Hardfire: Physics of 9/11

[femr2]

Nobody is hiding the information from you, as you seem to imply.
The number of panels can be calculated, so calculate.
The thickness at the base of the building is known. The thickness at the top is known (see earlier posts). Assume a linear thinning up the building.

Stop whining and get on with it, instead of demanding that others provide the information on a plate.

A linear thinning is not likely to be accurate.

Has anyone derived a formula which includes the relative strength/cross-section/load implications ?

(I assume strength <-> cross-sectional-area is not a linear scale)

 

[Minadin]

A linear thinning is not likely to be accurate.

Has anyone derived a formula which includes the relative strength/cross-section/load implications ?

(I assume strength <-> cross-sectional-area is not a linear scale)

Why do you think it is not likely to be accurate? I think that it would be a fair approximation for the purposes of modeling.

 

[femr2]

Why do you think it is not likely to be accurate? I think that it would be a fair approximation for the purposes of modeling.

Have you derived a formula which includes the relative strength/cross-section/load implications ?

(I assume strength <-> cross-sectional-area is not a linear scale)

As you say, it would be an approximation. I want the approximation to be as accurate as possible. If you don't have the information requested, no problem. Hopefully someone else will.

 

[aggle-rithm]

It is not my fault that you WORSHIP people you call engineers. I had that title at IBM. I just dealt with electronics not buildings.

What division did you work in?

 

[Newtons Bit]

A linear thinning is not likely to be accurate.

Has anyone derived a formula which includes the relative strength/cross-section/load implications ?

(I assume strength <-> cross-sectional-area is not a linear scale)

For the sizes used in the WTC, it is pretty dern close.

 

[psikeyhackr]

What division did you work in?

.
General Systems Division

What IBM refused to call minicomputers.

I called them Imperial Benevolent Malevalence.

It is truly amazing how that stuff is junk compared to today's. But the fundamentals are exactly the same. von Neumann RULES!

psik

 

[psikeyhackr]

Nobody is hiding the information from you, as you seem to imply.
The number of panels can be calculated, so calculate.
The thickness at the base of the building is known. The thickness at the top is known (see earlier posts). Assume a linear thinning up the building.

Stop whining and get on with it, instead of demanding that others provide the information on a plate.

.
There were 12 different weights of panels and they did not go all of the way to the base. Gregory Urich already did an interpolation. We know the weight of the heaviest from a 1970 engineering magazine. I don't know what Urich assumed about the top. But I do not really care.

The NIST had 3 years and $20,000,000 and produced 10,000 pages. It is totally ridiculous that the information isn't there regardless of the reason. How do you know why it isn't there?

Oh yeah, everybody is supposed to accept whatever AUTHORITY dishes out.

psik

 

[Newtons Bit]

.
There were 12 different weights of panels and they did not go all of the way to the base. Gregory Urich already did an interpolation. We know the weight of the heaviest from a 1970 engineering magazine. I don't know what Urich assumed about the top. But I do not really care.

The NIST had 3 years and $20,000,000 and produced 10,000 pages. It is totally ridiculous that the information isn't there regardless of the reason. How do you know why it isn't there?

Oh yeah, everybody is supposed to accept whatever AUTHORITY dishes out.

psik

The purpose of the NIST report was not to provide laypeople with enough information that they could completely replicate their job. It was there to provide engineers with a detailed explanation of what went wrong. Knowing the weight of every perimeter panel is not necessary.

They succeeded in their mission.

If you want to replicate what they did, order up a set of the WTC construction documents. Prepare to dish out several thousand dollars for replication fees.

 

[femr2]

The thickness at the base of the building is known. The thickness at the top is known (see earlier posts). Assume a linear thinning up the building.

Has anyone derived a formula which includes the relative strength/cross-section/load implications ?

(I assume strength <-> cross-sectional-area is not a linear scale)

For the sizes used in the WTC, it is pretty dern close.

