Gravity-driven demolition

[William Seger]

How many times have you heard something like this: "I'm sure demolition companies will be glad to learn that you can bring down a building with just gravity -- no need for all those explosives they've been using."

Well... it seems that at least one demolition company has learned something. Here's a demolition that was performed in France by weakening the columns on two floors and then yanking them out of the way with cables attached to hydraulic jacks:

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

I wonder why this looks so similar to the WTC tower collapses... anyone?

ETA: Better video: http://www.strimoo.com/video/12509995/Mort-d-un-batiment-MySpaceVideos.html
Note that one slow-motion view in this video shows that Bazant et al. nailed the "crush-down/crush-up" mechanism, too.

[greyl]

1. Is it because...

that demolition and the WTC collapses were all ultimately... Gravity Driven Collapses? You don't say.

Interesting that the 2 floors the demo team in France weakened were near the middle of the building - 5 or 6 floors from the top - and the thing still somehow collapsed all the way to the ground. Pretty big blow to the MIHOPers.

[William Seger]

4. MIHOPers are crush-proof (n/t)

[tetedur]

14. Un monticule de gravas, but certainly not "down to the ground"

Interesting the way they hollowed out the building...



and took out the "weakened" floors in one instant...



It would be very interesting to see if they could've "weakened" the top floors, pulled them and demolished the bottom 11 floors....

[greyl]

17. True.

However, I'm pretty sure all the lower floors can be considered demolished. The prepped building wasn't tall/massive enough to impart the crushing forces present in the WTC.

[tetedur]

18. If both of the WTCs destruction was just the crush of gravity

why didn't the cores go down when the rest of the buildings did?




Controlled demolition uses gravity too.

[William Seger]

28. Because the core was relatively strong

... just as conspiracists claim, and that picture indicates to me that the gravity-driven collapse broke floors away from the core before a crushing force could be applied to the columns. If the core had been cross-braced like a stand-alone tower -- what structural engineers call a moment frame -- it's seems very possible that some of the "spire" would have continued to stand. However, the core was designed only as a gravity frame, which depended on the floors for lateral support. Without that support, the core columns were susceptible to buckling, which they apparently did a few seconds after the main part of the collapse was over. It's seems likely that something similar was happening all the way down, but we just don't see it through that cloud of dust. When I try to visualize what was happening in that collapse, I don't see any mystery in that "spire." What mystery do you see?

[tetedur]

29. I don't see the top mass crushing down the lower mass.

I see the top masses disintegrating and for the most part, falling over the sides of the building's footprint. The speeds at which this happened suggests to me there wasn't much resistance in the lower masses.

[William Seger]

31. Do you have X-ray vision?

> "I see the top masses disintegrating..."

Please show me the video where you see any such thing; I haven't seen one. But I have read some people stating similar descriptions of videos I have seen, and those descriptions are simply not accurate. I've seen videos that appear to show that the bottom floor or two of the falling block has been destroyed along with the top floors of the lower structure, judging by the apparent position of the collapse front relative to the top of the tower. But then after that you can't possibly see what's happening at the collapse front because of the cloud of debris. I can tell from their descriptions that some of the people making that assertion have apparently been fooled by the fact that a cloud of lighter dust hangs in the air while the heavier debris falls downward, but the collapse front must actually be somewhere in between. And of course, no video show anything at all about what's happening at the core. Your description of "top masses disintegrating" is imaginary.

> "... and for the most part, falling over the sides of the building's footprint."

But it's not physically possible for the "most part" of the debris to be falling over the side, given that the growing debris pile is 208 feet wide. Only the stuff already near the edge can possibly fall over the side. Debris near the center can't possibly do that because it's trapped under the pile. It doesn't take much solid material like concrete and drywall to make a lot of dust. Again, your description is imaginary.

> "The speeds at which this happened suggests to me there wasn't much resistance in the lower masses."

And what does the speed of the Balzac building collapse suggest to you? The speed of the collapse simply indicates to me that the resistance in the lower structure (not "masses") was indeed small compared to the forces involved. The tower structure was designed such that it might actually carry as much as three times the static weight of the top part. But the top part wasn't static; it was falling. If you don't properly take that into account, then you will never understand the Balzac demolition, either.

[SDuderstadt]

37. all ''truthers'' have x-ray vision, ws...

didn't you know that's why they can see things the rest of us mere mortals simply can't see? sheesh.

[jberryhill]

2. Aha- so that's what "pull it" means....

Heh.

[SidDithers]

3. Thanks for posting that...

That second vid, in particular, is excellent.

Sid

[Realityhack]

5. That is a great vid. Thanks. n/t

[LARED]

6. Did anyone notice the squibs?

[William Seger]

7. How 'bout that "pyroclastic flow"

We need to get Jim Hoffman to calculate how many tons of silent explosives were hidden in the building. He's good at that.

[SDuderstadt]

39. i looked at it carefully several times...

and didn't see a single squid. i don't understand why you would expect to see marine life in this picture. can you help me out here?

[BooBluePotion]

8. That was the most pathetic display

of 9/11 comparisons I've ever witnessed on the Internet. You sir or madam have failed to initiate a proper lean in either demolition video. You've failed to prove if the structure was purposely weakened in its core columns and you definitely do not deserve praise for this unkept filthy city you've thrashed on my screen.

I take it you're not a deep thinker, so let me help you out here. The WTC's were not gravity induced collapses they were blast induced collapses proven by the bone, concrete, and steel fragments thrown atop surrounding buildings. Just review the North tower which was practically struck on top of its roof all of its columns were still connected. You are disinforming the good people of DU.

shame shame shame on you

[William Seger]

10. Take 2 aspirins and call me in the morning

These collisions with reality can cause severe headaches, but you'll probably recover. If symptoms persist for more than 24 hours, see your doctor.

[Theobald]

11. Ha Ha!

Quote from Boo Boo "failed to initiate a proper lean in either demolition video." Was the videographer supposed to stand on one foot or is this in reference to the leaning top of the WTC? What exactly is a 'proper' lean? Why would it matter if the top of the building in the above referenced video was leaning, since being off center would help with the demoliton?

Quote from Boo Boo "Just review the North tower which was practically struck on top of its roof all of its columns were still connected."

Your going to have to explain this sentance to me; it's non-sensical. What do you mean it was practically struck on it's roof; by the plane or did someone come in with a giant hammer when I wasn't looking? All of it's columns were not still connected, there is numerous videos that prove that, or are you suggesting all the videos were fake?

[BooBluePotion]

9. Since you have failed to answer

any of my questions, then maybe you can explain this. Where are the traces of concrete and glass projections that gravity should have surely thrust upon the surrounding buildings in your presentation?

I back slap the fact that you failed to show this!!! You should arm yourself before you leave your house since you can not think straight.

[Realityhack]

12. You DO understand do you not...

that this (video in the OP) was an intentional controlled demolition and as such people who are very good a their jobs did everything they could to reduce such debris including removing the windows?

It would then be very hard to tell much about where the glass went unless you followed the trucks a few weeks before the demolition.

I would also like to assume that you understand there are differences in construction and that this was no 110 story building. Rather it is a limited example of something that a few people have scoffed at. Unfortunately signs point to you not having such a nuanced understanding of the world.

[whatchamacallit]

13. So... you present a video of a DEMOLITION to prove the towers weren't demoed?

Gotta love that logic. :crazy:

[Realityhack]

15. How overly simplistic. It is a wonder how you fail to win a Nobel every year. n/t

[William Seger]

16. LOL, I'm pretty sure...

... that logical people can figure out what the video means. Need some help?

[Beam Me Up]

19. Wow, I'm now convinced I've been wrong all these years!

I'm completely stunned. By linking to an online video of a concrete and brick structure which was weakened in the middle such that when the props holding up the top half were pulled the top half crushed the lower half of the structure. WOW!

Who would have ever guessed that such a thing would work ON A STEEL FRAME BUILDING WITH A CORE OF STEEL AND STEEL PERIMETER, slinging hundred ton components to embed themselves in buildings across the street and leaving molten metal in the basements for weeks, especially using only the top 10 to 20 percent of it!

I'm so glad you posted this video. Now I understand that that Bush administration didn't LIE about EVERYTHING! What a fucking relief!!



:eyes:

[William Seger]

20. Glad to help

I'm thinking of developing a 12 Steps program.

[Beam Me Up]

21. I bet.

Does it involve small spaces and insects? I don't like insects, especially the biting/stinging kind.

I have to hand it to you though, who would ever have thought that a controlled demolition would look JUST LIKE a controlled demolition!!

typo

[William Seger]

22. Who would have ever thought...

... that the bottom of a building is not likely to survive having the top fall on it?

The very long list of people who knew that doesn't include this famous expert on controlled demolitions:

[Beam Me Up]

23. Yeah. Especially fall SYMMETRICALLY on it, just like a controlled demolition n/t

[William Seger]

24. Oh, so a symmetric fall...

... indicates the collapses were "just like a controlled demolition?"

So, what would an asymmetric fall indicate? Same thing?

[Realityhack]

26. Anaylogies are like sand castles...

Never mind...

The point is that neither WS nor anyone else is presenting this one video as clinching proof the twin towers colapsed due to gravity alone. That is your straw man. Beat him well for he deserves it.
Rather the video counters a very specific argument made by *some* CD advocates in a visual way as calculations have proven beyond their understanding.

Obviously this is not a recreation of the colapse of the twin towers. But neither is it unrelated entirely.

[wildbilln864]

25. Thanks for the laugh!

:rofl: :rofl: :rofl: :rofl:

[William Seger]

27. Well, at least you still have your sense of humor

Not many people are so cheerful after being proven to be so wrong about something.

[wildbilln864]

68. I haven't been proven wrong about anything!

Your opinion not withstanding.

[SDuderstadt]

69. You get thrashed here...

on a regular basis, Bill. It's a hoot to watch.

[wildbilln864]

70. I'll survive sduders! nt

[wildbilln864]

124. your opinion! nt

[scott75]

30. Tony Szamboti, a mechanical engineer, counters...

His message follows...

I noticed William Seger on DU is trying to use the Balzac-Vitry demolition in France to show that a building can be crushed by gravity alone without explosives. This is true, if there is a deceleration at impact to generate enough of an amplified load.

On the Balzac-Vitry they used jacks on two floors and cut/removed the columns and then pulled the jacks to let the two stories drop unimpeded. The same thing can be done with explosives. The important thing is to fall long enough to gain enough momentum to do the job at impact.

What Seger isn't explaining or showing is that after the unimpeded drop the upper block of the Balzac-Vitry building had a significant deceleration at impact, which is what was needed to generate the amplified load required to crush the bottom of the building and itself.

David Chandler measured the Balzac-Vitry building's roof fall for me and it shows the deceleration after the two story fall. The graph for WTC 1 does not have any deceleration. Without deceleration there is no natural mechanism to continue the collapse after the initial fall, so WTC 1's columns had to be being removed continuously for at least the nine stories or 114 feet we were able to measure while it was visible.

Linked to is a web page which shows the graphs Tony sent me of both the Balzac-Vitry building and WTC 1:
http://scott3x.tripod.com/arguments/tony/WTC_bal.html

[Bolo Boffin]

32. The "missing jolt"

Tony is measuring WTC 1 from the north. The south side is where the leading edge of the collapse is. The buildings were such large structures that the south part of the building began to fall before the north side did. That's what causes the illusion of the antenna "sinking" into the roof before the north side starts to fall.



I believe Mr. Szamboti should have his eyes examined.

[William Seger]

33. Here's the flaw in Mr. Szamboti's logic

People who are much more technically articulate than I have attempted to explain this to him, so I wouldn't expect my explanation to make any difference to him, but here is Szamboti's logic laid out in full:

1) The simplified linear model analyzed by Bazant would show a deceleration "jolt." True, but Bazant never represented that as a realistic model of the actual collapse. On the contrary, he explained that he was analyzing what he took to be a limiting, optimistic case -- in order to make the analysis tractable -- and stated his opinion that if that model failed, then failure of the real building was to be expected. That may or may not be the case, but the only other detailed model offered so far by "the other side" is Gordon Ross', which has been shown to be flawed. Most people familiar with structural mechanics seem to accept Bazant's opinion based on their own professional judgment rather than elaborate analysis, which is apparently why there are so few structural engineers in the AE911truth organization, but that in itself is not evidence of anything except broad consensus.

