RFC: Bazant and Zhou Simple Analysis refuted

[DGM]

The photos are quite interesting. As for the welds, I have calculated what it would take to generate the fracture stress due to bending in the welds of one of the large 52 x 22 x 1.875 wall 500 or 1000 series box columns in the middle of the tower. The weld is only on the long sides of the column and the section modulus (I/c) of that weld would be 1092 in**3. If the weld material was E70 then 70,000 psi had to be generated to fully fracture it. Just considering the bending stress, and not the shear, and using the assumption of a force applied 72 inches below the weld, that force would need to be approximately 1 million pounds. How much explosive would be needed to generate that force on the side of the column I am not sure of but we do know that RDX generates pressures of 3 million psi so what you are saying seems plausible, although I wouldn't necessarily call it a small kick. These forces would also cause the column to bow inward adjacent to the blast making it appear as though some buckling had occurred at the top of the column. The core column that Newtons Bit showed a few days ago, which was on a flatbed truck, and was buckled up at its end, seems like it could have been damaged with the type of mechanism of which you speak.

And make one hell of a noise! It's a shame he can't deal with this.

BTW Tony wouldn't you need to pre-heat the welded piece to obtain these strenghts?

 

[Tony Szamboti]

And make one hell of a noise! It's a shame he can't deal with this.

BTW Tony wouldn't you need to pre-heat the welded piece to obtain these strenghts?

Until we know how much explosive would be needed to generate this force we can't be sure what the noise level would be over distance which would also be damped by being inside the building.

Preheating is normally done to ensure that rapid cooling doesn't take place in the parent material to weld inteface which would set up residual stresses.

I am just going on the allowable strength of E70 weld metal for a rough conservative estimate of the force required. However, it is more likely that the interface between the A36 parent material and the weld material would have fractured first. In that case the yield strength would have been lower and a lower force required.

 

[DGM]

Until we know how much explosive would be needed to generate this force we can't be sure what the noise level would be over distance which would also be damped by being inside the building.

Preheating is normally done to ensure that rapid cooling doesn't take place in the parent material to weld inteface which would set up residual stresses.

I am just going on the allowable strength of E70 weld metal for a rough conservative estimate of the force required. However, it is more likely that the interface between the A36 parent material and the weld material would have fractured first. In that case the yield strength would have been lower and a lower force required.

Agreed! I'm just surprised that Major Tom would think that these welds would not break before the columns yielded. These straight columns are of no surprise to anyone in the trade.

 

[Heiwa]

Try your experiment with rectangular tubing instead of pipe. The results are completely different. I suspect you already know this that is why you specified pipe. I'm a welder and a metal fabricator so don't try to BS me. Your experiment is junk and fatally flawed by design.
Why did you do that? Did you think because you wrote this for children no one would catch on?

You can alternatively use two L-angles, say 35x35x1 mm and weld them together as a square box and use them as legs. Same result.

 

[Heiwa]

Why do you lie about the conclusions of Bazant and Zhou?

Because release of potential energy of a mass above (cause) does not cause global collapse due to lack of strain energy of the structure below (effect) as alleged by NIST and Bazant (and Zhou).

The two are not related! First of all the potential energy must be applied to the structure below - there is no evidence for that.

NIST and Bazant assume the application of potential energy is an impact at high velocity on the structure below. No evidence for that.

If the application is at low velocity, which is the case, stresses in the structure below (and above!) are hardly affected and will evidently be same before and after loading.

It like hitting a nail (structure below) with a hammer (potential energy released). Too little speed nothing happens. To much speed nail bends and hammer slides off the nail and the energy is lost. It is not easy to hit a nail.

Bazant actually assumes that WTC1 is hammered 90 times; mass above (rigid and stiff all the time) first drops one floor that magically disappeared due to heat (the initiation zone) and crushes the floor below, i.e. deforms/buckles the supporting columns there and sweeps them out of the way (no evidence for that), then it drops another floor with same effect, then again ... 90 times. Evidently the rubble does not show any buckled columns, like that. Anywhere.

So Bazant's and Zhou's basic assumption is 100% wrong. Garbage in = garbage out.

NIST has abandoned the hammer/nail theory and suggests (FAQ Dec 2007) that 5-10 floors (in mass above) suddenly dropped down in the initiation zone (cause) and overloaded the first floor of the structure below (effect).

There is no evidence for that cause at all. It is pure fantasy. Note that NIST actually assumes that the mass above first disintegrates (before it was solid and stiff) and that now some subparts of the mass above (floors) suddenly drop down and do the hammering!