A formula which takes cross-sectional area and relative strength into account would, I imagine, be more accurate.

I want to use something more accurate than a simple linear scale.
I also want to specify the mechanical floor external columns more accurately.

If you have the information, great, please post. If not, then hopefully someone else will.

 

[GlennB]

.
The NIST had 3 years and $20,000,000 and produced 10,000 pages. It is totally ridiculous that the information isn't there regardless of the reason. How do you know why it isn't there?

1. It wasn't NIST's job to publish every cross-section or weight of every steel component, top to bottom. Do you understand this?

2. Stop whining.

 

[Newtons Bit]

A formula which takes cross-sectional area and relative strength into account would, I imagine, be more accurate.

I want to use something more accurate than a simple linear scale.
I also want to specify the mechanical floor external columns more accurately.

If you have the information, great, please post. If not, then hopefully someone else will.

I highly recommend reading through some of the topics I started. I go into this kind of stuff quite deeply.

http://www.internationalskeptics.com/forums/showthread.php?t=82680
http://www.internationalskeptics.com/forums/showthread.php?t=86422
http://www.internationalskeptics.com/forums/showthread.php?t=97584

 

[alienentity]

psik,



psik, have you ever heard of an avalanche, or better, a rock slide? Small rocks start to fall, they encounter other small rock, or bigger ones. They do NOT have to pulverize the bigger rocks, they simply have to break them free from their attachments. Similarly, the WTC did not have to pulverize anything in order for the collapse to progress. The only thing that had to happen was that a bunch of small bolts & welds need to be snapped.

After the slide begins, you COULD ignore gravity and conclude that from any collision, there is as much force upwards as there is downwards. And you might ignore gravity and conclude that after a rock slide had begun and gained a bit of momentum, that it was just as likely to bounce the rocks UP the side of the mountain as it was to have the rocks all tumble (asymmetrically) down the mountain.

After all, there is "that little matter of action & reaction"...

But you would be wrong.



An avalanche will not spread from its initiating point 2000 meters downhill and plus 1000 meter up hill from its descending wavefront.

There is zero engineering basis for this 1:1, 2:1, 3:1 or any such ratio in the destruction of the lower & upper section. There is a solid engineering basis for the crush progressing in both directions for 1, perhaps 2 stories, and then progress one way: downward.



[snip]

tom

In the Bazant model, there is an allowance for a small amount of crush-up near the start of the collapse. I looked thru one of the papers just now, but I couldn't locate the exact quote. I think it's supposed to be around 1%.

Naturally, psik misses the point about landslides or other destructive natural events.

However, if he wishes to read 'Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions' Bazant and Verdure, he can find out more about natural forces specific to the WTC towers.

Regarding 'the propagation of the crushing front of a compacted block
of accreting mass....
It is shown that progressive collapse will be triggered if the total internal energy loss during the crushing of one story equal to the
energy dissipated by the complete crushing and compaction of one story, minus the loss of gravity potential during the crushing of that
story exceeds the kinetic energy impacted to that story. Regardless of the load capacity of the columns, there is no way to deny the
inevitability of progressive collapse driven by gravity alone if this criterion is satisfied for the World Trade Center it is satisfied with an
order-of-magnitude margin.'

It's a shame that psik isn't able to simply look at the equations and realize that they are very well conceived.

 

[femr2]

I highly recommend reading through some of the topics I started. I go into this kind of stuff quite deeply.

http://www.internationalskeptics.com/forums/showthread.php?t=82680
http://www.internationalskeptics.com/forums/showthread.php?t=86422
http://www.internationalskeptics.com/forums/showthread.php?t=97584

Well after much wading through energy transfer discussion, a lot being c-o-m based, I found nothing resembling an equation which relates external column steel mass distribution to it's columnar cross-sectional area. Perhaps I missed it in the several hundred discussions going on. If so, then I'm sure you'll be able to simply state the information if so inclined. (The buckling calcs may come in handy though. Thanks)

I want to use something more accurate than a simple linear scale for external column mass distribution.
I also want to specify the mechanical floor external columns more accurately.