2) The velocity calculations made by Szamboti (even after correcting a gross error in the original "peer reviewed" paper) do not show any "jolt" on the order that would be seen in the Bazant model. Apparently true, and I'll grant it for the sake of argument.

3) All natural gravity-driven collapses would show a "jolt" in the kind of video analysis performed by Szamboti.

4) Therefore, the tower collapses could not have been gravity-driven collapses.

Spelled out in full, you should that the suspect premise in Szamboti's logic is the one I've bolded, and that is the one that Szamboti has yet to substantiate. The obvious reason that it should not be blindly accepted is that it's well known that the tower collapses were not really like the simplified linear Bazant model, as Bazant himself explained. The tops tilted at the beginning of the collapse, which means the two parts probably did not meet column-to-column, nor were the impact forces directly aligned with the columns -- two conditions that exist in the Bazant model. In the one close-up of the south tower collapse, which I'll link below, you can see that the top falls inside of the lower perimeter columns and destroys the floor structure restraining those columns laterally. It can be seen that the tops of those columns are simply pushed outward, rather than buckling as the Bazant-model columns would. They are "destroyed" as load-carrying structural elements by having their structural integrity destroyed, which takes much less force than buckling. Therefore, there is no reason to expect to see the kind of large deceleration "jolt" that the simplified Bazant model would have. To make his argument, Szamboti needs to take that case -- and many more -- and demonstrate that the decelerations should show up in the kind of video analysis he is doing. Until he does that, his conclusion is not justified.

So far, the only thing that Mr. Szamboti has really demonstrated is that the Bazant model does not realistically represent the actual collapses -- a fact that was already well known and stated by Bazant at the outset. Szamboti is already engaged in debates with people who more or less represent the position I've outlined here, and who are more technically capable of pursuing it than I, so we'll just have to see how that plays out.

http://www.youtube.com/watch?v=gJbGm7GE1tA

ETA: One thing I should point out is that the Balzac demolition is much more like the Bazant model, since the top fell very squarely on the bottom. That is exactly why one would expect to see the kind of jolt that the Bazant model would predict. What the Balzac demolition shows clearly is that the falling section has plenty of energy to destroy the bottom by simply crushing it. But the logic of the Bazant analysis still holds: If there was enough energy to do that, then there was more than enough energy to destroy the building by destroying its structural integrity.

[Tony Szamboti]

34. What happened to the core columns

Mr. Seger,

Your above explanation does not explain the core column collapses.

Additionally, to expect the entire upper block exterior to fit inside the lower block's interior is folly and attests to the serious problems any apologetics for the present official explanation for the NYC building collapses are currently having.

We have shown how the Balzac-Vitry building's upper block experienced a real deceleration upon impact with it's lower block. This deceleration is not present in the fall of the upper block of WTC 1 and without it there is no mechanism for a natural collapse. There is a reason Dr. Bazant said there had to be a powerful jolt. It is because he knew that would be the only mechanism which could cause an amplification of the statically insufficient load above to overcome the columns below which were only loaded to at most 30% of their capacity. Unfortunately, Dr. Bazant did not measure the fall of the upper block to find evidence of his theorized jolt.

Tony Szamboti

[Bolo Boffin]

35. Szamboti, welcome to the forums.

Tell me something, Tony. What does this paragraph mean?

For our purpose, we may assume that all the impact forces go into the columns and are distributed among them equally. Unlikely though such a distribution may be, it is nevertheless the most optimistic hypothesis to make because the resistance of the building to the impact is, for such a distribution, the highest. If the building is found to fail under a uniform distribution of the impact forces, it would fail under any other distribution.

It's from the second page of Bazant Zhou.

[Tony Szamboti]

36. The deceleration needed for a natural collapse would have been massive

Bolo,

I fully understand Dr. Bazant's caveat you transcribe above. However, he never retreated from the need for a massive jolt. That is because he knew that that is the only way the lower columns, which were only loaded to at most 30% of their capacity by the mass above them, could be overcome by that mass above them.

Some, like yourself, seem to be misinterpreting what he says here to mean there wouldn't have to be a jolt. There most certainly would have to be one for the collapse of WTC 1 to be explainable by natural circumstances.

By the way, the areas of the velocity curve that you point to are not evidence of jolts, since there is no velocity loss. In one case it is a lower acceleration which means the velocity was still increasing and in the other no change in velocity for a couple hundred milliseconds. There is never any velocity loss in the fall of the upper block of WTC 1 for the 114 feet or nine stories it was measureable until it was obscured by smoke.

A jolt requires a velocity loss which would show itself as a negative slope on the velocity curve. In the case of what would be required to amplify the statically insufficient load of the upper block of WTC 1 to overcome the columns below, with their factors of safety of 3.00 to 1 for the core columns and 5.00 to 1 for the perimeter columns, a very sever velocity loss would have been observed if the collapse were a natural occurrence.

Without a serious jolt there simply is no mechanism to explain the collapse of WTC 1 in a naturally occurring way. Dr. bazant simply thought there had to be one to make sense of the collapse naturally. He did not know at the time that there was no evidence for it and wouldn't have been suspicious at the time, like most of us, including myself. We know better now and there needs to be a new investigation of these collapses.

[Bolo Boffin]

38. I don't think you do understand Bazant's caveat, but never mind.

Why do you measure the roofline of the north side of WTC 1 when the collapse started and the leading edge would have been on the south side?

[Tony Szamboti]

42. The south side is not visible

The reason for the measurements being done on the north side is that that side is fully visible. We are not trying to capture the initiation here, only whether or not there was a jolt when the first floor to floor collision should have occurred between the 98th and 99th floors and subsequent floor collisions during the visible first nine stories of the drop. As you can see from the curve there is no jolt or velocity loss during that entire time, just consistent downward acceleration and an increase in velocity.

[Bolo Boffin]

43. Then your point is moot.

If you aren't able to see the leading edge, and you are relying on measuring these jolts after they have been transmitted through the building's structure, you are hopelessly lost. The loss of velocity could have been contained in the destruction of leading edge structure, masking the true extent of the jolt after it gets to where you're measuring.

[Tony Szamboti]

44. You simply aren't following the point, it isn't moot

Bolo, you apparently don't understand that the collapse of the north face requires a jolt there as it collapsed vertically. On top of that you are ignoring the fact that there is no observable jolt for the entire nine stories of the drop of the upper block that we can measure.

The tortured explanations I have heard from some about mini-jolts and masked jolts, since we published this paper, is pure utter nonsense and folly. Dr. Bazant knew a natural collapse needed a powerful jolt and thought it had occurred. The only problem is he never measured the fall of the upper block. In reality there should have been a jolt at every floor collision, and the upper block did not seesaw it's way down after the initial tilt. The jolt scenario went zero for nine for the first nine stories and this shows there was no natural mechanism to overload columns which could support at least three times the load that was on them.

I am not going to continue debating this as I have said more than enough here for any rationale person to understand, so if you can't recognize what is happening then maybe you simply don't want to.

[scott75]

45. In fairness to Bolo...

In the last few posts of his, I thought his arguments were reasonable. The problem, ofcourse, is that neither me or Bolo are mechanical engineers. It would certainly be nice to have -Bazant- here. Wouldn't it be something if he said something like, "You know, I think Tony may have something here, I really should have measured to make sure that there was a deceleration of the upper block." But right now the only person with a solid understanding of structural engineering here is, I believe, Tony. So thanks Tony, for taking the time to explain these things.

[Bolo Boffin]

46. Correction: I'm not following you down the garden path

What's that?

[scott75]

61. Tony counters...

Velocity of WTC 1 upper block without trendline

The areas Boloboffin points to are not decelerations. A deceleration requires a negative slope. Arrow 1 points to an area which is only a little lower acceleration with velocity still increasing. Arrow 2 points to an area which has constant velocity.

These two points do not constitute a jolt or impulse, which requires real deceleration and a loss or drop in velocity.

At all points on the curve the velocity is increasing except for point 2 where it is constant for about 100 milliseconds. Bear in mind that this curve represents a drop of about 100 feet or eight stories, where no deceleration was observed.

To generate a dynamic load sufficient to cause a collapse in the twin towers the velocity drop would have been severe. The fact that there is no velocity drop whatsoever is very telling of what actually occurred.

Bolo, how did you get that image up? I can link to an image, but don't see how you can actually include one.

[Bolo Boffin]

65. You're cracking me up.

First, by being Szamboti's little cut-and-paste messenger. He's a member here, isn't he?

And it's really cute how a severe drop in acceleration in at least three places doesn't "constitute a jolt or impulse" for Szamboti. LARED linked to a chart that shows actual accelerations and there are severe acceleration dropoff in three places. By contrast, the Balzac-Vitry shows the same kinds of dips, but only after the crush-up phase of the upper section begins does the Balzac-Vitry go into actual negative acceleration.

Bottom line, this whole thing is hysterical. Tony has measured huge drops back and forth in acceleration, but because the number doesn't drop below zero, he claims controlled demolition.

[scott75]

66. He gets tired of you...

So do I. We both share the burden of responding. You're a foul mouthed specimen at times Bolo, but I won't deny that some truthers aren't exactly examples of gentility. Still, -I- have never used the f word on you and I don't appreciate your foul mouthed nature at times. You may not have been foul mouthed with Tony, but he's a mechanical engineer, whereas you don't seem to have much knowledge on the subject. A little more respect is in order I believe.

A drop in acceleration is not the same thing as a deceleration. I've read many good arguments that the towers shouldn't have had -1- floor collapse, let alone the whole thing at the speed in which it did, but it's easier to argue that it should have atleast fallen slower then it did, so that's the approach Tony is taking.

The Balzac-Vitry doesn't show the same kind of dips. It took the extra posts by Tony for me to finally understand this, but now I get it. Re-read his posts and perhaps you might as well. Notice how WTC 1 never goes into deceleration (what you call 'negative acceleration'?). This is the point that Tony is making and the point that you have apparently missed.

This whole thing is not 'hysterical'. Considering the fact that you have little knowledge concerning structural engineering, however, your cavalier know it all attitude is rather depressing. Especially since it's rather clear that you know very little on this subject. "Huge" drops in acceleration? Yeah. Right. Take a look at that graph again. And remember that there is -never- a -deceleration-, as in the Balzac-Vitry 3 story demolition/gravitational collapse for the rest.

[Bolo Boffin]

67. The deceleration in the Balzac-Vitry is when the top section is CRUSHING UP!

Before, when it's plowing through the bottom layers, it shows dips in acceleration, but never actually enters deceleration!

:rofl:

I can't believe that the crack research Tony Szamboti doesn't understand that! Maybe that's covered when you go for your Master's....

:rofl:

PS: I'm a lot easier to deal with when you don't talk such rot.

[scott75]

82. No deceleration in the WTC collapses..

I've had this impression that you think that it shouldn't matter, that there doesn't need to be any deceleration for it to be a gravitational collapse. Is this what you're saying?

Anyway, I think that many of your claims are fallacious.. but notice that I don't call them "rot". Or use the f word liberally. This is called being civilized. Like I said, I know some truthers aren't civilized at times as well. But 2 wrongs don't make a right.

[Bolo Boffin]

86. Because the section hadn't reached the crush up phase like the B-V had.

Rot is what I call your claims, scott75, because rot is what they are. I'm sorry that this hurts your feelings. But if you don't want your claims to be called rot, don't talk rot.

[scott75]

90. Bolo, don't you get it?

There -was- no 'crush up' phase in the Twin Towers. More like air resistance to the falling pulverized dust. A tiny bit of the inner infrastructure also held on a second or so after the collapse, so perhaps that held things up a smidgeon too. This is what Tony is trying to point out. I could copy you and say that your claims are rot too. But what's the point? Is your mission here to insult people or to try to clarify the truth?

[Bolo Boffin]

92. No, not in the section of the film Szamboti analyzed

It's all crush-down, and the B-V graph makes it clear.

