29 Structural & Civil Engineers Cite Evidence for Controlled Explosive Demolition

[Newtons Bit]

So to a layman like me, what this all means is that:

a- 7-8 stories were unbraced
b- the longer the unbraced length is, when it "goes", it gives less and less resistance the longer that length is, as shown by another poster ( I forget who) to be about 1% in this case.
c- 1% is not discernable on a youtube.
d- the 105 ft is about what the 7-8 stories is.
e- as the graph shows, once the 105 ft fall was finished, the shorter braced lengths gave more resistance to the falling structure
f- so the long unbraced length accounts for the "near freefall" phase
g- this is not unexpected.


About right?

That sums it up nicely.

 

[Newtons Bit]

Accepted by who?

[qimg]http://img31.imageshack.us/img31/1338/nistfreefallgraph.jpg[/qimg]


How can the upper portion hang there while 8 floors of columns buckle? The upper part would descend as the columns buckled, not after. Stage 1 and 2 as you describe them had to be simultaneous. That does not result in free fall acceleration. The columns were held together laterally with moment frames on every other floor. They would twist and bend. This would be fairly fast but not instantaneous.

The north west corner and west wall went from no movement to free fall acceleration instantly.

You have no clue what you're even looking at do you? During Stage 1, the 8 lower floors are buckling. As in: they are in the process of failing. With respect to time, they have increasingly less vertical resistance. The rest of the building, which is supported by those 8 floors, moves downwards as the 8 floors of columns crumple. At some point, the resistance of the 8 floors of columns becomes very nearly zero. These 8 floors are crumpled ruins and fall down on their own accord due to self-weight. This begins stage 2. Nothing is supporting the building over those 8 floors. It falls down 8 floors! Big surprise!

The insanity that one would have to wrap themselves in to believe that it would just magically float down on air instead of falling down at g must be mountainous. Gee, the columns supporting it all collapse and fell down, maybe the building should fall down. "NO! That's IMPOSSIBLE, it can't possibly fall down at "g" even though nothing is supporting it anymore!" God damn I've met some stupid people in my life, but this takes the cake.

You didn't even read the page that goes along with the graph did you? Are you incapable of doing anything other than looking at pictures?

 

[jhunter1163]

@ TFK:

Too bad about your post getting sent to AAH. I nominated it anyway, though. It was brilliant.

 

[Christopher7]

During Stage 1, the 8 lower floors are buckling. As in: they are in the process of failing.
With respect to time, they have increasingly less vertical resistance. The rest of the building, which is supported by those 8 floors, moves downwards as the 8 floors of columns crumple.

Correct. As the columns buckle, they get shorter. The wall above the buckle will descend. This will result in the wall moving down as an increasing rate during Stage 1, not at free fall acceleration. The only way that can happen is if the columns are removed suddenly.

The videos show that the columns buckled where the 'kink' developed and that area descended 7 ft in 1.75s. This is far below free fall acceleration. Had the columns buckled in succession, starting with column 14 on the west wall as NIST proposes, the roofline would descend accordingly. It did not do that. The north west corner did not start moving down until Stage 2 and it went from not moving to free fall acceleration.

 

[Cl1mh4224rd]

Correct. As the columns buckle, they get shorter. The wall above the buckle will descend. This will result in the wall moving down as an increasing rate during Stage 1, not at free fall acceleration. The only way that can happen is if the columns are removed suddenly.

The columns don't have to be removed; just their ability to support their load. This apparently also happens once deformation of those columns becomes severe enough.

Who knew?

 

[GlennB]

@ TFK:

Too bad about your post getting sent to AAH. I nominated it anyway, though. It was brilliant.

I headed off to nominate it, but it already was. So I seconded (or thirded, dunno).

How on earth did it end in AAH? Just caught up in the great vacuum cleaner of the interwebs? Shame.

 

[Christopher7]

The columns don't have to be removed; just their ability to support their load. This apparently also happens once deformation of those columns becomes severe enough.

During the 1.75s in Stage 1 the roofline would descend like the area that moved down 7 ft in 1.75s. It did not. The videos show that the only columns that buckled were the ones in the area where the 'kink' developed.

 

[BigAl]

I headed off to nominate it, but it already was. So I seconded (or thirded, dunno).

How on earth did it end in AAH? Just caught up in the great vacuum cleaner of the interwebs? Shame.

(Raises hand.) What's AAH?

 

[triforcharity]

Abandon All Hope. Its where all the "reported" posts go.

ETA: I have a few in there myself from the butt cream comments!

 

[R.Mackey]

It's (1) what I yell when reading idiocy from conspiracy believers, and (2) Abandon All Hope, a sort of gulag for trouble-making posts. You can see it under the Members Only part of the Forum, but there's no direct jump to it via the drop-down menu.

 

[jhunter1163]

How on earth did it end in AAH? Just caught up in the great vacuum cleaner of the interwebs? Shame.

Pretty much so. Pity, that. It was a tremendous post. Wish I'd thought of it.

 

[Christopher7]

It's (1) what I yell when reading idiocy from conspiracy believers, and (2) Abandon All Hope, a sort of gulag for trouble-making posts. You can see it under the Members Only part of the Forum, but there's no direct jump to it via the drop-down menu.

You post occasionally but offer nothing of substance. Can you understand this fact:

If the exterior columns buckled during Stage 1 as NIST proposes, the entire roofline would have descended like the area that moved down 7 ft in 1.75s. It did not. The videos prove the only columns that buckled were the ones in the area where the 'kink' developed.

 

[H'ethetheth]

NIST and Chandler are certain about it. They both came up with the same thing. A 1 or 2% difference is not significant.

I'm glad you agree. This is what I've been trying to tell you all along. The thing is, if the columns are weakened to 1 or 2% of their original load bearing capacity, you won't measure a difference from freefall accceleration.

Beg to differ. NIST admits that the further into the simulation the less accurate the model gets.

We're talking about the first 3 seconds of the global collapse here though. Were speeds are low and thus the difference in position in pixels is lower per frame.

 

[hokie]

That's a lot of conjecture, not science. David Chandler established free fall acceleration accurately.

You're quite wrong on this account C7. I have many years experience at collecting information from images.

You claim accurate. How accurate? Within 1%? Within 5% Within 10%?

I already know that better footage would be needed to get a value within 1%.

At one point you suggest

A 1 or 2% difference is not significant.

But that has nothing to do with the accuracy of the data. So how accurate is the data?

 

[hokie]

1.75s.

You also give times to 3 decimal digits. Why? How many digits of precision do your times actually have?

 

[Newtons Bit]

During the 1.75s in Stage 1 the roofline would descend like the area that moved down 7 ft in 1.75s. It did not. The videos show that the only columns that buckled were the ones in the area where the 'kink' developed.

It did. The graph that I've posted twice has a reference point AT THE ROOF.

This:


Is what the roof is doing. It moves!

 

[dropzone]

Structural Engineering is the art of molding materials we do not wholly understand into shapes we cannot precisely analyze so as to understand forces we cannot really assess in such a way that the community at large has no reason to suspect the extent of our own ignorance.

He missed the part about praying to multiple deities, most, if not all, ones that he doesn't believe in (but JIC) that he won't be proven wrong.

 

[Christopher7]

It did. The graph that I've posted twice has a reference point AT THE ROOF.

This:
http://www.internationalskeptics.com/forums/imagehosting/thum_163294a45444493da1.gif

Is what the roof is doing. It moves!

That point is moving as the kink starts to develop. The point NIST picked moved down 7 feet in 1.75s. Then north west corner and west wall started moving. At that time "the entire building above the buckled-column region moved downward as a single unit"

David chandler used the north west corner. He established and NIST confirmed free fall acceleration starting when the north west corner started to fall.

NIST used a point at the top of the parapet wall on the roofline aligned with the east edge of the louvers* on the north face where the 'kink' developed. This area starts to descend before onset of global collapse as can be seen in this video:
*dark area in center of top 2 floors
http://nate.flach.s3.amazonaws.com/NIST_WTC7_video1.mov[FONT=&quot]

Left click and hold on the 'button' and slide it back and forth slowly starting with the beginning of the collapse of the screenwall thru the onset of global collapse. [north west corner and west wall start to fall - entire building falling]

[/FONT]

 

[Arus808]

can you guys just stop engaing C7? he wont learn and you've all repeated the SAME damn thing since page 10. what's the point? all of these were ADDRESSED IN previous threads.

Stop. the OP was answered. let this thread die.

 

[H'ethetheth]

can you guys just stop engaing C7? he wont learn and you've all repeated the SAME damn thing since page 10. what's the point? all of these were ADDRESSED IN previous threads.

Stop. the OP was answered. let this thread die.

I disagree; I see progress. Some misunderstandings have been cleared away, and this is one of the first times I've seen a truther admit to a mistake.