The SINGLE MOST IMPORTANT ANALYSIS of the events of 9/11.

Comparison of the imperial and US customary measurement systems
United_States_customary_units
Imperial_units
International_System_of_Units

Ultimate_tensile_strength
Compressive_strength

en.wikipedia.org...
en.wikipedia.org...(engineering)

Deformation is often described as strain.

en.wikipedia.org...:Materials_science
en.wikipedia.org...

Title : Physical Properties of Structural Steels. Federal Building and Fire Safety Investigation of the World Trade Center Disaster (NIST NCSTAR 1-3E) :
www.nist.gov...

Disclaimer No. 2 :
The policy of NIST is to use the International System of Units (metric units) in all publications. In this document (1-3E), however, units are presented in metric units or the inch-pound system, whichever is prevalent in the discipline.

Yield strength (AISC usage) = Fy
Built-up core box columns were to be fabricated from two grades of steel with 36 ksi and 42 ksi minimum yield strengths.

Charles M. Beck : Core Columns (CCs) were made of structural steel which varied from nominal 36 KSI (ultimate 58 KSI) at the top to nominal 42 KSI (ultimate 60 KSI) at the bottom.

He found those figures in NIST NCSTAR 1-3E. (page 39 / 162) and 1-3A.
ksi = kilo-pounds force per square inch (ksi, or sometimes kpsi), which is equal to 1000 psi.
psi = pounds-force per square inch (lbf/in², or psi).
The Yield Strength (Fy) of the steel in those core columns varied from nominal 36,000 to 42,000 pounds per square inch (psi) and from ultimate 58,000 to 60,000 lbf/in² (psi); from top to bottom.

Title : Damage and Failure Modes of Structural Steel Components. Federal Building and Fire Safety Investigation of the World Trade Center Disaster (NIST NCSTAR 1-3C)
www.nist.gov...

I composed from above Wiki pages this explanation of strain and strength, and their unit expressions :

Tensile strength is not the same as compressive strength and the values can be quite different.
Tensile strength is the maximum stress that a material can withstand while being stretched or pulled before failing or breaking. When the top part of the North Tower tilted, some core columns must have endured tensile forces if it was caused by natural deformation forces.

Compressive strength is the capacity of a material or structure to withstand loads tending to reduce size. It can be measured by plotting applied force against deformation in a testing machine.
Some materials fracture at their compressive strength limit; others deform irreversibly, so a given amount of deformation may be considered as the limit for compressive load.
Compressive strength is a key value for design of structures.

Forces develop/arise throughout the entire material which oppose both tension or compression.

The "strain" is the relative change in length under applied stress.

Tension stress tends to lengthen an object and gives positive strain
Compressive stress shortens an object and gives negative strain.
Tension tends to pull small sideways molecular deflections back into alignment.
Compression tends to amplify such deflections into buckling.
Stress is measured as force per unit area.

In the SI system (Le Système International d'Unités), the unit is the pascal (Pa) (or a multiple thereof, often megapascals (MPa), using the mega- prefix); or, equivalently to pascals, newtons per square meter (N/m²).
The International System of Units (SI), the modern form of the metric system, is preferred for many uses by the US National Institute of Standards and Technology (NIST).

The international yard is defined as exactly 0.9144 meters.
The US survey foot is defined so that 1 meter is exactly 39.37 inches, making the international foot of 0.3048 meters two parts per million shorter.

A United States customary unit is pounds-force per square inch (lbf/in² or psi), or kilo-pounds per square inch (ksi, or sometimes kpsi), which is equal to 1000 psi; kilo-pounds per square inch are commonly used when measuring tensile strengths.

The word "kilo" means here 1000, and is not related to the European kilo weight. Thus, one kilo-pound equals 1000 psi.

4- He assumes that the columns can shorten by 20% before they buckle. That means that a 1000' lower part must shorten to 800' for it to buckle.

Where do you get that snippet from.?

Now I'm gonna study the Free Forum.
the911forum.freeforums.org...

There's a thing!

What happened to WTC-6? Where did it's columns disappear to?

a reply to: douglas5 Read Gold Warriors by Seagrave

originally posted by: LaBTop

Thus, according to you, all those columns would be still firmly standing there in New York, since they did not buckle.

Nope. If you don't understand how they could fall, just ask.

Why resort to a strawman?

This yet another try to avoid honest discussion. You've lost the argument here. Everyone can see it. This is why you don't debate honestly.

How then, did they manage to fall indeed, got perfectly cut at 3 floors lengths, and showed no signs of buckling at their ends AT ALL?