[scott75]

95. What are you talking about?

I have no idea what you mean by 'crush down'. There was a brief bit of the B-V where there is a clear deceleration, that is, a reduction of velocity. There was no deceleration in the twin towers. There was a minor reduction in the -acceleration-, which Tony has suggested may have been caused by the fact that not all the demolitions didn't take out every last bit of the infrustracture out immediately (one bit even lasted about a second after the rest, as can be seen in some videos). Also, explosive forces can certainly cause quite a temporary draft; as can be seen in the videos, you can see some material going -upwards-, which is quite consistent with explosions- and that's clearly what it looks like in many of the stills as well.

[Bolo Boffin]

99. "a minor reduction in the -acceleration-"

Let's look at what you're calling "a minor reduction in the -acceleration-".



First, from 24 f/s² to 15 f/s². That's a reduction of 37.5%.

Minor.

Next, a reduction from 32 f/s² to 8 f/s². That's a reduction of 75%.

Minor.

Next, a reduction from 32 f/s² to 16 f/s². That's a reduction of 50%.

Minor.

Finally, a reduction from 32 f/s² to 24 f/s². That's a reduction of 25%

Minor.

Let me hasten to point out to you that 32 f/s² is for all intents and purposes the acceleration rate of gravity. The descending section of WTC1, by Szamboti's own measurements, is going back and forth from freefall to severe resistance to freefall. Back and forth, back and forth -- almost as if the descending block is meeting areas of resistance again and again and again.

What kind of force would be operating on 100,000 pounds to slow acceleration by gravity by 25%? 50%? 75%? Ask yourself these questions. Ask yourself why Szamboti is not asking himself these questions.

[OnTheOtherHand]

113. and of course these are average estimates

Over each 1/6 second, gravitational acceleration should increase the velocity by over 5 ft/sec. So it's perfectly possible to have instantaneous deceleration (fractional, as if -- crazy talk -- the building were collapsing one floor at a time) while the average velocity continues to increase from interval to interval.

Szamboti's real issue is that he expects the velocity to drop by (if memory serves) 90% upon initial impact. If that were correct, certainly these plots ought to look different than they do.

[Bolo Boffin]

102. More fun - Szamboti is calculating an energy drain of crumpling the perimeter columns

Which didn't happen. The upper block is descending down, tearing the floors away from the perimeters, and pushing the perimeter columns out.



See them all laid out in a line? They peeled out from the destruction and fell over. They weren't crushed.

Time for Tony to pull a do over.

[Tony Szamboti]

119. The first two colliding stories didn't just peel away

Bolo, you are out in left field again.

The first two colliding stories of perimeter columns did not just peel away. They buckled as can be seen on video.

The Missing Jolt paper only calculates the energy drain due to deformation and buckling of the columns of the 97th and 99th floors which were those involved in the initial collision after the collapse initiation at the 98th floor.

You seem like you are desperate to discredit this paper and you are making serious errors exposing yourself as someone with an agenda whie doing it.

[Bolo Boffin]

122. But that buckling wasn't due to the falling section, it was due to fire.

You seem like you are desperate to discredit this paper and you are making serious errors exposing yourself as someone with an agenda whie doing it.

You also have this nasty habit of accusing other people of your own faults. Please stop doing that.

[Bolo Boffin]

107. More fun - Szamboti doesn't account for bowing steel due to massive fires

42, 26, 31 -- those aren't measurements for a top-heavy blonde. That's the number of pixels floor 96's perimeter columns are displaced due to the massive fires. (that's about five feet or so, IIRC) Szamboti's figures assume that all columns on the 96th floor are in peak performance condition. That wasn't the case.

95th got problems too. Look at that fire stretching out along those floors.

It's not until 94 that we get no exterior displacement. Just about the time the top block would experience a 75% reduction in acceleration, right?

:rofl:

[Tony Szamboti]

120. The collapse initiated at the 98th floor

Bolo, just can't help yourself can you? You just keep throwing things up there hoping something will stick. However, you are off in the woods again.

The collapse initiated at the 98th floor in WTC 1 where there was little damage and we looked at the energy requirements to deform and buckle the columns on the 97th and 99th floors which would have had to occur for the collapse to continue.

Your rants here about the 95th and 96th floors are not pertinent to the issue.

Face reality and realize that there was no jolt in the fall of the upper block of the North Tower and thus no mechanism to explain the collapse continuation in a natural way. That means something else was removing the strength of the columns.

[Bolo Boffin]

121. Tony, all of those floors already had severe deformation on the south side

You can see that in the picture I provided. There you see the perimeter columns buckling, not because of the plummeting upper section, but the sagging floor due to that massive fucking fire on about four or five floors.

Your calculations are of an undamaged building below the collapse floor. The reality is this:

As you can see, there is severe displacement on the perimeter columns of floor 96 (and 95 as well) due to the massive fires. Furthermore, the yield strength of these columns, both core and perimeter, would be drastically reduced at fires burning at 250 degrees Celcius. Szamboti doesn't account for this loss of yield strength either.

Szamboti is also measuring the fall of the upper section from the roofline of the north face. However, the building failed first on the south side. The assumption is that the building is falling as a rigid block, but no one who has viewed the rotation of WTC 7 before its final descent could believe that the upper section of WTC 1 would maintain utter rigidity after beginning to fall and lean. Some aspect of the jolt would have been absorbed by the structure twisting, and not all of its downward motion on the lower south edge would have been transmitted perfectly to the upper north edge of the block.

Szamboti also neglects to note that most of the perimeter columns were never put to buckling stress but were simply pushed out by the falling debris and fell out. This would take some energy to do as well, but nothing like what would be needed to buckle the column panels.

The only desperate person here is you. I'm the one laughing mightly at the silly antics you display.

[Tony Szamboti]

127. You can't be serious!

Bolo, steel does not lose ANY strength at 250 degrees Celsius (482 degrees F). It doesn't even start to lose strength until it is over 300 degrees Celsius (572 degrees F), has lost only 5% of it's strength at 400 degrees C (732 degrees F) and loses 50% at 600 degrees C (1,112 degrees F).

There was essentially no loss of yield strength in the columns as the NIST found no columns had experienced temperatures higher than 250 degrees C. In case you are wondering how this could be you would have to realize that steel and air temperatures are two different things and that it takes a long time to heat up large pieces of steel. Office fires generally burn out in a specific area long before the steel gets anywhere near hot enough to lose any of it's strength.

Below is a link to a Corus Construction chart and discussion about steel strength vs. temperature.

http://www.corusconstruction.com/en/design_guidance/structural_design/fire/steelwork_fire_resistance/

You show here that you are not competent to be having this debate and I am getting wore out answering your erroneous ninny comments.

[AZCat]

128. That doesn't agree with what the NIST found.

How do you reconcile your argument that

steel does not lose ANY strength at 250 degrees Celsius (482 degrees F). It doesn't even start to lose strength until approximately 300 degrees Celsius (572 degrees F), has lost only 5% of it's strength at 400 degrees C (732 degrees F) and loses 50% at 600 degrees C (1,112 degrees F).

with Figure 6.6 of NCSTAR 1-3D?

[Tony Szamboti]

133. I think figure 6-7 is the appropriate chart

and it agrees with the Corus Construction chart I linked to. If you notice figure 6-6 says "all characterized steels" but they don't say what steels they characterized, while figure 6-7 says the steels listed in table 1, which are the WTC steels in question.

[AZCat]

136. Figure 6.6 itself says which steels are characterized.

See where they call out the various components? That's what they mean by "all characterized steels". It's the same set of materials as Figure 6.7. Plus, Figure 6.6 is for yield strength, and Figure 6.7 is for tensile strength.

[OnTheOtherHand]

148. ouch -- that had to hurt n/t

[Bolo Boffin]

130. Oh, you're cute.

Read your Bazant papers. Columns under extraordinary stress (like gaining extra redistributed weight from nearby severed columns) lose yield strength at much lower temps.

Read, Tony. Learn. Stop embarrassing yourself.

[Tony Szamboti]

131. And there is still a bridge in Brooklyn you can buy

Bolo, I am willing to bet you don't know anything about structures or materials other than what you have read on the subject of the WTC collapses. So I am not surprised you are listening to the kinds of nonsense being spewed about by Bazant and others about creep at low temperatures and the like. All metals creep all the time, even at room temperature, but the amount of creep is so insignificant that it can be neglected. It would take a million years for a steel column to creep a half inch.

Don't worry about having to hurry to buy the bridge due to it creeping on you. It probably won't get to any significant problem point for twenty million years.

You aren't up to this debate and have nothing to offer yourself other than incredulity. Please go argue with someone your own speed.

[Bolo Boffin]

132. It's not missing any paint chips, is it?

So it's "nonsense" that columns under much more stress than normal will lose yield strength at lower temperature fires? That's simply untrue?

Really? That's your final answer?

Tell me something, Tony. Where'd you get your Ph.D?

Where'd you get your Masters?

What? You don't have a Ph.D? You don't have a Master's?

And yet you'll skulk down here and bad-mouth Bazant, who is one of the world's leading authorities on structural engineering? Who literally has written the textbooks?

:rofl:

Get the fuck outa here.

[Tony Szamboti]

138. You are simply appealing to authority here

All you are doing is appealing to authority here. Bazant is wrong when it comes to the WTC collapses. He thought there was a jolt, but he never measured for it. I accepted what he thought for five years but now we know better and his original hypothesis is no longer valid.

Bazant was referring to the creep rate being greater at 250 degrees C or resistance to creep being lower. That is not a yield strength change.

I explained to you that metals even creep at room temperature but that it is such an infinitismal amount that it can be neglected. At 250 degrees C the creep rate is higher than it is at room temperature but it is still infinitismal and can be neglected there also.

As for your last comment it seems you should be the one doing that.

[AZCat]

134. Wow, talk about an ad hominem!

This coming from the guy who has yet to provide a source for his 17 second claim regarding conservation of momentum.

[Bolo Boffin]

135. Can you believe this little BA mech engineer trashing Bazant?

Where the fuck does he get off?

[AZCat]

137. It's teh internet.

Everyone here has a doctorate in Google.

Besides, Judy Wood has a doctorate in mechanical engineering, and look at her. Fortunately for Bazant, his record stands on more than his degrees.

[Tony Szamboti]

139. And what degree and experience would you have Bolo?

Bolo, since you don't think much of a degreed mechanical engineer with thirty years of experience maybe you can tell us what qualifications you have to make that assessment.

Then you can tell us what applicable degree and experience you have which would allow you to competently understand the WTC collapses.

By the way my degree is a BSME not a BA. Just thought you should know

[AZCat]

141. You got a BA in ME?

There aren't too many BAME programs anymore, are there? The local university (U. of Arizona) had a bachelor or arts program in engineering (general, not mechanical), but they had difficulty attracting students. When the budget crisis hit, the program was axed.

[OnTheOtherHand]

151. looks like a Bachelor of Science, not a BA

Not that this wondrously transmutes Figure 6-7 into a yield strength curve.

Off topic: I spent a while arguing about exit polls with someone who was very proud of her masters degree in mathematics, but she had the damnedest ways of thinking about data -- and she was completely lacking in perspective. My first hint of the perspective problem was when I used an equation while omitting one step in the derivation, and she didn't see where I had gotten it from -- so she accused me of being a disruptor trying to undermine her work. I thought that would have been a pretty strange response even if the equation had been wrong. Upon further reflection, it's a somewhat natural response, just wildly at variance with the professional norms that I've begun to take for granted.

[AZCat]

157. Oh, he edited his post.

It said BA in ME, not BS, before he edited it.

[OnTheOtherHand]

161. oh, you were In Before The Edit

Looks like you had no more than a 2-minute window to read the typo. Funny how things happen.

ETA: Obviously not a big deal to type an A instead of an S -- I'm just amused by the sequence of trivial events.

[Tony Szamboti]

165. There was no typo and you are simply making that up

You and AZCat seem to make a number of things up and twist and distort others. It is obvious that you two have a mission to try and rile anyone who might be making legitimate points which show the present government explanation for the collapses of the three NYC high rise buildings to be inadequate and essentially false. Have a ball, without me of course.

