Merged Core-led collapse and explosive demolition

[Justin39640]

Fine.
How does that fit in with the rest of the day's events?

Or was it simply a massive coincidence?

It's a miracle it was the only other one.

 

[Dave Rogers]

Your formula should be doing that work. You shouldn't have to manually manipulate the calculations unless you're trying to work backwards from a result that you want.

Are you working backwards from a result that you want, Dave?

To quote Charles Babbage, "I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question." The energy lost to the buckling of columns is simply the integral of force over distance. The deceleration produced by the buckling of columns is determined either by integrating the force over the distance to yield the kinetic energy loss, or by integrating the force over time to yield the velocity loss directly; the two are mathematically equivalent. This has been understood since the 17th century. Therefore, it's equally valid to approach the modelling either way, by entering a specific force curve or by entering an energy loss as the means of representing the structural resistance due to column buckling. In neither case is there any question of working backwards from a result to an assumption.

In parenthesis, it's perfectly reasonable to model a process with a specific input used as a variable parameter, in order to assess the sensitivity of the model output to the value of that parameter. For example, the collapse time could be calculated with a range of different values for the energy loss due to column buckling, in order to determine its effect on the result. Frank Greening, in fact, performed exactly that calculation, and found that a range of realistic approximations to the column buckling energy loss gave variations of order half a second in the collapse time. If we find - as we do - that the collapse time is correctly predicted, within measurement error, by any plausible value for column resistance, then we can conclude - as, in fact, we do - that there is no reason to suspect any weakening of the columns by external means before or during the collapse.

I expect ergo to respond to this with another irrelevant and ignorant pseudo-objection, which I'll probably ignore. He has neither the will nor the ability to do the calculations for himself, so there seems little point trying to educate him on the details of how it can be done.

Dave

 

[BasqueArch]

To quote Charles Babbage, "I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question." The energy lost to the buckling of columns is simply the integral of force over distance. The deceleration produced by the buckling of columns is determined either by integrating the force over the distance to yield the kinetic energy loss, or by integrating the force over time to yield the velocity loss directly; the two are mathematically equivalent. This has been understood since the 17th century. Therefore, it's equally valid to approach the modelling either way, by entering a specific force curve or by entering an energy loss as the means of representing the structural resistance due to column buckling. In neither case is there any question of working backwards from a result to an assumption.

In parenthesis, it's perfectly reasonable to model a process with a specific input used as a variable parameter, in order to assess the sensitivity of the model output to the value of that parameter. For example, the collapse time could be calculated with a range of different values for the energy loss due to column buckling, in order to determine its effect on the result. Frank Greening, in fact, performed exactly that calculation, and found that a range of realistic approximations to the column buckling energy loss gave variations of order half a second in the collapse time. If we find - as we do - that the collapse time is correctly predicted, within measurement error, by any plausible value for column resistance, then we can conclude - as, in fact, we do - that there is no reason to suspect any weakening of the columns by external means before or during the collapse.

I expect ergo to respond to this with another irrelevant and ignorant pseudo-objection, which I'll probably ignore. He has neither the will nor the ability to do the calculations for himself, so there seems little point trying to educate him on the details of how it can be done.

Dave

The model (WTC1,2) for these calculations is based on resistance by the buckling columns, not the floor plates. It is interesting that the collapse times predicted in this manner matches closely the actual times of collapse.

Since the majority of interior and exterior columns were not deformed by buckling, it would be interesting to calculate collapse times by a model based on the floor plates falling onto each other and failing at the floor joist connections.

 

[Animal]

The model (WTC1,2) for these calculations is based on resistance by the buckling columns, not the floor plates. It is interesting that the collapse times predicted in this manner matches closely the actual times of collapse.

Since the majority of interior and exterior columns were not deformed by buckling, it would be interesting to calculate collapse times by a model based on the floor plates falling onto each other and failing at the floor joist connections.

I believe someone did the calculations to show that after one floor's columns buckled, the remaining tower falling exactly column to column would have still led to complete failure.

It would not require the floor plates falling on each other either, simply the upper portion of the tower hitting the floor plate would be a rather instantaneous failure of the floor plate....and onward through several floors. This destruction would cause the failure of the columns......both core and perimeter because they were dependent on the floor plates for lateral support, which is why some parts of the perimeter peeled away like a banana skin and ended up 500ft from the tower impaled in other buildings. Why troofers have such a hard time understanding that simple concept is beyond me.

 

[alienentity]

I believe someone did the calculations to show that after one floor's columns buckled, the remaining tower falling exactly column to column would have still led to complete failure.

I... Why troofers have such a hard time understanding that simple concept is beyond me.

You're referring to the series of papers going back to Bazant and Zhou (2002)

But there has also been a lengthy discussion about other models, such as the OOS Propagation model of 'Major Tom'

 

[BasqueArch]

I believe someone did the calculations to show that after one floor's columns buckled, the remaining tower falling exactly column to column would have still led to complete failure.

It would not require the floor plates falling on each other either, simply the upper portion of the tower hitting the floor plate would be a rather instantaneous failure of the floor plate....and onward through several floors. This destruction would cause the failure of the columns......both core and perimeter because they were dependent on the floor plates for lateral support, which is why some parts of the perimeter peeled away like a banana skin and ended up 500ft from the tower impaled in other buildings. Why troofers have such a hard time understanding that simple concept is beyond me.

Right.
Professional Conspiracist sites like AE911T claim multiton column assemblies thermwhatever silently exploded to 500 feet but don't show the overhead picture of the perimeter column assemblies toppled on the ground like a fallen ladder reaching out to the Winter Garden; and for WTC7 begin the video start of the collapse 6-7 seconds after the collapse of the east penthouse and without sound.

These lies, half-lies and similar anti-rational viruses then spread e-promiscuously and deceive the gullible, incompetent and uneducated. For these Truther-Believers, the political ends justify the lying means.

 

[Major_Tom]

Right.
Professional Conspiracist sites like AE911T claim multiton column assemblies thermwhatever silently exploded to 500 feet but don't show the overhead picture of the perimeter column assemblies toppled on the ground like a fallen ladder reaching out to the Winter Garden; and for WTC7 begin the video start of the collapse 6-7 seconds after the collapse of the east penthouse and without sound.

These lies, half-lies and similar anti-rational viruses then spread e-promiscuously and deceive the gullible, incompetent and uneducated. For these Truther-Believers, the political ends justify the lying means.

But wasn't that exactly what you were doing with Bazant?

The same long row of columns to the Winter Garden shows that Bazant and you in particular are hypocrites, too.

How can you not see the same proof applies to you?


Where did crush up, then crush down go.

Did you forget all about that?

 

[Major_Tom]

How could you forget about months of your own lying?

We have it all recorded if you forgot. Shall we review your previous opinions?


Is R Mackey still lying or did he quietly switch collapse mechanics also?

 

[Oystein]

M_T, I think most of us have realizes by now that Bazant does not model the specific twin tower collapses, but simplified versions to present limiting cases. I seem to remember that one of Bazant's model was viewed sceptically by some "debunkers", or at least ozeco.

No need to reheat that old didh, eh? Any deviation of the actual collapse from Bazant's models is expected as Bazant never meant to mimick them. He just showed that global collapse is inevitable.

In the most extreme, survival-friendly case, we'd see a perfect crush-up-crush-down scenario. As reality was more chaotic, some of that was blurred because of other processes that also happened.

 

[Major_Tom]

I think that what was posted a few months ago and what is posted these days is very, very different. I also think that almost none of you are honest enough to admit it.



BasqueArch, it this your post or did some impostor write this?

Major Tom
The collapse of the Towers is divided in two phases:
First Phase. The non-CD initial failure of one floor as explained by NIST and over a dozen other experienced non-CT structural engineers in their papers.
Second Phase. The non-CD progressive global collapse as explained by Bazant. NIST, and where mentioned by the engineers above, have reviewed and agree with Bazant’s second phase hypothetical collapse explanation.

In the main body of his first 2001 paper, Bazant assumes the most optimistic hypothesis, not the actual failure mode of the Towers because the actual collapse details are almost impossible to analyze precisely. So :

“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.”

[qimg]http://4.bp.blogspot.com/_aJeegFsC3nY/R3L_2XdW1SI/AAAAAAAAAbY/uR21-Fs5wXE/s400/Picture+3.png[/qimg]
Figure 1
Hypothetical collapse mode (my words)

Later in the same paper he answers a question about the actual collapse mode. You can see the top portion is tilted. This differs from the axial, uniform hypothetical collapse mode of Figure 1 above.

“Appendix II. Why Didn’t the Upper Part Pivot About Its Base?

Since the top part of the South Tower tilted [Fig. 3a], many
people wonder: Why didn’t the upper part of the tower fall to the
side like a tree, pivoting about the center of the critical floor?
[Fig. 3b]. To demonstrate why, and thus to justify our previous
neglect of tilting, is an elementary exercise in dynamics.
Assume the center of the floor at the base of the upper part …

…. From this we further conclude
that the reaction at the base of the upper part of South
Tower must have begun shearing the columns plastically already
at the inclination of approximately 2.8 degrees.
The pivoting of the upper part must have started by an asymmetric
failure of the columns on one side of building, but already at
this very small angle the dynamic horizontal reaction at the base
of the upper part must have reduced the vertical load capacity of
the remaining columns of the critical floor …..”

It’s this pivoting horizontal reaction thrust that contributes to the displacement of all columns in both towers and is missed by CTs.
[qimg]http://911review.com/coverup/fantasy/imgs/figure4.gif[/qimg]
http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/405.pdf

I can see your setup a mile away. You will claim the initial phase was CD’d at the core and that phase two was gravity driven. I will call this opinion MCCCDH – (Minimalist Core Columns Controlled Demolition Hypothesis.)

You allege numerous times in your paper that Bazant claims that the perimeter and core columns globally failed by actually being crushed. This allegation is wrong as explained above.

Truther critics of Bazant have not read his papers, or if they have they don’t understand them, or if they understand them they are misrepresenting him.

.

 

[Major_Tom]

BasqueArch, did you write this?

Major Tom still misses the big picture as previously explained, by not dividing the collapses into two phases.
​

The NIST WTC1,2 reports thoroughly analyze the actual events leading up to the initial collapses. The NIST WTC7 report thoroughly analyzes the actual initial and global collapse. Each report is integrated.

Bazant’s three papers and response to comments thoroughly explains actual global collapse of a building where the impact forces go into the columns and are distributed among them equally. Bazant applies this paradigm as the closest ideal analysis of the global collapse of WTC1,2. His calculations of the collapse times following this paradigm is corroborated by the close match to the actual collapse times of the Towers by multiple seismographs monitoring ground vibration in the general area. Review of Verinage demolitions indicate the validity of the crush down crush up phases of homogenous collapse propagation. The papers are integrated.



Bazant’s consistent refinement of the original WTC1,2 paradigm is the subject of another post. I personally don’t have the time now.

Both NIST and Bazant’s papers complement each other as the gravity only explanation of the collapse of all three Towers.

It is a mistake by Major Tom to criticize Bazant for not thoroughly explaining the initial collapses of WTC1,2 and initial and global collapse of WTC7. These were outside his respective scopes of study. See NIST.

The convention among civil/structural engineers is to distinguish between these two phases and as being complementary. Major Tom ignores this by scrambling ice cream and steak, steak a la mode, as it were. This creates the straw man bulk of his criticism.

First Bazant paper (written two days after 9/11/2001)




Second Bazant paper


1)Major Tom’s lightweight math free analysis reveals a lack of experience in any of these fields. (Structural engineering, mathematics, physics)

"To a truther, having double standards simply means they're better than the average person, because they have twice as many standards."- CI1mh4224rd

2)Wrong- Bazant has a strong background in all three. The literature is replete with structural engineers analyzing the mechanics of falling buildings and structural failures, not mathematicians or physicists.




Major Toms’ mistakes throughout all three papers continue similarly.

Major Tom believes CD occurred in NIST's Phase 1, Initial Collapse. Bazant is the wrong venue. The proper venue for Major Tom's CD claims is the NIST report. Analyze that instead.

It is like Major Tom showing up to play at a Bruins-Rangers game dressed in ballet tights. The proper venue for that is Nijinsky’s Le sacre du printemps at Lincoln Center.

You are about as smart as R Mackey. Shall I post a few examples of his understanding of collapse mechanics in 2010?


Remember, I didn't trick you into demonstrating how little you know. You volunteered that information.

 

[Major_Tom]

August 2010. R Mackey speaks.


Let us sit at the feet of the Master and learn about the mechanics of collapsing buildings:

It's the latter.



This is not the only factor, but it too is partially correct.

Think of it in terms of impulse -- the total change of momentum at a particular impact. Impulse is equal and opposite, by conservation of momentum. Impulse is equal to F delta-T (force times the time over which the force is applied), or M delta-V (the raw change of momentum in its familiar definition P = m V).

When we look at the "upper block," it's delta-V is smaller than the delta-V experienced by the newly broken part of the lower block. As you say, the upper block decelerates by an average 1/3 g, while the lower block accelerates by an average 2/3 g. This is because the participating part of the lower block masses less than the participating part of the upper block -- it really is the compacted mass and upper block versus a small number of floors at a time, not the entire lower block.

The reason only part of the lower block participates at any given time is because the lower block is still a mostly intact sparse structure of braced columns. When it's hit, the columns lose bracing, get loaded eccentrically, shear their welds and bolts, and in some cases are totally overwhelmed and fracture entirely. These pieces break at a stress much too low to actually support the descending mass. This also has nothing to do with the strength of the perfectly intact building -- the descending rubble heap isn't contacting the lower structure at its strongest points, and it's introducing brand new failure modes, so the effective opposing strength of the lower structure is far lower than its ideal carrying capacity. Furthermore, where the lower structure does resist at or near its ideal strength, it can only do so for a very brief delta-T -- until reaching its failure strain, which takes only about ten milliseconds at the speeds of collapse -- and this is not enough to amount to all that much total impulse.

The upper chunk, in contrast, is cushioned by a thick layer of rubble. This is compacted about as far as it can, thus it doesn't have those complex failure modes and it doesn't suffer much more "damage" even at much higher stresses. So the rubble pile remains, and the lower structure gives way. This is for the same reason you don't sink into the ground, even though you can push your finger easily through a cupful of soil.

The "upper block," what remains of it, rides on top of this cushion of debris. It is supported pretty well. It also only decelerates at that lower rate, thanks to the much greater inertia of the upper block + debris. So the only real force it suffers is the inertial force, i.e. its own self-weight times its deceleration, again about 1/3 g. It can be expected to survive this deceleration. It's only when the rubble pile has nowhere else to go and the upper block has to suddenly stop, dissipating all of its momentum in mere milliseconds, that it totally fails.

Again, this is slightly idealized, but you get the point. Unless you're a Truther.

Yes, it is all so clear unless you are a "twoofer".

Only Ozeco had the brains to question explanations like this.

Therefore, this post shows how many posters at JREF understood collapse mechanics as late as last August.


So what happened since last August, guys? Why the new change of heart?

 

[MinnesotaBrant]

I propose we turn the site into disney world, new york. Wow, wonder nobody has thought of that yet. Its still a crater from what I hear.

 

[Major_Tom]

SO, 2 110 story buildings collapse in front of our eyes.

Few people were able to discern the basic mechanism by which each collapsed for 8 years.

They are kind of big, no? Of you coundn't figure out the collapse mechanisms, how do you claim to know what initiated the collapses?


If you couldn't hit the broad side of a barn for 9 years, how can you claim any certainty concerning the initiation mechanisms?

Is there a single professional journal or a single academic paper in existence that identifies ROOSD as the collapse mechanisms for WTC1 or 2?

No. Our pros seem to have no clue. ROOSD is known through internet forums only.

 

[Major_Tom]

You know as much about WTC1 collapse initiation as you did about the collapse mechanism for 9 years.


This popped off the WTC1 west wall during the initial; collapse

It is called the "upper west wall", the part just above the failure line.


This fell off the south wall at the same time:

showing, just like for the west wall, upper fell out and over lower.


If you were a bit cleaver you could use such information to know everything you think you know about the WTC1 collapse initiation is a dream.

Everything the NIST told you about the initiation sequence is a dream.

WHen the upper wall falls within the lower wall, it looks something like this (WTC2 east wall):

Those are ROOSD type ejections. If lower falls within upper then the upper wall doesn't go into early free-fall as it does for the WTC1 north, west and south faces.

Minimal tilt angle should have told people it was a core-led collapse a while ago, but people were too busy pretending they know already.


But I don't have 9 more months to explain it to you while posters insult me with impunity.

If you were not a website focussed only on propaganda things like this could be studied and understood.

You create your own bed of ignorance. Please try to be less hostile to people who actually study before gabbing away.

 

[aggle-rithm]

But wasn't that exactly what you were doing with Bazant?

The same long row of columns to the Winter Garden shows that Bazant and you in particular are hypocrites, too.

How can you not see the same proof applies to you?


Where did crush up, then crush down go.

Did you forget all about that?

Apologies if I missed this, but do you have a theory that fits the evidence better?

 

[Oystein]

...ROOSD is known through internet forums only.

I think this is mainly the faulkt of the ROOSD proponents whoi have yet to submit a scientific paper to a respected peer-reviewed engineering journal.

Have you written that paper yet? Or even submitted? Planning to do so? When? Where?

I hope you don't propose that internet fora are the desired venue for this?

 

[Oystein]

...

...

The green line and red circle seem to be placed rather arbitrarily. What happens at that green line, and how do you know? Everything is blurred in this image.
Somehow you are not convincing me

 

[Major_Tom]

Green line ad red circle are for a separate point. East face is on the right. That is the place to look. That is what happens when upper sheet falls behind lower sheet.

If upper falls over lower like WTC1 north, west and south faces, your large falling objects cover the ROOSD ejection pattern.

It is not difficult to tell whether upper perimeter sheet falls out over the lower during collapse initiation for any specific side.


If you look real hard at the WTC1 south wall and collapse images, you will find that upper kicks out over lower., hence the large falling objects a few posts ago.

We could have known this years ago but the NIST was holding the proof out of sight. Recent FOIA releases shows what we should have known for years.

 

[MinnesotaBrant]

I am seeing a new york edition of dollywood going up soon.