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Truthers Don't Understand (WTC) structure

Discuss the classification of theories or hypotheses as well as the general issues regarding the different classes.

Truthers Don't Understand (WTC) structure

Postby SanderO » Tue May 18, 2010 3:54 pm

I have come to understand that one of the main issues concerning understanding of how the twin towers came down is rooted in the failure of many in the truth movement to understand the structure of the twin towers.

This leads to statement such as how could the collapse of 13 floors crush the 97 floors below if they had not done so for 40 years up until 9/11.

Of course much of this comes down to the notion that for the building to collapse the columns had to be crushed, buckled or destroyed because it is the columns which "hold the building up". While this is true it is neither completely accurate either.

Most of what we think of as "the building" are the floor system itself and their contents. The columns in plan view - cross sectional area are a very small portion of the building. Of course all the large areas (floors) which carry the loads are transferred to the columns. And so the more the load, the larger and stronger the columns must be. Simple. But this leads to the confusion of a small column up top destroying of crushing a stronger column lower down.

It also leads to all the misleading arguments about small blocks crushing larger blocks. This has nothing to do with what happened in the world trade center twins. Blocks were not crushed, columns were not crushed.

The key is that the floors were supported on truss seats - moment connections to the columns. Further the floors were designed with a safety factor to support only 100#/SF and once that safety factor was exceeded and yield strength was reached, the floors failed. Since they were composites consisting of multiple elements, concrete, metal decking, trusses with angles and bars and angle section for truss seats and beam stubs and bolts and welds it's hard to know which of those elements failed first, but fail they did.

And when one floor failed broke apart and dropped down, it created the same over load condition to the floor below and so on and so on.

This is how the floors ended up on the ground.

The question is what led to the floors being overloaded?

The dropping tops cause the floors to crash and accumulate and become overloaded.

What caused the tops to drop?

The majority of the truth movement sees the dropping tops as a sequence of bottom up explosions destroying them as weight dropped them down floor by floor and the a sequence of explosions from the top down imitating a collapse. In the case of WTC 2 the top was exploded to dust before it could tip over as one big 30 story block and then the top down explosive sequence took place.

The truth movement also uses basic physics principles such as Newton's 3rd law or the fact that the top "block" has to have a visible jolt or it can't impart "energy" to the bottom "block" as evidence that there was no collision but explosions. Yet again simplifying the interactions of 10's of thousands of structural moment connections and treating the structure as a rigid frame.

As gently as one could... pick up the top 30 stories and set them on the ground on their side 90°... that "block" of 30 stories would crush in an instant.

So the key to understanding the collapse IS the initiation of the movement of the top sections. What got them dropping and what made them tilt and torque and twist? That could be accomplished with explosives and it seems unlikely that office fires could do this in combination with plane strikes.

But even so, the initiation of the drop was a sequence of structural failures. What might they have been? That is what we need to determine. And that determination may be that it had to involve explosives and incendiaries.

Could collapsing floors (and structural) inside the core destroy most of the core? Why not then all of the core and how were those massive core columns eventually dropped? These are legitimate questions deserving answers. CD is not an answer not an explanation. It's lazy sloppy thinking.
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Re: Truthers Don't Understand (WTC) structure

Postby Enik » Tue May 18, 2010 4:21 pm

SanderO wrote:...

And when one floor failed broke apart and dropped down, it created the same over load condition to the floor below and so on and so on.

This is how the floors ended up on the ground.

...


This is pancaking which NIST dismissed. Other than watching the videos, what is the basis of this statement?
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Re: Truthers Don't Understand (WTC) structure

Postby SanderO » Tue May 18, 2010 5:35 pm

It's not pancakes. It's a progressive collapse from over yield strength conditions. NIST doesn't explain the collapse if I recall correctly.

Perhaps I was ambiguous with that statement. What was left of the floors ended up on the ground from the avalanche.

