QUOTE (einsteen+Oct 7 2007, 11:24 AM)
... But a constant force through the whole collapse is not realistic.
The velocity a story lower is independent on Fmax,
it's the area under the function that matters.
I agree. See Bazant/Le/Greening/Benson for a realistic estimate of the force during the entire crush-down.
False. Read the crush-down differential equation with some care. Pick some Z > Z0 with Z' > 0 and Z" > 0. Assume at that Z and thereafter that F(Z) is very large. Note that the collapse stops.
I don't understand what you are attempting to communicate.
=============================
Edited to add: I need to correct some comments in earlier posts. Indeed, the total resistive force does depend upon the speed of the collapse: both concrete comminution and air movement become significant only at high enough speeds. The resistance due to the intact structural components is not speed dependent.
The is a possibility of crush-down with a terminal speed: The requirements are just that Z" = 0 and Z' is constant so that the crush-down equation takes the form
F(Z) = Z - (1-s)(Z')^2.
So just for such a resistive force equal to Z less a constant the collapse stops accelerating and does not decelerate.
The velocity a story lower is independent on Fmax,
it's the area under the function that matters.
I agree. See Bazant/Le/Greening/Benson for a realistic estimate of the force during the entire crush-down.
False. Read the crush-down differential equation with some care. Pick some Z > Z0 with Z' > 0 and Z" > 0. Assume at that Z and thereafter that F(Z) is very large. Note that the collapse stops.
I don't understand what you are attempting to communicate.
=============================
Edited to add: I need to correct some comments in earlier posts. Indeed, the total resistive force does depend upon the speed of the collapse: both concrete comminution and air movement become significant only at high enough speeds. The resistance due to the intact structural components is not speed dependent.
The is a possibility of crush-down with a terminal speed: The requirements are just that Z" = 0 and Z' is constant so that the crush-down equation takes the form
F(Z) = Z - (1-s)(Z')^2.
So just for such a resistive force equal to Z less a constant the collapse stops accelerating and does not decelerate.
David, I admit that I have never worked out that paper (I'm not really familiar with your notations), although read the text but maybe we mean the same, my 10 days old girl is sleeping so I had some time to LaTeX it for you, see this gif image
http://i20.tinypic.com/2h5pbtu.gif
correction: can become imaginary dependent on the values of m,g,h etc instead of becomes imaginary
I've a small holiday so I hope to continue with my paper, but I've said that before, only words... life is hard, too less time, too much hobbies...
ps. OneWhiteEye thanks for your message and your blue/white chessboard pics where very cool
http://i20.tinypic.com/2h5pbtu.gif
correction: can become imaginary dependent on the values of m,g,h etc instead of becomes imaginary
I've a small holiday so I hope to continue with my paper, but I've said that before, only words... life is hard, too less time, too much hobbies...
ps. OneWhiteEye thanks for your message and your blue/white chessboard pics where very cool
QUOTE (einsteen+Oct 7 2007, 01:22 PM)
... maybe we mean the same ...
We don't. Your equation is not the crush-down equation.
The crush-down equation, in the form I am using it, assumes the same mass at every elevation. When the crushing front reaches any given elevation the mass there is crushed into a small fraction of the original height, called the stretch, s. A typical value for s is 0.15 or so. The bottom of the newly crushed materials becomes the new crushing front. In the crush-down equation, Z measures the relative location of the crushing front, beginning at some Z0 and progressing towards 1.
I'm rather uncertain what dynamics your equation is to represent, but given your conclusion it appears that you are ending up with Greening's floor-by-floor approximation. That's fine, once one takes enough floors into account. But that won't work for the first 0.6 seconds of WTC 1, which is before floor 98 first began to hit floor 97. Yet, even the first 0.6 seconds give accelerations of about 0.7g, demonstrating that there is some resistance. Hence, for such calculations the crush-down equation is to be preferred.
We don't. Your equation is not the crush-down equation.
The crush-down equation, in the form I am using it, assumes the same mass at every elevation. When the crushing front reaches any given elevation the mass there is crushed into a small fraction of the original height, called the stretch, s. A typical value for s is 0.15 or so. The bottom of the newly crushed materials becomes the new crushing front. In the crush-down equation, Z measures the relative location of the crushing front, beginning at some Z0 and progressing towards 1.
I'm rather uncertain what dynamics your equation is to represent, but given your conclusion it appears that you are ending up with Greening's floor-by-floor approximation. That's fine, once one takes enough floors into account. But that won't work for the first 0.6 seconds of WTC 1, which is before floor 98 first began to hit floor 97. Yet, even the first 0.6 seconds give accelerations of about 0.7g, demonstrating that there is some resistance. Hence, for such calculations the crush-down equation is to be preferred.
This is only the part between the collisions, the momentum transfer at the collisions is not taken into account, I have the full equation somewhere around but that is also with a constant E1. This analysis was only to show that the velocity behavior is independent of the exact function and that Fr=constant is a good approach to calculate the end velocity and the collapse time, for the end velocity it is even exact when also the momentum transfer between the floor collisions is taken into account.
QUOTE (einsteen+Oct 7 2007, 02:45 PM)
This is only the part between the collisions ...
In the Greening style analysis, there is no resistive force between the collisions of floors.
So if you introduce this resistive force, you'll need some mass (material) which gives rise to the resistance. Then you'll have to crush that material as well. So your equation does not properly account for all the inertial and kinematic effects.
(I am not doubting your mathematics. I am doubting that your dynamical equation has any close relationship to actual physics. Sorry.)
In the Greening style analysis, there is no resistive force between the collisions of floors.
So if you introduce this resistive force, you'll need some mass (material) which gives rise to the resistance. Then you'll have to crush that material as well. So your equation does not properly account for all the inertial and kinematic effects.
(I am not doubting your mathematics. I am doubting that your dynamical equation has any close relationship to actual physics. Sorry.)
There is indeed a kind of effective resistance due to conservation of momentum between the floors and and due to the compaction of a story. This force over the distance is indeed the famous E1 value and is indeed related with the crushing of material between the stories. It is not introduced but the logical physical result of crushing material. It is (when Fr=constant) 1-1 with Greening's paper, he calls it the Floor collapse energy (although meant for a story) which relative independency is plotted.
http://i23.tinypic.com/15doo60.gif
Could you confirm NEU-FONZE ? And would you like to review the calculation on top if you are reading..
http://i23.tinypic.com/15doo60.gif
Could you confirm NEU-FONZE ? And would you like to review the calculation on top if you are reading..
QUOTE (einsteen+Oct 7 2007, 03:20 PM)
There is indeed a kind of effective resistance due to conservation of momentum between the floors and and due to the compaction of a story.
This force over the distance is indeed the famous E1 value and is indeed related with the crushing of material between the stories.
Your saying so doesn't mean your equation actually reflects that. In particular you fail to account properly for compaction.
The mere fact of taking your equation and producing nice-looking graphs does not suffice to demonstrate that you have correctly captured the physics of the situation. Compare what you have done with Bazant & Verdure derivation of their crush-down equation and you will begin to see what I have in mind.
Edited to add: Your equation is, I believe,
mg - F(z) = mz"
where z" = (d/dt(d/dt(z)), the acceleration in the z direction.
You appear to have a constant mass m. But m is growing as more crushed materials are added. Furthermore, unless the crushed materials have a stretch of 0, that is, are infinitesimally thin, the crushing block grows thicker, vertically, so the location of crushing changes, becoming progressively further down. You haven't accounted for this, either.
The Bazant & Verdure crush-down equation takes all this into account.
This force over the distance is indeed the famous E1 value and is indeed related with the crushing of material between the stories.
Your saying so doesn't mean your equation actually reflects that. In particular you fail to account properly for compaction.
The mere fact of taking your equation and producing nice-looking graphs does not suffice to demonstrate that you have correctly captured the physics of the situation. Compare what you have done with Bazant & Verdure derivation of their crush-down equation and you will begin to see what I have in mind.
Edited to add: Your equation is, I believe,
mg - F(z) = mz"
where z" = (d/dt(d/dt(z)), the acceleration in the z direction.
You appear to have a constant mass m. But m is growing as more crushed materials are added. Furthermore, unless the crushed materials have a stretch of 0, that is, are infinitesimally thin, the crushing block grows thicker, vertically, so the location of crushing changes, becoming progressively further down. You haven't accounted for this, either.
The Bazant & Verdure crush-down equation takes all this into account.
That plot is not mine, it is Greening's one. I'm only saying that a constant resistive force is not what really happenes. It is a kind of average that simplifies the differential equation and it works of course because someone has found a solution, but the force provided by a story will increase linearly until a maximum is reached. The graph I created is the physical situation and the constant function E1/h is the mathematical simplification to set up the differential equations.
The force is not constant during the collapse, but if you adjust the model with nonconstant forces only then the collapse will also not be arrested.
ps. also edit: as I said before this is between the collisions, I have the complete formula around and that is 1-1 with Bazant although discrete. You'll see later.
The force is not constant during the collapse, but if you adjust the model with nonconstant forces only then the collapse will also not be arrested.
ps. also edit: as I said before this is between the collisions, I have the complete formula around and that is 1-1 with Bazant although discrete. You'll see later.
QUOTE (einsteen+Oct 7 2007, 03:57 PM)
I'm only saying that a constant resistive force is not what really happenes[sic].
ps. also edit: as I said before this is between the collisions, I have the complete formula around and that is 1-1 with Bazant although discrete. You'll see later.
Over the entire crush-down, I agree. But I reiterate that there clearly is some resistive force before floor impacts floor. And given the measurements, assuming a constant force for 3 seconds agrees very well with the data. So why look for something more complex? In particular, after 1.6 seconds, because of the tilt, three or four floors are in various stages of being crushed simultaneously. So it certainly appears to be continuous and close to constant.
Yes. Your equation is certainly going to be an adequate approximation for the time between floor collisions in a floor-by-floor collision model. So it is intermediate between a Greening style model and the continuous model of B & V. Ok.
ps. also edit: as I said before this is between the collisions, I have the complete formula around and that is 1-1 with Bazant although discrete. You'll see later.
Over the entire crush-down, I agree. But I reiterate that there clearly is some resistive force before floor impacts floor. And given the measurements, assuming a constant force for 3 seconds agrees very well with the data. So why look for something more complex? In particular, after 1.6 seconds, because of the tilt, three or four floors are in various stages of being crushed simultaneously. So it certainly appears to be continuous and close to constant.
Yes. Your equation is certainly going to be an adequate approximation for the time between floor collisions in a floor-by-floor collision model. So it is intermediate between a Greening style model and the continuous model of B & V. Ok.
If you're looking for some photos of WTC 1's collapse, here they are:
http://www.debunking911.com/wtc1top.htm
http://www.debunking911.com/wtc1top.htm
QUOTE (David B. Benson+Oct 7 2007, 05:04 PM)
And denied in the B. Blanchard report, available from the Implosion World web site. Mr. Blanchard interviewed all the lead people working on cleaning up Ground Zero, including the remains of WTC 7.
No evidence of explosives, by people who use such professionally.
How about sticking to facts instead of somebody's wacko idea...
It's still pretty strange that a demolition expert(who owns a demolition company) who's work is also on the implosionworld website says WTC 7 was a controlled demolition. He also explains why American demolition company's can't speak the truth about WTC 7 .
American demolition company's are not independent i believe ,because they need permission from authorities to do a job.
No evidence of explosives, by people who use such professionally.
How about sticking to facts instead of somebody's wacko idea...
It's still pretty strange that a demolition expert(who owns a demolition company) who's work is also on the implosionworld website says WTC 7 was a controlled demolition. He also explains why American demolition company's can't speak the truth about WTC 7 .
American demolition company's are not independent i believe ,because they need permission from authorities to do a job.
QUOTE (FactCheck+Oct 8 2007, 01:30 AM)
If you're looking for some photos of WTC 1's collapse, here they are:
http://www.debunking911.com/wtc1top.htm
Thanks, I can't sleep tonight, but after reading "Top collapses inside the lower section..." I'm sure I can now.
http://www.debunking911.com/wtc1top.htm
Thanks, I can't sleep tonight, but after reading "Top collapses inside the lower section..." I'm sure I can now.
QUOTE (atmosphere+Oct 7 2007, 11:23 AM)
There is no proof for explosives but that also goes for the collapse theory.
In this case i cant see how fire was able to heat vertical columns that far that they failed. I red the NIST report on WTC 1 and 2 and 7. Their explanation on the towers collapsing make sense , but i have doubts about the way WTC 7 is analyzed.
That's funny, since NIST hasn't yet released the WTC 7 report.
Might want to wait for the report to get released before you make up your mind about it.
By the way, what do you mean by comments like:
Arthur
In this case i cant see how fire was able to heat vertical columns that far that they failed. I red the NIST report on WTC 1 and 2 and 7. Their explanation on the towers collapsing make sense , but i have doubts about the way WTC 7 is analyzed.
That's funny, since NIST hasn't yet released the WTC 7 report.
Might want to wait for the report to get released before you make up your mind about it.
By the way, what do you mean by comments like:
QUOTE
i cant see how fire was able to heat vertical columns that far that they failed.
???????Arthur
David B. Benson:
Nulls can appear in raw data; these can be troublesome, depending. In manually derived data, features can be intermittently obscured:
T, X, X, X, X, X, X, X, X
T, X, X, X, X, , X, X, X
T, X, X, , X, X, X, X, X
T, X, X, X, X, X, , , X
T, X, X, X, X, X, X, X, X
T, X, X, , X, X, , X, X
T, X, X, X, X, X, , X, X
T, X, X, X, X, X, X, X, X
T, X, X, X, X, X, , X, X
Nulls can appear in raw data; these can be troublesome, depending. In manually derived data, features can be intermittently obscured:
CODE
T, X, X, X, X, X, X, X, X
T, X, X, X, X, , X, X, X
T, X, X, , X, X, X, X, X
T, X, X, X, X, X, , , X
T, X, X, X, X, X, X, X, X
T, X, X, , X, X, , X, X
T, X, X, X, X, X, , X, X
T, X, X, X, X, X, X, X, X
T, X, X, X, X, X, , X, X
or disappear from sight altogether after a certain time:
CODE
T, X, X, X, X, X, X, X, X
T, X, X, X, X, X, X, X, X
T, X, X, X, X, , X, X, X
T, X, X, X, X, , X, , X
T, X, X, X, X, , X, , X
T, X, X, X, X, , X, , X
Subpixel data derived from luminosity would have nulls of a different form in that there would be piecewise contiguous datasets that overlap coverage by some number of samples:
CODE
T, X, X, X, X, , , ,
T, X, X, X, X, , , ,
T, X, X, X, X, , , ,
T, X, X, X, X, X, X, X, X
T, X, X, X, X, X, X, X, X
T, , , , , X, X, X, X
T, , , , , X, X, X, X
T, , , , , X, X, X, X
The last, in particular, could be partitioned into different sets. I'm not looking for a response or comment, just making you aware.
QUOTE (atmosphere+Oct 7 2007, 06:56 PM)
American demolition company's are not independent i believe ...
They were there and he was not. The firemen were there and he was not. Read the interviews with the firemen on Firehouse.com.
Your naive beliefs seem to have little resemblance to reality. Demolition companies have to be licensed (as construction companies) and then bid on contracts to do the demolition work. The leaders of companies who bid on contracts are quite an independent and outspoken lot.
They were there and he was not. The firemen were there and he was not. Read the interviews with the firemen on Firehouse.com.
Your naive beliefs seem to have little resemblance to reality. Demolition companies have to be licensed (as construction companies) and then bid on contracts to do the demolition work. The leaders of companies who bid on contracts are quite an independent and outspoken lot.
Explosion heard 10 to 15 miles away ---
Propane tanker truck, carrying about 8,000 gallons.
Propane tanker truck, carrying about 8,000 gallons.
QUOTE (David B. Benson+Oct 8 2007, 02:35 PM)
Explosion heard 10 to 15 miles away ---
Propane tanker truck, carrying about 8,000 gallons.
If that's the Tacoma explosion, I've seen a video of it... a low resolution clip from a cell phone. It's on the same site as this clip of INSIDE Market Square Arena when it was demo'd.
inside of a demo
Propane tanker truck, carrying about 8,000 gallons.
If that's the Tacoma explosion, I've seen a video of it... a low resolution clip from a cell phone. It's on the same site as this clip of INSIDE Market Square Arena when it was demo'd.
inside of a demo
Atmosphere :
============
"There is no proof for explosives."
============
You are right!
But there are hundreds of threads of concordant evidence intractably convergent on such a theory:
exhibit A - a linear shaped charge:
http://www.whatreallyhappened.com/IMAGES/l...aped_charge.wmv
exhibit B - a 911 explosion:
http://www.youtube.com/watch?v=GPXKpbdfLd4
Arthur:
===========
[The 911 explosion is] clearly after both towers had fallen, but well before WTC 7 has fallen.
============
Indeed, there were numerous reports of secondary explosions following the collapse of the twin towers.
A CNN clip immediately preceding the collapse of 7 recorded a similar shaped-charged sound:
exhibit A - a linear shaped charge:
http://www.whatreallyhappened.com/IMAGES/l...aped_charge.wmv
exhibit B - a 911 explosion:
http://www.youtube.com/watch?v=GPXKpbdfLd4
Arthur:
===========
[The 911 explosion is] clearly after both towers had fallen, but well before WTC 7 has fallen.
============
Indeed, there were numerous reports of secondary explosions following the collapse of the twin towers.
A CNN clip immediately preceding the collapse of 7 recorded a similar shaped-charged sound:
Did you hear that?" (app 6 seconds)
http://www.youtube.com/watch?v=CwjmqkjwnvQ
"The building's about to blow up"
http://www.youtube.com/watch?v=n6roL1QZt80
7 - Falling Down vs. Falling Over (reprise)
Arthur:
==========
I'd assume its easier to make it go straight down.
==========
Your assumption is incorrect, even though I have already provided you with the correct answer.
Here it is again:
Arthur:
=============
The first issue appears to be nothing more than COPYRIGHT issues.
I can SHOW you a picture that I have a copyright on but I may choose to not let you PUBLISH that picture.
=============
Why would you choose to hide crucial evidence behind a shield of intellectual property rights?
Arthur:
=============
The FIRST quote was about WTC 1 & 2 and had to do with the physics of a top down collapse.
=============
The Kausel statement was designed to explain why the twin towers did not topple like a tree, even though the south tower had started to do so above the impact zone.
Building 7 also did not topple like a tree. What is the reason?
Arthur:
===============
The SECOND quote is about a CD, where one CAN make a building fall somewhat directionally, by placement/timing of the charges.
===============
The second quote was designed to explain the sequence in which structural damage should be inflicted on a building in order to make it topple like a tree.