If neither, then I'll put a configurable non-linear 'curved' distribution, favouring additional mass towards the base, and people can argue about the validity or specifics of the 'curve' later.

Thanks.

 

[rwguinn]

Well after much wading through energy transfer discussion, a lot being c-o-m based, I found nothing resembling an equation which relates external column steel mass distribution to it's columnar cross-sectional area. Perhaps I missed it in the several hundred discussions going on. If so, then I'm sure you'll be able to simply state the information if so inclined. (The buckling calcs may come in handy though. Thanks)

....
Thanks.

And you're supposed to be an Engineer?
Okie Dokie.

 

[psikeyhackr]

1. It wasn't NIST's job to publish every cross-section or weight of every steel component, top to bottom. Do you understand this?

2. Stop whining.

.
The NIST says this:

Why is NIST doing this investigation?
NIST scientists and engineers are world-renowned experts in analyzing a building’s failure and determining the most probable technical cause. Since NIST is not a regulatory agency and does not issue building standards or codes, the institute is viewed as a neutral, “third party” investigator.

.
The perimeter wall panels are not just ANY STEEL COMPONENT. The NCSTAR1 report says the weight of the building was divided between the core and the perimeter on a 47% to 53% distribution. So the perimeter had about 50% and it had to taper to the top and the designers had to figure out the taper. So I find it difficult to imagine how more information about the building could be put in 24 simple numbers. The quantity and weight of each of the 12 types of panel. Since they were all the same size it would be easy to figure out where the transitions occurred between types on the surface of the towers. The total weight of panels on each level would be easy too.

But the world-renowned experts don't need to tell us such trivia.

We are just supposed to be dumb laymen that accept what we are told.

Let us all bow down and worship the GREAT Engineers that don't need to tell us anything relevant about 300 year old Newtonian physics that grade school kids can understand.

psik

 

[GlennB]

Well after much wading through energy transfer discussion, a lot being c-o-m based, I found nothing resembling an equation which relates external column steel mass distribution to it's columnar cross-sectional area.

What a mysterious comment. Smileys might be called for.

Given that the wall column trees were the same dimensions (necessarily) all the way up the buildings, then mass would be proportional to solid x-sectional area. Not a difficult calculation, even to a retired software engineer like me.

eta: rwguinn beat me to it.

 

[Myriad]

Given that the wall column trees were the same dimensions (necessarily) all the way up the buildings, then mass would be proportional to solid x-sectional area. Not a difficult calculation, even to a retired software engineer like me

Or to be even more specific, mass of the columns per floor = cross sectional column area at that floor x the spacing between floors x the density of the steel.

This would remain true whether or not the cross-sectional shapes or exterior dimensions of the columns were consistent. It's simply how one determines the volume of any extruded solid of a given cross-sectional area, and how one converts volume into mass.

Respectfully,
Myriad

 

[aggle-rithm]

.
General Systems Division

What IBM refused to call minicomputers.

What did they use for electricity back then?

 

[femr2]

Or to be even more specific, mass of the columns per floor = cross sectional column area at that floor x the spacing between floors x the density of the steel.

This would remain true whether or not the cross-sectional shapes or exterior dimensions of the columns were consistent. It's simply how one determines the volume of any extruded solid of a given cross-sectional area, and how one converts volume into mass.

Respectfully,
Myriad

The original question was about mass distribution. The Urich paper uses a linear distribution from roof to base.

I'm after a more accurate distribution method.

 

[psikeyhackr]

What did they use for electricity back then?

This was my favorite machine back in the day.

http://www-03.ibm.com/ibm/history/exhibits/vintage/vintage_4506VV4024.html

My god that stuff looks primitive now. ROFL

8" floppy disk drives. They weren't even double sided. 256KBytes.

A download from Youtube wouldn't even fit on my first hard drive.

psik