[AZCat]

169. I think your perception of us and this forum is incorrect.

But I can see that you're not open to that possibility. Good luck with other forums, Tony. Maybe they'll be more compliant than this one.

[OnTheOtherHand]

175. he'd really like to respond to William Seger's points downthread

but now you've gone and hurt his feelings!!1! You old wily riler, you.

ETA: not to single out William's -- a bunch of us are awaiting responses to substantive posts. William's perhaps stands out for the number of disparate points he addressed.

[AZCat]

177. I've been called a lot of things, but never that.

When I think of our responses to his posts, I am a bit shocked. How dare we engage in such callous behavior! Tony is quite right to quit responding substantively because we wronged him so severely.

[OnTheOtherHand]

171. I'm making it up?

Look, Tony, reread the posts, and it will be obvious that I never saw you refer to a BA either. That's why I corrected AZCat. However, it didn't occur to me to insist that he must have misread your post -- which, in retrospect, seems more likely, given the timing of your edit and his post.

You'll find plenty of substance to respond to. There's no need to try to convince yourself that anyone has "a mission to try and rile" you.

[AZCat]

173. I don't think I misread it, but I could be wrong.

That's why it stood out for me, because it did appear unusual.

[OnTheOtherHand]

174. I think you may've had a cross-eyed moment

I almost think you must have, unless you spent several minutes looking for BAME programs before posting your reply.

Shrug. As candidate flame-war topics go, this certainly sets a new standard for innocuous irrelevance. ;)

[AZCat]

176. Never! I am pefrect! Flawless!

;)



On Edit: I was looking at something else for a while while I had the response window up, but I still could have made a mistake. I don't think that warrants Tony's response, though.

[Tony Szamboti]

164. It never said BA in my post

You must have been reading Bolo Boffin's post where he said BA. I stated BSME from the start.

[AZCat]

166. I seem to remember that it did.

Not terribly important, though. So what if you made a typo? You wouldn't be the first.

[Bolo Boffin]

143. What the fuck qualifications do you have to trash Bazant?

That's the question here - it's you v. Bazant. You think you've got him by the shorts. Meanwhile, I can understand how ludicrous your paper is.

ARE YOU DENYING THAT COLUMNS UNDER LARGE AMOUNTS OF STRESS DO NOT EXPERIENCE A SIGNIFICANT LOSS OF YIELD STRENGTH AT LOWER TEMPERATURE FIRES?

Will you be so foolish as to deny this? :popcorn:

[Tony Szamboti]

145. Yes, steel columns would not begin to lose yield strength below 300 degrees C

I stand by what I said. Steel does not start to lose yield strength below 300 degrees C (572 degrees F) no matter what the load on it is. This is not the same as creep rate as I explained earlier. However, creep occurs even at room temperature but is so insignificant that it can be neglected. At temperatures such as 250 degrees C the creep rate will be a little higher but is still insignificant enough that it may be neglected.

If you want to say creep is microscopic yield you can try but it is not the form of yield that is being discussed and does not have any appreciable effect on the steel's behavior.

[Bolo Boffin]

160. You are wrong. You couldn't be more wrong.

From Bazant et al. (2008):

The initial speculation that very high temperatures were necessary to explain collapse must be now revised since tests revealed a strong temperature effect on the yield strength of the steel used. The tests by NIST (2005, part NCSTAR 1-3D, p. 135, Fig. 6-6) showed that, at temperatures 150°C, 250°C and 350°C, the yield strength of the steel used in the fire stories decreased by 12%, 19% and 25%, respectively. These reductions apply to normal durations of laboratory strength tests (up to several minutes). Since the thermally activated decrease of yield stress is a time-dependent process, the yield strength decrease must have been even greater for the heating durations in the towers, which were of the order of one hour. These effects of heating are further documented by the recent fire tests of Zeng et al. (2003), which showed that structural steel columns under a sustained load of 50% to 70% of their cold strength collapse when heated to 250°C.

Bazant isn't just pulling that out of his ass, Szamboti. It's based on actual physical tests conducted by NIST and by J.L. Zeng et al. in a study published in the Journal of Construction Steel Research.

So on this side of the contention, we have one of the world's leading authorities on structural engineering backed up by peer-reviewed, reproducible scientific tests, and on the other hand, we've got Szamboti, the bachelor's degree with 30 years experience in the field and 7 years or so experience in the mighty halls of woo-woo 9/11 science.

Yeah, and I'm the one working off of incredulity.

[Realityhack]

162. It would appear this argument is diffinitively over and Tony Szamboti lost. n/t

[Bolo Boffin]

179. Oh, Tony?

In your last skirmish, you seemed to have missed this post.

[Tony Szamboti]

185. Well you are going to have to tell all of the construction people

One thing that is striking is that it doesn't happen unless the column is loaded to 50 to 70% of their cold strength. None of the columns in the towers were loaded to more than 30% of their cold strength and so few columns were damaged or destroyed on the actual collapse initiation floor of WTC 1 that this doesn't even apply.

I will give you credit for it though even though it would be very unlikely that it had anything to do with the tower collapses as the columns were not loaded the way they were in these tests. I also wouldn't get too uppity about it, as all of the other steel companies in the world still show steel does not lose any yield strength until after 300 degrees C and not much until over 500 degrees C. We also don't know all of the particulars of this test. It would be interesting to see the entire test procedure.

Additionally, even in the very unlikely event this new found phenomena could have caused a collapse initiation it would not eliminate the requirement for a jolt.

See ya, Joe.

[Bolo Boffin]

186. Can't just say that you were wrong. You've got to crank up the old spin machine.

The description of the NIST tests showed significant lowering of yield strength over the few minutes the beams were tested. Bazant notes correctly that beams in the towers were experiencing those temps for at least an hour.

This most certainly does apply. Back to the drawing board, Szamboti.

ETA: Someone really interested in the truth wouldn't be handwaving this factual information away, Szamboti. They would incorporate it into their theory. That's science.

Of course, if you truly dealt with this and other information, you wouldn't be making this silly claim. You'd be trying to find a rock to bury this paper under.

[Tony Szamboti]

189. An additional point to think about

One more thing to think about is that if the yield tests over temperature done by the NIST had any import or potential to explain the collapses the NIST would have built a model and showed how it could have.

However, even in that model they would need a jolt to collapse the lower stories after any initiation.

No jolt = no natural collapse. You can't get away from that and neither can Dr. Bazant and co.

[AZCat]

196. What do you think the NIST did?

They built something like five models. Yeah, they were computer-based, but did you really expect them to reconstruct the towers?

[Bolo Boffin]

198. An additional section of the NIST final report you need to read

NCSTAR 1-6, pp.60-65 (pdf 142-147) - They describe the tests and how that information was incorporated into their models.

Rather than lurching from fail to fail, Szamboti, why not simply get a shovel and give your paper a decent burial?

[AZCat]

188. That doesn't agree with what the NIST found.

Have you even read the section of the report where they calculated DCRs?

[Realityhack]

191. "One thing that is striking is that it doesn't happen..."

You said
"One thing that is striking is that it doesn't happen unless the column is loaded to 50 to 70% of their cold strength."

What specifically "doesn't happen" because as far as I can tell the thing that does not happen is failure of the beam. Lowering of the yield strength would still happen it just doesn't matter unless you get to the yield strength.

"None of the columns in the towers were loaded to more than 30% of their cold strength and so few columns were damaged or destroyed on the actual collapse initiation floor of WTC 1 that this doesn't even apply."

I am a little confused by this statement. After the impacts (but before collapse initiation) which destroyed many of the support beams there would of course be beams that were loaded to easily twice their normal load as the weight was re-distributed.
So I can only assume you are talking after initiation in which case... impact forces would far exceed even the cold strength of any column.
so um... wtf are you talking about?

"I also wouldn't get too uppity about it, as all of the other steel companies in the world still show steel does not lose any yield strength until after 300 degrees C and not much until over 500 degrees C. We also don't know all of the particulars of this test. It would be interesting to see the entire test procedure."

Could you please provide a source for this comment? Are we talking about the same grade steel used in the WTC?

Also it is two different tests not one.

[pennysworth]

217. Bazant and Bolo need to visit my kitchen.

So steel loses 50% to 70% of cold strength when heated to 250 degrees C? Really? And that's why the towers collapsed? Ha, ha, ha.

Maybe Bazant and Bolo need to visit my kitchen. I have a steel oven and regularly heat to this temperature. I could heat my oven to even higher temperatures but don't usually need to. I haven't noticed any loss of strength of my stove, no buckling of the sides, no sudden collapse. Even when there are heavy pots on top. And that's with much thinner steel and longer heating periods than at wtc.

I can't imagine that appliance manufacturing safety standards would allow kitchens in homes throughout the nation to be put at such potential danger if what Bolo says were true.

Regardless of where he pulled his information from, Bazant's figures are cooked!

[SDuderstadt]

218. Do you really claim the outside of your oven heats to...

250 degrees centigrade? Really? How on earth do you use it?

[William Seger]

219. Incorrect, it loses 50% at 600 degrees C

... which is about 1100 degrees F, far hotter than you oven, but your thinking is fuzzy anyway: If you needed to make an oven from steel that needed to operate at 600 degree C and you knew it would lose half it's strength at that temperature, you would just use more steel. For some strange reason, that's not how buildings are designed.

[Tony Szamboti]

146. So you don't have any qualifications

Since you couldn't state any it appears that you have no degree or experience which would help you understand issues that would pertain to the collapses of the twin towers and WTC 7.

It appears you are simply arguing from credulity.

I have stated my background and qualifications many times and they are mentioned in The Missing Jolt paper.

Dr. Bazant is wrong in the case of the collapses of the Twin Towers. Observation does not support his hypothesis. All i have done is show that and explain it.

[Realityhack]

159. Arguments of this type stand on their merits not on credentialism. n/t

[whatchamacallit]

167. Wow, you guys are all over the map

I just read post after post bashing mr. Szamboti for not having the credentials to challenge Bazant (some kind of supreme being to the OCT), yet when it comes to Bolo's BS "no credentials are necessary".

What a steaming pant load...

[Realityhack]

168. I for one say neithers credentials matter.

The issue is the strength of the arguments. And Mr. S isn't measuring up there.

[Bolo Boffin]

170. What I find interesting

is that the credentialed Mr. Szamboti just did some posting here, but instead of dealing with his 100% incorrect scientific statements, he just continued bickering about credentials and typos.

[Realityhack]

172. That is indeed interesting...

But you should have stuck to disproving his statements and stayed out of the credentialism. (IMO)

[Bolo Boffin]

178. Should I?

There is a place for credentialism - the appeal to authority. You should never simply assume an authority figure knows what they are talking about. Trust, but verify.

Yet it's clear that Szamboti is happy to trot his credentials around when talking to me, and yet pooh-poohs somebody like Dr. Bazant. And his braggadocio is ill-founded, especially when you dig into his "paper."

[AZCat]

180. Meh. Doesn't really matter, IMO.

It looks like Tony might abandon all his arguments anyway. This forum isn't working out for him quite like he thought it would, I guess.

[Realityhack]

193. That seems to happen to such people when their audience has some idea WTF they are doing n/t

[Realityhack]

192. I agree that there is a time to look at credentials...

And yes Szamboti is happy to trot out his credentials but I think pointing out Dr. Bazant has far better credentials and then re-directing back to the issues is better than saying 'what credentials do you have to challenge him' etc.

[Tony Szamboti]

74. You are dead wrong

Bolo,

You are so wrong it is pathetic. There are no decelerations in the velocity curve of the North Tower upper block's fall. You are apparently confusing a lower acceleration with deceleration. They aren't the same thing and you obviously haven't figured that out yet.

The Balzac-Vitry curve shows a real deceleration. That is one with a negative slope.

A lower acceleration still causes velocity to increase. For an impulse to occur and kinetic energy to be transferred velocity needs to decrease, which is only possible with a negative acceleration or deceleration.

You should do a little homework before having the balls to try and chastise someone with much more experience than yourself in these matters. You really sound like a smacked ass here.