Cuz they broke at the bolts.

You should know this by now.

The fact that you ask this question shows that either you've done poor research, or are going to set up yet another straw man.

Only cutter charges can do that.

False.

originally posted by: LaBTop

It's also proven through logic, that stuff falls on floors, and indeed it did during the progression. It's a known fact that the floors and their connection system cannot hold up the falling mass, and that is why there is so little resistance.
To put it simply, the floors resisted the collapsing, falling mass. Not the columns.
There can be no logical argument against that.

That's your kind of logic.

Everyone else in the world would agree with me that stuff falls on floors.

I see something else. Immediately after that failure of that exterior panel that hinges to the left in that video of the collapse initiation moment of the North Tower top, already that explosive ring of dust is spitting out of that floor. I don't see stuff falling, I see stuff flying.

Do you see the core columns, and core floor beams, and office floor trusses all flying? Nobody else does, so I hope you don't either.

And so if you don't, then that stuff is falling on floors.

You can't claim otherwise and still be expected to be taken seriously.

And you avoid Chandler's graph, which shows no resistance AT ALL during the first THREE seconds of the collapse, measured from a pixel-point situated on the sinking roof rim.

If he measured free fall acceleration, then his method is flawed.

If you're saying that he's measured an acceleration equal to .67G then I can agree to that.

But I think you're severely confused about rate of acceleration. If the rate of acceleration is less than G, then the falling mass is meeting resistance. Now, chandler claims that 90% of that resistance was removed by explosives cutting columns, which explains the .67G rate of acceleration.

But it's a proven fact that stuff falls on floors. It's a proven fact that the floors and their connection systems were weaker than the columns that supported them.

You totally avoid the fact that in your scenario, that roof rim would stand in place for those full three seconds, because all exterior and interior columns would also stand in place.
Only your progressive collapsing floors would fall inside these two walls of interior and exterior columns and their adjacent panels and crossbeams.
In your scenario, that roof rim would not move at all in those first 3 seconds. And neither would the radio mast sink first, followed by the whole fixed in place, four sinking roof lines.
That roof would be still firmly intact, holding those exterior columns together through the hat truss inside that roof, which extended over the 3 top floors, which were not failing at all in your scenario, since they were not burning equally, or at all.

I explained in no uncertain terms that what you are describing here - a pancaking collapse initiation - is not anything that I endorse, nor does NIST.

Therefore, you are a liar when you characterize it as "my" scenario.

And as such, deserves no rebuttal.

What we do see however, is an EQUALLY failing and falling hat truss and roof rim sinking down, taking the whole intact top 7 floors downwards into the next 8 failing floors.
And since that hat truss is firmly attached to ALL 51 core columns, and ALL 236 exterior columns, ALL these columns must have failed SOMEWHERE, equally.

47 core columns, not 51.

And no, the hat truss was not attached to ALL the ext columns.

Your scenario can not explain what we all can see clearly happening in those first three seconds.
ONLY an explosive scenario can explain that.

Well, when you quit lying about what I endorse as the initiating scenario we can discuss it.

However, you've already quoted me on the initiating scenario, so I'm quite sure that you are aware of what I endorse. Your reasons for doing that are a mystery.

originally posted by: LaBTop

lexygoth : He (Beck) says that the yield strain on the steel is 25%, but it's actually .2%. That's off by a factor of 125. that's more than 2 orders of magnitude.
Therefore, there's no need for further discussion.

Mathematical English not your first language?
No, he doesn't say that, he says it like this :

Beck, page 6, text just above equation (13) :

From the properties of structural steel(14) it is known that the yield strain under tension and compression are fairly similar, and is ~ 21 − 25%.
In our model this (LT : yield strain ) is represented by λ1, which we take to be λ1 = 0.2.
The value of compaction limit we take from Bazant(10), λ∞ = 0.2, which leaves λ2 = 1 − λ1 − λ∞ = 0.6.
From there, (r*, s*) in the continuous model are related to (r, s) in the discrete values as,
r*= 0.25 . r
s* = 0.25 . s

It's not so simple to read mathematical dissertations as you thought?
And you didn't look up the definition of yield strain.
~ 21 - 25 % can also be written as : about 0.21 - 0.25 (parts from 1.00 , or from 100 %).
Beck took the even lower value of

λ1 = 0.2

, to give NIST as much slack as possible.

Dude.