Recent novel claims describe a structural damage sequence that, if true, should have forced 7 to topple to the south. Yet the collapse resembled the kind of within-footprint state-of-the-art "implosion" that "only a handful of demolition companies in the world will attempt."
Why, despite alleged damage to one side only, did building 7 not topple?
OneEye:
==================
In the firefighter stories at Firehouse.com, ...
------------
Hayden: ... but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse.
-------------
==================
Trippy:
==================
http://wtc7lies.googlepages.com/accountsofwtc7damage
------------
Anyway, I was looking at WTC7 and I noticed that it wasn’t looking like it was straight. It was really weird. The closest corner to me (the SE corner) was kind of out of whack with the SW corner. It was impossible to tell whether that corner (the SW) was leaning over more or even if it was leaning the other way. With all of the smoke and the debris pile, I couldn’t exactly tell what was going on, but I sure could see the building was leaning over in a way it certainly should not be. I asked another guy looking with me and he said “That building is going to come down, we better get out of here.” So we did. – M.J., Employed at 45 Broadway
------------
==================
Davin Coburn, Popular Mechanics:
==================
CHARLES GOYETTE: You represent that there is a third of the face to the center and to the bottom, app 10 stories, about 25% of the depth of the building that was scooped out beforehand.
COBURN: Yeah. When the Nth twr collapsed, all of the debris and the wreckage from that collapse actually
took a massive chunk out of World Trade Center 7, and the first time that, you know, FEMA released its initial report, that wasn't entirely clear.
It wasn't known exactly how much damage that building had sustained, uh, because obviously no planes hit that. It was sort of standing off to the side and then eventually collapsed. Uh, and what we've found through the NIST report and through talking to other experts was that, like you said, about 25% of the buildings' south face had been carved away from it.
==================
If a third of the south face of building 7 was "scooped out" from center to ground level, and to a depth of 25%, why did it not fall to the south like a tree?
Arthur:
=============
The first issue appears to be nothing more than COPYRIGHT issues.
I can SHOW you a picture that I have a copyright on but I may choose to not let you PUBLISH that picture.
=============
Why would you choose to hide crucial evidence behind a shield of intellectual property rights?
Arthur:
=============
The FIRST quote was about WTC 1 & 2 and had to do with the physics of a top down collapse.
=============
The Kausel statement was designed to explain why the twin towers did not topple like a tree, even though the south tower had started to do so above the impact zone.
Building 7 also did not topple like a tree. What is the reason?
Arthur:
===============
The SECOND quote is about a CD, where one CAN make a building fall somewhat directionally, by placement/timing of the charges.
===============
The second quote was designed to explain the sequence in which structural damage should be inflicted on a building in order to make it topple like a tree.
Recent novel claims describe a structural damage sequence that, if true, should have forced 7 to topple to the south. Yet the collapse resembled the kind of within-footprint state-of-the-art "implosion" that "only a handful of demolition companies in the world will attempt."
Why, despite alleged damage to one side only, did building 7 not topple?
OneEye:
==================
In the firefighter stories at Firehouse.com, ...
------------
Hayden: ... but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse.
-------------
==================
Trippy:
==================
http://wtc7lies.googlepages.com/accountsofwtc7damage
------------
Anyway, I was looking at WTC7 and I noticed that it wasn’t looking like it was straight. It was really weird. The closest corner to me (the SE corner) was kind of out of whack with the SW corner. It was impossible to tell whether that corner (the SW) was leaning over more or even if it was leaning the other way. With all of the smoke and the debris pile, I couldn’t exactly tell what was going on, but I sure could see the building was leaning over in a way it certainly should not be. I asked another guy looking with me and he said “That building is going to come down, we better get out of here.” So we did. – M.J., Employed at 45 Broadway
------------
==================
Davin Coburn, Popular Mechanics:
==================
CHARLES GOYETTE: You represent that there is a third of the face to the center and to the bottom, app 10 stories, about 25% of the depth of the building that was scooped out beforehand.
COBURN: Yeah. When the Nth twr collapsed, all of the debris and the wreckage from that collapse actually
took a massive chunk out of World Trade Center 7, and the first time that, you know, FEMA released its initial report, that wasn't entirely clear.
It wasn't known exactly how much damage that building had sustained, uh, because obviously no planes hit that. It was sort of standing off to the side and then eventually collapsed. Uh, and what we've found through the NIST report and through talking to other experts was that, like you said, about 25% of the buildings' south face had been carved away from it.
==================
If a third of the south face of building 7 was "scooped out" from center to ground level, and to a depth of 25%, why did it not fall to the south like a tree?
Tipping a building over is something like felling a tree.
To topple the building to the north,
the blasters detonate explosives on the north side of the building first,
in the same way you would chop into a tree from the north side if you wanted it to fall in that direction.
- How Building Implosions Work, Tom Harris, HowStuffWorks
============
"There is no proof for explosives."
============
You are right!
But there are hundreds of threads of concordant evidence intractably convergent on such a theory:
QUOTE
"Like Gulliver tied down in Lilliput, it is unbudgeable, not because of some one or two huge chains of argument that might - hope against hope - have weak links in them, but because it is securely tied by thousands of threads of evidence..."
- Daniel Dennet on Evolution
- Daniel Dennet on Evolution
exhibit A - a linear shaped charge:
http://www.whatreallyhappened.com/IMAGES/l...aped_charge.wmv
exhibit B - a 911 explosion:
http://www.youtube.com/watch?v=GPXKpbdfLd4
Arthur:
===========
[The 911 explosion is] clearly after both towers had fallen, but well before WTC 7 has fallen.
============
Indeed, there were numerous reports of secondary explosions following the collapse of the twin towers.
A CNN clip immediately preceding the collapse of 7 recorded a similar shaped-charged sound:
QUOTE (->
| QUOTE |
| "Like Gulliver tied down in Lilliput, it is unbudgeable, not because of some one or two huge chains of argument that might - hope against hope - have weak links in them, but because it is securely tied by thousands of threads of evidence..." - Daniel Dennet on Evolution |
exhibit A - a linear shaped charge:
http://www.whatreallyhappened.com/IMAGES/l...aped_charge.wmv
exhibit B - a 911 explosion:
http://www.youtube.com/watch?v=GPXKpbdfLd4
Arthur:
===========
[The 911 explosion is] clearly after both towers had fallen, but well before WTC 7 has fallen.
============
Indeed, there were numerous reports of secondary explosions following the collapse of the twin towers.
A CNN clip immediately preceding the collapse of 7 recorded a similar shaped-charged sound:
Did you hear that?" (app 6 seconds)
http://www.youtube.com/watch?v=CwjmqkjwnvQ
"The building's about to blow up"
http://www.youtube.com/watch?v=n6roL1QZt80
7 - Falling Down vs. Falling Over (reprise)
Arthur:
==========
I'd assume its easier to make it go straight down.
==========
Your assumption is incorrect, even though I have already provided you with the correct answer.
Here it is again:
QUOTE
Ideally, a blasting crew will be able to tumble the building over on one side,
into a parking lot or other open area.
This sort of blast is the easiest to execute, and it is generally the safest way to go.
-- How Building Implosions Work, Tom Harris, HowStuffWorks
into a parking lot or other open area.
This sort of blast is the easiest to execute, and it is generally the safest way to go.
-- How Building Implosions Work, Tom Harris, HowStuffWorks
Arthur:
=============
The first issue appears to be nothing more than COPYRIGHT issues.
I can SHOW you a picture that I have a copyright on but I may choose to not let you PUBLISH that picture.
=============
Why would you choose to hide crucial evidence behind a shield of intellectual property rights?
Arthur:
=============
The FIRST quote was about WTC 1 & 2 and had to do with the physics of a top down collapse.
=============
The Kausel statement was designed to explain why the twin towers did not topple like a tree, even though the south tower had started to do so above the impact zone.
Building 7 also did not topple like a tree. What is the reason?
Arthur:
===============
The SECOND quote is about a CD, where one CAN make a building fall somewhat directionally, by placement/timing of the charges.
===============
The second quote was designed to explain the sequence in which structural damage should be inflicted on a building in order to make it topple like a tree.
Recent novel claims describe a structural damage sequence that, if true, should have forced 7 to topple to the south. Yet the collapse resembled the kind of within-footprint state-of-the-art "implosion" that "only a handful of demolition companies in the world will attempt."
Why, despite alleged damage to one side only, did building 7 not topple?
OneEye:
==================
In the firefighter stories at Firehouse.com, ...
------------
Hayden: ... but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse.
-------------
==================
Trippy:
==================
http://wtc7lies.googlepages.com/accountsofwtc7damage
------------
Anyway, I was looking at WTC7 and I noticed that it wasn’t looking like it was straight. It was really weird. The closest corner to me (the SE corner) was kind of out of whack with the SW corner. It was impossible to tell whether that corner (the SW) was leaning over more or even if it was leaning the other way. With all of the smoke and the debris pile, I couldn’t exactly tell what was going on, but I sure could see the building was leaning over in a way it certainly should not be. I asked another guy looking with me and he said “That building is going to come down, we better get out of here.” So we did. – M.J., Employed at 45 Broadway
------------
==================
Davin Coburn, Popular Mechanics:
==================
CHARLES GOYETTE: You represent that there is a third of the face to the center and to the bottom, app 10 stories, about 25% of the depth of the building that was scooped out beforehand.
COBURN: Yeah. When the Nth twr collapsed, all of the debris and the wreckage from that collapse actually
took a massive chunk out of World Trade Center 7, and the first time that, you know, FEMA released its initial report, that wasn't entirely clear.
It wasn't known exactly how much damage that building had sustained, uh, because obviously no planes hit that. It was sort of standing off to the side and then eventually collapsed. Uh, and what we've found through the NIST report and through talking to other experts was that, like you said, about 25% of the buildings' south face had been carved away from it.
==================
If a third of the south face of building 7 was "scooped out" from center to ground level, and to a depth of 25%, why did it not fall to the south like a tree?
QUOTE (->
| QUOTE |
| Ideally, a blasting crew will be able to tumble the building over on one side, into a parking lot or other open area. This sort of blast is the easiest to execute, and it is generally the safest way to go. -- How Building Implosions Work, Tom Harris, HowStuffWorks |
Arthur:
=============
The first issue appears to be nothing more than COPYRIGHT issues.
I can SHOW you a picture that I have a copyright on but I may choose to not let you PUBLISH that picture.
=============
Why would you choose to hide crucial evidence behind a shield of intellectual property rights?
Arthur:
=============
The FIRST quote was about WTC 1 & 2 and had to do with the physics of a top down collapse.
=============
The Kausel statement was designed to explain why the twin towers did not topple like a tree, even though the south tower had started to do so above the impact zone.
Building 7 also did not topple like a tree. What is the reason?
Arthur:
===============
The SECOND quote is about a CD, where one CAN make a building fall somewhat directionally, by placement/timing of the charges.
===============
The second quote was designed to explain the sequence in which structural damage should be inflicted on a building in order to make it topple like a tree.
Recent novel claims describe a structural damage sequence that, if true, should have forced 7 to topple to the south. Yet the collapse resembled the kind of within-footprint state-of-the-art "implosion" that "only a handful of demolition companies in the world will attempt."
Why, despite alleged damage to one side only, did building 7 not topple?
OneEye:
==================
In the firefighter stories at Firehouse.com, ...
------------
Hayden: ... but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse.
-------------
==================
Trippy:
==================
http://wtc7lies.googlepages.com/accountsofwtc7damage
------------
Anyway, I was looking at WTC7 and I noticed that it wasn’t looking like it was straight. It was really weird. The closest corner to me (the SE corner) was kind of out of whack with the SW corner. It was impossible to tell whether that corner (the SW) was leaning over more or even if it was leaning the other way. With all of the smoke and the debris pile, I couldn’t exactly tell what was going on, but I sure could see the building was leaning over in a way it certainly should not be. I asked another guy looking with me and he said “That building is going to come down, we better get out of here.” So we did. – M.J., Employed at 45 Broadway
------------
==================
Davin Coburn, Popular Mechanics:
==================
CHARLES GOYETTE: You represent that there is a third of the face to the center and to the bottom, app 10 stories, about 25% of the depth of the building that was scooped out beforehand.
COBURN: Yeah. When the Nth twr collapsed, all of the debris and the wreckage from that collapse actually
took a massive chunk out of World Trade Center 7, and the first time that, you know, FEMA released its initial report, that wasn't entirely clear.
It wasn't known exactly how much damage that building had sustained, uh, because obviously no planes hit that. It was sort of standing off to the side and then eventually collapsed. Uh, and what we've found through the NIST report and through talking to other experts was that, like you said, about 25% of the buildings' south face had been carved away from it.
==================
If a third of the south face of building 7 was "scooped out" from center to ground level, and to a depth of 25%, why did it not fall to the south like a tree?
Tipping a building over is something like felling a tree.
To topple the building to the north,
the blasters detonate explosives on the north side of the building first,
in the same way you would chop into a tree from the north side if you wanted it to fall in that direction.
- How Building Implosions Work, Tom Harris, HowStuffWorks
*
Acoustic Realities
wcelliot:
Although my stereo doesn't run on C4 or catastophic brittle failure, and therefore can't accurately reproduce comparative information, please provide a reference to the sound you are attempting to "explore".
Here are some examples of how to point to an audio referent:
============
Did you hear that?" (app 6 seconds)
http://www.youtube.com/watch?v=CwjmqkjwnvQ
"The building's about to blow up"
http://www.youtube.com/watch?v=n6roL1QZt80
exhibit A - a linear shaped charge:
http://www.whatreallyhappened.com/IMAGES/l...aped_charge.wmv
exhibit B - a 911 explosion:
http://www.youtube.com/watch?v=GPXKpbdfLd4
==================
wcelliot:
Although my stereo doesn't run on C4 or catastophic brittle failure, and therefore can't accurately reproduce comparative information, please provide a reference to the sound you are attempting to "explore".
Here are some examples of how to point to an audio referent:
============
Did you hear that?" (app 6 seconds)
http://www.youtube.com/watch?v=CwjmqkjwnvQ
"The building's about to blow up"
http://www.youtube.com/watch?v=n6roL1QZt80
exhibit A - a linear shaped charge:
http://www.whatreallyhappened.com/IMAGES/l...aped_charge.wmv
exhibit B - a 911 explosion:
http://www.youtube.com/watch?v=GPXKpbdfLd4
==================
wcelliot:
The real distinction between the sound of an explosion and the sound of a sudden release of mechanical energy coupled to a large diaphragm would be in the frequency range that microphones and recorders don't record and speakers don't reproduce.
Ignoring a progressive loss of high-frequency perception that follows puberty, 20Hz-20kHz represents the full spectrum of human hearing. Recording and playback equipment is engineered to record and reproduce precisely this spectrum -- particularly when the objective is high fidelity.
Hence, recording equipment and hifi will capture the distinction between a crash or a boom; a collision or an explosion - and you are engaging in technical sophistry beyond your capacity.
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
You should look at the Bell-shaped Curve, and recognize that there are a lot more stupid people than smart people. That's why you should expect more dumb opinions than correct ones.
You should look at the Bell-shaped Curve, and recognize that there are a lot more stupid people than smart people. That's why you should expect more dumb opinions than correct ones.
QUOTE
The real distinction between the sound of an explosion and the sound of a sudden release of mechanical energy coupled to a large diaphragm would be in the frequency range that microphones and recorders don't record and speakers don't reproduce.
Ignoring a progressive loss of high-frequency perception that follows puberty, 20Hz-20kHz represents the full spectrum of human hearing. Recording and playback equipment is engineered to record and reproduce precisely this spectrum -- particularly when the objective is high fidelity.
Hence, recording equipment and hifi will capture the distinction between a crash or a boom; a collision or an explosion - and you are engaging in technical sophistry beyond your capacity.
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
A high-explosive releases its energy in microseconds, requiring a bandwidth of megahertz to accurately reproduce. A speaker can't reproduce the high-frequency components of the explosive detonation. It's the high-frequency components that distinguish between C-4 going off and someone kicking a steel garbage can with steel-toe boots. The difference between 20kHz and 1MHz is factor of 50x. No audio recorder goes up that high in bandwidth. Everything short of that (i.e., all audio recordings) is inconclusive, you won't be able to tell the difference.
Your argument still centers on the fact that you feel your speakers are capable of recreating accurately the sound of an explosion, yet you assert that nothing other than explosives going off can ever sound like an explosion. Look carefully at that speaker when you play your recordings of explosions. That's recreating the sound of an explosion (what you think explosions sound like, at least). No explosives are necessary to make something sound like an explosion (to someone who doesn't know what they sound like). Just a rigid diaphragm moving suddenly in one direction, creating a sudden gust of air. (Your speakers, no matter how expensive, can't actually create a shockwave, but your ears have limited bandwidth, as you've already noted. A sudden gust will approximate that shockwave.)
Every surface in the WTC towers was large, flat, and connected to steel under load that failed at some point in the collapse. That includes the floors that collapsed (and sorry, DBB, but the sound would've been attenuated by glass, but not extinguished) and the exterior walls. I suspect that the BANGS initially heard with the non-tilting collapse were the floors detaching from the perimeter walls and the walls recoiling from the sudden release.
If you want to do some experimenting with your own equipment, make a sound file from scratch that has one vertical spike, like this:
___________|_____________
Play it through your expensive speakers and you'll hear a single POP! That's as close to an explosive detonation as your speakers will recreate.
If you want a mechanical system that sounds like an explosive, get a steel garbage can and a pair of sturdy steel-toe boots and kick the bottom of the empty garbage can.
Or, you can drill a tiny hole in the bottom of the garbage can and put a string through it like a giant tin-can-telephone, tie a knot, pull the string tighter and tighter until it breaks. BANG! That's a sound like an explosion that your neighbors will think was C-4 going off. Your neighbors will call the cops, and then you can show the cops this explanation and try to make them understand what I've just explained to you, that despite the loud BANG!, no explosives were present.
For the columns that were heated by fire, I would expect that the deformation was plastic, but for the floors below the fire, I would expect that all deformation was elastic.
Similarly, when that load exceeds the bearing limit of the perimeter-floor supports, and those supports break (more or less simultaneously), they'll release the horizontal-inward load simultaneously and allow the perimeter wall to recoil (outwards), generating a BANG!.
This is, IMO, the source of the loud bangs heard when WTC1 first started falling (three or four loud BANGs trending towards a sustained roar during the rest of the collapse).
How about sticking to facts instead of somebody's wacko idea...
Just to be clear, by "somebody", you mean Jowenko, do you not?
wcelliot:
QUOTE
But what I'm trying to explore is the initial "BANG-BANG-BANG..." that was associated with the other tower's initial collapse
Although my stereo doesn't run on C4 or catastophic brittle failure, and therefore can't accurately reproduce comparative information, please provide a reference to the sound you are attempting to "explore".
Here are some examples of how to point to an audio referent:
============
Did you hear that?" (app 6 seconds)
http://www.youtube.com/watch?v=CwjmqkjwnvQ
"The building's about to blow up"
http://www.youtube.com/watch?v=n6roL1QZt80
exhibit A - a linear shaped charge:
http://www.whatreallyhappened.com/IMAGES/l...aped_charge.wmv
exhibit B - a 911 explosion:
http://www.youtube.com/watch?v=GPXKpbdfLd4
==================
wcelliot:
QUOTE (->
| QUOTE |
| But what I'm trying to explore is the initial "BANG-BANG-BANG..." that was associated with the other tower's initial collapse |
Although my stereo doesn't run on C4 or catastophic brittle failure, and therefore can't accurately reproduce comparative information, please provide a reference to the sound you are attempting to "explore".
Here are some examples of how to point to an audio referent:
============
Did you hear that?" (app 6 seconds)
http://www.youtube.com/watch?v=CwjmqkjwnvQ
"The building's about to blow up"
http://www.youtube.com/watch?v=n6roL1QZt80
exhibit A - a linear shaped charge:
http://www.whatreallyhappened.com/IMAGES/l...aped_charge.wmv
exhibit B - a 911 explosion:
http://www.youtube.com/watch?v=GPXKpbdfLd4
==================
wcelliot:
The real distinction between the sound of an explosion and the sound of a sudden release of mechanical energy coupled to a large diaphragm would be in the frequency range that microphones and recorders don't record and speakers don't reproduce.
Ignoring a progressive loss of high-frequency perception that follows puberty, 20Hz-20kHz represents the full spectrum of human hearing. Recording and playback equipment is engineered to record and reproduce precisely this spectrum -- particularly when the objective is high fidelity.
Hence, recording equipment and hifi will capture the distinction between a crash or a boom; a collision or an explosion - and you are engaging in technical sophistry beyond your capacity.
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
QUOTE (Al Khwarizmi - step-by-step+Oct 9 2007, 03:07 AM)
Atmosphere :
============
"There is no proof for explosives."
============
You are right!
But there are hundreds of threads of concordant evidence intractably convergent on such a theory:
There is NO EVIDENCE of CD.
NONE.
ZIP
NADA.
NOTHING.
And, Al, for all your irrelevant posts about what happens in a CD, you have STILL shown no evidence that any explosives were used in WTC 7.
Asking questions like 'why didn't it fall this way' are SILLY since it ignores the damage that was done to the building by the subsequent fires.
Arthur
.
============
"There is no proof for explosives."
============
You are right!
But there are hundreds of threads of concordant evidence intractably convergent on such a theory:
There is NO EVIDENCE of CD.
NONE.
ZIP
NADA.
NOTHING.
And, Al, for all your irrelevant posts about what happens in a CD, you have STILL shown no evidence that any explosives were used in WTC 7.
Asking questions like 'why didn't it fall this way' are SILLY since it ignores the damage that was done to the building by the subsequent fires.
Arthur
.
QUOTE
But there are hundreds of threads of concordant evidence intractably convergent on such a theory:
You should look at the Bell-shaped Curve, and recognize that there are a lot more stupid people than smart people. That's why you should expect more dumb opinions than correct ones.
QUOTE (->
| QUOTE |
| But there are hundreds of threads of concordant evidence intractably convergent on such a theory: |
You should look at the Bell-shaped Curve, and recognize that there are a lot more stupid people than smart people. That's why you should expect more dumb opinions than correct ones.
QUOTE
The real distinction between the sound of an explosion and the sound of a sudden release of mechanical energy coupled to a large diaphragm would be in the frequency range that microphones and recorders don't record and speakers don't reproduce.
Ignoring a progressive loss of high-frequency perception that follows puberty, 20Hz-20kHz represents the full spectrum of human hearing. Recording and playback equipment is engineered to record and reproduce precisely this spectrum -- particularly when the objective is high fidelity.
Hence, recording equipment and hifi will capture the distinction between a crash or a boom; a collision or an explosion - and you are engaging in technical sophistry beyond your capacity.
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
A high-explosive releases its energy in microseconds, requiring a bandwidth of megahertz to accurately reproduce. A speaker can't reproduce the high-frequency components of the explosive detonation. It's the high-frequency components that distinguish between C-4 going off and someone kicking a steel garbage can with steel-toe boots. The difference between 20kHz and 1MHz is factor of 50x. No audio recorder goes up that high in bandwidth. Everything short of that (i.e., all audio recordings) is inconclusive, you won't be able to tell the difference.
Your argument still centers on the fact that you feel your speakers are capable of recreating accurately the sound of an explosion, yet you assert that nothing other than explosives going off can ever sound like an explosion. Look carefully at that speaker when you play your recordings of explosions. That's recreating the sound of an explosion (what you think explosions sound like, at least). No explosives are necessary to make something sound like an explosion (to someone who doesn't know what they sound like). Just a rigid diaphragm moving suddenly in one direction, creating a sudden gust of air. (Your speakers, no matter how expensive, can't actually create a shockwave, but your ears have limited bandwidth, as you've already noted. A sudden gust will approximate that shockwave.)
Every surface in the WTC towers was large, flat, and connected to steel under load that failed at some point in the collapse. That includes the floors that collapsed (and sorry, DBB, but the sound would've been attenuated by glass, but not extinguished) and the exterior walls. I suspect that the BANGS initially heard with the non-tilting collapse were the floors detaching from the perimeter walls and the walls recoiling from the sudden release.
If you want to do some experimenting with your own equipment, make a sound file from scratch that has one vertical spike, like this:
___________|_____________
Play it through your expensive speakers and you'll hear a single POP! That's as close to an explosive detonation as your speakers will recreate.
If you want a mechanical system that sounds like an explosive, get a steel garbage can and a pair of sturdy steel-toe boots and kick the bottom of the empty garbage can.
Or, you can drill a tiny hole in the bottom of the garbage can and put a string through it like a giant tin-can-telephone, tie a knot, pull the string tighter and tighter until it breaks. BANG! That's a sound like an explosion that your neighbors will think was C-4 going off. Your neighbors will call the cops, and then you can show the cops this explanation and try to make them understand what I've just explained to you, that despite the loud BANG!, no explosives were present.
QUOTE (Al Khwarizmi - step-by-step+Oct 9 2007, 07:07 AM)
OneEye:
==================
In the firefighter stories at Firehouse.com, ...
------------
Hayden: ... but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse.
-------------
Speaking of which...
In deputy chief Hayden's account, a bulge was visible at the SW corner of WTC7 around floors 10-13 and a transit was sighted on the bulge. In checking this out, I kept running across this photo:
http://www.studyof911.com/articles/winston...ages/Fig02L.jpg
As you can see, there is no SW corner at floors 10-13. This is the corner NIST said was damaged on floors 8-18, possibly established with the aid of this very photo. Could the deputy chief have meant there was a bulge NEAR the corner? Perhaps, but obviously not too close.
If anyone does happen to see a transit in any of the photos near building 7, please let me know. Perhaps that portion of Peter Hayden's story is not incorrect.
==================
In the firefighter stories at Firehouse.com, ...
------------
Hayden: ... but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse.
-------------
Speaking of which...
In deputy chief Hayden's account, a bulge was visible at the SW corner of WTC7 around floors 10-13 and a transit was sighted on the bulge. In checking this out, I kept running across this photo:
http://www.studyof911.com/articles/winston...ages/Fig02L.jpg
As you can see, there is no SW corner at floors 10-13. This is the corner NIST said was damaged on floors 8-18, possibly established with the aid of this very photo. Could the deputy chief have meant there was a bulge NEAR the corner? Perhaps, but obviously not too close.
If anyone does happen to see a transit in any of the photos near building 7, please let me know. Perhaps that portion of Peter Hayden's story is not incorrect.
I guess the NSA pulled the above picture just as I was posting. Clever rascals. Good thing I have a copy I could put up myself.
http://i23.tinypic.com/111p301.jpg
http://i23.tinypic.com/111p301.jpg
QUOTE (Alan (ex elevator man)+Oct 8 2007, 08:09 PM)
If that's the Tacoma explosion ...
Yes.
Yes.
QUOTE (wcelliott+Oct 9 2007, 08:21 AM)
I suspect that the BANGS initially heard with the non-tilting collapse were the floors detaching from the perimeter walls and the walls recoiling from the sudden release.
WTC 1: tilt of at least 10.6 degrees of arc
WTC 2: tilt of at least 28(?) degrees of arc, plus rotation of top block
For WTC 1 this was sufficient so that by 1.6 seconds into the collapse, three or four floors were in various stages of being crushed simultaneously.
For WTC 1, the external truss seats failed vertically. Completely disconnecting all the truss seats, both external and internal, required only less than 12% of the total energy consumption.
I opine that the BANGs were largely due to forcing the air out of each story, but the thought of exterior wall panels moving quite suddenly (outwards) remains an interesting possibility.
WTC 1: tilt of at least 10.6 degrees of arc
WTC 2: tilt of at least 28(?) degrees of arc, plus rotation of top block
For WTC 1 this was sufficient so that by 1.6 seconds into the collapse, three or four floors were in various stages of being crushed simultaneously.
For WTC 1, the external truss seats failed vertically. Completely disconnecting all the truss seats, both external and internal, required only less than 12% of the total energy consumption.
I opine that the BANGs were largely due to forcing the air out of each story, but the thought of exterior wall panels moving quite suddenly (outwards) remains an interesting possibility.
Well, the exterior walls were bowing inwards by 22-55 inches at the time of the collapse over an area of several floors.
It's just a question of if the deformation was plastic or elastic.
If it was plastic there would have been no restorative force.
It's just a question of if the deformation was plastic or elastic.
If it was plastic there would have been no restorative force.
QUOTE
It's just a question of if the deformation was plastic or elastic.
If it was plastic there would have been no restorative force.
If it was plastic there would have been no restorative force.
For the columns that were heated by fire, I would expect that the deformation was plastic, but for the floors below the fire, I would expect that all deformation was elastic.
Even for inelastic (plastic) deformations, if the load is removed the steel recovers some of its former shape.
What I had in mind is that the exterior wall panels receive a sudden horizontal load in the form of the crushed materials falling on the inside while the air is being rapidly forced out. (Already at 1.6 seconds the speed is about 11 m/s, completely crushing a floor in about a third of a second.)
What I had in mind is that the exterior wall panels receive a sudden horizontal load in the form of the crushed materials falling on the inside while the air is being rapidly forced out. (Already at 1.6 seconds the speed is about 11 m/s, completely crushing a floor in about a third of a second.)
This is true.
QUOTE
What I had in mind is that the exterior wall panels receive a sudden horizontal load in the form of the crushed materials falling on the inside while the air is being rapidly forced out. (Already at 1.6 seconds the speed is about 11 m/s, completely crushing a floor in about a third of a second.)
Similarly, when that load exceeds the bearing limit of the perimeter-floor supports, and those supports break (more or less simultaneously), they'll release the horizontal-inward load simultaneously and allow the perimeter wall to recoil (outwards), generating a BANG!.
This is, IMO, the source of the loud bangs heard when WTC1 first started falling (three or four loud BANGs trending towards a sustained roar during the rest of the collapse).
QUOTE (carterelliott+Oct 9 2007, 04:12 PM)
... they'll release the horizontal-inward load simultaneously and allow the perimeter wall to recoil (outwards), generating a BANG!.
This is, IMO, the source of the loud bangs heard when WTC1 first started falling (three or four loud BANGs trending towards a sustained roar during the rest of the collapse).
This was actually a very modest force for intact trussed floors. NIST attempts to estimate what this was for floor with sagging trusses, but I disremember the estimate.
Another possibility is the loud BANGs were whole sections of exterior wall panels, not just single panels, breaking loose, snapping all the blots at (almost) the same instant. Several large sections of exterior wall can been seen falling away to the west in at least one video.
This is, IMO, the source of the loud bangs heard when WTC1 first started falling (three or four loud BANGs trending towards a sustained roar during the rest of the collapse).
This was actually a very modest force for intact trussed floors. NIST attempts to estimate what this was for floor with sagging trusses, but I disremember the estimate.
Another possibility is the loud BANGs were whole sections of exterior wall panels, not just single panels, breaking loose, snapping all the blots at (almost) the same instant. Several large sections of exterior wall can been seen falling away to the west in at least one video.
QUOTE (OneWhiteEye+Sep 29 2007, 02:39 AM)
This purports to be a picture at the intersection in question; I think it is. That is 7 still standing on the left, correct? Looks like the side street to the west of 7 is filled with debris. Now it seems like the only possible place for that transit to be is the intersection, most of which is shown in this photo.
That photo appears as Figure 5-15 in chapter 5 of the FEMA report WORLD TRADE CENTER BUILDING PERFORMANCE STUDY. The photo is credited to George Miller, NYCTA. The street between WTC7 and the Verizon building is Washington Street.
Photo:
http://i134.photobucket.com/albums/q91/sha...tc7/wtc7515.jpg
That photo appears as Figure 5-15 in chapter 5 of the FEMA report WORLD TRADE CENTER BUILDING PERFORMANCE STUDY. The photo is credited to George Miller, NYCTA. The street between WTC7 and the Verizon building is Washington Street.
Photo:
http://i134.photobucket.com/albums/q91/sha...tc7/wtc7515.jpg
Take a real close look at the fireman in the lower left midground of this image.
He appears to be hunched over something mounted on a tripod.
He appears to be hunched over something mounted on a tripod.
QUOTE (Trippy+Oct 9 2007, 04:57 PM)
He appears to be hunched over something mounted on a tripod.
Indeed.
Can anybody recognize the building to the left and so what street he was in?
Indeed.
Can anybody recognize the building to the left and so what street he was in?
The smoke says that we're looking at the south face, and I want to say that the charred window visible looks like the damage in this photo
Which suggests it's the same corner visible in this photo. The structure of the 'other' building is consistent with that as well.
Which suggests it's the same corner visible in this photo. The structure of the 'other' building is consistent with that as well.
QUOTE (David B. Benson+Oct 7 2007, 05:04 PM)
How about sticking to facts instead of somebody's wacko idea...
Just to be clear, by "somebody", you mean Jowenko, do you not?
for the conspiracy theorists on the thread.
http://www.youtube.com/watch?v=qLShZOvxVe4
So much for free fall speed.
Oh, and notice, of course, that there are no explosions recorded in the audio from the of North Tower.
http://www.youtube.com/watch?v=qLShZOvxVe4
So much for free fall speed.
Oh, and notice, of course, that there are no explosions recorded in the audio from the of North Tower.
Thank you shagster and Trippy.
QUOTE (David B. Benson+Oct 10 2007, 12:13 AM)
Indeed.
Can anybody recognize the building to the left and so what street he was in?
That's the Verizon building. The camera would be somewhere near the intersection of West Street and Vesey Street.
Can anybody recognize the building to the left and so what street he was in?
That's the Verizon building. The camera would be somewhere near the intersection of West Street and Vesey Street.
QUOTE (shagster+Oct 10 2007, 05:58 PM)
That's the Verizon building. The camera would be somewhere near the intersection of West Street and Vesey Street.
I've come across several photos where some bulging appears to be visible, but I can't work out if it's a camera artifact or a real thing.
I've come across several photos where some bulging appears to be visible, but I can't work out if it's a camera artifact or a real thing.
wcelliot:
My tweeter diaphrams, being extremely thin and of miniscule mass, can be propelled backwards and forwards at a staggering 20,000 cycles per second without difficulty. I can not hear the 20,000 Khz frequency that is produced, because I am nearly 40.
But I can still recognize the difference between a crash, a bang, a boom, or a crash-bang-whoosh-boom-rumble.
A high-explosive, as demonstrated with a conspicuouly ignored link to a real recording made with a real shaped-charged explosive, produces a sound that has a significant duration (sustain) lasting several seconds when coupled to the atmosphere and environment in which it is detonated.
For some reason, wc, you seem to be exceedingly interested in the exploration of abstract hypothetical sounds, but not real ones like these:
exhibit A - a linear shaped charge
exhibit B - a 911 explosion:
High-fidelity audio recording and reproduction equipment is designed to record and reproduce the entire spectrum of human hearing. Any frequencies produced in an explosion in the "megahertz" region (!) are, by definition, inaudible to humans.
The attack time of a sound (rate of rise to maximum amplitude) is only one feature of an extremely complicated wave structure (attack, sustain, decay, spectral composition, spectral distribution, spectral amplitude, etc.)
A humanly discriminably explosive rate of attack certainly does not require a megahertz bandwidth to achieve.
My tweeter diaphrams, being extremely thin and of miniscule mass, can be propelled backwards and forwards at a staggering 20,000 cycles per second without difficulty. I can not hear the 20,000 Khz frequency that is produced, because I am nearly 40.
But I can still recognize the difference between a crash, a bang, a boom, or a crash-bang-whoosh-boom-rumble.
A high-explosive, as demonstrated with a conspicuouly ignored link to a real recording made with a real shaped-charged explosive, produces a sound that has a significant duration (sustain) lasting several seconds when coupled to the atmosphere and environment in which it is detonated.
For some reason, wc, you seem to be exceedingly interested in the exploration of abstract hypothetical sounds, but not real ones like these:
exhibit A - a linear shaped charge
exhibit B - a 911 explosion:
High-fidelity audio recording and reproduction equipment is designed to record and reproduce the entire spectrum of human hearing. Any frequencies produced in an explosion in the "megahertz" region (!) are, by definition, inaudible to humans.
The attack time of a sound (rate of rise to maximum amplitude) is only one feature of an extremely complicated wave structure (attack, sustain, decay, spectral composition, spectral distribution, spectral amplitude, etc.)
A humanly discriminably explosive rate of attack certainly does not require a megahertz bandwidth to achieve.
yet you assert that nothing other than explosives going off can ever sound like an explosion
I asserted nothing of the sort. Rather, I requested that you provide a reference to a real world example of supporting evidence for us to "explore."
Perhaps your evident disinterest in reality explains why you ignored my request:
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
QUOTE
A high-explosive releases its energy in microseconds, requiring a bandwidth of megahertz to accurately reproduce.
My tweeter diaphrams, being extremely thin and of miniscule mass, can be propelled backwards and forwards at a staggering 20,000 cycles per second without difficulty. I can not hear the 20,000 Khz frequency that is produced, because I am nearly 40.
But I can still recognize the difference between a crash, a bang, a boom, or a crash-bang-whoosh-boom-rumble.
A high-explosive, as demonstrated with a conspicuouly ignored link to a real recording made with a real shaped-charged explosive, produces a sound that has a significant duration (sustain) lasting several seconds when coupled to the atmosphere and environment in which it is detonated.
For some reason, wc, you seem to be exceedingly interested in the exploration of abstract hypothetical sounds, but not real ones like these:
exhibit A - a linear shaped charge
exhibit B - a 911 explosion:
High-fidelity audio recording and reproduction equipment is designed to record and reproduce the entire spectrum of human hearing. Any frequencies produced in an explosion in the "megahertz" region (!) are, by definition, inaudible to humans.
The attack time of a sound (rate of rise to maximum amplitude) is only one feature of an extremely complicated wave structure (attack, sustain, decay, spectral composition, spectral distribution, spectral amplitude, etc.)
A humanly discriminably explosive rate of attack certainly does not require a megahertz bandwidth to achieve.
QUOTE (->
| QUOTE |
| A high-explosive releases its energy in microseconds, requiring a bandwidth of megahertz to accurately reproduce. |
My tweeter diaphrams, being extremely thin and of miniscule mass, can be propelled backwards and forwards at a staggering 20,000 cycles per second without difficulty. I can not hear the 20,000 Khz frequency that is produced, because I am nearly 40.
But I can still recognize the difference between a crash, a bang, a boom, or a crash-bang-whoosh-boom-rumble.
A high-explosive, as demonstrated with a conspicuouly ignored link to a real recording made with a real shaped-charged explosive, produces a sound that has a significant duration (sustain) lasting several seconds when coupled to the atmosphere and environment in which it is detonated.
For some reason, wc, you seem to be exceedingly interested in the exploration of abstract hypothetical sounds, but not real ones like these:
exhibit A - a linear shaped charge
exhibit B - a 911 explosion:
High-fidelity audio recording and reproduction equipment is designed to record and reproduce the entire spectrum of human hearing. Any frequencies produced in an explosion in the "megahertz" region (!) are, by definition, inaudible to humans.
The attack time of a sound (rate of rise to maximum amplitude) is only one feature of an extremely complicated wave structure (attack, sustain, decay, spectral composition, spectral distribution, spectral amplitude, etc.)
A humanly discriminably explosive rate of attack certainly does not require a megahertz bandwidth to achieve.
yet you assert that nothing other than explosives going off can ever sound like an explosion
I asserted nothing of the sort. Rather, I requested that you provide a reference to a real world example of supporting evidence for us to "explore."
Perhaps your evident disinterest in reality explains why you ignored my request:
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
trippy:
Attacks Held To Be A Conspiracy
LA Times headline, September 11, 2001
"When I use a word," said Humpty Dumpty in a rather scornful tone,
"it means just what I choose it to mean, neither more, nor less."
"The question is," replied Alice, "wether you can make words mean so many different things."
Trippy - what does RDX residue smell like, and would you recognize it?
What does HDX residue smell like, and would you recognize it?
What does C4 residue smell like, and would you recognize it?
What does thermite residue smell like, and would you recognize it?
What does thermate residue smell like, and would you recognize it?
What does cordite residue smell like, and would you recognize it?
A couple of Israelis in a moving van were arrested in May 2002 for suspicious behavior. Bomb-sniffing dogs reacted as if they had detected explosives, later confirmed in the laboratory as traces of RDX on both the steering wheel and the clothing of the occupants.
http://www.foxnews.com/story/0,2933,52681,00.html
The Israelis were subsequently cleared because the canines and the laboratory had been confused by ...
... cigarette lighter residue - !!!!!
http://seattlepi.nwsource.com/local/70305_explosives14.shtml
1) Do you believe it?
2) How might cigarette lighter residue impede the discovery of explosive residues at ground zero?
wcelliot, and everyone else describing pops and bangs and crashes:
Attacks Held To Be A Conspiracy
LA Times headline, September 11, 2001
"When I use a word," said Humpty Dumpty in a rather scornful tone,
"it means just what I choose it to mean, neither more, nor less."
"The question is," replied Alice, "wether you can make words mean so many different things."
Trippy - what does RDX residue smell like, and would you recognize it?
What does HDX residue smell like, and would you recognize it?
What does C4 residue smell like, and would you recognize it?
What does thermite residue smell like, and would you recognize it?
What does thermate residue smell like, and would you recognize it?
What does cordite residue smell like, and would you recognize it?
A couple of Israelis in a moving van were arrested in May 2002 for suspicious behavior. Bomb-sniffing dogs reacted as if they had detected explosives, later confirmed in the laboratory as traces of RDX on both the steering wheel and the clothing of the occupants.
http://www.foxnews.com/story/0,2933,52681,00.html
The Israelis were subsequently cleared because the canines and the laboratory had been confused by ...
... cigarette lighter residue - !!!!!
http://seattlepi.nwsource.com/local/70305_explosives14.shtml
1) Do you believe it?
2) How might cigarette lighter residue impede the discovery of explosive residues at ground zero?
wcelliot, and everyone else describing pops and bangs and crashes:
This is, IMO, the source of the loud bangs heard when WTC1 first started falling (three or four loud BANGs trending towards a sustained roar during the rest of the collapse).
Wrong.
All of the sound that an explosive produces that is unique to an explosion is in the range above human hearing. All the "extremely complicated wave structure" is due to the environment of the explosion. The explosion itself is over in microseconds, and that 20kHz bandwidth doesn't come close to reproducing it. It only reproduces the low-bandwidth (sub-20kHz) multiple reflections of that unit impulse. You think that the reflections *are* the characteristics sounds of the explosion, but those aren't the characteristic of the explosion, they're the characteristic of the environment of the explosion. The same explosive will sound different in different environments in that audio bandwidth. The explosion is one sharp spike with MHz bandwidth. Your speakers don't reproduce 2% of the bandwidth necessary (and less than that of the amplitude).
You need to bone-up on acoustics. It's a real branch of physics, there are books out there on the topic. I'd recommend avoiding the audiophile BS, unless you're talking about music. It doesn't apply.
All of the sound that an explosive produces that is unique to an explosion is in the range above human hearing.
Initimidatory ipse dixit assertion is not a demonstration of real world evidence.
Why won't you listen to the recording of a shaped-charge explosion?
Why won't you listen to the recording of a 911 explosion?
Why won't you compare the two?
Why won't you provide a REAL WORLD EXAMPLE of a "catastrophic brittle failure," or "something heavy falling on the floor from above,"
so that we may compare the three?
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
I will keep repeating the question until you address it, wc - and I will not be intimidated by your scornful and abusive histrionics.
OK, take an acoustic guitar, remove all but one string. With that one string taut, cut it with a wire cutter.
BANG!
The concrete in the floors was 4inches thick, and covered an area 208feet x 208feet. It was 600x thinner than it was wide, about the same as a playing card. That's a diaphragm, thinner than the wood in an acoustic guitar.
A few pages back someone posted the detonation speed for C-4. It was in fractions of a microsecond/cm, IIRC. So multiply the major dimension of a block of C-4 by that detonation rate and you'll have the amount of time it takes for that block of C-4 to turn into a puff of hot gas. Nothing happens to it after it detonates, other than the hot gas expanding in all directions at the speed of sound (just above, actually, but the difference is moot after a few microseconds). On an oscilloscope, that looks like:
_____________|______________
The "complex acoustic waveform" you're looking at with all those recordings are the sounds made by that spike bouncing around inside the environment. That makes it an artifact of the environment, not a characteristic of the explosive.
Learn something and get back to us if you have any further questions.
QUOTE
for the conspiracy theorists on the thread.
Attacks Held To Be A Conspiracy
LA Times headline, September 11, 2001
"When I use a word," said Humpty Dumpty in a rather scornful tone,
"it means just what I choose it to mean, neither more, nor less."
"The question is," replied Alice, "wether you can make words mean so many different things."
Trippy - what does RDX residue smell like, and would you recognize it?
What does HDX residue smell like, and would you recognize it?
What does C4 residue smell like, and would you recognize it?
What does thermite residue smell like, and would you recognize it?
What does thermate residue smell like, and would you recognize it?
What does cordite residue smell like, and would you recognize it?
A couple of Israelis in a moving van were arrested in May 2002 for suspicious behavior. Bomb-sniffing dogs reacted as if they had detected explosives, later confirmed in the laboratory as traces of RDX on both the steering wheel and the clothing of the occupants.
http://www.foxnews.com/story/0,2933,52681,00.html
The Israelis were subsequently cleared because the canines and the laboratory had been confused by ...
... cigarette lighter residue - !!!!!
http://seattlepi.nwsource.com/local/70305_explosives14.shtml
1) Do you believe it?
2) How might cigarette lighter residue impede the discovery of explosive residues at ground zero?
wcelliot, and everyone else describing pops and bangs and crashes:
QUOTE (->
| QUOTE |
| for the conspiracy theorists on the thread. |
Attacks Held To Be A Conspiracy
LA Times headline, September 11, 2001
"When I use a word," said Humpty Dumpty in a rather scornful tone,
"it means just what I choose it to mean, neither more, nor less."
"The question is," replied Alice, "wether you can make words mean so many different things."
Trippy - what does RDX residue smell like, and would you recognize it?
What does HDX residue smell like, and would you recognize it?
What does C4 residue smell like, and would you recognize it?
What does thermite residue smell like, and would you recognize it?
What does thermate residue smell like, and would you recognize it?
What does cordite residue smell like, and would you recognize it?
A couple of Israelis in a moving van were arrested in May 2002 for suspicious behavior. Bomb-sniffing dogs reacted as if they had detected explosives, later confirmed in the laboratory as traces of RDX on both the steering wheel and the clothing of the occupants.
http://www.foxnews.com/story/0,2933,52681,00.html
The Israelis were subsequently cleared because the canines and the laboratory had been confused by ...
... cigarette lighter residue - !!!!!
http://seattlepi.nwsource.com/local/70305_explosives14.shtml
1) Do you believe it?
2) How might cigarette lighter residue impede the discovery of explosive residues at ground zero?
wcelliot, and everyone else describing pops and bangs and crashes:
This is, IMO, the source of the loud bangs heard when WTC1 first started falling (three or four loud BANGs trending towards a sustained roar during the rest of the collapse).
a reference please.
(multiple UBBortion edits - AK)
(multiple UBBortion edits - AK)
QUOTE
High-fidelity audio recording and reproduction equipment is designed to record and reproduce the entire spectrum of human hearing. Any frequencies produced in an explosion in the "megahertz" region (!) are, by definition, inaudible to humans.
The attack time of a sound (rate of rise to maximum amplitude) is only one feature of an extremely complicated wave structure (attack, sustain, decay, spectral composition, spectral distribution, spectral amplitude, etc.)
The attack time of a sound (rate of rise to maximum amplitude) is only one feature of an extremely complicated wave structure (attack, sustain, decay, spectral composition, spectral distribution, spectral amplitude, etc.)
Wrong.
All of the sound that an explosive produces that is unique to an explosion is in the range above human hearing. All the "extremely complicated wave structure" is due to the environment of the explosion. The explosion itself is over in microseconds, and that 20kHz bandwidth doesn't come close to reproducing it. It only reproduces the low-bandwidth (sub-20kHz) multiple reflections of that unit impulse. You think that the reflections *are* the characteristics sounds of the explosion, but those aren't the characteristic of the explosion, they're the characteristic of the environment of the explosion. The same explosive will sound different in different environments in that audio bandwidth. The explosion is one sharp spike with MHz bandwidth. Your speakers don't reproduce 2% of the bandwidth necessary (and less than that of the amplitude).
You need to bone-up on acoustics. It's a real branch of physics, there are books out there on the topic. I'd recommend avoiding the audiophile BS, unless you're talking about music. It doesn't apply.
QUOTE
All of the sound that an explosive produces that is unique to an explosion is in the range above human hearing.
Initimidatory ipse dixit assertion is not a demonstration of real world evidence.
Why won't you listen to the recording of a shaped-charge explosion?
Why won't you listen to the recording of a 911 explosion?
Why won't you compare the two?
Why won't you provide a REAL WORLD EXAMPLE of a "catastrophic brittle failure," or "something heavy falling on the floor from above,"
so that we may compare the three?
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
I will keep repeating the question until you address it, wc - and I will not be intimidated by your scornful and abusive histrionics.
QUOTE (Al Khwarizmi - step-by-step+Oct 10 2007, 08:10 PM)
Trippy - what does RDX residue smell like, and would you recognize it?
What does HDX residue smell like, and would you recognize it?
What does C4 residue smell like, and would you recognize it?
What does thermite residue smell like, and would you recognize it?
What does thermate residue smell like, and would you recognize it?
What does cordite residue smell like, and would you recognize it?
A couple of Israelis in a moving van were arrested in May 2002 for suspicious behavior. Bomb-sniffing dogs reacted as if they had detected explosives, later confirmed in the laboratory as traces of RDX on both the steering wheel and the clothing of the occupants.
http://www.foxnews.com/story/0,2933,52681,00.html
The Israelis were subsequently cleared because the canines and the laboratory had been confused by ...
... cigarette lighter residue - !!!!!
http://seattlepi.nwsource.com/local/70305_explosives14.shtml
1) Do you believe it?
2) How might cigarette lighter residue impede the discovery of explosive residues at ground zero?
Your ignorance is showing.
Seriously, it's time for a reality check.
Just need to get my post organized first (In other words, don't bother replying yet).
What does HDX residue smell like, and would you recognize it?
What does C4 residue smell like, and would you recognize it?
What does thermite residue smell like, and would you recognize it?
What does thermate residue smell like, and would you recognize it?
What does cordite residue smell like, and would you recognize it?
A couple of Israelis in a moving van were arrested in May 2002 for suspicious behavior. Bomb-sniffing dogs reacted as if they had detected explosives, later confirmed in the laboratory as traces of RDX on both the steering wheel and the clothing of the occupants.
http://www.foxnews.com/story/0,2933,52681,00.html
The Israelis were subsequently cleared because the canines and the laboratory had been confused by ...
... cigarette lighter residue - !!!!!
http://seattlepi.nwsource.com/local/70305_explosives14.shtml
1) Do you believe it?
2) How might cigarette lighter residue impede the discovery of explosive residues at ground zero?
Your ignorance is showing.
Seriously, it's time for a reality check.
Just need to get my post organized first (In other words, don't bother replying yet).
Trippy:
Won't don't you organize your post before you post it?
Are you simply marking territory, or "is your ignorance showing"?
addendum - some questions for Fonze:
===================================================
1) What is the function of the sulphur in thermate?
2) At what temperature will iron and sulphur combine to form iron-sulphide?
3) At what temperature will sulphur dissolve in a low-carbon steel? (say, 0.2%)
4) At what temperature will iron-sulphide dissolve in the same steel?
====================================================
cheers.
Won't don't you organize your post before you post it?
Are you simply marking territory, or "is your ignorance showing"?
addendum - some questions for Fonze:
===================================================
1) What is the function of the sulphur in thermate?
2) At what temperature will iron and sulphur combine to form iron-sulphide?
3) At what temperature will sulphur dissolve in a low-carbon steel? (say, 0.2%)
4) At what temperature will iron-sulphide dissolve in the same steel?
====================================================
cheers.
QUOTE
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
OK, take an acoustic guitar, remove all but one string. With that one string taut, cut it with a wire cutter.
BANG!
The concrete in the floors was 4inches thick, and covered an area 208feet x 208feet. It was 600x thinner than it was wide, about the same as a playing card. That's a diaphragm, thinner than the wood in an acoustic guitar.
A few pages back someone posted the detonation speed for C-4. It was in fractions of a microsecond/cm, IIRC. So multiply the major dimension of a block of C-4 by that detonation rate and you'll have the amount of time it takes for that block of C-4 to turn into a puff of hot gas. Nothing happens to it after it detonates, other than the hot gas expanding in all directions at the speed of sound (just above, actually, but the difference is moot after a few microseconds). On an oscilloscope, that looks like:
_____________|______________
The "complex acoustic waveform" you're looking at with all those recordings are the sounds made by that spike bouncing around inside the environment. That makes it an artifact of the environment, not a characteristic of the explosive.
Learn something and get back to us if you have any further questions.
QUOTE (Al Khwarizmi - step-by-step+Oct 10 2007, 09:18 PM)
Trippy:
Won't don't you organize your post before you post it?
Are you simply marking territory, or "is your ignorance showing"?
Because I like my posts to be logical and coherrent, and normally I do this by typing part of the post and then editing it.
Apparently I took too long to do it this time.
And as far as your comments about marking territory, you know what you can do with them, right?
Your ignorance is showing.
Show me where I claimed to be an explosives expert. Oh wait, that's right, I didn't.
Seriously, it's time for a reality check.
Won't don't you organize your post before you post it?
Are you simply marking territory, or "is your ignorance showing"?
Because I like my posts to be logical and coherrent, and normally I do this by typing part of the post and then editing it.
Apparently I took too long to do it this time.
And as far as your comments about marking territory, you know what you can do with them, right?
Your ignorance is showing.
Show me where I claimed to be an explosives expert. Oh wait, that's right, I didn't.
Seriously, it's time for a reality check.
QUOTE (Al Khwarizmi - step-by-step+Oct 10 2007, 08:10 PM)
Trippy - what does RDX residue smell like, and would you recognize it?
What does HDX residue smell like, and would you recognize it?
What does C4 residue smell like, and would you recognize it?
First off, I can only assume that you mean HBX rather then HDX.
HBX and Composition 4 both contain RDX - that is, they're mixtures of RDX and something else.
RDX is a cyclic trinitro triazine (1,3,5-trinitroperhydro-1,3,5-triazine-1,3,5-trinitro-1,3,5-triazacyclohexane) that's actually very easy to manufacture (no, I'm not going to go into details). C4 and HBX are just RDX mixed with various things. C4 is 90-something percent RDX mixed with a plasticizer and a taggant (more on this later) HBX is a little more complicated, it's RDX and TNT mixed with Aluminium powder, wax, and calcium chloride.
Unless by HDX, you meant HMX (I gather that HDX is another name for HMX) which is related to RDX, except where RDX is a trinitro triazine, HMX is a tetranitro tetrazine (1,3,5,7-tetranitro-1,3,5,7-tetrazocane).
Trivia: HMX stands for High Molecular Weight RDX.
HMX also occurs as a by product in the manufacture of RDX.
As far as distinctive odours go, HMX and RDX by themselves, logical, should produce NOx on detonation, which has a distinctive smell, but that doesn't deal with the taggant. The taggant is deliberitly volatile to make it (and thus the explosives) detectable.
There's a reason why specific tests are carried out, including spectroscopy.
If they had a distinctive smell, over and bove the NOx, and I had the opportunity to smell it, then yes, I imagine that I would recognize it afterwards.
What does HDX residue smell like, and would you recognize it?
What does C4 residue smell like, and would you recognize it?
First off, I can only assume that you mean HBX rather then HDX.
HBX and Composition 4 both contain RDX - that is, they're mixtures of RDX and something else.
RDX is a cyclic trinitro triazine (1,3,5-trinitroperhydro-1,3,5-triazine-1,3,5-trinitro-1,3,5-triazacyclohexane) that's actually very easy to manufacture (no, I'm not going to go into details). C4 and HBX are just RDX mixed with various things. C4 is 90-something percent RDX mixed with a plasticizer and a taggant (more on this later) HBX is a little more complicated, it's RDX and TNT mixed with Aluminium powder, wax, and calcium chloride.
Unless by HDX, you meant HMX (I gather that HDX is another name for HMX) which is related to RDX, except where RDX is a trinitro triazine, HMX is a tetranitro tetrazine (1,3,5,7-tetranitro-1,3,5,7-tetrazocane).
Trivia: HMX stands for High Molecular Weight RDX.
HMX also occurs as a by product in the manufacture of RDX.
As far as distinctive odours go, HMX and RDX by themselves, logical, should produce NOx on detonation, which has a distinctive smell, but that doesn't deal with the taggant. The taggant is deliberitly volatile to make it (and thus the explosives) detectable.
There's a reason why specific tests are carried out, including spectroscopy.
If they had a distinctive smell, over and bove the NOx, and I had the opportunity to smell it, then yes, I imagine that I would recognize it afterwards.
QUOTE (Al Khwarizmi - step-by-step+Oct 10 2007, 08:10 PM)
What does thermite residue smell like, and would you recognize it?
What does thermate residue smell like, and would you recognize it?
What does cordite residue smell like, and would you recognize it?
The residue of thermite is molten iron (or solid iron) if you want to know what Iron smells like...
Thermate contains sulphur, and thus (should) have the distinctive choking odour of SOx.
Cordite has a distinctive odour that most people would describe as being 'Metallic'.
Thanks, Trippy, I appreciate the info.
Actually, though, I don't think people are asserting that the C-4 or whatever was laid-out in a 208foot line (or 208' square sheet), so we'd be talking about lumped-masses of explosives. A ten-cm brick of C-4 would take about 11microseconds to detonate, give or take. After that, it's just a puff of hot gas expanding at the speed of sound.
So take a CD-quality recorder that's sampling at 40kHz, and that corresponds to each sampling interval being 25microseconds. The entire detonation is over, start-to-finish, in less than one sampling interval. You get one number to "characterize" that "complex waveform". It'll be the biggest number that your A/D converter registers, but the waveform is zero before the C-4 detonates. What you get after the initial 11microseconds is what that 11microsecond pulse sounds like when it's bouncing around the interior of the environment. In other words, it's a characteristic of the environment, not of the explosive charge. All the complexities you're talking about got lumped into that one sample interval. Here's what that sample interval looks like in the sound file: 111111111111 (binary).
What you're saying "sounds like an explosion" is what any impulse of sound sounds like when it's bouncing around inside an environment, and that can be caused by any sudden release of mechanical energy coupled to any large/flat surface. The less-massive that surface, the more it'll move in response to a given force, that's why violins are made of thin wood instead of thick lead. Four-inch concrete doesn't sound like a good diaphragm until you realize it's supported exactly the same way that your speaker-cones are supported, at the edge and in the middle, with large areas free-floating in between, and that the concrete is 600x thinner than it is wide. That makes it a loudspeaker for the sudden forces coupled to it from failing structural members, those sudden failures act just like a voice-coil, moving the speaker cone and converting mechanical energy into massive quantities of air moving suddenly in one direction.
That's all explosives do, except they create those gusts of air in 10microseconds or so, faster than your recording equipment can capture or your ears can detect. But the low-end bandwidth of the explosive detonation can sound a lot like a drum getting struck or a garbage can getting kicked. In the audio band, they all sound pretty much the same.
By then, no discernable "BANGS" can be heard, it's just one loud ROAR at that point.
In this thread, many pages back, someone posted a link to a video that had three or four BANGS at the onset of the collapse. The gist of the discussion posted along with the link was that the BANGS heard in the video "proved" that explosives brought down the tower(s). Maybe the audio was faked. It came from a "troother" site.
In this thread, many pages back, someone posted a link to a video that had three or four BANGS at the onset of the collapse. The gist of the discussion posted along with the link was that the BANGS heard in the video "proved" that explosives brought down the tower(s). Maybe the audio was faked. It came from a "troother" site.
The Penn & Teller debunking show contains a clip with damped audio (and a narration on top) that I interpret as a very heavy non-mechanically caused rumble.
In this thread, many pages back, someone posted a link to a video that had three or four BANGS at the onset of the collapse. The gist of the discussion posted along with the link was that the BANGS heard in the video "proved" that explosives brought down the tower(s). Maybe the audio was faked. It came from a "troother" site.
It wouldn't be the first time that 'truthers' have lied about things - for example, there have been several steel structures that have failed as a result of fires, and some of them in less time then on September 11.
Indeed, and I've mentioned that there's a website (someplace) that belonged to an ex fire chief who'd posted a "Lessons Learned" article he'd written, saying that steel truss structures in fires will start making noises when they're about to fail, and that that's the time that you should pull your firemen out. It's such a common occurrance that it isn't even news, you can ask just about any fireman about steel-truss roof fires and how dangerous they are. The WTC construction can be thought of as a stack of steel-truss warehouses, with lightweight concrete poured on the roof as the floor for the next-higher story.
When I have time, I'll go back through the previous pages and find that link with the BANGS in the collapse footage audio. Nobody suggested it was faked audio at the time, so I assumed that all the footage of that tower's collapse had the same BANGs. We'd discussed the source of those BANGs at-length in this thread, so I don't think I'm the only one who got suckered-in, if it was indeed faked audio.
I still would expect floors failing all-at-once to make BANGs audible at street-level. If they didn't make BANGs, then I'd say that the floor supports failed in a zipper-like manner, rather than dropping all at once (like the pallbearers dropping the heavy casket in my example of how things can happen simultaneously without requiring synchronization).
Thanks.
Pages ago, I stated in a reply to poster metamars that I would be willing to undertake such a comparison with any one-dimensional equation he (or others) cared to provide. The Beck equation is such and offers a fairly severe test of the naive Bayes factor method of making such comparisons.
Please do. Though I'm doubtful I'll fully understand the comparison, I think that Beck would. Also, recall that Beck finds some inconsistency in BV, wrt initial assumptions and reasonableness of later values (I don't have time right now to look up the quote). A fairer comparison is over the course of the entire collapse.
Does anybody know what Beck meant by "lines"? I suppose he means column lines.
Intuitively, any realistic one dimensional model is going to have problems fitting observations re the beginning of collapse. I think any such model will work much better after the collapse has progressed to the point where destruction of entire storeys is assured (as opposed to floor panels collapsing, and columns "spearing" opposing blocks and becoming simply entangled and bent. For a mental picture, consider the "famous" chicken wire WTC model. If you disconnect across a horizontal plane, and drop a top block onto its bottom, it will not collapse).
What does thermate residue smell like, and would you recognize it?
What does cordite residue smell like, and would you recognize it?
The residue of thermite is molten iron (or solid iron) if you want to know what Iron smells like...
Thermate contains sulphur, and thus (should) have the distinctive choking odour of SOx.
Cordite has a distinctive odour that most people would describe as being 'Metallic'.
QUOTE (Al Khwarizmi - step-by-step+Oct 10 2007, 08:10 PM)
A couple of Israelis in a moving van were arrested in May 2002 for suspicious behavior. Bomb-sniffing dogs reacted as if they had detected explosives, later confirmed in the laboratory as traces of RDX on both the steering wheel and the clothing of the occupants.
http://www.foxnews.com/story/0,2933,52681,00.html
The Israelis were subsequently cleared because the canines and the laboratory had been confused by ...
... cigarette lighter residue - !!!!!
http://seattlepi.nwsource.com/local/70305_explosives14.shtml
1) Do you believe it?
2) How might cigarette lighter residue impede the discovery of explosive residues at ground zero?
I find it potentialy believable, and understandable - (one of) the taggant(s) used in RDX/HMX is a Butane derivative, and lighter fluid is, after all, Butane. As far as any impedence goes, your own article tends to disagree with you.
In order for one thing to impede another, it supplies/forces a false negative result.
This article is an example of a false positive positive result.
So the only influence it would seem that your conjecture would have on the presence of RDX/HMX explosives, is for people to think they were present when there was in fact none present.
http://www.foxnews.com/story/0,2933,52681,00.html
The Israelis were subsequently cleared because the canines and the laboratory had been confused by ...
... cigarette lighter residue - !!!!!
http://seattlepi.nwsource.com/local/70305_explosives14.shtml
1) Do you believe it?
2) How might cigarette lighter residue impede the discovery of explosive residues at ground zero?
I find it potentialy believable, and understandable - (one of) the taggant(s) used in RDX/HMX is a Butane derivative, and lighter fluid is, after all, Butane. As far as any impedence goes, your own article tends to disagree with you.
In order for one thing to impede another, it supplies/forces a false negative result.
This article is an example of a false positive positive result.
So the only influence it would seem that your conjecture would have on the presence of RDX/HMX explosives, is for people to think they were present when there was in fact none present.
QUOTE (Trippy+Oct 5 2007, 07:08 AM)
So, we have that something (essentially) flexible landed on something else, and that this process was asymetric, proceeding from south to north, the distance covered is (essentially) 208 feet, and the time it took to do this was 146 ms (provided by DBB).
Now, PETN has a detonation velocity of 8.28 (±0.1) mm/μs (J.J *** et al, Journal of Applied Physics, July 1, 2000).
That means that it would take 525 ms for PETN to detonate along a 208 foot length.
Compare this to the 146 ms it took for the collapse to proceed along the same horizontal distance.
Still wonder why it sounded like a detonation?
WCElliot: It was me, here's the original post.
Additionaly:
HMX has a detonation velocity of 9.1 mm/μs and RDX has a detonation velocity of 8.75 mm/μs.
So it would take HMX 477 ms to detonate along a 208 foot length, and RDX 496 ms to detonate along a 208 foot length.
Again, compare this to the 146 ms it took for the collapse to cover the same horizontal distance.
It would be expected, based on this data alone that the collapses would sound like explosions - after all, that's 12 acre-feet of air that has to be expelled, and it's (probably) going to be moving preferentialy in one direction.
So the collapse is producing a much sharper shockwave then HMX, RDX, PETN, TNT, Nitroglycerine, or Acetone Peroxide are capable of producing.
As far as C4 or HBX goes, the addition of impurties (Plasticizers, taggants, etc) into an explosive mixture slows the detonation velocity. This is one of the reasons we sometimes add boosters such as PETN or aluminium powder.
Now, PETN has a detonation velocity of 8.28 (±0.1) mm/μs (J.J *** et al, Journal of Applied Physics, July 1, 2000).
That means that it would take 525 ms for PETN to detonate along a 208 foot length.
Compare this to the 146 ms it took for the collapse to proceed along the same horizontal distance.
Still wonder why it sounded like a detonation?
WCElliot: It was me, here's the original post.
Additionaly:
HMX has a detonation velocity of 9.1 mm/μs and RDX has a detonation velocity of 8.75 mm/μs.
So it would take HMX 477 ms to detonate along a 208 foot length, and RDX 496 ms to detonate along a 208 foot length.
Again, compare this to the 146 ms it took for the collapse to cover the same horizontal distance.
It would be expected, based on this data alone that the collapses would sound like explosions - after all, that's 12 acre-feet of air that has to be expelled, and it's (probably) going to be moving preferentialy in one direction.
So the collapse is producing a much sharper shockwave then HMX, RDX, PETN, TNT, Nitroglycerine, or Acetone Peroxide are capable of producing.
As far as C4 or HBX goes, the addition of impurties (Plasticizers, taggants, etc) into an explosive mixture slows the detonation velocity. This is one of the reasons we sometimes add boosters such as PETN or aluminium powder.
Thanks Trippy, I didn't know that Jimmy Walter was a fruitcake, how could he be a millionaire ? But did you notice this sample from it
http://www.youtube.com/watch?v=WH_iBZEHEdE
http://www.youtube.com/watch?v=WH_iBZEHEdE
About nr 7 :
Fact is that nobody could be sure it was going to collapse and when,or remain standing. The fire department was not going to do an attempt to fight the fire anyway after the terrible collapses of the Twin towers. I believe the smallest risk was enough for the chiefs to not send their men in .
The fact the firefighters weren't going to fight the fire doesn't mean they expected the building to collapse for sure , without leaving open any other options . What were the options after the decision to stop fighting the fires?
-Bringing it down with explosives was an option ,because it was possible to place explosives in the basement for example and because of the reasons I mentioned in an other post.
-Just evacuate the area and do nothing with the building , just led the fires spread
and wait for a possible uncontrolled collapse.
The fire department commander didn't call the buildings owner just to say he pulled out his men ( which is a standard procedure). The buildings owner wants to know wat happens with the building, so he informed him on the decisions they made. "ma by the smartest thing to do is to pull it " because if we don't we will face a possible inferno or the building collapsing outside its footprint !!
The WTC 7 must have been a real pain in the *** that day .
Fact is that nobody could be sure it was going to collapse and when,or remain standing. The fire department was not going to do an attempt to fight the fire anyway after the terrible collapses of the Twin towers. I believe the smallest risk was enough for the chiefs to not send their men in .
The fact the firefighters weren't going to fight the fire doesn't mean they expected the building to collapse for sure , without leaving open any other options . What were the options after the decision to stop fighting the fires?
-Bringing it down with explosives was an option ,because it was possible to place explosives in the basement for example and because of the reasons I mentioned in an other post.
-Just evacuate the area and do nothing with the building , just led the fires spread
and wait for a possible uncontrolled collapse.
The fire department commander didn't call the buildings owner just to say he pulled out his men ( which is a standard procedure). The buildings owner wants to know wat happens with the building, so he informed him on the decisions they made. "ma by the smartest thing to do is to pull it " because if we don't we will face a possible inferno or the building collapsing outside its footprint !!
The WTC 7 must have been a real pain in the *** that day .
QUOTE (einsteen+Oct 10 2007, 07:37 AM)
I didn't know that Jimmy Walter was a fruitcake, how could he be a millionaire ?
The most obvious way.
He INHERITED it.
Arthur
The most obvious way.
He INHERITED it.
Arthur
QUOTE (atmosphere+Oct 10 2007, 09:03 AM)
I believe the smallest risk was enough for the chiefs to not send their men in .
But you believe that:
A) People who work for a demolition company would WILLINGLY go into a DAMAGED BURNING UNSTABLE Building, over and over again, carrying det cord and placing high explosives?????
B ) After doing what would be clearly a very HEROIC ACT for the City of NY by people from a PRIVATE COMPANY, they would then participate with the City, the NYPD, the BATF and the FDNY to COVER UP ALL EVIDENCE that they had acted heroicly?
C ) Keep the fact that the City/NYFD/FDNY had placed explosives and blown up WTC 7 hidden from both FEMA and NIST and allow them to spend MILLIONS of dollars trying to figure out how the WTC 7 tower collapsed
Arthur
But you believe that:
A) People who work for a demolition company would WILLINGLY go into a DAMAGED BURNING UNSTABLE Building, over and over again, carrying det cord and placing high explosives?????
B ) After doing what would be clearly a very HEROIC ACT for the City of NY by people from a PRIVATE COMPANY, they would then participate with the City, the NYPD, the BATF and the FDNY to COVER UP ALL EVIDENCE that they had acted heroicly?
C ) Keep the fact that the City/NYFD/FDNY had placed explosives and blown up WTC 7 hidden from both FEMA and NIST and allow them to spend MILLIONS of dollars trying to figure out how the WTC 7 tower collapsed
Arthur
QUOTE (Al Khwarizmi - step-by-step+Oct 10 2007, 03:49 AM)
Why won't you provide a REAL WORLD EXAMPLE of a "catastrophic brittle failure," or "something heavy falling on the floor from above,"
so that we may compare the three?
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
No concrete involved, but then none need be.
The fact is a sudden failure of an object under great strain, however that condition is arrived at may sound like an EXPLOSION.
This is the sound of a wing on a 777 being put under an increasing load until it fails explosively:
http://www.youtube.com/watch?v=6Uo0C01Fwb8
So Al, how come a BUNCH of Audio Engineers have not come forward to support your view that the NOISES recorded that day HAD to have come from explosives?
Arthur
so that we may compare the three?
Can you reference a real world example of sound produced by "a sudden release of mechanical energy coupled to a large (reinforced concrete) diaphram"?
No concrete involved, but then none need be.
The fact is a sudden failure of an object under great strain, however that condition is arrived at may sound like an EXPLOSION.
This is the sound of a wing on a 777 being put under an increasing load until it fails explosively:
http://www.youtube.com/watch?v=6Uo0C01Fwb8
So Al, how come a BUNCH of Audio Engineers have not come forward to support your view that the NOISES recorded that day HAD to have come from explosives?
Arthur
QUOTE
WCElliot: It was me, here's the original post.
Additionaly:
HMX has a detonation velocity of 9.1 mm/μs and RDX has a detonation velocity of 8.75 mm/μs.
So it would take HMX 477 ms to detonate along a 208 foot length, and RDX 496 ms to detonate along a 208 foot length.
Additionaly:
HMX has a detonation velocity of 9.1 mm/μs and RDX has a detonation velocity of 8.75 mm/μs.
So it would take HMX 477 ms to detonate along a 208 foot length, and RDX 496 ms to detonate along a 208 foot length.
Thanks, Trippy, I appreciate the info.
Actually, though, I don't think people are asserting that the C-4 or whatever was laid-out in a 208foot line (or 208' square sheet), so we'd be talking about lumped-masses of explosives. A ten-cm brick of C-4 would take about 11microseconds to detonate, give or take. After that, it's just a puff of hot gas expanding at the speed of sound.
So take a CD-quality recorder that's sampling at 40kHz, and that corresponds to each sampling interval being 25microseconds. The entire detonation is over, start-to-finish, in less than one sampling interval. You get one number to "characterize" that "complex waveform". It'll be the biggest number that your A/D converter registers, but the waveform is zero before the C-4 detonates. What you get after the initial 11microseconds is what that 11microsecond pulse sounds like when it's bouncing around the interior of the environment. In other words, it's a characteristic of the environment, not of the explosive charge. All the complexities you're talking about got lumped into that one sample interval. Here's what that sample interval looks like in the sound file: 111111111111 (binary).
What you're saying "sounds like an explosion" is what any impulse of sound sounds like when it's bouncing around inside an environment, and that can be caused by any sudden release of mechanical energy coupled to any large/flat surface. The less-massive that surface, the more it'll move in response to a given force, that's why violins are made of thin wood instead of thick lead. Four-inch concrete doesn't sound like a good diaphragm until you realize it's supported exactly the same way that your speaker-cones are supported, at the edge and in the middle, with large areas free-floating in between, and that the concrete is 600x thinner than it is wide. That makes it a loudspeaker for the sudden forces coupled to it from failing structural members, those sudden failures act just like a voice-coil, moving the speaker cone and converting mechanical energy into massive quantities of air moving suddenly in one direction.
That's all explosives do, except they create those gusts of air in 10microseconds or so, faster than your recording equipment can capture or your ears can detect. But the low-end bandwidth of the explosive detonation can sound a lot like a drum getting struck or a garbage can getting kicked. In the audio band, they all sound pretty much the same.
Al Khwarizmi - step-by-step
Couple of questions for you.
If shaped charges were used, where are all the channels???
If explosives are used, where are all the blasting caps and wires??? Det cord remains??? Detonators???
If thermite/thermate were used, how were the VERTICAL beams cut(Thermite/thermate ONLY cuts in a vertical direction, IE straight down).
How were ALL signs of explosives hidden from the ATF, FBI and explosives sniffing dogs, perfume???
Why was not a single explosives cut beam found anywhere in the WTC complex???
I have a very simple explanation...NO EXPLOSIVES WERE USED(OR NEEDED) TO EXPLAIN THE TOWERS COLLAPSE.
Grumpy
Couple of questions for you.
If shaped charges were used, where are all the channels???
If explosives are used, where are all the blasting caps and wires??? Det cord remains??? Detonators???
If thermite/thermate were used, how were the VERTICAL beams cut(Thermite/thermate ONLY cuts in a vertical direction, IE straight down).
How were ALL signs of explosives hidden from the ATF, FBI and explosives sniffing dogs, perfume???
Why was not a single explosives cut beam found anywhere in the WTC complex???
I have a very simple explanation...NO EXPLOSIVES WERE USED(OR NEEDED) TO EXPLAIN THE TOWERS COLLAPSE.
Grumpy
QUOTE (einsteen+Oct 11 2007, 12:37 AM)
Thanks Trippy, I didn't know that Jimmy Walter was a fruitcake, how could he be a millionaire ? But did you notice this sample from it
http://www.youtube.com/watch?v=WH_iBZEHEdE
You don't have to be sane to be rich.
http://www.youtube.com/watch?v=WH_iBZEHEdE
You don't have to be sane to be rich.
QUOTE (wcelliott+Oct 11 2007, 03:49 AM)
Thanks, Trippy, I appreciate the info.
Actually, though, I don't think people are asserting that the C-4 or whatever was laid-out in a 208foot line (or 208' square sheet), so we'd be talking about lumped-masses of explosives. A ten-cm brick of C-4 would take about 11microseconds to detonate, give or take. After that, it's just a puff of hot gas expanding at the speed of sound.
That wasn't the point I was making.
The point that I was making was we know that it took 146ms for each floor to be compressed.
We also know (or suspect) that the collapse wasn't a symmetric process - I made the analogy of a falling wedge.
The point that I was making was that the collapse front was propagating across the floors faster then the speed at which a detonation propagates through High Explosives.
In other words - the collapse front covered the 208 feet of each floor faster then the detonation in various forms of high explosive could have, and backing my assertions up with facts and figures.
Actually, though, I don't think people are asserting that the C-4 or whatever was laid-out in a 208foot line (or 208' square sheet), so we'd be talking about lumped-masses of explosives. A ten-cm brick of C-4 would take about 11microseconds to detonate, give or take. After that, it's just a puff of hot gas expanding at the speed of sound.
That wasn't the point I was making.
The point that I was making was we know that it took 146ms for each floor to be compressed.
We also know (or suspect) that the collapse wasn't a symmetric process - I made the analogy of a falling wedge.
The point that I was making was that the collapse front was propagating across the floors faster then the speed at which a detonation propagates through High Explosives.
In other words - the collapse front covered the 208 feet of each floor faster then the detonation in various forms of high explosive could have, and backing my assertions up with facts and figures.
For WTC 1:
The first floor to be impacted, floor 77, took about 1.2 seconds for the impact to complete, south to north.
By 1.6 seconds into the collapse, the impacted floors were fully crushed in about 1/3 second.
At the time the collapse front speed reached 25 m/s then each floor was crushed in 0.146 seconds.
At the end of crush-down, with the collapse front speed slightly in excess of 50 m/s, the floors were crushed in a mere 70 milliseconds or so.
The first floor to be impacted, floor 77, took about 1.2 seconds for the impact to complete, south to north.
By 1.6 seconds into the collapse, the impacted floors were fully crushed in about 1/3 second.
At the time the collapse front speed reached 25 m/s then each floor was crushed in 0.146 seconds.
At the end of crush-down, with the collapse front speed slightly in excess of 50 m/s, the floors were crushed in a mere 70 milliseconds or so.
QUOTE
At the time the collapse front speed reached 25 m/s then each floor was crushed in 0.146 seconds.
By then, no discernable "BANGS" can be heard, it's just one loud ROAR at that point.
Which would make 25 m/s the average speed, and 146 ms the average time taken (it might seem simplistic, but in general if you work out the graphs, that is what it works out at).
Following up on a previous post for DBB and OneWhiteEye, the video of the WTC1 collapse is in the DVD 'The First 24 Hours". This is the high-resolution, close-up, stable, and nearly straight-on view of the north face of WTC1 as it collapses.
QUOTE (shagster+Oct 10 2007, 02:23 PM)
Following up on a previous post for DBB and OneWhiteEye, the video of the WTC1 collapse is in the DVD 'The First 24 Hours". This is the high-resolution, close-up, stable, and nearly straight-on view of the north face of WTC1 as it collapses.
Wonderful!
Two questions:
(1) Does floor 110, just above the uppermost pair of mechanical floors, have windows?
(2) Is there audio and if so do you hear BANGs near the beginning? If so, how many and how far apart?
Wonderful!
Two questions:
(1) Does floor 110, just above the uppermost pair of mechanical floors, have windows?
(2) Is there audio and if so do you hear BANGs near the beginning? If so, how many and how far apart?
QUOTE (David B. Benson+Oct 10 2007, 09:43 PM)
Wonderful!
Two questions:
(1) Does floor 110, just above the uppermost pair of mechanical floors, have windows?
(2) Is there audio and if so do you hear BANGs near the beginning? If so, how many and how far apart?
I can't tell if there are windows on 110 from that video.
The audio is natural for the WTC1 collapse and the other clips. I don't hear any explosive sounds. A helicopter can be heard along with sirens and a crowd of people reacting as WTC1 collapses.
The First 24 Hours shows the aircraft impact on WTC2, the collapse of WTC2, and the collapse of WTC1 all from stable cameras north of the towers.
The video is good for looking at the tilt angle of WTC2 as it starts to collapse. The camera is steady and the perimeter columns are seen clearly as the tower tilts toward the east. The roof of WTC2 can also be seen moving downward.
This DVD contains the video where the bird flies off a building in the foreground as WTC2 is impacted by the aircraft. Also, three people jump off the west side of WTC1 just after WTC2 is impacted. One appears as a small object (I assume that is a person) followed by two more larger objects (people). The aerodynamic effects of the aircraft striking WTC2 are seen in WTC1 as a brief increase in the flames coming out the windows. That's probably what caused people to jump off WTC1 just after the impact of WTC2.
There's also a person who was waving a white cloth near the window washing machine of WTC1 who seems to have been jolted by the effects of the aircraft striking WTC2. He stops waving the cloth just after the impact.
Two questions:
(1) Does floor 110, just above the uppermost pair of mechanical floors, have windows?
(2) Is there audio and if so do you hear BANGs near the beginning? If so, how many and how far apart?
I can't tell if there are windows on 110 from that video.
The audio is natural for the WTC1 collapse and the other clips. I don't hear any explosive sounds. A helicopter can be heard along with sirens and a crowd of people reacting as WTC1 collapses.
The First 24 Hours shows the aircraft impact on WTC2, the collapse of WTC2, and the collapse of WTC1 all from stable cameras north of the towers.
The video is good for looking at the tilt angle of WTC2 as it starts to collapse. The camera is steady and the perimeter columns are seen clearly as the tower tilts toward the east. The roof of WTC2 can also be seen moving downward.
This DVD contains the video where the bird flies off a building in the foreground as WTC2 is impacted by the aircraft. Also, three people jump off the west side of WTC1 just after WTC2 is impacted. One appears as a small object (I assume that is a person) followed by two more larger objects (people). The aerodynamic effects of the aircraft striking WTC2 are seen in WTC1 as a brief increase in the flames coming out the windows. That's probably what caused people to jump off WTC1 just after the impact of WTC2.
There's also a person who was waving a white cloth near the window washing machine of WTC1 who seems to have been jolted by the effects of the aircraft striking WTC2. He stops waving the cloth just after the impact.
The First 24 Hours is an excellent video. It's all raw video, high quality, and natural audio. No special effects and no narration. There are a few clips where WTC7 can be seen burning. Most of the video on the DVD is of ground zero.
QUOTE (shagster+Oct 10 2007, 04:42 PM)
I don't hear any explosive sounds.
Thank you.
Thank you.
QUOTE
QUOTE (shagster @ Oct 10 2007, 04:42 PM)
I don't hear any explosive sounds.
Thank you.
I don't hear any explosive sounds.
Thank you.
In this thread, many pages back, someone posted a link to a video that had three or four BANGS at the onset of the collapse. The gist of the discussion posted along with the link was that the BANGS heard in the video "proved" that explosives brought down the tower(s). Maybe the audio was faked. It came from a "troother" site.
For those interested in explosions, here's an explosive event in the rubble at ground zero. There's a loud bang accompanied by a bright flash. Not clear what caused this. There were many materials burning in the rubble. This clip is from the DVD 'The First 24 Hours'.
http://s134.photobucket.com/albums/q91/sha...=wtcexplos2.flv
http://s134.photobucket.com/albums/q91/sha...=wtcexplos2.flv
QUOTE (shagster+Oct 10 2007, 09:23 PM)
Following up on a previous post for DBB and OneWhiteEye, the video of the WTC1 collapse is in the DVD 'The First 24 Hours". This is the high-resolution, close-up, stable, and nearly straight-on view of the north face of WTC1 as it collapses.
Thank you. I'm going to get that one and the Naudet video, at least. Soon.
Thank you. I'm going to get that one and the Naudet video, at least. Soon.
QUOTE (wcelliott+Oct 11 2007, 12:12 AM)
In this thread, many pages back, someone posted a link to a video that had three or four BANGS at the onset of the collapse. The gist of the discussion posted along with the link was that the BANGS heard in the video "proved" that explosives brought down the tower(s). Maybe the audio was faked. It came from a "troother" site.
The Penn & Teller debunking show contains a clip with damped audio (and a narration on top) that I interpret as a very heavy non-mechanically caused rumble.
QUOTE (wcelliott+Oct 11 2007, 01:12 PM)
In this thread, many pages back, someone posted a link to a video that had three or four BANGS at the onset of the collapse. The gist of the discussion posted along with the link was that the BANGS heard in the video "proved" that explosives brought down the tower(s). Maybe the audio was faked. It came from a "troother" site.
It wouldn't be the first time that 'truthers' have lied about things - for example, there have been several steel structures that have failed as a result of fires, and some of them in less time then on September 11.
QUOTE
there have been several steel structures that have failed as a result of fires,
Indeed, and I've mentioned that there's a website (someplace) that belonged to an ex fire chief who'd posted a "Lessons Learned" article he'd written, saying that steel truss structures in fires will start making noises when they're about to fail, and that that's the time that you should pull your firemen out. It's such a common occurrance that it isn't even news, you can ask just about any fireman about steel-truss roof fires and how dangerous they are. The WTC construction can be thought of as a stack of steel-truss warehouses, with lightweight concrete poured on the roof as the floor for the next-higher story.
When I have time, I'll go back through the previous pages and find that link with the BANGS in the collapse footage audio. Nobody suggested it was faked audio at the time, so I assumed that all the footage of that tower's collapse had the same BANGs. We'd discussed the source of those BANGs at-length in this thread, so I don't think I'm the only one who got suckered-in, if it was indeed faked audio.
I still would expect floors failing all-at-once to make BANGs audible at street-level. If they didn't make BANGs, then I'd say that the floor supports failed in a zipper-like manner, rather than dropping all at once (like the pallbearers dropping the heavy casket in my example of how things can happen simultaneously without requiring synchronization).
Thanks.
QUOTE (wcelliott+Oct 12 2007, 09:15 AM)
Indeed, and I've mentioned that there's a website (someplace) that belonged to an ex fire chief who'd posted a "Lessons Learned" article he'd written, saying that steel truss structures in fires will start making noises when they're about to fail, and that that's the time that you should pull your firemen out. It's such a common occurrance that it isn't even news, you can ask just about any fireman about steel-truss roof fires and how dangerous they are. The WTC construction can be thought of as a stack of steel-truss warehouses, with lightweight concrete poured on the roof as the floor for the next-higher story.
Yeah, I've heard the same thing about steel truss structures for floors/roofs in fires,a nd I'm pretty sure that I've mentioned it in this trhead several times as well (as I imagine that you have). But it's something that the CDiots continue to ignore.
I know that there was an interstate in the US that failed in... I think it was 2005, and it collapsed exclusively due to fire, and I think there was a sky scraper, that was under construction in madrid in '97 that caught fire. The steel only part of the structure collapsed exclusively as a reuslt of the fire, but the conmcrete reinforced sections remained standing.
Yeah, I've heard the same thing about steel truss structures for floors/roofs in fires,a nd I'm pretty sure that I've mentioned it in this trhead several times as well (as I imagine that you have). But it's something that the CDiots continue to ignore.
I know that there was an interstate in the US that failed in... I think it was 2005, and it collapsed exclusively due to fire, and I think there was a sky scraper, that was under construction in madrid in '97 that caught fire. The steel only part of the structure collapsed exclusively as a reuslt of the fire, but the conmcrete reinforced sections remained standing.
Here is a link to a .pdf file by Charles M. Beck which is full of mistakes, at least in the interpretation of the structure of the towers:
Mathematical Models of Progressive Collapse and the Question of How Did the World Trade Centers Perish
How many of the mistakes can you find?
Mathematical Models of Progressive Collapse and the Question of How Did the World Trade Centers Perish
How many of the mistakes can you find?
DBB:
Well, I do see that Charles Beck is pushing Gordon Ross' argument about compression waves extending down "the full length of the column", meaning the height of the building vs. a single storey height. (See page 11, Section 2 (entitled: Rigidity assumption), of his paper)
Actually I think a "stressed column" distance closer to about six stories might be a more realistic compomise, in which case the kinetic energy available from the collapse of 15 floors through a distance of one floor easily overwhelms the elastic strain capacity of six floors-worth of structural steel.
Well, I do see that Charles Beck is pushing Gordon Ross' argument about compression waves extending down "the full length of the column", meaning the height of the building vs. a single storey height. (See page 11, Section 2 (entitled: Rigidity assumption), of his paper)
Actually I think a "stressed column" distance closer to about six stories might be a more realistic compomise, in which case the kinetic energy available from the collapse of 15 floors through a distance of one floor easily overwhelms the elastic strain capacity of six floors-worth of structural steel.
QUOTE (NEU-FONZE+Oct 11 2007, 04:42 PM)
... compression waves extending down "the full length of the column" ...
I completely demolished this in several previous posts on this thread:
Elastic compression available over the entire height, top to lowest sub-basement: 0.877 m.
Of this, about 1/3 occurred via the so-called construction sequence, the mass above compressing the core columns.
With the top block tilted only 1 degree of arc (WTC 1), another 0.55 m compression had occurred. So the structure was almost up to the elastic yield limit at collapse initiation.
But the paper has even worse problems. Beck fails to take any account of the tilt, which is important in the destruction of the connections in the core.
I haven't reread the paper yet, but I suspect there is another problem related to his assumptions about the exterior wall failures.
If he had simply read NCSTAR1--2A, B, etc. most of his misconceptions about the strengths of materials and the actual failure modes would not appear. Looks like sloppy research to me.
I completely demolished this in several previous posts on this thread:
Elastic compression available over the entire height, top to lowest sub-basement: 0.877 m.
Of this, about 1/3 occurred via the so-called construction sequence, the mass above compressing the core columns.
With the top block tilted only 1 degree of arc (WTC 1), another 0.55 m compression had occurred. So the structure was almost up to the elastic yield limit at collapse initiation.
But the paper has even worse problems. Beck fails to take any account of the tilt, which is important in the destruction of the connections in the core.
I haven't reread the paper yet, but I suspect there is another problem related to his assumptions about the exterior wall failures.
If he had simply read NCSTAR1--2A, B, etc. most of his misconceptions about the strengths of materials and the actual failure modes would not appear. Looks like sloppy research to me.
QUOTE (David B. Benson+Oct 11 2007, 12:00 AM)
Thank you.
Check out the Naudet DVD. Naudet was on the NW side of WTC1 just north of the pedestrian bridge when the collapse started. You can hear the rumble from start to finish. It looks like he was at the intersection of West. St. and Vesey St. and ran west down Vesey when the collapse started. He took shelter near the front bumper of a CBS news truck.
Check out the Naudet DVD. Naudet was on the NW side of WTC1 just north of the pedestrian bridge when the collapse started. You can hear the rumble from start to finish. It looks like he was at the intersection of West. St. and Vesey St. and ran west down Vesey when the collapse started. He took shelter near the front bumper of a CBS news truck.
QUOTE (NEU-FONZE+Oct 11 2007, 11:42 PM)
DBB:
Well, I do see that Charles Beck is pushing Gordon Ross' argument about compression waves extending down "the full length of the column", meaning the height of the building vs. a single storey height. (See page 11, Section 2 (entitled: Rigidity assumption), of his paper)
Actually I think a "stressed column" distance closer to about six stories might be a more realistic compomise, in which case the kinetic energy available from the collapse of 15 floors through a distance of one floor easily overwhelms the elastic strain capacity of six floors-worth of structural steel.
Newtons Bit who is at JREF thinks that the strength of the stories increases when you go to the bottom. This means in fact that the E1s become larger when we go to the bottom and has a value of about 400 MJ at story 15. The reason he came with that is that since in a uniform structure the weakest story will fail first. I agree with him that is a good idea, but there are some problems with it
- It does not explain why crush-down happenes first and then crush-up
- It does not explain why in a conventional from-the-bottom demolition (with no charges on higher levels) the strongest bottom stories crush first (thanks to Arthur who came with that example), although I don't believe that is physically correct
I think the layer model is really needed, i.e. this must happen
http://i24.tinypic.com/2uztni1.gif
i.e. a crush-down with a small crush-up, but the latter can be ignored and the block model is a good 1st order approach.
In my humble opinion after collapse initiation a small amount of strain energy is released because the block is in fact detached from the building during that fall. Now when it hits floor 96 the whole structure provides a resisting force that can completely be determined by the 2g/3 acceleration. But then when we take the new block 14+1 floors into account it is the resisting force of the structure without that story. It is wrong to threat them as independent entities, because they arent, they are coupled.
Well, I do see that Charles Beck is pushing Gordon Ross' argument about compression waves extending down "the full length of the column", meaning the height of the building vs. a single storey height. (See page 11, Section 2 (entitled: Rigidity assumption), of his paper)
Actually I think a "stressed column" distance closer to about six stories might be a more realistic compomise, in which case the kinetic energy available from the collapse of 15 floors through a distance of one floor easily overwhelms the elastic strain capacity of six floors-worth of structural steel.
Newtons Bit who is at JREF thinks that the strength of the stories increases when you go to the bottom. This means in fact that the E1s become larger when we go to the bottom and has a value of about 400 MJ at story 15. The reason he came with that is that since in a uniform structure the weakest story will fail first. I agree with him that is a good idea, but there are some problems with it
- It does not explain why crush-down happenes first and then crush-up
- It does not explain why in a conventional from-the-bottom demolition (with no charges on higher levels) the strongest bottom stories crush first (thanks to Arthur who came with that example), although I don't believe that is physically correct
I think the layer model is really needed, i.e. this must happen
http://i24.tinypic.com/2uztni1.gif
i.e. a crush-down with a small crush-up, but the latter can be ignored and the block model is a good 1st order approach.
In my humble opinion after collapse initiation a small amount of strain energy is released because the block is in fact detached from the building during that fall. Now when it hits floor 96 the whole structure provides a resisting force that can completely be determined by the 2g/3 acceleration. But then when we take the new block 14+1 floors into account it is the resisting force of the structure without that story. It is wrong to threat them as independent entities, because they arent, they are coupled.
einsteen
While it is true that the strength of the core columns and outer frame members DOES increase the lower the floor, the floors themselves were basically identical in the strength of the connections to those stronger beams. Also, the load those beams were carrying means that the RESERVE(or remainder after subtracting the static load) was basically the same at each height above ground. Since the total resistence each floor could exert was determined by the strength of it's connections to the frame, and since those connections were nearly identical for all floors, the resistive force was also nearly identical for all floors, the increasing strength of the frames was also limited by the floor connections.
Grumpy
While it is true that the strength of the core columns and outer frame members DOES increase the lower the floor, the floors themselves were basically identical in the strength of the connections to those stronger beams. Also, the load those beams were carrying means that the RESERVE(or remainder after subtracting the static load) was basically the same at each height above ground. Since the total resistence each floor could exert was determined by the strength of it's connections to the frame, and since those connections were nearly identical for all floors, the resistive force was also nearly identical for all floors, the increasing strength of the frames was also limited by the floor connections.
Grumpy
QUOTE (David B. Benson+Oct 11 2007, 02:04 PM)
Mathematical Models of Progressive Collapse and the Question of How Did the World Trade Centers Perish
And there is a quite careless mistake regarding the B & V crush-down equation. What happens is that Beck's non-dimensionalization differs by sqrt(2) from that of B & V. Beck ignores this and goes off to rant about aspects of B & V which do not exist and then states that because of those he'll just ignore the B & V crush-down equation.
However, once I resolve the differences in non-dimensionalization (and have the time), Beck's equation provides a fine opportunity to compare the two hypotheses against the measured drops and determine how much better one hypothesis is at explaining the data than the other.
Pages ago, I stated in a reply to poster metamars that I would be willing to undertake such a comparison with any one-dimensional equation he (or others) cared to provide. The Beck equation is such and offers a fairly severe test of the naive Bayes factor method of making such comparisons.
And there is a quite careless mistake regarding the B & V crush-down equation. What happens is that Beck's non-dimensionalization differs by sqrt(2) from that of B & V. Beck ignores this and goes off to rant about aspects of B & V which do not exist and then states that because of those he'll just ignore the B & V crush-down equation.
However, once I resolve the differences in non-dimensionalization (and have the time), Beck's equation provides a fine opportunity to compare the two hypotheses against the measured drops and determine how much better one hypothesis is at explaining the data than the other.
Pages ago, I stated in a reply to poster metamars that I would be willing to undertake such a comparison with any one-dimensional equation he (or others) cared to provide. The Beck equation is such and offers a fairly severe test of the naive Bayes factor method of making such comparisons.
I think this data came from the LERA plans zip file that's been floating around the web. The txt file was dated 16-aug-2002.
PRIVILEGED AND CONFIDENTIAL - ATTORNEY WORK PRODUCT
FLOOR HEIGHTS FOR TOWERS A AND B
================================
REFERENCES: CD ARCH (020220_1611) /DRAWINGS/LERA-PLANS-021802/PAC3 TOWERS A&B
DRAWING NO = A-AB-201, FILES = A-AB-201.TIF, A-AB-201tif.TIF
DRAWING NO = A-AB-301, FILE = A-AB-301.TIF
TOWER A TOWER B
FLOOR HEIGHT HEIGHT
===== ======= =======
sub-level no 5 11' 0" 11' 0"
sub-level no 4 11' 0" 11' 0"
sub-level no 3 10' 0" 10' 0"
sub-level no 2 10' 0" 10' 0"
sub-level no 1 10' 0" 10' 0"
service level 16' 0" 16' 0"
1-concourse 22' 0" 22' 0"
2-plaza 12' 0" 12' 0"
3-storage 11' 6" 11' 6"
4-storage 11' 6" 11' 6"
5-storage 11' 6" 11' 6"
6-storage 11' 6" 11' 6"
7-lower mechanical 14' 0" 14' 0"
8-upper mechanical 10' 0" 10' 0"
9-typical 12' 0" 12' 0"
10 12' 0" 12' 0"
11 12' 0" 12' 0"
12 12' 0" 12' 0"
13 12' 0" 12' 0"
14 12' 0" 12' 0"
15 12' 0" 12' 0"
16 12' 0" 12' 0"
17 12' 0" 12' 0"
18 12' 0" 12' 0"
19 12' 0" 12' 0"
20 12' 0" 12' 0"
21 12' 0" 12' 0"
22 12' 0" 12' 0"
23 12' 0" 12' 0"
24 12' 0" 12' 0"
25 12' 0" 12' 0"
26 12' 0" 12' 0"
27 12' 0" 12' 0"
28 12' 0" 12' 0"
29 12' 0" 12' 0"
30 12' 0" 12' 0"
31 12' 0" 12' 0"
32 12' 0" 12' 0"
33 12' 0" 12' 0"
34 12' 0" 12' 0"
35 12' 0" 12' 0"
36 12' 0" 12' 0"
37 12' 0" 12' 0"
38 12' 0" 12' 0"
39 12' 0" 12' 0"
40 14' 0" 14' 0"
41 lower mechanical 14' 0" 14' 0"
42 upper mechanical 14' 0" 14' 0"
43 lower esc floor 14' 0" 12' 0"
44 sky lobby 14' 0" 14' 0"
45 upper esc floor 12' 0" 12' 0"
46 typical 12' 0" 12' 0"
47 12' 0" 12' 0"
48 12' 0" 12' 0"
49 12' 0" 12' 0"
50 12' 0" 12' 0"
51 12' 0" 12' 0"
52 12' 0" 12' 0"
53 12' 0" 12' 0"
54 12' 0" 12' 0"
55 12' 0" 12' 0"
56 12' 0" 12' 0"
57 12' 0" 12' 0"
58 12' 0" 12' 0"
59 12' 0" 12' 0"
60 12' 0" 12' 0"
61 12' 0" 12' 0"
62 12' 0" 12' 0"
63 12' 0" 12' 0"
64 12' 0" 12' 0"
65 12' 0" 12' 0"
66 12' 0" 12' 0"
67 16' 0" 12' 0"
68 12' 0" 12' 0"
69 12' 0" 12' 0"
70 12' 0" 12' 0"
71 12' 0" 12' 0"
72 12' 0" 12' 0"
73 12' 0" 12' 0"
74 14' 0" 14' 0"
75 lower mechanical 14' 0" 14' 0"
76 upper mechanical 14' 0" 14' 0"
77 upper esc floor 12' 0" 12' 0"
78 sky lobby 14' 0" 14' 0"
79 upper esc floor 12' 0" 12' 0"
80 typical 12' 0" 12' 0"
81 12' 0" 12' 0"
82 12' 0" 12' 0"
83 12' 0" 12' 0"
84 12' 0" 12' 0"
85 12' 0" 12' 0"
86 12' 0" 12' 0"
87 12' 0" 12' 0"
88 12' 0" 12' 0"
89 12' 0" 12' 0"
90 12' 0" 12' 0"
91 12' 0" 12' 0"
92 12' 0" 12' 0"
93 12' 0" 12' 0"
94 12' 0" 12' 0"
95 12' 0" 12' 0"
96 12' 0" 12' 0"
97 12' 0" 12' 0"
98 12' 0" 12' 0"
99 12' 0" 12' 0"
100 12' 0" 12' 0"
101 12' 0" 12' 0"
102 12' 0" 12' 0"
103 12' 0" 12' 0"
104 12' 0" 12' 0"
105 12' 0" 12' 0"
106 typical 14' 4" 14' 4"
107 restaurant 17' 6" 17' 6"
108 lower mechanical 14' 0" 14' 0"
109 upper mechanical 11' 8" 11' 8"
110 roof to top of roof panels 15' 4" 15' 4"
NOTE: DRAWING NO. A-AB-201 SHOWS THAT TOP OF PENTHOUSE IS HIGHER
THAN 15' 4" DIMENSION GIVEN FOR FLOOR 110.
PRIVILEGED AND CONFIDENTIAL - ATTORNEY WORK PRODUCT
FLOOR HEIGHTS FOR TOWERS A AND B
================================
REFERENCES: CD ARCH (020220_1611) /DRAWINGS/LERA-PLANS-021802/PAC3 TOWERS A&B
DRAWING NO = A-AB-201, FILES = A-AB-201.TIF, A-AB-201tif.TIF
DRAWING NO = A-AB-301, FILE = A-AB-301.TIF
TOWER A TOWER B
FLOOR HEIGHT HEIGHT
===== ======= =======
sub-level no 5 11' 0" 11' 0"
sub-level no 4 11' 0" 11' 0"
sub-level no 3 10' 0" 10' 0"
sub-level no 2 10' 0" 10' 0"
sub-level no 1 10' 0" 10' 0"
service level 16' 0" 16' 0"
1-concourse 22' 0" 22' 0"
2-plaza 12' 0" 12' 0"
3-storage 11' 6" 11' 6"
4-storage 11' 6" 11' 6"
5-storage 11' 6" 11' 6"
6-storage 11' 6" 11' 6"
7-lower mechanical 14' 0" 14' 0"
8-upper mechanical 10' 0" 10' 0"
9-typical 12' 0" 12' 0"
10 12' 0" 12' 0"
11 12' 0" 12' 0"
12 12' 0" 12' 0"
13 12' 0" 12' 0"
14 12' 0" 12' 0"
15 12' 0" 12' 0"
16 12' 0" 12' 0"
17 12' 0" 12' 0"
18 12' 0" 12' 0"
19 12' 0" 12' 0"
20 12' 0" 12' 0"
21 12' 0" 12' 0"
22 12' 0" 12' 0"
23 12' 0" 12' 0"
24 12' 0" 12' 0"
25 12' 0" 12' 0"
26 12' 0" 12' 0"
27 12' 0" 12' 0"
28 12' 0" 12' 0"
29 12' 0" 12' 0"
30 12' 0" 12' 0"
31 12' 0" 12' 0"
32 12' 0" 12' 0"
33 12' 0" 12' 0"
34 12' 0" 12' 0"
35 12' 0" 12' 0"
36 12' 0" 12' 0"
37 12' 0" 12' 0"
38 12' 0" 12' 0"
39 12' 0" 12' 0"
40 14' 0" 14' 0"
41 lower mechanical 14' 0" 14' 0"
42 upper mechanical 14' 0" 14' 0"
43 lower esc floor 14' 0" 12' 0"
44 sky lobby 14' 0" 14' 0"
45 upper esc floor 12' 0" 12' 0"
46 typical 12' 0" 12' 0"
47 12' 0" 12' 0"
48 12' 0" 12' 0"
49 12' 0" 12' 0"
50 12' 0" 12' 0"
51 12' 0" 12' 0"
52 12' 0" 12' 0"
53 12' 0" 12' 0"
54 12' 0" 12' 0"
55 12' 0" 12' 0"
56 12' 0" 12' 0"
57 12' 0" 12' 0"
58 12' 0" 12' 0"
59 12' 0" 12' 0"
60 12' 0" 12' 0"
61 12' 0" 12' 0"
62 12' 0" 12' 0"
63 12' 0" 12' 0"
64 12' 0" 12' 0"
65 12' 0" 12' 0"
66 12' 0" 12' 0"
67 16' 0" 12' 0"
68 12' 0" 12' 0"
69 12' 0" 12' 0"
70 12' 0" 12' 0"
71 12' 0" 12' 0"
72 12' 0" 12' 0"
73 12' 0" 12' 0"
74 14' 0" 14' 0"
75 lower mechanical 14' 0" 14' 0"
76 upper mechanical 14' 0" 14' 0"
77 upper esc floor 12' 0" 12' 0"
78 sky lobby 14' 0" 14' 0"
79 upper esc floor 12' 0" 12' 0"
80 typical 12' 0" 12' 0"
81 12' 0" 12' 0"
82 12' 0" 12' 0"
83 12' 0" 12' 0"
84 12' 0" 12' 0"
85 12' 0" 12' 0"
86 12' 0" 12' 0"
87 12' 0" 12' 0"
88 12' 0" 12' 0"
89 12' 0" 12' 0"
90 12' 0" 12' 0"
91 12' 0" 12' 0"
92 12' 0" 12' 0"
93 12' 0" 12' 0"
94 12' 0" 12' 0"
95 12' 0" 12' 0"
96 12' 0" 12' 0"
97 12' 0" 12' 0"
98 12' 0" 12' 0"
99 12' 0" 12' 0"
100 12' 0" 12' 0"
101 12' 0" 12' 0"
102 12' 0" 12' 0"
103 12' 0" 12' 0"
104 12' 0" 12' 0"
105 12' 0" 12' 0"
106 typical 14' 4" 14' 4"
107 restaurant 17' 6" 17' 6"
108 lower mechanical 14' 0" 14' 0"
109 upper mechanical 11' 8" 11' 8"
110 roof to top of roof panels 15' 4" 15' 4"
NOTE: DRAWING NO. A-AB-201 SHOWS THAT TOP OF PENTHOUSE IS HIGHER
THAN 15' 4" DIMENSION GIVEN FOR FLOOR 110.
That is so excellent. Thank you, shagster.
QUOTE (David B. Benson+Oct 12 2007, 08:51 PM)
Pages ago, I stated in a reply to poster metamars that I would be willing to undertake such a comparison with any one-dimensional equation he (or others) cared to provide. The Beck equation is such and offers a fairly severe test of the naive Bayes factor method of making such comparisons.
Please do. Though I'm doubtful I'll fully understand the comparison, I think that Beck would. Also, recall that Beck finds some inconsistency in BV, wrt initial assumptions and reasonableness of later values (I don't have time right now to look up the quote). A fairer comparison is over the course of the entire collapse.
Does anybody know what Beck meant by "lines"? I suppose he means column lines.
Intuitively, any realistic one dimensional model is going to have problems fitting observations re the beginning of collapse. I think any such model will work much better after the collapse has progressed to the point where destruction of entire storeys is assured (as opposed to floor panels collapsing, and columns "spearing" opposing blocks and becoming simply entangled and bent. For a mental picture, consider the "famous" chicken wire WTC model. If you disconnect across a horizontal plane, and drop a top block onto its bottom, it will not collapse).
Arthur:
===============
"your view that the (explosion) NOISES recorded that day HAD to have come from explosives"
===============
I wish you luck in finding my claim to that effect when you quote me.
"Noise" in acoustic parlance, btw, refers to the simutaneous production of all frequencies in the audible spectrum at the same time. It is analogous to that mess of all visible freqencies we call "white."
wcelliot:
============
OK, take an acoustic guitar, remove all but one string. With that one string taut, cut it with a wire cutter.
BANG!
=============
My steel-string acoustic doesn't produce a sound resembling an explosion on those rare ocassions when a string snaps -- nor does "bang" adequately describe the sound produced when intentionally cutting any string, regardless of how many remain. Not surprisingly, "SNAP!" is a very appropriate description.
I would be astonished if my guitar ever produced a noise similar to a shaped-charge explosive under any circumstances.
Oh - and it is best to replace guitar strings one at a time.
"I heard they had a space program when they sing you can't hear there's no air sometimes I think I kinda like that and other times I think I'm already there."
-- They Might Be Giants.
Did you know that you can't hear an explosion without an atmosphere in which to propogate a cascade of particle collisions?
Did you know that you have thrice argued that an explosion produces a physically impossible sound envelope with attack, sustain and release occuring at the same instant -- a zero duration waveform?
What is the rate of attack in this graph of a classic waveform?
What will this wave sound like when played once at maximum amplitude on an average modern HiFi system?
What will this wave sound like when repeated 100 times per second (100Hz) for several seconds?
===============
"your view that the (explosion) NOISES recorded that day HAD to have come from explosives"
===============
I wish you luck in finding my claim to that effect when you quote me.
"Noise" in acoustic parlance, btw, refers to the simutaneous production of all frequencies in the audible spectrum at the same time. It is analogous to that mess of all visible freqencies we call "white."
wcelliot:
============
OK, take an acoustic guitar, remove all but one string. With that one string taut, cut it with a wire cutter.
BANG!
=============
My steel-string acoustic doesn't produce a sound resembling an explosion on those rare ocassions when a string snaps -- nor does "bang" adequately describe the sound produced when intentionally cutting any string, regardless of how many remain. Not surprisingly, "SNAP!" is a very appropriate description.
I would be astonished if my guitar ever produced a noise similar to a shaped-charge explosive under any circumstances.
Oh - and it is best to replace guitar strings one at a time.
"I heard they had a space program when they sing you can't hear there's no air sometimes I think I kinda like that and other times I think I'm already there."
-- They Might Be Giants.
Did you know that you can't hear an explosion without an atmosphere in which to propogate a cascade of particle collisions?
Did you know that you have thrice argued that an explosion produces a physically impossible sound envelope with attack, sustain and release occuring at the same instant -- a zero duration waveform?
QUOTE
_____________|______________
"Learn something and get back to us if you have any further questions."
"Learn something and get back to us if you have any further questions."
What is the rate of attack in this graph of a classic waveform?
What will this wave sound like when played once at maximum amplitude on an average modern HiFi system?
What will this wave sound like when repeated 100 times per second (100Hz) for several seconds?
QUOTE (Al Khwarizmi - step-by-step+Oct 13 2007, 11:51 AM)
Arthur:
===============
"your view that the (explosion) NOISES recorded that day HAD to have come from explosives"
===============
I wish you luck in finding my claim to that effect when you quote me.
Is this CLOSE ENOUGH?
============
============
You are right!
But there are hundreds of threads of concordant evidence intractably convergent on such a theory:
If not, then what were we to sumise from your CLAIM that there are HUNDREDS OF THREADS OF CONCORDANT EVIDENCE that the sound WAS from explosives.
Here's a clue, Al.
That evidence only exists in your mind and in Wooo Wooo land.
Arthur
That's it????
You think you've put together a CONCLUSIVE LIST that proves demolition?????
ROTFLMAO
(Oh, and Al, I particularly liked your including the Silverstein "Pull it" reference. although it typically is only employed by those with IQs significantly < normal, )
Arthur
Did you know that that "_________|_________" waveform I suggested you synthesize and play on your expensive sound system also has the same spectrum as white noise?
A "snap" is just a small "BANG!", look at its waveform. To scale-up from a guitar string to a structural truss, increase the amplitude and slow-down the playback speed. That sound will become more and more like a BANG!, right before your eyes/ears.
That waveform I suggested, "_______|________", is precisely what you'd get if you recorded an actual explosive going-off in an environment lacking acoustically-reflective surfaces. If you were to hang a C-4 charge from a long string from a hot-air balloon and record it from another balloon at a safe distance. Without the echoes of the environment, the sound is one simple spike. I'm not asserting that it is a "zero-duration" waveform, I'm just pointing out that a 4-inch brick of C-4 detonates in about 10microseconds.
So how long is a sampling interval? If you're sampling at 40kHz, that sampling interval is 25microseconds.
What will the sample be immediately prior to detonation? Zero.
What will it be DURING detonation? MaxVal for your digital word - all ones in binary.
What will it be the next sample after it detonates? Zero again, when there's no reflections/echoes present - The C-4 is already gone, turned into hot gasses expanding in all directions uniformly.
Zero-MaxVal-Zero...
_________|__________
The attack and decay, etc., aren't instantaneous, they're just faster than your recording equipment can resolve, so the whole detonation takes **one sample** to reproduce. The rest is zero, or echoes from that BANG! reflecting off the surfaces in the environment, which, by definition, is **artifact**.
Your recordings of "explosives" aren't recordings of explosives, they're recordings of the reflections of that spike bouncing around the environment. That "complex waveform" isn't the characteristic of the detonation, it's a characteristic of the environment of the explosion. The whole duration of the explosion itself took less than one sampling interval in your digital recording. Do the math, and you'll understand, if you can accept the possibility that you're wrong.
===============
"your view that the (explosion) NOISES recorded that day HAD to have come from explosives"
===============
I wish you luck in finding my claim to that effect when you quote me.
Is this CLOSE ENOUGH?
QUOTE
"There is no proof for explosives."
============
QUOTE (->
| QUOTE |
| "There is no proof for explosives." |
============
You are right!
But there are hundreds of threads of concordant evidence intractably convergent on such a theory:
If not, then what were we to sumise from your CLAIM that there are HUNDREDS OF THREADS OF CONCORDANT EVIDENCE that the sound WAS from explosives.
Here's a clue, Al.
That evidence only exists in your mind and in Wooo Wooo land.
Arthur
Misrepresentative and out-of-context, Arthur:
Let's put those "threads of evidence" for explosive demolition in context:
16 Unusual Orbits
1) pre-collapse metal fire
http://history-bytes.blogspot.com/2006/09/metal-fire.html
2) pre-collapse ejection of a "large piece of debris" at "an extremely high velocity." (NIST)
3) pre-collapse molten metal cascade
http://www.youtube.com/watch?v=P_jiCyMkrRM
4) post-collapse molten metal pools under bldgs 1,2,6, and 7
http://history-bytes.blogspot.com/2006/09/...etal-magic.html
5) persistence of (4)
http://history-bytes.blogspot.com/2006/09/...-migration.html
6) red-hot beams
http://history-bytes.blogspot.com/2006/09/...etal-magic.html
7) almost resistance-free rate of explosive collapse (Sth & Nth twr)
8) resistance-free rate of structural 'implosion' (bldg 7)
9) thick plumes of smoke billowing from both ends of rapidly ejected neatly-cut column sections during collapse
10) visible explosions in Sth twr during collapse of Nth
http://melbourne.indymedia.org/uploads/sth..._cmp_sml_cr.jpg
11) jubilant explosives-tainted men with "maps linking them to the bombing plot" (Bergen Record, Forward, Ha'aretz, NYT, ABC)
http://history-bytes.blogspot.com/2006/10/hot-potatoes.html
12) "we heard and/or felt explosions" - multiple firefighters and first responders
13) "We were told" - Guiliani
14) "high officials just left....as if they had information that we didn't" - Chief Joseph Pfeifer
15) "and we made that decision to pull it" - Lucky Larry
16) fine particle emissions redolent with sulphur exceeding levels registered downwind of the Kuwait oil fires ("it stinks in here")
one incendiary solution at center
QUOTE
If not, then what were we to sumise from your CLAIM that there are HUNDREDS OF THREADS OF CONCORDANT EVIDENCE that the sound WAS from explosives.
Let's put those "threads of evidence" for explosive demolition in context:
16 Unusual Orbits
1) pre-collapse metal fire
http://history-bytes.blogspot.com/2006/09/metal-fire.html
2) pre-collapse ejection of a "large piece of debris" at "an extremely high velocity." (NIST)
3) pre-collapse molten metal cascade
http://www.youtube.com/watch?v=P_jiCyMkrRM
4) post-collapse molten metal pools under bldgs 1,2,6, and 7
http://history-bytes.blogspot.com/2006/09/...etal-magic.html
5) persistence of (4)
http://history-bytes.blogspot.com/2006/09/...-migration.html
6) red-hot beams
http://history-bytes.blogspot.com/2006/09/...etal-magic.html
7) almost resistance-free rate of explosive collapse (Sth & Nth twr)
8) resistance-free rate of structural 'implosion' (bldg 7)
9) thick plumes of smoke billowing from both ends of rapidly ejected neatly-cut column sections during collapse
10) visible explosions in Sth twr during collapse of Nth
http://melbourne.indymedia.org/uploads/sth..._cmp_sml_cr.jpg
11) jubilant explosives-tainted men with "maps linking them to the bombing plot" (Bergen Record, Forward, Ha'aretz, NYT, ABC)
http://history-bytes.blogspot.com/2006/10/hot-potatoes.html
12) "we heard and/or felt explosions" - multiple firefighters and first responders
13) "We were told" - Guiliani
14) "high officials just left....as if they had information that we didn't" - Chief Joseph Pfeifer
15) "and we made that decision to pull it" - Lucky Larry
16) fine particle emissions redolent with sulphur exceeding levels registered downwind of the Kuwait oil fires ("it stinks in here")
one incendiary solution at center
That's it????
You think you've put together a CONCLUSIVE LIST that proves demolition?????
ROTFLMAO
(Oh, and Al, I particularly liked your including the Silverstein "Pull it" reference. although it typically is only employed by those with IQs significantly < normal,
)Arthur
QUOTE
"Noise" in acoustic parlance, btw, refers to the simutaneous production of all frequencies in the audible spectrum at the same time. It is analogous to that mess of all visible freqencies we call "white."
...
Not surprisingly, "SNAP!" is a very appropriate description.
...
Did you know that you have thrice argued that an explosion produces a physically impossible sound envelope with attack, sustain and release occuring at the same instant -- a zero duration waveform?
...
Not surprisingly, "SNAP!" is a very appropriate description.
...
Did you know that you have thrice argued that an explosion produces a physically impossible sound envelope with attack, sustain and release occuring at the same instant -- a zero duration waveform?
Did you know that that "_________|_________" waveform I suggested you synthesize and play on your expensive sound system also has the same spectrum as white noise?
A "snap" is just a small "BANG!", look at its waveform. To scale-up from a guitar string to a structural truss, increase the amplitude and slow-down the playback speed. That sound will become more and more like a BANG!, right before your eyes/ears.
That waveform I suggested, "_______|________", is precisely what you'd get if you recorded an actual explosive going-off in an environment lacking acoustically-reflective surfaces. If you were to hang a C-4 charge from a long string from a hot-air balloon and record it from another balloon at a safe distance. Without the echoes of the environment, the sound is one simple spike. I'm not asserting that it is a "zero-duration" waveform, I'm just pointing out that a 4-inch brick of C-4 detonates in about 10microseconds.
So how long is a sampling interval? If you're sampling at 40kHz, that sampling interval is 25microseconds.
What will the sample be immediately prior to detonation? Zero.
What will it be DURING detonation? MaxVal for your digital word - all ones in binary.
What will it be the next sample after it detonates? Zero again, when there's no reflections/echoes present - The C-4 is already gone, turned into hot gasses expanding in all directions uniformly.
Zero-MaxVal-Zero...
_________|__________
The attack and decay, etc., aren't instantaneous, they're just faster than your recording equipment can resolve, so the whole detonation takes **one sample** to reproduce. The rest is zero, or echoes from that BANG! reflecting off the surfaces in the environment, which, by definition, is **artifact**.
Your recordings of "explosives" aren't recordings of explosives, they're recordings of the reflections of that spike bouncing around the environment. That "complex waveform" isn't the characteristic of the detonation, it's a characteristic of the environment of the explosion. The whole duration of the explosion itself took less than one sampling interval in your digital recording. Do the math, and you'll understand, if you can accept the possibility that you're wrong.
Perhaps Beck could be invited, maybe he would like to discuss.
Further to what WCElliot is saying - this is precisely why we use explosives in Geology to dunduct Seismology, because they make a nice, simple, sharp wave form (just as wcelliot is describing) which makes deconvoluting the echoes much simpler.
Incidentally - one of the other techniques we use sometimes in seismology is to drops a large weight onto a steel body coupled to the ground. We do this because it produces the same kind of wave form as an explosion.
Now, I wonder where we can find and analogous process in WTC1 and WTC2 that could produce a similar sound. Hmmmmmmmmmm.
Incidentally - one of the other techniques we use sometimes in seismology is to drops a large weight onto a steel body coupled to the ground. We do this because it produces the same kind of wave form as an explosion.
Now, I wonder where we can find and analogous process in WTC1 and WTC2 that could produce a similar sound. Hmmmmmmmmmm.
QUOTE (einsteen+Oct 13 2007, 12:40 PM)
Perhaps Beck could be invited, maybe he would like to discuss.
He has been here and then he went away.
Please do invite him back.
He has been here and then he went away.
Please do invite him back.
Einsteen:
I saw your plot (on JREF) derived from a video of the F-4 crash test .... very interesting!
You know I am only reporting Sugano's work. If you could get his paper you would see for yourself that the tail of the F-4 slows as I (and Sugano) describe it. If you are finding something significantly different... well, we have a problem!
I saw your plot (on JREF) derived from a video of the F-4 crash test .... very interesting!
You know I am only reporting Sugano's work. If you could get his paper you would see for yourself that the tail of the F-4 slows as I (and Sugano) describe it. If you are finding something significantly different... well, we have a problem!
QUOTE (David B. Benson+Oct 13 2007, 08:14 PM)
He has been here and then he went away.
Please do invite him back.
Of course, stoopid me, I think I even posted one of the links, he came here himself didn't he?
Please do invite him back.
Of course, stoopid me, I think I even posted one of the links, he came here himself didn't he?
QUOTE (NEU-FONZE+Oct 13 2007, 08:18 PM)
Einsteen:
I saw your plot (on JREF) derived from a video of the F-4 crash test .... very interesting!
You know I am only reporting Sugano's work. If you could get his paper you would see for yourself that the tail of the F-4 slows as I (and Sugano) describe it. If you are finding something significantly different... well, we have a problem!
well, it was only a quick bitmap dump, I think we should consult OneWhiteEye, I will convert the wmv (again because I deleted it already) and upload an .avi file and post it here
I saw your plot (on JREF) derived from a video of the F-4 crash test .... very interesting!
You know I am only reporting Sugano's work. If you could get his paper you would see for yourself that the tail of the F-4 slows as I (and Sugano) describe it. If you are finding something significantly different... well, we have a problem!
well, it was only a quick bitmap dump, I think we should consult OneWhiteEye, I will convert the wmv (again because I deleted it already) and upload an .avi file and post it here
QUOTE (metamars+Oct 13 2007, 05:24 AM)
... Though I'm doubtful I'll fully understand the comparison ...
Also, recall that Beck finds some inconsistency in BV, wrt initial assumptions and reasonableness of later values ...
A fairer comparison is over the course of the entire collapse.
... any realistic one dimensional model is going to have problems fitting observations re the beginning of collapse. I think any such model will work much better after the collapse has progressed to the point where destruction of entire storeys is assured ...
Try Wikipedia regarding Bayes factor. Actually, the result is simply a number, for which Sir Harold suggested some terminology for various ranges.
Beck's criticisms of B & V are simply wrong (where such are not simply incoherent). He fails to understand that their nondimensionalized form differs by sqrt(2) from his attempt at nondimensionalization, wherein he has made a mistake involving sqrt(2)^2 = 2.
Certainly, but we can only use the data we have.
At 1.2 seconds into the collapse of WTC 1, floor 97 has been entirely crushed. For the first second, the observations and calculations also agree quite well.
Also, recall that Beck finds some inconsistency in BV, wrt initial assumptions and reasonableness of later values ...
A fairer comparison is over the course of the entire collapse.
... any realistic one dimensional model is going to have problems fitting observations re the beginning of collapse. I think any such model will work much better after the collapse has progressed to the point where destruction of entire storeys is assured ...
Try Wikipedia regarding Bayes factor. Actually, the result is simply a number, for which Sir Harold suggested some terminology for various ranges.
Beck's criticisms of B & V are simply wrong (where such are not simply incoherent). He fails to understand that their nondimensionalized form differs by sqrt(2) from his attempt at nondimensionalization, wherein he has made a mistake involving sqrt(2)^2 = 2.
Certainly, but we can only use the data we have.
At 1.2 seconds into the collapse of WTC 1, floor 97 has been entirely crushed. For the first second, the observations and calculations also agree quite well.
NEU-FONZE,
The source used is http://www.f1-express.net/perso/F4CrashTest.wmv (22MB)
The converted video is now at http://rapidshare.com/files/62348332/F4CrashTest.avi.html (52.7M)
25 fps, 320 x 240 pix
I did another extraction, now 320 x 1 bitmaps and this image shows the result
http://i23.tinypic.com/2937sk6.png
I used a part where the contrast between the white tail and the sky is good, at the other side it is harder to see.
To me it looks very linear, even although the block moves a little bit to the right, which can also
be seen at the right hand side of the image.
Maybe OneWhiteEye likes to have a look at it.
The source used is http://www.f1-express.net/perso/F4CrashTest.wmv (22MB)
The converted video is now at http://rapidshare.com/files/62348332/F4CrashTest.avi.html (52.7M)
25 fps, 320 x 240 pix
I did another extraction, now 320 x 1 bitmaps and this image shows the result
http://i23.tinypic.com/2937sk6.png
I used a part where the contrast between the white tail and the sky is good, at the other side it is harder to see.
To me it looks very linear, even although the block moves a little bit to the right, which can also
be seen at the right hand side of the image.
Maybe OneWhiteEye likes to have a look at it.
shagster --- Thank you!
For floor 110 I am going to use 12 feet.
For floor 111 (PH Roof) I am going to use 10.5 feet.
With this adjustment, from the floor of the concourse to the roofline is 1353.333 feet. The widely advertised 1368 feet is probably the height above the nominal ground level, about ten feet below the floor of the concourse. Not sure what to make of the residual, 4.667 feet.
Edited to add: However, the elevations for floors 2 and 3 are given in NCSTAR1-2A. Assuming that floor 1 remains at elevation 310, this data gives that the concourse was 17.25 feet high and the lobby was 21 feet high. Using these figures gives an additional 4.25 feet and the residual is only 0.417 feet, entirely negligible.
For floor 110 I am going to use 12 feet.
For floor 111 (PH Roof) I am going to use 10.5 feet.
With this adjustment, from the floor of the concourse to the roofline is 1353.333 feet. The widely advertised 1368 feet is probably the height above the nominal ground level, about ten feet below the floor of the concourse. Not sure what to make of the residual, 4.667 feet.
Edited to add: However, the elevations for floors 2 and 3 are given in NCSTAR1-2A. Assuming that floor 1 remains at elevation 310, this data gives that the concourse was 17.25 feet high and the lobby was 21 feet high. Using these figures gives an additional 4.25 feet and the residual is only 0.417 feet, entirely negligible.
Here are the nondimensional crush-down equations for the simple case of uniform mass distribution, where Z is the normalized position of the crushing front, larger is downwards, Z0 <= Z <= 1, Z' is the speed, Z" is the acceleration, F is the resisting force and s is the stretch:
B & V:
(1-s)(ZZ" + Z'^2) - Z = -F
Beck:
ZZ + (Z'^2)/2 - Z = -F
where the notation and nondimensionalization is that of B & V and Beck's error in carrying out the nondimensionalization has been corrected.
While Beck's equation is easily modified to include a stretch, he specifically rejects this notion. So the above two equation will be compared, using the WTC 1 data with a value of
s = 0.14.
The question is which provides the better fit to the data, using the best value for F in each separate case, and indeed, how much better is one equation than the other...
B & V:
(1-s)(ZZ" + Z'^2) - Z = -F
Beck:
ZZ + (Z'^2)/2 - Z = -F
where the notation and nondimensionalization is that of B & V and Beck's error in carrying out the nondimensionalization has been corrected.
While Beck's equation is easily modified to include a stretch, he specifically rejects this notion. So the above two equation will be compared, using the WTC 1 data with a value of
s = 0.14.
The question is which provides the better fit to the data, using the best value for F in each separate case, and indeed, how much better is one equation than the other...
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