[Bolo Boffin]

84. No, sorry, I'm exactly right.

Your graphs, big talker:



Up and down, up and down, up and down. What does that section weigh, Szamboti? Around 100,000 pounds? What could stop gravity from accelerating 100,000 pounds straight to the ground in such a way?

:rofl:

The Balzac-Vitry shows real deceleration? Right, but only at the end -- only during the crush-up phase!




See? In the first phase, the B-V is experiencing dips in acceleration. Not as drastic up and down as with the WTC 1 (and that should cause you to think, think, think -- does this upper section weigh as much as the upper section of WTC 1? No! What in the world could be giving 100,000 pounds that much resistance?)

But then at the end, the B-V goes into deceleration. This is when the top has already crushed the floors below, and now is crushing itself -- now it experiences actual deceleration!

Your graphs prove that WTC1 is crushing down the floors below! If the top was crushing itself, there would be deceleration!

Don't you 9/11 Truth scientists get tired of proving the "official story" to be true? Chandler verified the NIST WTC7 model with his 2.25 seconds of freefall, and now here you are confirming Bazant Zhou. You guys are PRICELESS. Don't go changing.

[scott75]

91. Bolo, Bolo, Bolo..

Don't you get it Bolo? -Ofcourse- there is deceleration in the B-V example. That was a -true- gravitational collapse, after 3 stories were demolished. The same can't be said for WTC 1, however. What could be giving 100,000 pounds that much resistance? How about the -rest- of the building, which weighed more and was designed to carry those 100,000 pounds without a hitch. Even if a floor between the upper and lower block collapsed, as Tony has made clear in his paper, not only the acceleration would have been arrested immediately upon hitting the lower block but 90% of the velocity would have been arrested as well. And that's just on first contact.

[Bolo Boffin]

93. I think you better clear a few of those statements with your fearless leader. n/t

[scott75]

96. There are times when I don't need Tony's guidance...

I believe he's said more then enough to clarify the issue now.

[William Seger]

104. No, you haven't clarified anything

I'd especially be interested in your clarifying how your repetition of Szamboti's assertions match up to the graphs Bolo is showing. If Bolo is misrepresenting them or misinterpreting them, please clarify.

[William Seger]

40. Why would you expect the core columns to be so much different

... if they were also subject to asymmetric forces? With the sequential, lateral progressive failure starting on one side and proceeding through the core and then to the other side, why couldn't the "jolt" that you are looking for not actually be a series of smaller jolts, undetectable by your method, spread out over the time of that progressive failure?

Sorry, I'm on my way out the door and won't be home until late tonight, but I'll be more than happy to continue this then. In the meantime, if you have a few minutes, perhaps you could address the content of my post above? Also, perhaps you could see if you can get some comment from Bazant to see if he really agrees that there "had to be a powerful jolt," detectable by the type of analysis you are doing.

[Tony Szamboti]

41. The core columns would not be subject to lateral forces from the floors

The point you made earlier, concerning the perimeter columns, is that they would be pushed outward by the floors collapsing. This would not apply to the core columns. This also would not happen to the perimeter columns until at least a few stories into the fall. Another issue is that it would seem that the effect of any southward tilt would be insignificant on the east and west side perimeter columns. Their failure is a real puzzle as they would be the stiffeners in the beam with forces running north/south.

As for a series of smaller jolts it would be interesting for you to explain the mechanism for that, especially in light of no jolt being measured throughout the visible fall of the upper block, which was for 114 feet or the first nine stories of drop.

I sent Dr. Bazant a copy of "The Missing Jolt" paper two weeks ago and while he has not yet replied directly to me I saw Dr. Frank Greening say on the 911 free forum that he was discussing/debating the paper with Prof. B. I assume this is Dr. Bazant, as Greening was involved in the writing of one of Bazant's papers on the subject.

I had to show Dr. Greening that it was the velocity curve which would show a jolt, if it occurred, as he was using the displacement curve and saying there wasn't one for the Balzac-Vitry building. When he did the differentiation and saw the jolt he was taken aback and thanked me.

[William Seger]

103. "laterel forces from the floor"? I'm talking about loss of lateral restraint from the floor

... and also the fact that whatever happens to the columns, when the floors broke free from the columns they were going to keep heading down. Whether the columns continued to stand for a while or were immediately pushed aside is not really relevant; the relevant issue is whether or not that could halt the falling mass. I do not see how they could, once structural integrity with the floors was lost.

We don't have any direct evidence of what was happening at the core, but we do have some for the perimeter walls: Your statement that "This {pushing outward} also would not happen to the perimeter columns until at least a few stories into the fall" simply doesn't match what I see in the video I linked to, nor does it make any sense. The first set of columns on the impacted floor are pushed outward as soon as the floor joist connections holding them in place are broken.

> "As for a series of smaller jolts it would be interesting for you to explain the mechanism for that..."

The collapse was clearly not a one-dimensional impact -- it was a three-dimension collision of an upper block which tilted as it fell -- so I presume you will accept that it was a series of smaller collisions, not one large one. So, I would explain the mechanism that could likewise produce a series of smaller jolts as being the result of a series of connection disruptions -- resulting in a loss of structural integrity and stability -- and probably some columns receiving large bending moments in addition to their axial loading. These types of failures mean that not all the columns needed to be axially compressed beyond their elastic limits. These types of failurs would require much less force than buckling, which also means less deceleration of the falling mass. It would also mean that, whatever "jolts" there were, would be spread out over time in a structure that's only semi-rigid, so the "jolts" could be largely absorbed in flexing and deformation of the upper block, which could make the roof-line appear to be falling smoothly at less than g, with no measurable decelerations, at least using your method.

> "... especially in light of no jolt being measured throughout the visible fall of the upper block, which was for 114 feet or the first nine stories of drop." {my emphasis}

There's one problem that needs to be resolved, even if deceleration is required: How much, for how long, and would it be detectable using your methods? Your estimate of a 31g "jolt" is fallacious -- and a gross misinterpretation of B&Z's "overload ratio" -- since, if the columns would fail with a 3g static load, they could not possibly impart much more than a 3g deceleration to the falling mass, at least not for more than the briefest instant. And whatever deceleration rate there was, the other point of contention is how long it was applied, since that is also critical in determining the change in velocity that your analysis is searching for. I see that Dr. Greening estimates that even in pure axial overloading, the columns would have been pushed through their elastic limit in 20ms, or even much less in some scenarios.

I believe I understand what your claims are, so you needn't keep repeating them. What I would like to see is a demonstration that they are valid, and more importantly that they are accepted as valid by people more qualified than I am. That is why real peer review in real journals is so important. Perhaps if you would submit your paper to a real journal, we could get to the bottom of this much sooner.

[wildbilln864]

48. Welcome Mr. Szamboti to the DUngeon and...

thank you for your contributions! :hi:

[Name removed]

62. Deleted message

Message removed by moderator. Click here to review the message board rules.

[wildbilln864]

64. You replied to me

SFB, not Tony!

[LARED]

49. It's been a pretty long time since I took calculus

but the velocity curve and the acceleration curve you present for the WTC roof is completely inconsistent with each other. One of them is wrong.

http://scott3x.tripod.com/arguments/tony/WTC_bal.html

[Tony Szamboti]

51. Velocity and acceleration are different entities

Lared, I can't tell from your comment what you mean that the velocity and acceleration curves are inconsistent with each other.

The velocity is the change in distance with respect to time and acceleration is the change in velocity with respect to time. They are different entities. If you took calculus you would know that.

The slope of the velocity curve is acceleration when it is positively sloped and deceleration with a negative slope.

The acceleration curves really aren't needed to see there is or isn't deceleration in the fall of the upper block of WTC 1's fall as it would show itself as a negative slope on the velocity curve.

If you notice the Balzac-Vitry building has a negative slope or deceleration in its velocity graph at 1.5 seconds into the fall.

The velocity curve for the upper block of WTC 1 never has a negative slope and thus no deceleration ever occurred.

Without deceleration there is no amplification of the weight of the buildings above the columns which were designed to take several times that weight.

It sounds like you should look up what an impulse is and how it can amplify the weight of an impacting object. To do this it requires deceleration.

[AZCat]

52. You keep stating this but I don't think it is correct.

You said the same thing over at the JREF, that an impulse requires deceleration. I think you're forgetting that the top portion was undergoing a constant acceleration downward, and the impact and application of force to lower portions could be indicated by a lower magnitude acceleration downward (in other words, an acceleration < 1.0 g) rather than a deceleration.

On Edit: Draw a FBD - that will help you visualize the problem.

[Bolo Boffin]

53. Now I understand

You say that unless acceleration goes negative, there is no jolt.

You're doing the same thing that no-planers do when they cry about how the plane seemed to melt into the side of the building. In fact, they could use your paper to write their own paper. If the plane never demonstrates negative acceleration as it plows through the side of the building, that proves it couldn't have busted through the building.

:rofl: Tony, you're a champ. Don't go changing.

[OnTheOtherHand]

55. and as I read the article...

the fact that Bazant and Zhou used the phrase "one powerful jolt" in the appendix constitutes their endorsement of his argument. Seems to me that Bazant and Zhou make crystal clear that they think the collapse proceeded at close to free fall, and explain why. (Actually, I was thinking it would be interesting if someone argued that only CD can explain why the tower fell so slowly.)

[AZCat]

57. Coincidentally, Tony has been arguing...

over at the JREF forums that the towers fell too quickly, according to conservation of momentum (links here and here). Unfortunately , he doesn't seem to be inclined to provide his calculations showing that "a 17 second time would still not be possible in a natural collapse of the North Tower due to conservation of momentum."

[Tony Szamboti]

58. Plenty of others have done that

What are you trying to do there AZ? There are plenty of others who have looked at the conservation of momentum issue and written about it.

I simply made a point that even if the collapses took 17 seconds that would still not allow for the conservation of momentum in a natural collapse and now you want to say I should have done my own work to be able to make that point.

No, I based it off of my understanding of the work of others.

I guess I really don't understand yours or On the other hand's point here, if you even have one.

[OnTheOtherHand]

59. "there are plenty of others"

OK, well, in my discipline we're a bit more rigorous about citations. In this case (ETA: that is, with respect to minimum collapse times), your analysis, or "understanding of the work of others," or whatever is very much at odds with Bazant's -- so if you intend to illuminate the topic at issue, it would be obviously be useful to explore why that is.

[AZCat]

60. I'm a bit surprised, Tony.

It isn't difficult to do a rough conservation of momentum calculation for the collapse of the towers - the concept and implementation should be well within your technical skillset. Most engineers I know would do something similar, even if only to check for similarity with more detailed calculations.

Given that you haven't done your own calcs, could you at least provide a link to the "work of others"?

[Tony Szamboti]

77. Why do I need to do it

AZ, I guess I don't understand why you are so fixated on me doing the calculations myself for conservation of momentum. Others have done it. Their calculations, which I agree with, show that 11, 12, or even 17 second collapse times are far too rapid for a natural collapse of the twin towers.

Have you done the calculations yourself? If so, please share them with us.

[scott75]

85. I agree with you Tony...

But he also did ask if you could provide a link to your source(s). The only one I have on hand is this one:
http://letsrollforums.com/number-one-smoking-gun-t16540.html

[AZCat]

97. Thanks for providing the link, scott.

Hopefully Tony and I can clear up whether this is the source of his claim regarding theoretical collapse times.

[William Seger]

117. Well, that's certainly not a calculation based on conservation of momentum

It's a silly argument based on completely ignoring conservation of momentum: It assumes that at each level the debris would have come to a complete stop and then began accelerating again from 0. It's Judy Wood's idiotic "billiard ball" model -- the first clue that most people had that Wood was incompetent in basic physics.

[AZCat]

94. We don't NEED to do it, but I'm surprised you didn't out of curiosity.

That's why lots of engineers go into engineering, at least in my experience - interest in the way the world works. We generally don't trust other people's calculations, either (a bit arrogant, I suppose). I guess not everyone thinks this way.

Anyway, scott75 was kind enough to provide a link (his post here) to a set of calculations. Do you support the methods and conclusions of the calculations he linked to?

