one floor height to drop. This was enough to overwhelm the static loading of the floor below. A 30 floor section moving as one unit is like a Mack truck impacting a bike. So the first floor below get destroyed. Now, you have the mass of the 30 floors above plus the newly accquired mass of the floor destroyed below. Now its going to impact the floor below. Now that floor is being impacted with the increasing mass and velocity of 31 floors. So now its going to be destroyed as well. The floor below is being impacted with the mass and velocity of 32 floors. And so on and so on. The mass was constantly increasing during the collapse as was its velocity. Each floor that was destroyed, now added to the mass of the collapse. In effect, it was the top whole section impacting separate floor sections below. The Towers were basically hollow tubes which allowed the for towers to telescope in. The exterior columns peeled away as well, appearing to "launch" steel columns hundreds of feet, but in reality, they were just tipping over once stripped free from the floors. I dont know why you are thinking that it only can be seen as one block hitting another block, ala Richard "BoxBoy" Gage. If that is where you are taking your physics lessons fom, well....

Once again, you are going down the over simplistic road where its just wrong!

Also, how come this can happen:

reply to post by GenRadek


I tried to suffer through another Bazant paper. Here's as far as I could get before I couldn't suspend disbelief anymore:

The destruction of the World Trade Center _WTC_ on September 11, 2001 was not only the largest mass murder in U.S. history but also a big surprise for the structural engineering profession, perhaps the biggest since the collapse of the Tacoma Bridge in 1940.

“Biggest mass murder in US history”, but also a surprise! Is he trying to reach for the emotional angle again, or is logic his bag?

It’s only a surprise if you don’t consider explosives.

No experienced structural engineer watching the attack expected the WTC towers to collapse. No skyscraper has ever before collapsed due to fire. The fact that the WTC towers did, beckons deep examination.

Deep examination still beckons, hopefully from someone without the name of Bazant.

Although the structural damage inflicted by aircraft was severe, it was only local. Without stripping of a significant portion of the steel insulation during impact, the subsequent fire would likely not have led to overall collapse _Bažant and Zhou 2002a; NIST 2005_. As generally accepted by the community of specialists in structural mechanics and structural engineering _though not by a few outsiders claiming a conspiracy with planted explosives_, the failure scenario was as follows:

Note how the get right into it with talk of the “outsiders” and “conspiracy”. Why doesn’t he use the same thinly veiled disdain for the "insiders" of OS “conspiracy”? This guy’s the biggest bought and paid for shill on the planet. His name is on almost every OS whitewash report you guys throw at us, as if he’s Moses down from the mountain.

In this paper _based on Bažant and Verdure’s _2006_ identical report presented at the U.S. National Congress of Theoretical and Applied Mechanics, Boulder, Colo., June 26, 2006; and posted on June 23, 2006, at www.civil.northwestern.edu/people/bazant.html_

Referencing his own work again…what the heck, is he the only “independent engineer” willing to associate his name with these reports?

, attention will be focused on the progressive collapse, triggered in the WTC by fire and previously experienced in many tall buildings as a result of earthquake or explosions_including terrorist attack_.

“Progessive collapse, triggered in the WTC by fire? What, no planes?

The images of the North tower show at least one person standing in the gash waving for quite some time, without much fire at all visible:
thewebfairy.com...#

A simplified one-dimensional analytical solution of the collapse front propagation will be presented. It will be shown how this solution can be used to determine the energy absorption capability of individual stories if the motion history is precisely recorded.

Okay, so now it gets good…he’s going to build his model.

Because of the shroud of dust and smoke, these histories can be identified from the videos of the collapsing WTC towers only for the first few seconds of collapse, and so little can be learned in this regard from that collapse.

Maybe not…hes out with an excuse to not put too much stock in the video record.

However, monitoring of tall building demolitions, which represent one kind of progressive collapse, could provide such histories. Development of a simple theory amenable to inverse analysis of these histories is the key. It would permit extracting valuable information on the energy absorption capability of various types of structural systems in various collapse modes, and is, therefore, the main objective of this paper.

So, this is a theoretical paper? Oh. I thought this was offered as proof of something.

Many disasters other than the WTC attest to the danger of progressive collapse, e.g., the collapse of Ronan Point apartments in the United Kingdom in 1968 _Levy and Salvadori 1992_

He uses Ronan Point Apartments to bolster his argument that the WTC could have collapsed. Lets look at Ronan Point:

The Ronan Point Apartment Tower was constructed using the Larsen-Neilsen system. Developed in Denmark in 1948, the Larsen-Neilsen system was “composed of factory-built, precast concrete components designed to minimize on-site construction work. Walls, floors and stairways are all precast. All units, installed one-story high, are load bearing” (ENR 1968), p. 54). The ‘know how’ of the Larsen-Neilsen system is a combination of production techniques, erections methods, and jointing details (Griffiths et al. 1968). The system was not intended for buildings over six stories (Wearne 2000, p. 140).

Designed as a precast concrete flat-plate structure, each floor of Ronan Point was supported by the load-bearing walls directly beneath. The only path of gravity load transfer was through these loadbearing walls.

failures.wikispaces.com...

So he’s comparing Ronan Point to the WTC…do you think this is an accurate comparison? Ronan Point was made of precast concrete flats all stacked on top of each other, but even then only one corner of the building collapsed, not the whole thing reduced to rubble as we’re led to believe is inevitable.

What’s next on his list of examples?

the bombing of the Murrah Federal Building in Oklahoma City, Okla., in 1995, where the air blast pressure sufficed to take out only a few lower floors, whereas the upper floors failed by progressive collapse;

Again a smaller concrete structure, which although was shattered, still did not completely collapse. Why not? Concrete seems much stronger than steel so far, Too bad they didn’t make the WTC out of concrete…at least some of it…or did they?

Oxford University in 1992 published this on the WTC concrete cores:

Modern Skyscrapers such as the World Trade Center, New York, have steel and concrete hull-and-core structures. The central core, a reinforced concrete tower, contains lift shafts, staircases, and vertical ducts. From this core the concrete and steel composite floors span on to a steel perimeter structures: a lightweight aluminum and glass curtain wall encloses the building.

algoxy.com...

Next up is the 2000 Commonwealth Ave. tower in Boston in 1971

In January of 1971, half of the 16-story, #2000 Commonwealth Avenue condominium in the suburbs of Boston, Massachusetts collapsed. High winds had blown over space heaters on the top floor, causing a fire in the timber shoring underneath the concrete pour made at roof level the day before...the shoring under the roof slab failed.

www.controlled-demolition.com...

Why is he comparing the WTC to a building that was still under construction? Even this one didn’t completely collapse.

The New World Hotel in Singapore is next. This one actually did collapse completely, but it was a six story structure which was poorly built and over loaded. Is it fair to compare that to the WTC?

What’s next? For further examples he includes:

Many buildings in Armenia, Turkey, Mexico City, and other earthquakes, etc.

Earthquakes and "etc". He forgot Borneo?

And then he goes for the coup de grace, and includes:

A number of ancient towers failed in this way, too…

Ancient towers. Nuf said.