RFC: Bazant and Zhou Simple Analysis refuted

[Major_Tom]

The gist of the argument seems to be:

1. A vastly simplified model, designed to be conservative against sustained collapse, assumes that lots of the potential energy released in the collapse will be absorbed by the formation of multiple sharp inelastic bends in the columns before they fracture.

2. The actual columns in the rubble don't exhibit these sharp bends; instead, the columns (though careful measurement revealed that most were bent to some degree) snapped at the welds.

Therefore,

3a. The model is too conservative against collapse because clearly the formation of multiple sharp inelastic bends in the columns did not occur and therefore could not have absorbed large amounts of energy, leaving even more energy to sustain collapse than the analysis based on the simplified model suggests.

or

3b. Collapse from gravity alone could not have occurred.

... and the argument is whether 3a or 3b is the conclusion that should be drawn.

Does that about sum it up? Or am I missing something?

Missing something. I don't even recognize the argument you attribute to me.

A 1-D model is hardly a conservative estimate against sustained collapse. I am not a part of the Bazant refutation. That is Gurich. To me the original premises within the model are a joke (12.5 foot freefall, solid upper block, simultaneous and instantaneous failure of groups of columns, ect...) whereas Gurich tentatively accepts the initial assumptions and initial conditions and argues from there.

In 3 dimensions objects can miss each other completely. In 1-D things just keep making contact. But I am not interested in the Bazant analysis. It's a cartoon.


For the present purposes I'd simply be content with the present audience (Gravy excluded) accepting that forensic evidence strongly suggests that "weld failure" was the chief failure mechanism within the core. That results from the following 2 verifiable facts:

1) The large, large majority of core box columns within the rubble are remarkably straight.

2) The large, large majority of core box columns within the rubble have squared-off ends, meaning they had pretty clean breaks along their original weld surfaces.


Like a giant pimple on ones nose, the core box columns and the pre-fab perimeter sections are the 2 main objects that stand out in the rubble. You cannot miss them. Photo after photo after photo have the same patterns and you really would have to be blind not to see it.


After most of you agree on this I'll show you a more accurate model of the core (3-D this time) which will show how weld failure as a collapse mechanism of the core is inconsistent with gravity driven collapse.


How will I do this? A model based on weld failure with remarkably straight columns will basically result in a CD and a gravity-driven collapse theory which looks like this:


1) Gravity-driven (chaotic) weld failure.

2) CD: "Assisted" weld failure. This means timed and coordinated weld failure. I will show that the symmetry and timing of the failures suggests human (or divine) intervention (human in this case).

I'll show you that the "squibs" or "pressure pulses" correspond very well to the geometry of the core and individual weld locations and that the suggestion that collapsing floors cannot be the cause (note that columns crashing through floors, which is a necessary feature of a gravity-driven collapse involving weld failure with remarkably straight columns (spearing) already rules out that these "near hermetically sealed" floors could build up pressure).


And then, after you folks convince yourselves that these welds were pretty weak anyway, we can focus on the nearly 60 floor "spire" of the North Tower (both towers had spires), which were unsupported columns taller than the entire WTC 7 building. We can also look at the many, many welds that didn't break even after the collisions they must have experienced and after crashing to the ground.


For example, rwguinn, in the satellite photo I posted before, do many of these straight lines look like they are 38 feet long to you?

Every one of those longer columns in the photo are multiple column sections held together by welds.

You would never know a weld is there because there is no bending whatsoever at the weld location.

Any core box column you see in the rubble longer that 38 feet (more or less) you will find to be multiples of 38 feet (more or less).


And then we can identify the actual core columns which made up the North Tower spire. That is very interesting.


But if we can't get past "gee wiz, are those things really straight?", the rest won't make much sense to you.

 

[rwguinn]

In the December 2007 FAQ NIST claims a dynamic amplification of 2.0 due to sudden loading, which is a maximum for sudden loading. One problem with that is that with Greg Urich's mass analysis and the core columns cross section being known it shows that the central core had a factor of safety of 3.0 and the perimeter a factor of safety of 5.0, when considering gravity loads only.

Both of which are ludicrous.