I have done the calculations, as have several other DUers. I don't know where they are (I think I did them on the old computer), but they're not difficult to recreate.

[scott75]

98. Thinking about it...

Tony has said that his paper "The Missing Jolt" provides evidence that the upper block on WTC 1 would have had to have had its velocity reduced by 90% on first contact; isn't that the type of calculation you're looking for AZ? Here's the link to it:
http://journalof911studies.com/volume/2008/TheMissingJolt4.pdf

I'll give you the synopsis:

Graeme MacQueen
Tony Szamboti
January 14, 2009

In its Final Report on the Collapse of the World Trade Center Towers, the National Institute of Standards and Technology summarizes its three year study and outlines its explanation of the total collapse of WTC 1 and WTC 2. <1>

Readers of the report will find that the roughly $20 million expended on this effort have resulted in an explanation of the total collapse of these buildings that is so vague it barely qualifies as a hypothesis. But it does have one crucial feature of a hypothesis: it is, in principle, falsifiable. In fact, it is easy to demonstrate that it is false.

In this paper we will, concentrating on the North Tower, offer a refutation that is:

• easy to understand but reasonably precise • capable of being stated briefly • verifiable by any reader with average computer skills and a grasp of simple mathematics.

[AZCat]

101. Probably not, because he has said he hasn't performed the calculations himself.

Therefore I wouldn't expect them to appear in his own paper, unless MacQueen did the calcs for him. I'll look at it anyway, but I'm still interested in his opinion of the calculations you linked to.

[OnTheOtherHand]

105. distinguishable issues

Missing Jolt doesn't reckon a collapse time, but it does offer a calculation of 90% reduction in velocity on first impact. I didn't notice any attempt there to 'correct' other, much smaller estimates.

[Tony Szamboti]

150. Here is a conservation of momentum paper I agree with

Below is a link to a conservation of momentum discussion on the collapses of the Twin Towers that I agree with

http://www.journalof911studies.com/letters/ProfKuttlerWTC1CollapseTimeCalculations.pdf

By the way AZCat, apparently you didn't read the thread right in the JREF forum where you got this 17 seconds from which you are attributing to me.

It was Alienentity who made the 17 second comment after asking me what I thought the collapse times were.

All I said in response was that if the 0.7g acceleration of the upper block of the North Tower were to continue then the time would be 11 seconds. I don't know for sure what the exact times were. What I do know is that they were well below what the conservation of momentum for a natural collapse predicts they would be.

You should be more careful before you start quoting someone.

[OnTheOtherHand]

152. you may want to edit this comment

Following AZCat's link, I find -- sure enough -- "Tony Szamboti" writing inter alia, "Even a 17 second time would still not be possible in a natural collapse of the North Tower due to conservation of momentum...." I'm going to assume that that is you.

I assume we will all respect your apology for this honest, if odd, mistake on your part.

[Tony Szamboti]

153. That was after Alienentity said it was 17 seconds

What are you trying to do here?

The 17 seconds was brought up by Alienentity and I replied to that saying it was too violated the conservation of momentum for a natural collapse.

I am not the person who said the collapses occurred in 17 seconds.

I did not bring it up and that is clear, so it is a horse's ass thing to even ask me for an apology here.

It is obvious that you and AZCat are playing games and even putting words in my mouth.

Don't you have anything better to do?

[OnTheOtherHand]

155. what on earth?

AZCat quoted you entirely accurately. It does not matter whether you were the first person to bring "17 seconds" into the JREF discussion; AZCat never said you were, and it is immaterial anyway.

The following is obviously incorrect: "All I said in response was that if the 0.7g acceleration of the upper block of the North Tower were to continue then the time would be 11 seconds." You said, inter alia, exactly what AZCat quoted you as saying. I'm not sure why you are defensive about this, much less why you think AZCat should be more careful about quoting you.

There is no reason to personalize the discussion; you only have to take responsibility for your words. You put them in your own mouth.

If you think it would be better to stick to substance, well, I agree. In the time you spent unreasonably criticizing AZCat, you could have been responding to the critics of Kuttler.

[AZCat]

158. No, OnTheOtherHand and I have it correct.

You might want to be more careful with your remarks in the future. You're not impressing me, Tony, not with either your attitude or your technical savvy.


On Edit: Thanks for providing the link to your reference for collapse times of the towers. I'll look through it, but I don't know if I'll write a response this week (kind of busy).

[Tony Szamboti]

56. But the plane does decelerate

The no planers tried to simply say there was no deceleration of the plane but that is not true and it was verified that there was deceleration.

It is essentially the same mechanism. Statically the weight of the plane would not have caused the columns to shear or break in bending. However, the pressure impulse caused a large amplification of the plane's static weight to be applied as the force. To do that there needed to be significant deceleration and velocity loss of the impacting object which was the plane. However, the deceleration would not have been anywhere near enough in that case to stop the plane from entering the building.

There are several factors which go into this with the actual force applied and the strength of the columns and mechanics involved. I have seen a finite element study showing that if the columns had twice the thickness they had that the planes would not have been able to apply enough force to breach the perimeter given their mass and velocity and the structure of the perimeter columns.

[LARED]

71. Simply put

the velocity curve for WTC 1 roof clearly indicates a near constant acceleration. This is observed as the data shows just about a perfect liner relationship between time and velocity (V = 22.81*t; a form of a straight line ). In fact according to your regression analysis acceleration is just about 22.81 with a Rsquare coefficient of .9961. A very good fit for a linear relationship.

If acceleration is a near constant when measuring velocity the acceleration chart should be consistent. In short it should be a line very close to horizontal.

On a final note you seen to be confusing acceleration and deceleration with a change in direction. There is no need to change direction. If an object is accelerating at 20 f/s^2 at 2 seconds and 10 f/s^2 at 3 seconds it decelerated.

[Tony Szamboti]

73. No deceleration is not just a lessening of acceleration

Lared, deceleration is negative acceleration and not just a lesser acceleration. For example, if something is accelerating at 5 ft/sec/sec and then slows it's acceleration to 3 ft/sec/sec it is still accelerating and increasing it's velocity but at a slower rate. It is not decelerating. A deceleration would only occur if there was velocity loss. To do that you need a negative acceleration. If, in the above example, an acceleration of 5 ft/sec/sec went to
-3 ft/sec/sec you would have deceleration.

[LARED]

76. Ok

So please explain

Why you believe deceleration is a requirement for a "natural collapse"? An impulse (jolt) requires only a change in velocity. As an example if you measured a fall of a brick from a drop of ten feet you would find a constant acceleration of 32 ft/s^2 and a linear relationship between time and velocity. If you redid the test with a brick dropped from ten feet through two dozen wet paper towels, you would find the acceleration to be a bit slower as energy is used to break the towels, but still have a pretty linear relationship between velocity and time, although with a slightly smaller slope.

[Tony Szamboti]

78. There would have been a loss in velocity at the moment of impact between the brick and the towels

Lared, the brick would have been slowed and decelerated momentarily at the moment of impact with the towels. Otherwise the brick could not transfer energy to the towels. There is no way around it.

Another issue here is the amount of energy required to cause column failure of both floors on either side of the impact. We calculated this energy requirement to determine what the velocity loss would be in the first impact, if it had occurred, in the Missing Jolt paper. Have you read it? It is here http://www.journalof911studies.com/volume/2008/TheMissingJolt7.pdf

[LARED]

79. Assuming this is true

Lared, the brick would have been slowed and decelerated momentarily at the moment of impact with the towels. Otherwise the brick could not transfer energy to the towels. There is no way around it.

Do you think you could detect this with a standard video camera?

[Tony Szamboti]

83. Probably not

I doubt that the brick and towel issue would be detectable, but it really depends on just how much towel the brick has to go through and how much energy the brick had to begin with.

However, there is a world of difference between this and the collision of the first two floors in the North Tower. There the energy requirements are quite high and as I said we calculated a velocity loss of over 90% would have occurred to meet this energy demand. That then can be used to see whether a sufficient impact had occurred due to it taking time to recover to pre-impact velocity.

[scott75]

87. Well said Tony...

A velocity loss of 90% isn't chump change; and it's a world away from a mere reduction in acceleration. I think that after that heavy a loss, it might have stopped dead a floor or 2 after. Ofcourse, in one of the towers, the upper block disintegrated before even hitting the lower block; there's so many holes in the official story.. the problem is most people don't have a good understanding of structural engineering; I still don't know many things, but through reading and with your guidance, I think I've been learning a fair amount.

[Bolo Boffin]

88. Siss, boom, bah! n/t

[LARED]

100. You have a calculation?

That's great I'd love to see it.

[LARED]

72. A note about impulse (or jolts)

An impulse (F * delta t) is manifested by a change in momentum (m*delta v).

To clarify, if the floor of the wtc was at an acceleration of 9.8 m/sec^2 when it impacted the floor below, and if it changed it's acceleration to 9.7 m/sec^2 for a moment there was an impulse. Note that acceleration is still positive and there was an impulse.

[Tony Szamboti]

75. No that is not an impulse

Lared, an impulse can only take place with a deceleration, not by a change or lowering of acceleration.

The momentum-impulse equation is F = MiVi-MfVf/dT = M x dV/dT.

What you are showing is dA/dT and it is not the same thing.

Described in words, at the moment of the collision if there is no velocity loss and in fact a continuing velocity increase then there was no energy transfer.

[LARED]

80. I should have been more clear

I was trying to say when the acceleration changed the velocity changed and with a change in velocity there was an impulse.

Your whole argument is patently ridiculous. You are saying that if there was no deceleration there was no energy transfer. Without deceleration there was no jolt, hence explosives were used.

Well unless every single support member was removed by explosives, so there would be no energy transfer, your theory fails.

[Tony Szamboti]

81. You are wrong

I showed you how the brick must lose velocity when it collides with the towels in order to transfer energy.

The brick cannot go through the towels without transferring some of it's kinetic energy and this is then manifested in a velocity loss since kinetic energy = 1/2MV**2.

In the case of the North Tower collapse, at the moment of impact on even a small number of columns there would be an energy loss and velocity reduction. The problem is that it wasn't nearly as much as it would need to be if a lot of the columns weren't removed and is not very discernable.

You are just trying to be cute or tricky (pick your word), knowing there were some columns which weren't cut, which does account for the 0.7g average acceleration. There is a reason I also told you we calculated what the energy loss would have to be to deform and buckle the columns on either side of the first impact. It is over 90% of the kinetic energy the upper block of the North Tower would have had at the time. Their would have been a huge deceleration if the collapse was natural and that would be quite discernable especially because it would take time to recover to the pre-impact velocity. We calculated that it would take nearly a second to recover the pre-impact velocity and during that time we had five data points which show no reduction in velocity. You can't see the actual impulse as it would be too short but you can see if the effects are there and they are not.

Sorry Lared, nice try, but you lose.

[scott75]

89. Trying to make a clarifying analogy...

This is my take: a loss of acceleration does indicate there is -some- resistance. Very marginal, to be sure, but something; a few columns that weren't cut by the demolition charges, as I think you mention. But it is -worlds- away from a 90% loss in -velocity-.

It's like a car, going 90 miles an hour, accelerating, going 10 miles an hour faster a minute; it reaches 100 miles an hour when suddenly, it hits a gust of wind; the gust of wind makes it so that the next minute, it's only 105 miles an hour instead of 110 miles an hour.

Now picture a car going at 90 miles an hour, accelerating; it reaches 100 miles an hour when suddenly it crashes into a stationery car and decelerates 90%. That is, it goes from 100 miles an hour to 10; the driver had his foot wedged on the gas, but after hitting yet another car (the twin towers didn't just have -1- floor underneath the top block), it stops completely.

[William Seger]

116. 1) The 90% loss seems to be an error

... i.e. an apparent miscalculation of the resulting velocity, and an unjustified "doubling" of the strain energy:
http://the911forum.freeforums.org/new-jones-paper-by-szamboti-and-graeme-macqueen-t119-225.html

... and 2) Mr. Szamboti has yet to demonstrate that a single large "jolt" is a realistic thing to expect, given the asymmetric nature of the collapse.