But again, there is no evidence that even one floor suddenly dropped!

In my article for children I just politely ask NIST and Bazant to re-do their analysises. No big deal! Very often mistakes are done in technical papers for various reasons.

 

[Norseman]

The photos are quite interesting. As for the welds, I have calculated what it would take to generate the fracture stress due to bending in the welds of one of the large 52 x 22 x 1.875 wall 500 or 1000 series box columns in the middle of the tower. The weld is only on the long sides of the column and the section modulus (I/c) of that weld would be 1092 in**3. If the weld material was E70 then at least 70,000 psi had to be generated to fully fracture it. Just considering the bending stress, and not the shear, and using the assumption of a force applied 72 inches below the weld, that force would need to be approximately 1 million pounds. How much explosive would be needed to generate that force on the side of the column I am not sure of but we do know that RDX generates pressures of 3 million psi so what you are saying seems plausible, although I wouldn't necessarily call it a small kick. These forces would also cause the column to bow inward adjacent to the blast making it appear as though some buckling had occurred at the top of the column. The core column that Newtons Bit showed a few days ago, which was on a flatbed truck, and was buckled up at its end, seems like it could have been damaged with the type of mechanism of which you speak.

No, the explosive would cut through the steel plate on the side it was applied like the column was not there. It would not affect the weld 72 inches below. Simply because the steel in contact with the explosive would not be able to transfer any significant amount of force from the detonation to the remainder of the column before it yields. Note the enormous difference in the pressure numbers per square inch you quoted realcddeal. If there is not enough explosive to cut the steel it will leave a local plastic deformation/cracking. Even less it would only soil the paint. In other words the effect would be very local. It is a bit like the old tablecloth trick. Or like putting a banana in cup so that it stands up vertically and swing a knife at high speed horizontally at it. The knife will cut the banana in half like it was not there. Doing it at slow speed you will just push it and the cup over.

If you are going to bend the whole column with the pressure wave from an explosive, you would need to detonate a very large bomb away from the column. That would subject the column to a lower pressure per square inch, but it would be applied over a larger surface area. But even this is difficult. The 1993 car bomb was parked close to the south wall of WTC 1 did not manage to do it. That was a 1500 pound bomb.

 

[Newtons Bit]

The photos are quite interesting. As for the welds, I have calculated what it would take to generate the fracture stress due to bending in the welds of one of the large 52 x 22 x 1.875 wall 500 or 1000 series box columns in the middle of the tower. The weld is only on the long sides of the column and the section modulus (I/c) of that weld would be 1092 in**3. If the weld material was E70 then at least 70,000 psi had to be generated to fully fracture it. Just considering the bending stress, and not the shear, and using the assumption of a force applied 72 inches below the weld, that force would need to be approximately 1 million pounds. How much explosive would be needed to generate that force on the side of the column I am not sure of but we do know that RDX generates pressures of 3 million psi so what you are saying seems plausible, although I wouldn't necessarily call it a small kick. These forces would also cause the column to bow inward adjacent to the blast making it appear as though some buckling had occurred at the top of the column. The core column that Newtons Bit showed a few days ago, which was on a flatbed truck, and was buckled up at its end, seems like it could have been damaged with the type of mechanism of which you speak.

 

[Norseman]

Until we know how much explosive would be needed to generate this force we can't be sure what the noise level would be over distance which would also be damped by being inside the building.

You should check out how small the charges used in real CD implosions are, they are surprisingly small. And they do it with the smallest amount of explosives possible, thats with pre weakening. And yet the detonations are not exactly soundless. You should watch all the videos in this post and especially note the comments about the windows:
http://www.internationalskeptics.com/forums/showthread.php?postid=3301537#post3301537

And there is no way that you and Major Tom can get away with bombs smaller than what is used in the demolition industry. Quite the contrary. And they would have been heard very loud and clear.

 

[Major_Tom]

DGM says

Agreed! I'm just surprised that Major Tom would think that these welds would not break before the columns yielded. These straight columns are of no surprise to anyone in the trade.

Do you see much mention of the abundance of straight core columns in the thousands of pages of the NIST reports? It wasn't obvious to them.

If it is so obvious, why doesn't Bazant mention it in his analysis? It wasn't obvious to him.

Many people have imagined bucked, mangled core and perimeter columns for 6 years.

Many of you folks have been steeped in that illusion, and your posts reflected that.

