Tower Collapse Questions for Critical Thinkers

[Hokulele]

Hokulele IS a woman, so you got that one right.

But I am not a mod (thank goodness), so it's only half a point.

 

[kylebisme]

http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/466.pdf

Crap! the links to 'What Did and Did not Cause Collapse
of WTC Twin Towers in New York ' are dead. Gravy's site has exceeded bandwidth.

Cool. You can view it as an html doc off Gravy's site. Hehe.
http://74.125.155.132/search?q=cach...il.northwestern.edu+bazant&cd=4&hl=en&ct=clnk
Read these. Perhaps they will answer some of your questions.

I'll check them out, but if you could be so kind as to quote what you believe addresses the topic at hand, I'd be much obliged.

Are you saying that, once the original fulcrum point was destroyed, that upon impacting each of the lower floors that a temporary fulcrum point would be created, imparting more angular momentum as each lower floor was hit?

No, I mean parallel to the original fulcrum point the other supporting beams momentarily act as fulcrums themselves until progressing to the outside corner.

Do you mean to say the the angular momentum which was imparted upon the upper part of the tower before the fulcrum pointed collapsed is insufficient to account for how far it was tilted, so it must have received additional angular momentum afterwards?

Rather, the progression of fulcrums towards the corner is consistent with the continuing the angular momentum of observed results.

While the upper part of the tower will continue to rotate after the fulcrum point is destroyed (due to conservation of angular momentum), that rotation will be around it's center of gravity, and the center of gravity isn't going to receive any more horizontal acceleration after the fulcrum point is destroyed. It's lateral velocity at the moment the fulcrum was destroyed wasn't very large and was thus quickly overtaken by its downwards acceleration, leading to a extremely steep parabolic curve which would allow for it to crush down on the floors immediately below. Once enough of the lower floors had been crushed their combined downwards momentum would have been enough to continue collapse, even if the rotating upper portion of the tower completely fell off to the side.

But right from the start, as seen in the picture in the OP, the upper section of mass tilted well over while the lower section is crumbling away horizontally to the ground. So how do we get from there to the point were enough floors are crushed?

 

[alienentity]

I did.
'Read these. Perhaps they will answer some of your questions. '

Your questions were the topic at hand, weren't they? I figure, the best persons to confer with regarding engineering questions are engineers, particularly if they've studied the collapses. Hence the references for your perusal.

btw Hokulele, nice change of scenery.

 

[beachnut]

I'm simply pointing out an apparent inconsistency between the observed collapse and the commonly accepted explanation for that collapse.

Please feel free to present a whatever you might consider a better one.

No you are exposing your vast ignorance on 911 and science. Impacts and fires precipitated a gravity collapse. Your failed inconsistency claim is based on your own opinion which is lacking in evidence and science. You need to use some engineering instead of what you think it should be based on nothing but your feelings, hearsay, and lies. If you actually think there is a problem why have you ignored engineers here, and why are you incapable of contacting engineers, and why are you not in engineering school. At least you have company from a few fringe nut case conspiracy theorists engineers and scientist; a small list. You will find support for you from world engineers is about 0.00087 percent. A fringe few nut bars.

The brick will lean over as it sinks into the wetter corner more than the dryer one, assuming you use a heavy enough brick and loose enough dirt.

Brick and mud engineering axiom, reminds me of our expert pizza box delusional engineer with 2 mile drops which can't destroy the lower section of the WTC on 911 issues. When will you roll out the lemons? I love truther attempts at modeling the WTC collapse with moronic models.

What does the chief structural engineer think about the collapse, the gravity collapse? Did you ask the person who built the WTC?

Robertson , “the collapse mechanism of the trade center, is as we anticipated it would be, when we first designed it”

Oops, there are zero inconsistencies except in your conspiracy minded delusions. This is not an "appeal to authority", it is a fact he built and structurally designed the WTC and is the number one authority (unless you can prove he is not he trumps all your experts you can dig up from the pit of ignorance know as 911 truth); the rest of the world would be hearsay compared to Robertson. But don't take my word go talk to some independent engineers.

the upper section of mass tilted well over while the lower section is crumbling away horizontally to the ground

Why not tell us the exact tilt? Well over is not a great engineering term, and crumbling horizontally to the ground? At least you make no sense. I love the crumbling horizontally; have not seen that one until you showed up. something new

 

[Hokulele]

No, I mean parallel to the original fulcrum point the other supporting beams momentarily act as fulcrums themselves until progressing to the outside corner.