What explanation is there other than they were exploded apart in "sequence"?
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Re: Truthers Don't Understand (WTC) structure

Postby femr2 » Tue May 18, 2010 5:54 pm

Enik wrote:This is pancaking which NIST dismissed. Other than watching the videos, what is the basis of this statement?

Video is the primary evidence, but assume you have read the ROOSD threads ?

NIST dismissed *the pancake theory* as it does not account for the core.

ROOSD does not directly include the core.

It is clear (to me at least) that ROOSD is an accurate description of the actual mechanism through which the OOS floor region and perimeter were stripped to ground, and which essentially requires nothing except gravity once initiated.

Close study of the visual evidence really does indicate ROOSD type destruction.

The observations ROOSD is based upon do not indicate explosive events, especially the SW ejecta streams from WTC 1.

Focus should indeed be primarily upon initiation.
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Re: Truthers Don't Understand (WTC) structure

Postby Enik » Tue May 18, 2010 5:59 pm

This seems like a redundant thread. We have several others trying to describe the collapse initiation sequence without the need for explosives. I also don't understand the reason for the title "Truthers don't understand (WTC) structure." I have a deep understanding of the structure.
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Re: Truthers Don't Understand (WTC) structure

Postby femr2 » Tue May 18, 2010 6:20 pm

Am not keen on the title either, but don't have a problem with a thread which highlights some of the incorrect analogies used by elements of *the truth movement* (whatever that is).

Small block crushing big block, and actually using cardboard boxes to illustrate the point is shame-worthy.

I'm classified as a *twoofer*/*nut job* I suppose, but that kind of rubbish (and worse) results in the fact that I have a skeptical (but not rigid) viewpoint being a *negative*. It really shouldn't be. If everyone here all agree on the basics, that's fine by me.
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Re: Truthers Don't Understand (WTC) structure

Postby SanderO » Tue May 18, 2010 7:28 pm

What I was trying to get at was there seems to be a whole group of 911 truth folks who have all latched on to the same narrative and misconstrue the structure and therefore seem to assign it all to CD and explosives explains what happened. If you don't tow that line you are immediately cast as an OCT advocate, someone who supports everything NIST stated or some sort of spy sent into the truth universe to dilute and ruin their message.

So this rather vocal group has "hijacked" the phrase 911 Truth and you're either with them or against them. They doggedly refuse to consider anything other than CD CD and CD to explain everything... and I mean every aspect of the destruction.

The ROOSD seems to account for the floor and the facade destruction and part of the core as well, but it's impossible to have a conversation with these folks... because they refuse to discuss the basic structure of the twin towers. Recently we saw an ice crushing experiment which had nothing to do with the structure of the twin towers. YIKES!
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Re: Truthers Don't Understand (WTC) structure

Postby Enik » Tue May 18, 2010 8:41 pm

That is still not correct. Many in the 911 Truth do feel explosives (whether conventional or classified governmental) can only explain away what happened to WTC #1, #2, and #7.

But NIST is far from being correct on anything to do with WTC #1. They cannot show through FEA that truss sag caused the perimeter to bow in. Their analysis doesn't show any truss sag/perimeter column bow in at floor 97 column 316 (from their infamous picture). However it can be shown through FEA that the perimeter wall will bow in if the core is displaced downward (something that was analyzed in great detail here on another thread).

Likewise, everyone assumes dropping an entire floor structure onto a lower floor structure automatically means the two combined will drop onto the next one, onto the next one, etc. again without any FEA to back it up. That first floor structure is still attached to the perimeter columns so it isn't quite so free to simply drop down on to the first floor structure to begin with.
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Re: Truthers Don't Understand (WTC) structure

Postby femr2 » Tue May 18, 2010 8:56 pm

Enik wrote:Likewise, everyone assumes dropping an entire floor structure onto a lower floor structure automatically means the two combined will drop onto the next one, onto the next one, etc. again without any FEA to back it up. That first floor structure is still attached to the perimeter columns so it isn't quite so free to simply drop down on to the first floor structure to begin with.

That's not quite true either.

ROOSD (best we have at the mo imo) simply states that once appropriate (still unconfirmed) volume of material impacts a floor assembly, it's probable it will fail. Once the initial condition is met, is't very very probable it will continue. Visual evidence seems to confirm that behaviour. The initial conditions have not been fully explored.

I'd love to see FEA of a floor assembly hitting a static one with appropriate connections.

We did a calc a while back that suggested about 73MJ to shear the supports of an entire floor assembly from core, which ain't a lot, given the KE of a floor that's fallen a few m.

I don't think, initially, a single floor would do it, but from my asynchronous model, once velocity increases it's possible (in 1D terms) for a single floor mass to have more than enough KE to dwarf the 73MJ requirement.

Bring on the FEA :)
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Re: Truthers Don't Understand (WTC) structure

Postby SanderO » Tue May 18, 2010 11:55 pm

Enik,

I will tell you without an FEA that if the floors are overloaded past the yield strength of the weakest component in the composite the floor will "collapse"/ fail. Each floor supported by trusses was designed to support 100 #/SF. However there are safety factors and it likely could support 200 #/ft or even 300#/SF before it would fail. This is basic engineering.

The floors collapsed because more and more weight was landing on a floor until it exceeded the yield strength ... No not one floor... but the weight of several floors and this was the result of the collisions of the top's bottom floors with the bottom's top floors.

And once this collapse from being over loaded occurred it would drop onto the floor below and repeat... again and again. The floors don't take the columns with them. Their connections are destroyed TO the columns and the columns remain... and the facade then peels away without lateral support. The floors to column connection was the weak link.

NIST tried to link fire to sagging trusses to pulled in facades to discontinuity of facade columns to overloading of core columns to their buckling and global collapse. That was hooey. Fire did not cause the trusses to sag and pull the facade columns in. LIE

The 911 truth claims I am referring to is not that there were explosives or incendiaries used... but they were used to completely destroy the towers, to turn every slab to dust in "mid air" and to do it sequentially to mimic a collapse from top to bottom, and that the core columns were neatly exploded by CD into convenient sections to be hauled away and destroyed so not one could analyze them. They don't accept the idea that the facade peeled off. They claim it was explosively ejected

There like WAS explosives and incendiaries which led to the tilting and dropping tops and then to the progressive collapse of the outside the core floors and peeling off of the facade. This same type of destruction - collapse and cascade of material down in a destructive avalanche may have also gutted the core. But we don't know why some of the core columns seemed to drop straight down and break apart at their splices. Was this simply that they were too slender and unstable? Were to splices much too weak to hold them in column 50 stories high and they fractured?

Dunno.

When you simplify the structure to basic physics principles you often gloss of the details of what's going on structurally.
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Re: Truthers Don't Understand (WTC) structure

Postby SanderO » Mon Feb 11, 2013 1:46 pm

Dwain Deets was a presenter at the Vancouver Hearings. He attempted to summarize the main theories explaining the destruction of the WTC. His four theories were:

AE911T - Explosive Controlled Demolition
ROOSD plus explosives - 9/11 FF (Tom's website referenced) (ROOSD not perfectly understood nor described - no explosives!)
Mini Nukes - Jeff Praeger, Ed Ward
Directed Energy Weapons - Judy Wood

He's written an after report scoring the 4 theories. I've encouraged him to put the report on 9/11 Free Forums... If he doesn't perhaps he will give me permission to post his report. I suspect he will allow review and comment.

His scoring method for 9 criteria had ROOSD *winning* until the last test which was for the nuclear materials found. Mini Nukes edges out ROOSD with his scoring criteria and his misconception of ROOSD

However, ROOSD does not address initiation and only describes the collapse phase demonstrating the collapse to be a mass flow caged by the facade with no requirement for any explosive devices.

Stay tuned
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