[Tony Szamboti]

126. The strain energy isn't doubled:Greening is wrong

I was copied on an e-mail sent by Frank Greening to a group as he is attempting to criticize David Chandler at this time also. I used the opportunity to explain to him what his error was in contending that we are doubling the strain energy in the columns during the impact.

The e-mail is below.

Frank,

I might as well reply here to your criticism that in The Missing Jolt we are doubling the strain energy during the first impact.

You seem to believe that the columns on either side of the impact would couple and act like springs in series, effectively reducing their stiffness.

The spring rate or axial stiffness of a column is calculated using the equation K = AE/L and it can be seen that if one has two equal length springs with one sitting on top of the other the effective stiffness would be half of what an individual spring would have. For two equal length and size springs in parallel the stiffness would be doubled as the effective area is then doubled while length stays the same.

The series spring situation is not applicable to the opposite sides of an impulse as the elastic waves on either side are propagating in opposite directions. The springs in series situation would only apply to the columns if they received their load from the same direction.

Tony Szamboti

[William Seger]

129. I believe Dr. Greening is correct

The parallel springs analogy doesn't make sense at all to me in this case, whereas the serial springs would obviously be correct if the force was acting from one end of one spring while the opposite end of the other spring was restrained. If I had to pick a single point from which the force was acting, it would be the center of mass of the top block. So, I should think the (somewhat more) correct answer would be to use a spring length that was the full height of the lower part of the tower plus half the height of the upper block.

[Tony Szamboti]

140. You obviously have no idea

Seger, it is easy to see from your reply that you simply don't know what you are talking about and are simply siding with Greening because that is what you want to think.

[SDuderstadt]

142. Logic isn't your strong suit, Tony

You are literally "begging the question" here.

[William Seger]

144. Uh, no

I'm saying what makes sense to me, which I didn't write until I had given it some thought. What you said about parallel springs makes no sense for the case under discussion, and apparently you aren't prepared to explain to me where I went wrong. There are a couple other examples of the exact same thing in this thread already: You make assertions, they're challenged, and you don't seem to be capable of really defending them. Suit yourself.

[Tony Szamboti]

147. The explanation I gave Greening shows you are wrong

I did not need to re-explain and show where you were wrong as the explanation I gave Greening shows you are wrong.

You apparently DO NOT understand. You need to give it more thought.

Please show where I have been wrong in this thread.

What type of work do you do for a living Seger?

[OnTheOtherHand]

149. sorry, fail

If you have an argument, state it. Otherwise the inference is that you don't have an argument -- or more precisely, that you may well have an argument that is obvious and compelling in your own mind, but there is no reason for anyone else to suppose that it would withstand scrutiny.

This is how technical discussion works. No one gets to pound the table in lieu of actual argument (certainly not someone who appears to be sketchy on the distinction between yield strength and tensile strength).

[Tony Szamboti]

154. We weren't talking tensile strength

You seem to be another that doesn't know his behind from first base about structural engineering.

We weren't talking the difference between yield strength and tensile strength.

I was talking about creep vs. yield strength, because it is creep that Bazant is discussing when saying it is greater at low fire temperatures. What he leaves out is that it is still insignificant and would not play any role in a yield strength reduction.

[OnTheOtherHand]

156. correct: we weren't talking tensile strength

Hence our surprise that you consider Figure 6-7 more pertinent than Figure 6-6. It's strange that this has to be explained once, much less repeatedly.

By the way, did you ever straighten out that little issue about how "the rock's gravitational effect on the earth... isn't an equal and opposite force to that of the earth on it"?

[William Seger]

163. Well, I believe the explanation you gave Greening actually shows why YOU are wrong

You said in the email you copied:

> "The springs in series situation would only apply to the columns if they received their load from the same direction."

But the springs ARE receiving their load from the same direction: It's straight down, the direction of the momentum vector! I'd love to see the response you got from Dr. Greening on that.

I see that you don't have any comment on the other error Dr. Greening pointed out -- the one where you apparently took the wrong velocity units -- and you still haven't corrected that error even though it was pointed out last summer.

Another instance where you made an unsupported assertion was when you claimed that there could be no energy transfer without a velocity loss. I gave the example of a brick falling through water, accelerating but obviously transferring energy to the water to move it out of the way. No response.

Another is that I pointed out that you had misinterpreted Bazant's overload factor of 31 as meaning there should be a 31g deceleration, when in fact with a 3x FoS the columns in Bazant's linear model could not possibly impart more than a 3g acceleration for anything other than the briefest instant. No response.

On the JREF forum, I pointed out that disintegrated concrete and steel from the floors and broken columns could be receiving considerable deceleration in their collisions with the floors below and none of that deceleration would be visible as velocity changes at the roof-line, because that debris is obviously not connected to the roof-line. No response.

And that's just my interactions with you, and I may have missed one or two, but it isn't hard to find many such examples on this and other boards.

Not that it matters, but I am a software engineer. But I'm not entirely unfamiliar with the basic principles of structural engineering: After dropping out in my second year in Virginia Tech's engineering program (to play bass for an ill-fated rock group) and before returning to school to study computer science, I worked for about 5 years as a structural draftsman. As it happens, I was working at an A&E office in Alexandria, Va., in 1973 when the Skyline Towers collapsed a few miles away at Baileys Crossroads, so I suppose you can imagine that I got to listen to quite a bit of discussion of progressive collapses among the engineers.

[Tony Szamboti]

181. The loads are from different directions

Seger, the load on the top columns of the lower Block come from the upper block and are in the downward direction. The load applied to the lower columns of the upper block are a reaction load from the lower block and act upward. So you are wrong.

The velocity issue was about averaging, and although it had nothing to do with the premise I fixed that and resubmitted an update which has been available since Feb. 5th. So you are wrong again.

There can be not be enough transfer of kinetic energy for the required impulse without a velocity loss. There needed to be a large impulse with a deceleration of much more than g for the upper block to overcome the factors of safety of the columns. You can't amplify the upper block's weight otherwise. Take a look at the math. In your example of the brick moving down through water, that is not an impulse. The brick moves through the water continuously accelerating until it reaches terminal velocity, due to the water not having the strength to support the brick's weight. I don't think you fully appreciate what an impulse is, why it was necessary, and are wrong about things here again.

How am I misinterpreting Bazant's 31g overload ratio? He is the one who postulated it using equations which contained a stiffness for the columns. I have never said a 31g load would be applied and in the paper say that it couldn't happen anyway as the upper block would have come completely apart. Of course, the load would finally be limited to whatever the columns below could take and in the paper I show a 6g jolt and what it would look like on the velocity curve. The factor of safety of the perimeter columns was 5.00 to 1 and the core columns were 3.00 to 1. Even a 3g jolt would show an abrupt obvious deceleration.

Your postulation about loose material breaking up the lower structure is something even Bazant considers to be impossible. Read the Addendum to the 2001 Bazant and Zhou paper. It is the proverbial losse sand situation and would not have broken up the lower structure in any significant way. You obviously don't understand the concept of transmissibility in a shock load. If there was loose material below the upper block, that prevented the upper block from experiencing a deceleration, that would mean that the upper block's load was not being applied through the loose material.

You and several of your friends here simply don't want to accept the reality that something other than the upper block of the North Tower was removing the strength of the columns in the lower structure because there is no mechanism other than a jolt, which is not observed, for the upper block to do so.

I have had enough here for now, so goodbye for now.

[AZCat]

182. I didn't realize your understanding of impulse was so poor.

No wonder you've been making these mistakes. Impulse is dependent on all forces acting externally on the body considered, not just those involved in the collision. Draw a free-body diagram and you'll see what I'm talking about.

[Tony Szamboti]

183. What a joke of a comment

Why don't you draw the diagram you think shows I am wrong somehow Mr. Smarty Pants? You seem to make a lot of half baked comments with no basis provided. It is time to put up or shut up.

[Bolo Boffin]

184. Hey, Mr. Smarty Pants

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=242399&mesg_id=243095

You missed one.

[AZCat]

187. Actually, it's you who needs to do a little work.

You don't appear to have sufficiently learned the material, either in your classes or your 30(?) years of experience. Maybe you should go check with someone who actually knows what they're talking about before trying to correct me (or anyone else here, for that matter). See, when I took Dynamics, we covered impulse and momentum. Maybe at your school they skipped that section?

[Realityhack]

194. Even a high school physics student should be able to understand this one. n/t

[AZCat]

199. I've had at least one person...

who has had only high school-level physics tell me the flaws were apparent in Tony's arguments. This isn't complicated stuff we're discussing, yet Tony is getting it wrong.

[Realityhack]

200. To be honest...

I have no further formal education in physics or engineering beyond high school.
The argument is quite bad indeed.

[scott75]

190. I believe that your detractors...

Would rather go 'nya nya' then discuss real structural engineering. None of them have much of a grasp of structural engineering. I've begun to think they're a waste of time for you Tony.. and if they're a waste of time for you I think they're probably a waste of time for me as well.

I'm glad that you got the point across to Dr. Greening; I have a strong feeling that these guys are simply way below his level of understanding and yet are incapable of recognizing it.

[OnTheOtherHand]

195. don't kid yourself, scott

I don't see how you're in a position to evaluate AZCat's grasp of structural engineering. Regardless, on this branch AZCat is stating something simply true: impulse, in the physical sense, isn't limited to "jolts," and certainly not to jolts involving all the upper floors as a unit. It's certainly possible, as Bazant and Zhou say in their addendum, that the breakup of the upper floors could allow a lower floor to withstand the ensuing series of small impacts -- but Szamboti hasn't offered any warrant for his insistence that there had to be a 3g deceleration. He also hasn't demonstrated that a relatively small instantaneous deceleration would be detectable using 1/6-second increments, or that it has to be detectable at the roof line.

There's a reason (several reasons, in fact) why Szamboti hasn't convinced the expert community -- never mind the DU community -- that the towers could not have fallen without CD or other help. He apparently believes the reason is that the experts are lost in denial, and he isn't above venting his frustrations on people he regards as smaller as himself. But he palpably isn't winning the argument. Maybe he is a prophet without honor. Or maybe his arguments just aren't that good. Looks to me like the latter.

[scott75]

201. Maybe not...

But Tony certainly was. And he found you all wanting.

[AZCat]

202. Tony certainly was what? n/t

[SDuderstadt]

203. I'd say getting his ass kicked by just about....

well, everyone.

[AZCat]

204. Well, yes, but...

I don't think that's what scott75 meant, even if it was rather obvious to the rest of us.

[scott75]

205. In a position to find OCTers knowledge wanting...

None of you guys have much knowledge concerning structural engineering, and yet the way you guys acted with Tony, you'd think you were experts, laugh :-p. Well in some time, you may all be shaking your heads at how much you didn't understand, but for now, carry on I suppose...

[AZCat]

206. I don't think you're in a position to make that determination.

You don't seem to have a very good grasp of engineering issues, so pardon me if I don't grant much weight to your opinion of my knowledge or skillset.

Regarding your hero - Tony has displayed a woeful understanding of basic physics for a BSME. This is apparent to people without extensive education or experience. Why it isn't apparent to you, I don't know.

[scott75]

212. I don't understand all the issues...

Tony, on the other hand, as a mechanical engineer, had a much better understanding of the issues; this doesn't mean that many of you OCTers realized this, however, and he was able to show me many flaws in the logic if various OCT arguments.

One thing I'm curious about is whether -you- have any qualifications or whether you are, as I expect, just another person "without extensive education or experience".

[Bolo Boffin]

213. Tony needs some work on his grasp of the issues

His paper has the distinct honor, if proving anything at all, of proving that Bazant's admittedly hypothetical best case scenario did not happen. And no one has ever claimed that the best case scenario ever happened. With the rotation present in the upper section of the tower, there is no reason to expect that the upper section ever connected to the lower columns completely in an instant.

[AZCat]

215. Your appeal to authority is quite ineffective.

Tony has authored papers and has posted here, so we can judge his arguments on their merits, which we should be doing for any arguments. Tony's credentials are useless if he can't put his acquired knowledge to good use. Just because he's a mechanical engineer doesn't mean he knows what he's talking about. I've known plenty of engineers, mechanical and otherwise, and some of them are not very bright. More importantly, why hasn't the "truth movement" granted this authority to the engineers on the other side? Bazant gets the shaft, to say nothing of the engineers who post in this very forum. If you're going to act like it means something, don't be a fucking hypocrite about it.