Rather, the progression of fulcrums towards the corner is consistent with the continuing the angular momentum of observed results.

What portion of the structure do you think acted as the initial fulcrum?

btw Hokulele, nice change of scenery.

Thank you. That is my winter avatar, now that the north swells are starting to come in.

 

[Darat]

Some posts moved to AAH and as ever - attack the argument not the arguer.

Replying to this modbox in thread will be off topic  Posted By: Darat

 

[kylebisme]

My bolding.

This would require a fulcrum sufficiently strong to support the entire weight of the upper section as it tilted (i.e. a see-saw arrangement). There was no such fulcrum.
It would also require the upper section to be sufficiently rigid as to be able to retain a stable geometry as it tilted. It wasn't.
These are my educated guesses. I'm not an engineer.

Well it couldn't have lasted long anyway, but again NIST claims the fulcrum was towards the middle in the diagram I mentioned previously, NCSTAR1-6D figure 4-120. You can find it here

I did.
'Read these. Perhaps they will answer some of your questions. '

Your questions were the topic at hand, weren't they? I figure, the best persons to confer with regarding engineering questions are engineers, particularly if they've studied the collapses. Hence the references for your perusal.

Am I to take it you are not even sure if those links you provide discuss the discrepancy between the angle of the upper section of mass and the destruction below it?

 

[beachnut]

Go straight to the source.

1) "Tilt of approximately 3 to 4 degrees to the south and 7 to 8 degrees to the east occurred before bulding section fell." NIST NCSTAR1-6D, Table E-1.

2) A graphical representation of the stress at the moment of collapse initiation (predicted) is given in NCSTAR1-6D, figures 4-120.

3) Not directly, no. The columns above can only transmit a force through them equal to their individual buckling strength, which does not account for the magnitude or complexity of impacts at the interface. Force and destruction are also not directly related quantities in any event.

What was wrong with this post answering the OP? When does the thermite card come out?

If this is not good enough then the OP author is not looking for rational answers.

 

[kylebisme]

What portion of the structure do you think acted as the initial fulcrum?

My guess is a collection of beams in the region highlighted in NCSTAR1-6D, though I'm still curious to know if NIST simply guessed too, as I've yet to find any mention of how they derived their claim.

What was wrong with this post answering the OP?

See my response.

 

[Hokulele]

My guess is a collection of beams in the region highlighted in NCSTAR1-6D, though I'm still curious to know if NIST simply guessed too, as I've yet to find any mention of how they derived their claim.

Which beams? To what were they attached?

The reason why I am asking you these questions is to see if you understand the figure (4-120 from NCSTAR 1-6D) you are citing as support for your idea. Even more importantly, do you understand figures 4-118 and 4-119?

 

[beachnut]

My guess is a collection of beams in the region highlighted in NCSTAR1-6D, though I'm still curious to know if NIST simply guessed too, as I've yet to find any mention of how they derived their claim.


See my response.

It was not a response, it was proof you failed to read the entire NIST report.
That was not a response it was more dumb questions. You failed to read NIST, all of NIST so you are forced to ask more questions due to your own lack of knowledge. When you finish all of NIST you should try again.

 

[bill smith]

[qimg]http://img16.imageshack.us/img16/3619/startlight.jpg[/qimg]

Here is a video for reference sake, if someone knows of a better one, please share it and I will add it to this post.

For ease of responding, I'll number the questions below:

1) What is the orientation of the upper portion mass?

2) How does this orientation relate to the force exerted on the lower portion of mass?

3) Is that distribution of force reflected in the destruction of the lower portion of mass?

Here's a video that gives an interesting perspective. I have a longer clip if you need it.

http://video.google.com/videoplay?docid=-1615521411849861778#

 

[Macgyver1968]

I should not have even responded in this thread. It's so incredibly dumb. The mods should definitely remove the thread for just for being excessively stupid.

Dude...if stupidity was grounds for deletion of threads...this subforum would be empty.

 

[funk de fino]

Obviously one can't derive how the pieces landed where they did, but then I never suggested otherwise. My comment was in the lack of analysis of the structural failure beyond the section where the collapse initiated.

I suggest you read the NIST Dec FAQ's. They explain the collapse propogation.

Think of a seesaw built on a very high fulcrum point with one very fat man and one not so fat man. It will tip towards the very fatman. Unfortunately the weight of the two fatmen is too much for the fulcrm to support. It fails.