It's .2%

NOT .2

The Towers still came down at free fall speed after the explosions at the bases. As per First Responder, Police, Fire Fighter and Reporter witness testimony after the event and during the event there were explosions at the bases of the towers. And in all the videos shot live on that day you can clearly hear the explosions. And clearly here the Fire Fighters talking about the explosions and the possible use of detonators as the towers were demolished!

You can go on and on about G force E = Mc2 all you want.

It's just too obvious what happened especially looking at WTC 7 which was scarily obviously a Controlled Demolition. As people and researchers have said "How can they rig WTC-7 for a Controlled Demolition so fast?" They didn't. It was rigged days before hand! Just like WTC-1 and 2. And looking at WTC-6 probably that one too. But why WTC-6? Was it just part of the act or was there some other plan involved?

What was WTC-6?

originally posted by: Tedgoat
The Towers still came down at free fall speed

So how does material from the walls fall FASTER than the collapse front as can be seen on the videos!

a reply to: Tedgoat

Can you show us all where the Towers fell from the base after the alleged "basement explosions"? Also, explain why the cores of the towers remained standing after the initial collapses and why people survived in the core stairwells, if there were basement blasts that were suppose to destroy the Towers from the bottom up?

WTC7 had no detonation charges heard at any point indicative of demolition. Not one. Explosions were heard, but then again why wouldnt there be in a massive fire where over 30+ acres of floors are burning, two aircraft, and hundreds of cars/trucks/police/fire/port authority/buses/etc crushed, buried, burned, and gas lines exploding, steam pipes, electrical conduits, electrical transformers and vaults, exploding, etc etc etc? Come on now.

As for WTC6, didnt you notice what was next to it? I'l give you a hint: the WTC Towers.............. look inside the holes, you maybe shocked at what was inside! I'll give you another hint: WTC Towers.......... Give up?

a reply to: lexyghot

Dude.

It's .2%

NOT .2

From my post :

""Strains are dimensionless and are usually expressed as a decimal fraction, or a percentage or in parts-per notation.""

From my Beck-excerpt post above that post :

In our model this (LT : yield strain ) is represented by λ1, which we take to be λ1 = 0.2.

I see your 0.2 value, you see Beck's 0.2 value for the yield strain of the WTC steel at the failing floors.
He took the ~21 - 25 percentage value from a by him referenced book about the properties of steel, where the writer used percentages.
He himself CLEARLY used the CORRECT decimal fraction value in his mathematical equations.

Let's cut the crap.

Show me pictures of the aftermath of the 2 first WTC tower collapses, where I can see heaps of broken and cracked floors, with their intact thin steel floor pans under them, stacked upon each other.
INSIDE THE FOOTPRINT of those 2 towers.
Because you say those floors were simply falling down onto each other, while not being laterally expelled.

Do you realize, that those COMPOSITE floors must have failed ALL, as if floor-"donuts" were progressively pancaking onto each other, in your scenario. As square "rings" of which ALL core and perimeter connections were ALL broken at the same time, over and over again, over the height of 93 floors.
Because that's what we see in all those videos, rings of dust spitting out of ONE whole 4-sides perimeter of ONE floor. REPEATEDLY.
Rings of dust that are then racing to the ground.
Not chaotic, as expected in a chaotic, natural collapse, but organized. As with explosives.

The only collapsed WTC tower where we can see those stacked up floors in its footprint, is WTC 7. A clear case of a bottom up demolition.
Blow out some lower floors and use the weight of the much bigger amount of upper floors to crash themselves by sudden deceleration when suddenly meeting the Manhattan bedrock, after falling through the more then ten empty floors-crevasse created by that blow-out, during that 2.5 first seconds period of the start of its global collapse. Those 2.5 first seconds showing a truly gravitational collapse speed. Proved first by Chandler, then admitted afterwards by NIST, whose calculations showed an even closer match.

Then explain to me, how your floor collapsing scenario can occur without failing of the core columns in those first three seconds of the collapse of the WTC-1N tower, taking in account that while at the same time CLEARLY all the 47 core columns (or 51 according to Beck) are failing and SINKING AS ONE ENTITY. Because we all see that roof line coming down as one entity.
With its hat truss clearly intact connected to the 3 top floors perimeters, during those first, three seconds of measurements.

Thus, it were the CORE COLUMNS that were failing.
I don't see 47 column tops connected to a hat truss with a radio mast on top of that, sticking out of a falling heap of collapsing perimeter columns and floors, in those first three seconds.

And Chandler's WTC-1N tower graph indicates that in the first three seconds, there's no BUILD-UP of resistance. As is normal for a natural collapse.
As is demonstrated in the French demolition which was executed without explosions, but with hydraulic jacks that pressed/scattered all the columns at one floor halfway up the total height of that building. To force a natural collapse.
In that French graph we see already after 1 second that the upper parts meet INCREASING deceleration. Shown by an upwards dip in Chandler's collapse graph line. (see my signature LINKS French demolition video)

There is a constant 0.67 % of G acceleration speed, as if there is the same resistance, during all those three seconds, which is not natural.
That can only be achieved by explosives which cut/displaced the core columns, after which event, only the floors and perimeters are left to offer resistance, which is far too little to halt that organized core collapse.

That 0.67 % of true gravitational (G) acceleration speed is accomplished by the resistance of the floors/perimeters which are subsequently failing, while in the mean time the core columns are severed. Otherwise we would not see the whole roof plus radio mast attached to the hat truss, sink with a 67 % part of 100 % true gravitational acceleration in the first three seconds of the North Tower collapse.

Page 15, post by lexygoth :
There was very little, if any, column to column impacts. Not in the first half second, nor three seconds, nor at any time during the actual collapse initiation nor progression.

Why is the radio mast then the first to sink down?
Either it sunk down together with that part of the hat truss it firmly stood on, that must have failed to make that sinking possible, or that radio mast must have sunken down as a lone entity, which again, is only possible if you introduce human hands who placed explosives.

Why is the whole intact roof rim also sinking down as one intact entity?
While it's not breaking up in those first three seconds of the North Tower collapse. It maintains its structural rigidity in those three seconds.

Why didn't we see that whole roof rim including the radio mast, stay firmly upright in those first three seconds?
According to your above quote, the columns were not involved in the collapse mechanism initiation.

Those core columns were already failing in the very beginning of those first three collapse seconds.

originally posted by: LaBTop
Let's cut the crap.




Do you realize, that those COMPOSITE floors must have failed ALL, as if floor-"donuts" were progressively pancaking onto each other, in your scenario. As square "rings" of which ALL core and perimeter connections were ALL broken at the same time, over and over again, over the height of 93 floors.
Because that's what we see in all those videos, rings of dust spitting out of ONE whole 4-sides perimeter of ONE floor. REPEATEDLY.
Rings of dust that are then racing to the ground.
Not chaotic, as expected in a chaotic, natural collapse, but organized. As with explosives.

Once again an item looked at in ISOLATION what also formed rings around the tower which would turn to dust floor by floor, sheetrock, insulation , sprayed on fire protection etc etc.

Also you were shown floorslabs that ended up in the basement levels were you may expect them to end up.

a reply to: wmd_2008

Sure. They were the two lowest THICK CONCRETE+Re-bar basement floor slabs. Not above-ground floor slabs.
Pay attention to my next post, read everything in those links, it will be enlightening.

the911forum.freeforums.org...

Bringing those floor sections into lower Manhattan was one of the biggest challenges of the construction era. During a tugboat strike there were midnight caravans of flatbed trucks with police escorts who cleared the roads. The guy who organized the truck runs actually helped truck away the debris after 9/11. Tom Petrizzo.

When WTC steel erector Karl Koch “asked him if he'd seen any floor sections,” Tom replied :

“No, that's what I don't understand. […] I didn't see one goddamn floor deck come here with a bar joist in it. They must have disintegrated. Because they did not get here. And I handled this from day fu*kin' one.”
“Did they send you any decking that was loose, no joists?” [Koch] asked.
“None,” Tom said.
“None? Well, that's impossible. There were six thousand of them.”
“There's stuff crumpled up, but go identify it as a floor deck if you can. Impossible. A lot of guys come and ask me, they know I was involved in bringing 'em over, but Karl, not one came where I could say, 'Oh, here's one.' I could not show anybody a floor deck and say, 'This is what I hauled over.'”
I [Karl] couldn't believe it. Not one goddamn floor panel.

- Karl Koch III with Richard Firstman, Men of Steel: The Story of the Family that Built the World Trade Center, Crown Publishers, New York, 2002, p. 375.

So, lexyghot, where are your failed, stacked up floor panels?
They were DISINTEGRATED ! Ask Tom Petrizzo.

And not by some severed core columns, AFTER these floors pancaked/fell onto each other, as evidenced by the still standing spires after a few seconds into the collapses.
And we saw those spires SINK down, not laterally tip over.
Thus, they could not break those first failing top floors that should have been laying as a stack of partly broken floors on top of the rest of the rubble. INCLUDING their steel floor panels.
Because they were the last floors to reach the underlaying already formed rubble pile. They should lay ON TOP of that.

As can be seen at the WTC 7 rubble pile.

Made by Matt Nelson, matt[AT]911conspiracy.tv , member of the 911forum.freeforums.org :

9/11 Debris: Investigation of Ground Zero, Pt. 1
www.youtube.com...


9/11 Debris: Investigation of Ground Zero, Pt. 2
www.youtube.com...


The following two articles are the best ever repository of media articles about the rubble piles-cleanup I have ever seen.

What happened to the Twin Towers? New 2014 free e-book by Matt Nelson from the 911forum.freeforums.org.
This is a MASSIVE study on the pulverization of the two WTC Towers.

Evidence for extreme ruin and molten steel in the debris piles at the WTC complex :
911conspiracy.wordpress.com...

- William Langewiesche, American Ground: Unbuilding the World Trade Center, North Point Press, New York, 2002, p. 32.

“In his reporting for ‘American Ground,’ Langewiesche explored the shifting debris with construction workers and engineers, documenting the crises and questions as they arose. He crawled through ‘the pile’ with survey parties and descended deep below street level to areas where underground fires still burned and steel flowed in molten streams.”
– www.theatlantic.com... (See quote from Langewiesche himself above.)

Peter Tully of Tully Construction was the contractor responsible for the eastern quadrant of the pile– the South Tower, WTC 4 and 5, and the 425,000 square foot underground mall. Tully granted an interview that proved most interesting:

‘Think of the thousands of file cabinets, computers, and telephones in those towers – I never saw one – everything was pulverized,’ he said. ‘Everything that was above grade – above the 6th and 7th floor – disintegrated…it was like an explosion.’ Tully Construction specializes in concrete. I asked Mr. Tully if he had ever seen concrete pulverized as it was at the WTC.

‘No – never,’ he said.

Tully said that there were hot spots where he observed ‘literally molten steel.’ Asked about what could have caused such intense heat, Tully said, ‘Think about the jet fuel.’

- Christopher Bollyn, “Foreign Firms Destroyed Crucial Evidence,” August 14, 2002, online at www.bollyn.com...

“I saw melting of girders in World Trade Center.” – Structural Engineer Abolhassan Astaneh at www.pbs.org...

‘It’s still cooking,’ said Thomas O’Connor, who manages the construction and engineering work at the site for the Port Authority of New York and New Jersey, which owned the buildings and arranged for the tour through the basement.

In the days after the collapse of the towers two months ago, the tangled steel was still so hot that it glowed like charcoal briquets in the unlighted basement, Mr. O’Connor said, adding, ‘For seven weeks it was surreal down here.’

- James Glanz, “Below Rubble, a Tour of a Still-Burning Hell,” NY Times, Nov. 15, 2001, New York Edition p. B1. Online at www.nytimes.com... (See the same article to hear this: “A three-foot stalagmite of steel, which looks for all the world like a drip candle, sits next to one of the immense steel columns that held up the north face of the tower.”)

This excerpt comes from about halfway up this article. Read the huge amount of other witness accounts about the extreme heat in the basement rubble pile, above and below that excerpt.

As said before, the only explanation I can give for that extreme heat, is the charcoal-pit one, like the locals in Africa and Asia still make their cooking-stoves charcoal from fresh cut wood branches and trunks.

I would also like to ad the missing glass from the 68,000 windows.
We should expect to find HUGE amounts of broken glass, and shards of it, in the two rubble piles.
They were absent. Nearly N O glass was found recognizable with human eyes as former glass from all those windows.
Only a FEW pieces, as shown in photos in the above huge articles written by Matt Nelson.

While we see numerous INTACT perimeter panels flying outwards of the collapse fronts.

Thus we may expect to find lots of broken THICK glass pieces still embedded in those Vierendeel triplet panels.
If it was a NATURAL collapse.

NOT ONE ! Still embedded in the rims of the window panes, not one !

Conclusion : That glass was the first victim of the huge explosive force of the ignited THERMOBARIC bombs at those floors that spat out all around the towers, in that cadence of ring shaped dust clouds.
That dust was partly made up by the finely shattered windows GLASS.
The rest was concrete and plywood dust. Formed in those TB explosions clouds.

originally posted by: LaBTop

""Strains are dimensionless and are usually expressed as a decimal fraction, or a percentage or in parts-per notation.""

Ok.

Then .2% is .002.

NOT .2