I mention it, show an overwhelming amount of photographic evidence to back what I say, and now you call it common knowledge.


Realcddeal remarks

If the weld material was E70 then at least 70,000 psi had to be generated to fully fracture it. Just considering the bending stress, and not the shear, and using the assumption of a force applied 72 inches below the weld, that force would need to be approximately 1 million pounds.

Being totally open to possibilities, we would consider the placing of the device right on the weld.

Or, like a baseball bat has a "sweet spot", placing the device at an optimum location along the column to provide the maximum .....destructive vibrations?

We would be totally open to the device used. The highly skilled planners would carefully choose, or "fine tune" the device to serve the task at hand.

I would never want to suggest that these planners were not VERY TALENTED at what they do.

Limiting ourselves to the most conventional devices would be unwise.



Like the use of any hand tool, the craftsman uses the proper tool for the task at hand and has a shop full of specialty tools.

They are much better at choosing the proper tool than we are. The best we can do is to know the general possibilities and to keep our minds open.


How would it be possible to know expected noise levels without a general knowledge of possible choices of device and particular welds under attack.

There is no generic answer. Why do people keep asking generic questions as if the perpetrators were amateurs?

 

[Newtons Bit]

No, the explosive would cut through the steel plate on the side it was applied like the column was not there. It would not affect the weld 72 inches below. Simply because the steel in contact with the explosive would not be able to transfer any significant amount of force from the detonation to the remainder of the column before it yields. Note the enormous difference in the pressure numbers per square inch you quoted realcddeal. If there is not enough explosive to cut the steel it will leave a local plastic deformation/cracking. Even less it would only soil the paint. In other words the effect would be very local. It is a bit like the old tablecloth trick. Or like putting a banana in cup so that it stands up vertically and swing a knife at high speed horizontally at it. The knife will cut the banana in half like it was not there. Doing it at slow speed you will just push it and the cup over.

If you are going to bend the whole column with the pressure wave from an explosive, you would need to detonate a very large bomb away from the column. That would subject the column to a lower pressure per square inch, but it would be applied over a larger surface area. But even this is difficult. The 1993 car bomb was parked close to the south wall of WTC 1 did not manage to do it. That was a 1500 pound bomb.

No columns were destroyed in that terrorist attack. The reason why is fairly obvious to anyone who has spent a little bit of time looking at blast engineering. I'll elaborate a little:

Structural members only carry forces that can be delivered to them. A single steel column itself is extremely resistant to non-shaped charge blast events because it has a small surface area. Walls and floors have very large surface areas, and even low pressures can mean huge forces at the connections. A typical floor slab in a parking garage will be designed for 100-200psf of live load. That's equivalent to about 1psi. Interior walls that will never see wind are typically designed for 5psf pressure loads (typically from HVAC units on the fritz), and that's only 0.07psi.

Pressures from blast easily overload the the floors and walls, either at the members themselves or the connections, but typically don't overload the columns. This is because the columns are designed to take many floors at something just less than what can cause the floors and walls to collapse.

This applies to steel columns. Concrete columns, such as the ones at the Murrah Building in OKC, have much larger surface areas and are more susceptible to blast.

If non-shaped charge explosives were used to "aid" the destruction of the towers on 9/11, we would expect to hear them, and we would expect to see them. This would be evident in extremely large ejections of glass and wall.

 

[beachnut]

.. but we do know that RDX ...

So Jones is wrong, it was RDX. Silent RDX? Do you have a sample of this silent RDX? I need to see the silent RDX. I have never seen silent RDX yet. But no thermite, just RDX? Wow, realcddeal has RDX for WTC failure, the silent kind! Wow.

If you read your papers you would never see a single piece of evidence for RDX, and your failure to prove a simple model like Bazant and Zhou's wrong. BTW, you can not prove Bazant and Zhou's model wrong, because it is a model, and it is just exactly what it is. Who is dumb enough to refute a simple model?

Funny stuff, damped by the 200 foot building? So your damping is only 100 feet MAX!!? The 95% air building damped the sound of RDX. NEXT dumb idea please. NEXT! Do you know how far damped RDX sounds go? Do you know the blast effects of RDX? Do you know why the experts wrap the charges in mattresses? Do you know anything about anything related to 9/11?

Are you sure you are an engineer?

 

[Gravy]

Yoo-hoo! Major Toooooom!

Fourth time: how many core columns were able to be matched with as-built locations in the collapse initiation zones? I know. Do you, Major Tom? You'd better, if you're going to keep raising this issue.

Answer the question now, please.

 

[Gravy]

Until we know how much explosive would be needed to generate this force we can't be sure what the noise level would be over distance which would also be damped by being inside the building.

Once again, I demand that you point out when the detonations occurred. Tell us the minutes and seconds in this video when the charges that blew out the core columns detonated.

http://video.google.com/videoplay?docid=2873871255585611926#1m10s

Afraid to do it, Tony? Of course you are. Because you've also seen clips like these:

http://video.google.com/videoplay?docid=2873871255585611926#11m55s

 

[Gravy]

This, of course, is the best example of inward pulling of perimeter columns seen.

No, this is:

http://video.google.com/videoplay?docid=2873871255585611926#1m10s

Note that there are no detonations. How does this fit in with your hypothesis – if you can even manage express a hypothesis – Major Tom?

 

[Major_Tom]

Once again, I demand that you point out when the detonations occurred. Tell us the minutes and seconds in this video when the charges that blew out the core columns detonated.

You demand?


Realcddeal, in a different thread you mentioned

The welds would have maintained most of the moment of inertia of the columns since they were on the outside. The weld planes would thus have had nearly the same bending strength as the column itself. This would have allowed the central core to be self supporting.

However, if their welds did not have the complete cross section of the columns in the core then they would not have maintained the same resistance to shear at the weld planes.

and

We calculate the strength of welds by treating them as a line using the moment of inertia of the weld. We then determine fillet size needed based upon the area stress imparted to it. They would not need to be the same thickness as the cross section to retain most of the moment of inertia of the column. Haven't you ever heard the saying that "pound for pound tubes or pipes are stronger than solids"? The reason is that the tube retains the moment of inertia, which is an exponential function of distance from the center.

Enough resistance to bending from buckling under their own weight is all the central core welds would need for it to be self supporting, as it is obvious it had the cross section to withstand compressive loads. I have a surprise for you also, it could have taken some level of wind load also. Maybe not 100 mph but I would not doubt it could take 50 mph while also being self supporting. A simple analysis will show these things to be true. Do you care to show something different?

and

Lets take a 503 box column at the 60th floor. It is 52" x 20" x 1.875" wall thickness. Taking it as a complete box and ignoring the insets of the end plates, for simplicity, the moment of inertia for that box column about the axis parallel to the 20" width is 17,413 in.e4. If the weld has a one inch penetration it's moment of inertia is 9,213 in.e4 which is 53% of the moment of inertia of the full column cross section. About the axis crossing the width it retains 57% of the moment of inertia. This is significant like I said. You are the one placing the 75% factor on it. I didn't.

Considering the fact that the weld is made of material which has a significantly higher yield strength than that of the parent material, in the case of A36 yield is 36,000 psi and E70 weld metal is 58,000 psi, it would have nearly the same resistance to bending stresses.

Realcddeal, I find what you said to be interesting because it seems to be consistent with the photographs and video of the North Tower spire.

About 15 seconds of swaying was witnessed and there was no recognizable strong base seen after the smoke cleared holding up these core columns standing close to 50 stories high.


The distinction you mention between the ability of these columns to experience limited swaying in the wind, as opposed to the ability of the weld to resist lateral forces is interesting.


I can't help notice that photos and video of the North Tower spire seem to show that you had a good point.

It also seems to show that your critics were probably mistaken in their underestimation of the ability of these columns to "fight back".


Any more information you have on the distinction between the welds ability to resist lateral forces as opposed to the ability to withstand swaying would be greatly appreciated.

 

[Gravy]

You demand?

A bizarre question, from someone who says this:

Once again, can anyone show me a few photos of recovered buckled core columns from the collapse initiation zones?

Why do you think that you can't find some representative samples of core columns from that area? There should be close to 100 of them. They are about 38 feet long. Hard to miss.

Sceptics?

Show me a few.


Where did they all go?


Buckling? Can you show me a few?

I think the ultimate refutation of the Bazant paper is the inability of anyone to find sets of buckled columns from the collapse initiation zones.

I can come up with many other arguments but the lack of "heat affected" core buckled columns is simple and none of you can debunk that.

...So if yourselves or NIST cannot explain collapse initiation by showing the the failed core column sections from that zone, then you have pretty much been debunked, no?

...Your move. Please produce some representative damaged core columns from the collapse initiation zones or simply admit that you can't.

I'll be pestering you until you do.

And again:

I think the ultimate refutation of the Bazant paper is the inability of anyone to find sets of buckled columns from the collapse initiation zones.

I can come up with many other arguments but the lack of "heat affected" core buckled columns is simple and none of you can debunk that.

...So if yourselves or NIST cannot explain collapse initiation by showing the the failed core column sections from that zone, then you have pretty much been debunked, no?

...Core columns within the rubble are remarkably well preserved and the damage patterns contain all the information we need to understand what initiated collapse.

...Your move. Please produce some representative damaged core columns from the collapse initiation zones or simply admit that you can't.

I'll be pestering you until you do.

Show them to me , Gravy. If you can't, then there is very little difference between your approach and that of Steven Jones.

Show or you are lying, too.

Nobody is showing any images of the buckled columns in the collapse initiation zone.

I really thought that you folks could come up with at least a few.

...I am sensing that the weakness in your entire argument and the Bazant collapse mechanism is the lack of buckled columns from the collapse initiation regions.

...As of this moment I would like to give some of the wiser folks posting here a chance to show me some actual evidence for your belief in collective buckling of core columns in the collapse initiation zones.

Dave? Apollo20? NB? Myriad? cmcaulif if you are reading? Others who answer with reason?

I know you must have some sounder reason for believing that core column heat-induced buckling was a major cause of collapse initiation than mere faith in NIST.

...Please don't let Gravy's dribblings be the best you have to offer. You must have more than faith and insults.

All of which prompts the question, which I ask for the fifth time, how many core columns were able to be matched with as-built locations in the collapse initiation zones? I know. Do you, Major Tom? You'd better, if you're going to keep raising this issue.

Answer the question now, please.

 

[Tony Szamboti]

a chapter about explosives from a NAVSEA handbook

Below is a link to a chapter about various explosive methods and the blast effects from a NAVSEA handbook. I would imagine a number of individuals here would be interested.

http://wetlands.simplyaquatics.com/d/14926-1/chap_10.pdf

 

[Tony Szamboti]

[qimg]http://upload.wikimedia.org/wikipedia/commons/f/f2/WTC_1993_ATF.jpg[/qimg]

No columns were destroyed in that terrorist attack. The reason why is fairly obvious to anyone who has spent a little bit of time looking at blast engineering. I'll elaborate a little:

Structural members only carry forces that can be delivered to them. A single steel column itself is extremely resistant to non-shaped charge blast events because it has a small surface area. Walls and floors have very large surface areas, and even low pressures can mean huge forces at the connections. A typical floor slab in a parking garage will be designed for 100-200psf of live load. That's equivalent to about 1psi. Interior walls that will never see wind are typically designed for 5psf pressure loads (typically from HVAC units on the fritz), and that's only 0.07psi.

Pressures from blast easily overload the the floors and walls, either at the members themselves or the connections, but typically don't overload the columns. This is because the columns are designed to take many floors at something just less than what can cause the floors and walls to collapse.

This applies to steel columns. Concrete columns, such as the ones at the Murrah Building in OKC, have much larger surface areas and are more susceptible to blast.

If non-shaped charge explosives were used to "aid" the destruction of the towers on 9/11, we would expect to hear them, and we would expect to see them. This would be evident in extremely large ejections of glass and wall.

Explosive blasts decay exponentially so one would not expect any columns to have been destroyed in the 1993 WTC bombing with the distance of the explosion and the surface area and strength of the columns.

However, one would think that tamping could be used to loosely direct the force of a wide but relatively light ribbon charge at close range to generate the force and create a large bending moment at the weld. This would be different from a shaped charge which would be used to highly focus the energy for cutting. Take a look at the chapter on explosives from a NAVSEA handbook that I provided.

 

[DGM]

Explosive blasts decay exponentially so one would not expect any columns to have been destroyed in the 1993 WTC bombing with the distance of the explosion and the surface area and strength of the columns.

However, tamping could be used to loosely direct the force of a small charge at close range and create a large bending moment at the weld. This would be different from a shaped charge which would be used to highly focus the energy for cutting. Take a look at the chapter on explosives from a NAVSEA handbook that I provided.

Small as in how many pounds where they are placed and how many of them?

 

[Gravy]

Take a look at the chapter on explosives from a NAVSEA handbook that I provided.

Second time, Tony Szamboti: for a change, take a look at reality and tell us exactly when the detonations occurred:

http://video.google.com/videoplay?do...85611926#1m10s

Afraid to do it, Tony? Of course you are. Because you've also seen clips like these:

http://video.google.com/videoplay?do...5611926#11m55s