What will happen to the fatmen? Will they fall straight down?

 

[Sherman Bay]

kylebisme, what's your point? What are you trying to prove? That the tower didn't collapse? Went up? Sideways?

I'm simply pointing out an apparent inconsistency between the observed collapse and the commonly accepted explanation for that collapse.

The commonly accepted explanation for that collapse is the columns and spans were weakened and the weight of the top floors caused them to break, while gravity did the rest.

The observed action shows the top floors falling onto the bottom ones. What inconsistency?

Parts of the building were weaker than others, so parts fell a little sooner or at angles. Parts fell on other parts and changed the angles. Weakened parts became weaker. Gravity pulled them all down. Absolutely consistent with what we would expect.

Now if you are suggesting that tests on models or computer modeling provides a slightly different outcome, remember that there are many, many factors here and no model, computer or otherwise, can perfectly account for them all. This is a chaotic system -- study that sometime. So if the building fell at 10 degrees tilt and your model says it should have been 15, you are just ignorant about how models work.

 

[WildCat]

Oh I get it - another truther who thinks the top portion should have toppled over the side thanks to some mystery horizontal force.

Why do these people have a hard time with the concept of GRAVITY?

Because gravity isn't nearly as interesting as space beams, keebler elves, gigantic invisible rockets forcing it back, sooper-nano-therm*te which does anything you want it to, etc etc.

 

[WildCat]

If you took a bucket of loose dirt, set a brick on it, and wet down one corner, would you expect the brick to sink straight down?

Try this experiment kyle: Stand a pencil on your palm, and let it start to tilt. Then quickly move your palm downward and away to simulate the destruction of the fulcrum which can't possible hold the load of the top portion of the tower. Notice how the pencil at that point falls straight down?

It can't goe sideways because there is no force making it go sideways. Gravity pulls it straight down, incidentally the same problem you have trying to cut a column with therm*te.

 

[leftysergeant]

What force are you suggesting pushed the top portion of the tower to the side, and what force are you suggesting eliminated it?

It actually appears to me the the top was not forced to the side, but, rather, that the bottom was pulled toward the opposite side.

In this respect, the tower behaved more like a tree that did not fall quite as the lumberjack expected.

I always get the impression, when looking at the news rooftop camera footage that Peter Jennings was watching, that the bottom moves toward the camera.

Now go back up to your picture and look at the corner of the structure on both sides of the failure point, and consider the angle of the top corner. I cannot see the point of contact between the upper and lower blocks because there is dust in the way by this point. It is possible that it has come to over-hang the edge by at least a few feet at this point. My guess would be that the core columns had folded over somewhat (Think of the "horseshoe beam" in the recovered wreckage) in the direction that would correspond with the right-hand side of the tower in your picture, thus accelerating the bottom of the block, possibly moving it off of the core. The surviving perimeter columns held the top from tipping off for a matter of perhaps tenths of a second. By the time they ceased to hold the upper block in place, the center of gravity would have shifted to the right, in terms of the picture, thus preventing an immediate topple-over. The upper block is now accelerating both downward and , very slightly, to the right. It continues for some time to do so because it is losing floor slabs, thus weight, more slowly on that interface than on the other side.

It would also, of course, be sliding off the tops of the lower core columns, agaain, simulating to some extent a badly-felled tree. This shifts the center of gravity to the right, preventing a topple-over as a unit. Think of the surviving lowercore columns acting like a spindle to guide the core columns in the upper block.

All of this complex process continue to function only for a short while, but that time span is enough to somewhat even-out the collapse. It still collapses in a less perfect symetry than does the north tower when it finally fails.

I hope that this makes as much sense as I think it does.

Of course the top of the tower wouldn't just slide off unless it broke free, but the angle of the upper portion of the mass has direct relationship to the distribution of force on the lower section regardless.

It was trying to slide off in the oposite direction of the tilt.

 

[WildCat]

Path of least resistance, distribution weight, and ever other relevant principle of physics. I'm not interested in proposing theories on what happen here though, just discussing what observably did.

Path of least resistance is straight down. If you don't believe me then drop a boling ball directly over your mama's glass coffee table. If you believe in your definition the bowling ball will stop in mid-air, float over to the side, and then drop harmlessly on the floor. Do you think this will happen?

 

[WildCat]

Obviously one can't derive how the pieces landed where they did, but then I never suggested otherwise.

Yes, you did. That's what "model the collapse" entails.