 

[Tony Szamboti]

"The weld" is not just the filler material
There is an area outside the actual weld, called the "Heat Affected Zone" where the cracks will actually start, which is more brittle, and weaker.
It ain't bending--its local effects--like outer fiber tension--a load path and condition that was never intended, never designed for, and likely, fatal.
A crack starts in the outer fiber, further weakening the beam (column), increasing the stress, enlarging the crack, further reducing area, increasing local stress, causing the crack to grow, reducing the area, increasing stress, causing the crack to grow----do you need more, mr "engineer"?

You are right that the welded area includes the Heat Affected Zone which would have been in the A36 material not the weld material. It sounds like you are saying there were residual tensile stress induced cracks in the Heat Affected Zone.

Do you believe there were cracks in it then? It sounds like you are saying that and that these cracks grew and weakened the columns, so that they were already weak by Sept. 11, 2001. If so, why would these cracks grow?

If there were residual tensile stress cracks in the Heat Affected Zone they would have been very minute as this area would have been inspected when the welds were inspected. Cracks starting in outer fibers are usually due to tensile stresses from bending loads. However, even if there were some from heat and cooling induced stresses, which weren't caught during inspection, cracks only grow when there are a number of stress cycles. When would these tensile stress cycles have occurred?

 

[Tony Szamboti]

Both of which are ludicrous.

Can you support that statement? I can support these factors of safety. We have the information.

 

[beachnut]

In the December 2007 FAQ NIST claims a dynamic amplification of 2.0 due to sudden loading, which is a maximum for sudden loading. One problem with that is that with Greg Urich's mass analysis and the core columns cross section being known it shows that the central core had a factor of safety of 3.0 and the perimeter a factor of safety of 5.0, when considering gravity loads only.

What would DRG say? You better check with your source on your realcdeal, realcddeal.

 

[Newtons Bit]

In the December 2007 FAQ NIST claims a dynamic amplification of 2.0 due to sudden loading, which is a maximum for sudden loading. One problem with that is that with Greg Urich's mass analysis and the core columns cross section being known it shows that the central core had a factor of safety of 3.0 and the perimeter a factor of safety of 5.0, when considering gravity loads only.

But Greg's paper is a peer-reviewed paper as part of the Journal of 911 Studies! Shouldn't you be taking his results as fact?

 

[Gravy]

In the December 2007 FAQ NIST claims a dynamic amplification of 2.0 due to sudden loading, which is a maximum for sudden loading. One problem with that is that with Greg Urich's mass analysis and the core columns cross section being known it shows that the central core had a factor of safety of 3.0 and the perimeter a factor of safety of 5.0, when considering gravity loads only.

My question was for Gregory, but since you have your own answer, please show your math. Oh, and remember how in your ridiculous paper you calculated a safety factor for the exterior columns at the base of the building and assumed the same factor for the columns in the collapse initiation area? Don't do that again. And when discussing safety factors be sure to differentiate between static and dynamic loads.

Off topic, but how are you coming along with proving the single biggest specific claim the "truth" movement's come up with: your claim that on a business show Larry Silverstein said WTC 7 was demolished for safety reasons? Should I start another thread so you can fill us in on your progress with this amazing sure-to-win-a-Pulitzer story?

 

[Newtons Bit]

I'm trying to come from a place where if a reliable explanation is provided, I will accept it. Earlier today I was at 3a.2, but right now I'm at 3a.7 (3b coming after 3a.9).

I agree with Major Tom that there is insignificant evidence of column buckling other than at welded joints. This implies a 6 story buckle (assuming 3 hinges) using less energy for deforming the columns but possibly even more energy to overcome the horizontal members, floors and floors trusses--followed by a 6 story freefall. Einsteens video analyses would have caught this by showing varying accelerations.

I think you're not completely understanding the problem at hand. Imagine for a moment a 3-story section of exterior column just below where the collapse initiates. The top block impacts the top part of this 3-story column and delivers an overload ratio of say 1.0. The maximum force applied anywhere in this column will be at the bottom, oddly enough where the splice is. This is because each floor is adding to the force applied to the column.

But we really need to step back and look at what "buckling" really is. It's not some arcane inexplainable thing, it involves this (note, you can take Pu2*e to be equal to Mu, or the moment demand):

The closer a column gets to it's predicted maximum axial capacity, the larger the effect of the bending moments in the columns get. By default, even with an axial only impact, there are bending moments in the columns. This is due to two things: the columns are part of the lateral resisting system which resists wind forces (even minor ones) through bending moments, and the floor truss to column connections are eccentric.

If the moment in the column is great enough, the moment will be magnified and destroy the column splices in the exterior columns. These splices were bolted and had less capacity than the column itself. We would expect to see them fail even with little permanent deflection in the column itself.

The core columns are similar, but of course unique in their own way which you're familiar with. I imagine that they failed due to non-axial strikes from the upper block (which is probably how most of the exterior columns failed as well).

 

[GregoryUrich]

How do you know?

Yet he is completely unaware of all the photos that show clearly deformed core box columns, but if he were aware, he'd claim that they weren't deformed while in place, except for the columns that he wants you to believe were deformed while in place, like the two on previous pages of this thread. Raise your standards, Gregory. Major Tom is incompetent, dishonest, and immature.

I looked through the photos myself Gravy. A column that failed in buckling mode is obvious in the pictures so slightly bent is not all that interesting. The great majority in his collection appear perfectly straight. I have also been through Meyerowitz's book and other collections online. Same conclusion.

Are your photos showing bending representative? Are they a scientific sample?

The high-res satellite shot is representative at least and there is no exclusion based on the sample method but rather the level reached during cleanup.

MT has said he has tried to collect as many photos as he could. We will see if MT is dishonest if he fails to include your photos.

 

[GregoryUrich]

But Greg's paper is a peer-reviewed paper as part of the Journal of 911 Studies! Shouldn't you be taking his results as fact?

My mass paper has also been scrutinized here and no significant omissions or mistakes have been pointed out. Please, if there are mistakes let me know.

If the journal is the issue, please point out another journal which would publish a 43 page article with a calculation spreadsheet that is 3 pages wide.

 

[Arus808]

sorry, to derail, but christophera is using Bazant's paper, to prove his claims. ... back to the thread

 

[Dave Rogers]

A 1-D model is hardly a conservative estimate against sustained collapse. I am not a part of the Bazant refutation. That is Gurich. To me the original premises within the model are a joke (12.5 foot freefall, solid upper block, simultaneous and instantaneous failure of groups of columns, ect...) whereas Gurich tentatively accepts the initial assumptions and initial conditions and argues from there.

In 3 dimensions objects can miss each other completely. In 1-D things just keep making contact.

Which, however much you choose to keep denying it, is exactly why the Bazant model is highly conservative. Bazant assumes that the upper columns impact axially on the lower columns, i.e. in the direction in which they are able to resist collapse most effectively. A more realistic model would include impacts between columns and floor slabs (because of the upper core columns missing the lower core columns), which would overload the floor slabs very easily, resulting in progressive floor collapse ahead of the column collapse. A more realistic model would include eccentric impacts (because of the upper perimeter column trees not being coplanar than the lower perimeter column trees), which would cause columns to fail in bending with much less resistance than axial impacts. A more realistic model would consider the fact that unsupported columns, after the floor collapse zone has passed, would not in fact need any further energy input to collapse, as they would be too slender to bear their own weight. And a more realistic model would include multifloor buckles in the columns which, after the floor collapse zone has passed, have no lateral bracing and cannot therefore be regarded as restrained at every floor. All these considerations reduce the energy requirement for collapse. You have yet to come up with any argument as to why a more complete model might increase the energy requirement; any suggestions?

Dave

 

[GregoryUrich]

Gregory Urich:

The first five impacts of a momentum transfer model of the collapse of WTC 1 takes only about 2.5 seconds. In this time interval the building is calculated to have dropped by about 16 meters. This time is confirmed by observation: The upper section of WTC 1 has been measured to drop ~ 18 meters in 2.5 seconds. The velocity at this point is about 16 m/s and the acceleration is thus about 6 m/s^2. To now expect to see changes in this acceleration in a 2.5 second time interval is not realistic or feasible.

I calculate 2.7 seconds using Newtons strain energy and my mass. If the buckles are 6 stories we should see free fall for six stories.

 

[GregoryUrich]

A little hint for you:
One of the things budding engineers learn early is that
without post-weld heat treatment, welds tend to be the weakest part of the structure.
Go back and look at the premises leading to the 3a conclusion.

ETA: And by the way:
The welds were never intended to take ANY, repeat, ANY tension loading. None. Zilch. Nada. Zero.
What happens when you start trying to bend a large member at the root (weld)?
Amazingly enough, the outer fiber (weld) is in..
....are you ready?...
wait for it......

YES!!! We have Tension!

Are you talking about the horizontal members? From the evidence available, most horizontal members failed not at the connections but in the member itself.

 

[Heiwa]

Gregory Urich:

The first five impacts of a momentum transfer model of the collapse of WTC 1 takes only about 2.5 seconds. In this time interval the building is calculated to have dropped by about 16 meters. This time is confirmed by observation: The upper section of WTC 1 has been measured to drop ~ 18 meters in 2.5 seconds. The velocity at this point is about 16 m/s and the acceleration is thus about 6 m/s^2. To now expect to see changes in this acceleration in a 2.5 second time interval is not realistic or feasible.

In order for five impacts to take place - five floors must first be disconnected from the columns and then the columns buckle over a distance of six floors.

Evidently we do not see the walls buckle outwards (?) but let's assume it.

The first impact is the first floor above (2000 tons falling 3.7 m) is 23 kWh and is no problem. The next is the second floor above (another 2000 tons falling 7.4 m) is 46 kWh a fraction of a second later. No problem. The third, fourth and fifth floor impacts contribute 69, 92 and 115 kWh and should not be a problem either. The structure below can easily absorb these energy impacts when the are separate over 2.5 seconds. Now five floors (10 000 tons) are stacked on top of the 'impact' floor and in theory it should hold it.

At this time 22 meters of walls should have dropped down beside the building.

And no collapse of the structure below has started.

And then comes the rest of the top part (23 000 tons) and lands on the five floors that pancaked. Another impact! But is this what we see on the real time forensic evidence = the videos? Evidently not.

And now the collapse of the first floor below the impact floor should start.

 

[Norseman]

In order for five impacts to take place - five floors must first be disconnected from the columns and then the columns buckle over a distance of six floors.

Evidently we do not see the walls buckle outwards (?) but let's assume it.

The first impact is the first floor above (2000 tons falling 3.7 m) is 23 kWh and is no problem. The next is the second floor above (another 2000 tons falling 7.4 m) is 46 kWh a fraction of a second later. No problem. The third, fourth and fifth floor impacts contribute 69, 92 and 115 kWh and should not be a problem either. The structure below can easily absorb these energy impacts when the are separate over 2.5 seconds. Now five floors (10 000 tons) are stacked on top of the 'impact' floor and in theory it should hold it.

At this time 22 meters of walls should have dropped down beside the building.

And no collapse of the structure below has started.

And then comes the rest of the top part (23 000 tons) and lands on the five floors that pancaked. Another impact! But is this what we see on the real time forensic evidence = the videos? Evidently not.

And now the collapse of the first floor below the impact floor should start.

Wrong, the whole upper block moved as one block after the heat weakened columns in the area of floor 98 failed under the gravity load. It was funneled into the lower block at collapse initiation. The upper block then impacted the floors inside the lower block one after the other while accelerating. That would be 1, 2, 3, 4, 5, etc down to bottom. In videos of the WTC 1 collapse you can se parts of the exterior walls of the lower block still standing for a moment or pivoting out of the dust cloud after the upper block has passed. This is also visible in the WTC 2 videos.

WTC 1. Keep an eye on the west face of the lower block (right hand side) in this one. A part of the exterior wall is still visibly standing after the upper block has passed:


WTC 1. Notice an exterior panel from the north face of the lower block pivoting out of the dust cloud after the upper block has passed:


WTC 1. Notice the enormous part of the west face exterior wall falling towards the world financial center at the end:

 

[Tony Szamboti]

My question was for Gregory, but since you have your own answer, please show your math. Oh, and remember how in your ridiculous paper you calculated a safety factor for the exterior columns at the base of the building and assumed the same factor for the columns in the collapse initiation area? Don't do that again. And when discussing safety factors be sure to differentiate between static and dynamic loads.

Off topic, but how are you coming along with proving the single biggest specific claim the "truth" movement's come up with: your claim that on a business show Larry Silverstein said WTC 7 was demolished for safety reasons? Should I start another thread so you can fill us in on your progress with this amazing sure-to-win-a-Pulitzer story?

Greg's substantiated mass is what I used to determine these factors of safety. I haven't published it yet. I did differentiate between a dynamic and static load on my post above as this is the first time NIST discussed a dynamic load. Why do you think I mentioned NIST's sudden loading amplification factor above? I guess you didn't understand. In my paper I reduced the previously estimated factors of safety for damage if you recall. After doing that there was still a substantial factor of safety remaining (it turns out there was even more than I originally estimated with the purported 500,000 ton mass) and there is no evidence of high enough steel temperatures to cause failure of the remaining structure. Without better information it is not a poor assumption that the factor of safety was somewhat constant throughout the height of the building. We have better information now and that assumption turns out to be true. The gist of my paper is that there was no basis for the columns failing. Amazing how you feel entitled to call something ridiculous when it is apparent that you don't understand.

As for Silverstein's comment on that History Channel show, I showed proof here that he was on that show. I called to get a tape. It isn't available. That is all I can do. Have you tried to get a copy of the show? I have asked you that several times and not gotten a reply so I doubt it. You just want to call me a liar with no basis for it. I do not like to call people liars, without a basis, but I have a basis for calling you one in this situation.

At least with me it seems that when you can't forcibly argue the facts you delve into nebulous areas with attempts to smear and it is obvious. What a shame.

 

[Tony Szamboti]

But Greg's paper is a peer-reviewed paper as part of the Journal of 911 Studies! Shouldn't you be taking his results as fact?

Greg's paper and the NIST SAP2000 data for the core column cross sectional areas is what I am using to determine the factors of safety. Greg was able to determine the perimeter column weight for each floor so knowing the height per floor and number of columns, an approximate cross section can be determined there also, since we don't have the perimeter cross sections from NIST. It turns out with the substantiated mass and these cross sections that the core had a factor of safety of 3.00 to 1 and the perimeter a factor of safety of 5.00 to 1, when considering gravity loads only.

I will be revising my paper to show these now substantiatable factors of safety. Using the erroneously purported 500,000 ton mass and estimating cross sections from Engineering News Record articles I had previously estimated the factors of safety as 1.67 to 1 for the core and and 5.00 to 1 for the perimeter wall.

 

[SDC]

I looked through the photos myself Gravy. A column that failed in buckling mode is obvious in the pictures so slightly bent is not all that interesting. The great majority in his collection appear perfectly straight. I have also been through Meyerowitz's book and other collections online. Same conclusion.

Are your photos showing bending representative? Are they a scientific sample?

The high-res satellite shot is representative at least and there is no exclusion based on the sample method but rather the level reached during cleanup.

MT has said he has tried to collect as many photos as he could. We will see if MT is dishonest if he fails to include your photos.

Jumping back a little here... Mr/ Dr (whatever) Urich, do you maintain it is acceptable procedure to say "well, some of the photos look like such-and-such"? In the same discussion as highly technical engineering data and calculations?

I suspect apples and oranges. The one, very impressionistic piece of information (I don't say evidence) is used to support and extend actual technical calculations.

Guys, I'm from the humanities. In my research I would be extremely careful about mixing this way. Has it now become the norm in engineering?

 

[Major_Tom]

Gravy says:

Yet he is completely unaware of all the photos that show clearly deformed core box columns,

I keep a separate photo album of all core box columns I encounter that show bending and distortions at

http://www.sharpprintinginc.com/911/index.php?module=photoalbum&PHPWS_Album_op=view&PHPWS_Album_id=3

If you have photos of damaged core box columns that are not in the album, please let us all know.

But if you don't show any, then your veil is wearing thin, even to those who support your other conclusions.

We will see if MT is dishonest if he fails to include your photos.

More photos the better. Just let me know how I can obtain them.