[Bolo Boffin]

207. Maybe we will be shaking our heads

But more than likely it will be at the next person who rolls along pushing the same old crapola and claiming it's new and improved or in the least bit valid and respectable.

[OnTheOtherHand]

208. hey, can you carry an argument, or not?

Your faith in Szamboti's knowledge is touching. I certainly don't assume a priori that all criticisms of a paper from late 2001 are bound to be wrong. But Szamboti faced, and failed to overcome, some very grave objections here. Nor did he cover himself in glory from the standpoint of professionalism; nor did he demonstrate the capacity to interpret graphs correctly and to make careful, consistent use of technical terms. ("Impulse" ordinarily doesn't mean "jolt"; Szamboti sometimes uses it in the technical sense, sometimes not, and sometimes it is hard to tell what meaning he intends.) I find nothing in the written record that would allow me to conclude that Szamboti has the better side of this argument or greater ability to conduct it.

I get a strong sense that you are predisposed to think he does. For some reason, you are firmly convinced that the towers fell 'too fast'; if the expert community overwhelmingly disagrees, so much the worse for the experts. That is your privilege; die Gedanken sind frei -- and I don't assume that expert communities are invariably correct. However, if the best reason you can give me to agree with you is that Szamboti himself knows enough to warrant my credulity, that isn't a very good reason. If you think you can argue more effectively than he did, I welcome you to try.

[Realityhack]

210. well put n/t

[Realityhack]

209. I am shaking my head right now... at what Tony said about steel at 300 degrees.

And his idea that if an object is experiencing acceleration in one direction that any acceleration in the opposite direction will result in a net negative from the first direction.

And several other such points.

Tony was proven wrong on several basic points by the people who you are saying lack knowledge on structural engineering. How knowledgeable does that make him?

[William Seger]

197. Baloney

> "The load applied to the lower columns of the upper block are a reaction load from the lower block and act upward."

Good grief, Tony. Even though you correctly call the upward force a reaction, you still deny that the loading could only be in the direction of the momentum and the gravity vectors? Amazing! But there would be an upward reaction in the lower part, too, wouldn't there? And a downward reaction in the upper part, eh? And in fact, wouldn't there be equal and opposite reactions at every point? But that's completely irrelevant to Dr. Greening's point about spring stiffness. If you are going to treat the columns as springs and calculate a stiffness, then two end-to-end springs reacting to one downward loading vector is what you physically have, and nobody needs a freakin' BSME to understand that. Since you're leaving, I guess we'll never know what Greening's response to your argument was, huh.

> "The velocity issue was about averaging, and although it had nothing to do with the premise I fixed that and resubmitted an update which has been available since Feb. 5th. So you are wrong again."

Nope, that's not the math error Dr. Greening mentioned in the link I provided: It was in the appendix where you attempted to calculate the lost velocity as a function of "lost" energy -- i.e. the same section that contains your misconception about springs. And the "velocity issue" you now mention was not "about averaging"; it was about a completely invalid method being used in an attempt to calculate instantaneous velocity, and that gross error was the premise of the conclusion drawn the first version of your paper. Since that method wouldn't have shown any "jolt" even if the mass came to a complete stop, it's essentially coincidental that a more correct method still didn't show the "jolt" you were looking for and you were able to salvage anything at all from the paper. Unfortunately, the issues of how large a "jolt" should be seen in the real world collapse (rather than in Bazant's simplified model), and whether or not you could actually detect those using your method still remain to be resolved.

> "There can be not be enough transfer of kinetic energy for the required impulse without a velocity loss."

OK, so now you agree that that there could be an energy transfer without velocity loss -- just "not enough" to meet your "required impulse." Which reminds me, you haven't yet demonstrated what's "required" or that you can actually detect it using your method.

> "How am I misinterpreting Bazant's 31g overload ratio? He is the one who postulated it using equations which contained a stiffness for the columns."

Well, either you misinterpreted it or you misrepresented it, in this part of your paper:

Bazant claims that a minimum force amplification of 31g, or 31 times the static weight of the upper stories, could have occurred in a collision between the upper and lower blocks of the Twin Towers after a fall of one story. <17>

Absolutely not; Bazant claims no such thing. Rather, he claims that the dynamic force was 31 times more than the structure could absorb without failing (at least in his simplified, linear model). That you either mistakenly or disingenuously take that as a 31g deceleration is clear in the immediately following sentences:

With the 98th story columns completely collapsing, a distance between floor slabs of approximately 11.44 feet, and the actual measured velocity of 22.81 ft./s of the upper block at this point, the first collision would have occurred approximately one second into the fall. A 31g impulse at the impact zone between the 98th and 99th story floor slabs would cause the columns on at least the first stories on either side of the impact to deform elastically and plastically and then to buckle. These deformations and buckling of the columns of the impacting stories, on both the lower and upper blocks, would cause a kinetic energy drain, which would reduce the velocity of the rigidly attached falling mass above them.

A 31x overload does not imply a 31g impulse, or anything else about the deceleration. And why do you think an estimate of even a 6g deceleration "jolt" has anything to do with it, if the columns could not possibly offer more than 3g resistance even under the best possible axial loading situation?

> "Your postulation about loose material breaking up the lower structure is something even Bazant considers to be impossible. Read the Addendum to the 2001 Bazant and Zhou paper."

I think we've already established that you're not very good at understanding what Bazant says in the paper. In a later paper (not the original), Bazant says that the structure "might" have been able to survive a series of small impacts, not that it was "impossible" for loose material to cause any damage. In fact, it's loose material that causes Bazant's "crush down" phase and prevents much "crush up." In the original paper, Bazant said his simplified analysis "disregard{ed} various complicating details (e.g., the possibility that the failures of floor-column connections and of core columns preceded the column and tube failure, or that the upper tube got wedged inside the lower tube), etc." His justification for using the simplified model: "If the tower is found to fail under these very optimistic assumptions, it will certainly be found to fail when all the detailed mechanisms are analyzed." What you are trying to do is estimate decelerations in that simplified model (and not being particularly successful at it!), claiming that you could detect those decelerations using your method (without any serious discussion of error margins), and then you claim that this "proves" something about reality.

> "You obviously don't understand the concept of transmissibility in a shock load. If there was loose material below the upper block, that prevented the upper block from experiencing a deceleration, that would mean that the upper block's load was not being applied through the loose material."

That certainly doesn't mean that you can ignore the destructive potential of the loose material; it's still mass in motion. If you've got an argument about "tranmissibility" allowing you to ignore that, you seem to have neglected to include it in your paper. It appears that you didn't even consider it, as you expected all the "jolting" to appear as velocity changes in the roof.

> "You and several of your friends here simply don't want to accept the reality that something other than the upper block of the North Tower was removing the strength of the columns in the lower structure because there is no mechanism other than a jolt, which is not observed, for the upper block to do so."

Baloney, Mr. Szamboti; I'm quite comfortable accepting reality, and my reality is that when I look at the real collapse and look at what you are doing in that paper and try to reconcile the two, your conclusions are simply not justified. For you to call this nonsense "reality" makes you look like a fool.

> "I have had enough here for now, so goodbye for now."

Yes, please do come back when you think you've got a convincing argument.

[OnTheOtherHand]

106. you don't even have "moment" estimates

You made sure of that by discarding 80% of your data. :shrug:

ETA: In fairness, that's largely because given your source, you can't do much better. But it would be kind of fun to model the expected error in your acceleration graph.

[William Seger]

111. How about the case of...

.. a brick falling through water. The 1g force of gravity is resisted by the viscosity of the water which has to be pushed out of the way, so the acceleration of the brick is less than g, while the velocity is strictly increasing. Would you claim that there was "no energy transfer" between the brick and the water?

[LARED]

50. Also, could you explain this statement

There is no deceleration in the WTC 1 acceleration graph, only greater or lesser acceleration.

Its meaning seems to escape me.

[OnTheOtherHand]

54. presumably that acceleration is always positive, never negative n/t

[wildbilln864]

47. check this out William and...

tell me why the "crush down" theory didn't happen. short video of a failed building demolition :popcorn:

[William Seger]

110. Are you suggesting

... that the details of the construction don't matter -- that all structures would either fail or not in that scenario? Dang, then we don't need structural engineers, huh.

If you really want to understand (:eyes:) why that grain tower failed to collapse, you'd need to look into the details of its construction -- something that the demo guys apparently didn't do.

[wildbilln864]

63. And did you notice how...

both sections impacting each other are the same size? Now had they dropped 2 floors onto six, I doubt all four below would collapse completely to the ground.
How long did that collapse take? About 10 seconds? Hmmm. :dilemma:

[William Seger]

108. Gee, maybe just one more time explaining the exact same thing will do it, huh

No, I don't think so -- I'm convinced that you are totally hopeless -- but for anyone else: In a progressive vertical collapse, floors are destroyed one at a time, with each collision involving more energy than the one before. If the falling six floors of the Balzac building caused the floor immediately below to fail, then seven floors of mass would hit the next floor with even higher velocity. Why in hell would you expect that floor to stop the collapse, when it just got hit with greater kinetic energy than the floor that just failed? If the building had been a 100 stories tall, it wouldn't have mattered: The whole thing would have collapsed, because the floors were destroyed one at a time.

I have no idea whether or not two floors falling would have the same result, although it's certainly possible (unless the floors had quite a bit more reserve strength than is typical). But if two floors falling could break through the next floor, then the end result would certainly be the same: It simply doesn't matter how many floors were below that.

As for the timing, I suggest that you try again, and be sure to use the full-speed version.

[wildbilln864]

112. Sure buddy!

We believe you now! :rofl:

"In a progressive vertical collapse, floors are destroyed one at a time, with each collision involving more energy than the one before."
False premise. Please show examples of said progressive collapses ever taking place in history.


"If the falling six floors of the Balzac building caused the floor immediately below to fail, then seven floors of mass would hit the next floor with even higher velocity. Why in hell would you expect that floor to stop the collapse, when it just got hit with greater kinetic energy than the floor that just failed?"

I didn't say one floor would stop the collapse. I think the undamaged floors below eventually would arrest the collapse. Much of the weight goes over the sides as is clearly visible!

"If the building had been a 100 stories tall, it wouldn't have mattered: The whole thing would have collapsed, because the floors were destroyed one at a time."
One at a time eh? And how many floors per second was that rate of destruction William? Do you have a figure? I bet not. I think about ten. And the collapses didn't seem to slow down.

[William Seger]

109. (dup)

[golda_2003]

114. "September Clues"

http://www.youtube.com/watch?v=oqEpuTGc98s&feature=related

just WAIT til you see the tower explode with NO PLANE -


and, i'd love to hear what debunkers think of this - i don't have any answers for the things this video shows me

i thought i'd seen every theory on 911 and every video - THIS is different than all of them


thoughts?

[Beam Me Up]

115. Off topic.

Please stop.

[Realityhack]

118. Posting off topic violates forum rules.

You should read the rules before posting.

[golda_2003]

123. Off Topic? How So?

this thread is talking about how the towers fell and i provided a link to something that questions the planes being involved in that collapse

[Realityhack]

125. No. The OP is about how a specific gravity driven CD...

relates to statements that gravity could not cause the collapse. The crap you linked to which has been discussed and debunked in detail in other threads is talking about wither or not planes were involved.

These are completely distinct issues.

Furthermore simply linking to a video is considered bad form. At the very least take the time to comment on what you think is relevant in the video and how it relates to the discussion.

[wildbilln864]

211. So why do we need demolition companies charging millions?

We can just take out the bottom floor and presto! The rest will "gravity driven demolition" to the fucking ground! :rofl:

Oh wait! :dilemma: So what happenedhere? :shrug:
another video

[Bolo Boffin]

214. What a facile argument. n/t

[AZCat]

216. Kick for relevance to Mackey-Szamboti debate. n/t

[vincent_vega_lives]

220. Debate

What went on here was a serious thrashing. :spank: