QUOTE (newton+Feb 27 2008, 04:47 PM)
buddy, when hot corrosives are melting through a bolt/hole the first thing to deteriorate is the space between the bolt and the hole, and subsequently, the first place that the liquid will flow through and around.
so, once again, your argument is not working for me.
nor does it explain the distribution of the corrosion, which is in the form of traces formed by running liquid, and not the traces formed by purposefully directed thermite torches(which usually have molten slag drippings around the cut).
newton, its simple LOGIC.
Stop for a second and really LOOK at that picture.
The traces of corrosion are TINY.
They are NOT sufficient to destroy the bolts.
Further, they run off to the right in the picture, thus the piece in question was not vertical (as it would be in the tower prior to collapse) when this MINOR amount of corrosion happened.
And much of that water was salt water pumped from the Hudson river.
Arthur
so, once again, your argument is not working for me.
nor does it explain the distribution of the corrosion, which is in the form of traces formed by running liquid, and not the traces formed by purposefully directed thermite torches(which usually have molten slag drippings around the cut).
newton, its simple LOGIC.
Stop for a second and really LOOK at that picture.
The traces of corrosion are TINY.
They are NOT sufficient to destroy the bolts.
Further, they run off to the right in the picture, thus the piece in question was not vertical (as it would be in the tower prior to collapse) when this MINOR amount of corrosion happened.
QUOTE
As for steel corrosion, pouring lots of water on the steel for weeks on end obviously resulted in much rust. As the chemists here have pointed out, the debris pile was hardly a pristine environment.
And much of that water was salt water pumped from the Hudson river.
Arthur
QUOTE (adoucette+Feb 27 2008, 03:26 PM)
And much of that water was salt water pumped from the Hudson river.
Can you link an authoritative source? Thanks.
Can you link an authoritative source? Thanks.
QUOTE (David B. Benson+Feb 27 2008, 05:38 PM)
Can you link an authoritative source? Thanks.
http://www.nae.edu/nae/bridgecom.nsf/webli...RH?OpenDocument
The primary source of water at the WTC complex was fireboats on the Hudson River. Figure 2 is an aerial view of the WTC site, showing the deployment of four fireboats (Firefighter, McKean, Kane, and Smoke II). The tie-up locations and hose paths are shown for each boat. Although the combined pumping capacity of the fireboats was 180,000 liters per minute, only a small fraction of that, approximately 28,000 liters per minute, was conveyed to the WTC complex, partly because the water was relayed through relatively small hoses (90-mm and 125-mm-nominal-diameter) (O’Rourke et al., 2003). Nevertheless, water from the fireboats was about 150 percent of the water available from hydrants and was critical to containing and extinguishing fires on the site.
Arthur
http://www.nae.edu/nae/bridgecom.nsf/webli...RH?OpenDocument
The primary source of water at the WTC complex was fireboats on the Hudson River. Figure 2 is an aerial view of the WTC site, showing the deployment of four fireboats (Firefighter, McKean, Kane, and Smoke II). The tie-up locations and hose paths are shown for each boat. Although the combined pumping capacity of the fireboats was 180,000 liters per minute, only a small fraction of that, approximately 28,000 liters per minute, was conveyed to the WTC complex, partly because the water was relayed through relatively small hoses (90-mm and 125-mm-nominal-diameter) (O’Rourke et al., 2003). Nevertheless, water from the fireboats was about 150 percent of the water available from hydrants and was critical to containing and extinguishing fires on the site.
Arthur
QUOTE (adoucette+Feb 27 2008, 03:52 PM)
http://www.nae.edu/nae/bridgecom.nsf/webli...RH?OpenDocument
That was prompt! Also of interest from that document is
That was prompt!
Also of interest from that document isQUOTE
Records of water flow to the WTC area and nearby neighborhoods show that immediately after the buildings collapsed, water flow suddenly increased by 210 million liters per day, then rose gradually another 30 million liters per day (O’Rourke et al., 2003). The initial jump was caused by water pouring through broken water mains beneath and around the WTC complex. The additional flow represents, approximately, the amount of water drawn from fire hydrants to fight fires in adjacent buildings. Water pressures at hydrants around the WTC complex declined throughout the afternoon. Measurements at 6:00 p.m. showed pressure two to three blocks from the site at approximately one-third of normal. Of course, firefighting was impaired by the falling pressure.
QUOTE (Chainsaw,+Feb 27 2008, 10:15 PM)
Newton it is not a high temperature reaction, it does not produce Fe 3O4 so it was a low temperature reaction in the fires, that is all, with sulfates and chlorides.
If it were really hot the yellow iron oxide would have oxidized away, it looks like a low temperature chemical reaction.
http://www.reade.com/Products/Oxides/yellow_iron_oxide.html
Sorry newton it looks like simple chemical reactions in the fires with water in the vapor stage, sulfides, and Chlorides.
no need to apologize.
i'm not emotionally attached to microscopic data. and besides that, i still think it's wierd the way it's NOT torn metal, but rather CUT metal. surface corrosion does not separate metal so neatly.
ripping metal does not separate it so neatly.
only cutting or extreme sheering forces do, but sheering forces give a smoother cut(VERY smooth), and you can see the fracture faults. the metal is separated along the lines of corrosion.
if some low temperature chemical reaction nearby can cause this, i'm certainly interested.
and to NIST, er, arthurs; IF the corrosion was a result of salt water, it would be more uniform, as they pumped thousands of gallons onto the pile. it would look 'spray-painted' and not 'brush painted'.
If it were really hot the yellow iron oxide would have oxidized away, it looks like a low temperature chemical reaction.
http://www.reade.com/Products/Oxides/yellow_iron_oxide.html
Sorry newton it looks like simple chemical reactions in the fires with water in the vapor stage, sulfides, and Chlorides.
no need to apologize.
i'm not emotionally attached to microscopic data. and besides that, i still think it's wierd the way it's NOT torn metal, but rather CUT metal. surface corrosion does not separate metal so neatly.
ripping metal does not separate it so neatly.
only cutting or extreme sheering forces do, but sheering forces give a smoother cut(VERY smooth), and you can see the fracture faults. the metal is separated along the lines of corrosion.
if some low temperature chemical reaction nearby can cause this, i'm certainly interested.
and to NIST, er, arthurs; IF the corrosion was a result of salt water, it would be more uniform, as they pumped thousands of gallons onto the pile. it would look 'spray-painted' and not 'brush painted'.
QUOTE (newton+Feb 27 2008, 04:21 PM)
IF the corrosion was a result of salt water, it would be more uniform, as they pumped thousands of gallons onto the pile. it would look 'spray-painted' and not 'brush painted'.
Does not follow. Depends upon where the water ran.
Does not follow. Depends upon where the water ran.
QUOTE (David B. Benson+Feb 27 2008, 11:28 PM)
Does not follow. Depends upon where the water ran.
perhaps.
doesn't change the pattern of the separation. looks cut, not torn.
perhaps.
doesn't change the pattern of the separation. looks cut, not torn.
QUOTE (newton+Feb 27 2008, 06:31 PM)
perhaps.
doesn't change the pattern of the separation. looks cut, not torn.
And here we have an excellent example of the mindless drivel that Twoofers peddle as their "Proof"
Pathetic.
Arthur
doesn't change the pattern of the separation. looks cut, not torn.
And here we have an excellent example of the mindless drivel that Twoofers peddle as their "Proof"
Pathetic.
Arthur
i already showed various metal failure modes, and what we see in the picture is not one of them.
QUOTE (newton+Feb 27 2008, 05:05 PM)
i already showed various metal failure modes, and what we see in the picture is not one of them.
I fail to follow. Fractures develop along the weakest part, wherever that is.
Cutting usually leaves some slag. See any?
I fail to follow. Fractures develop along the weakest part, wherever that is.
Cutting usually leaves some slag. See any?
.
HI all!
Does anybody know whether the CITY MAINS water was CHLORINED for killing bacteria/parasites?
Also, was it FLUORIDED (the usual anti-tooth decay additive) drinking water quality as well?
And what was the chemical composition of all the various FIRE-suppression FOAMS/FLUIDS pumped onto the pile?
All those separate streams of diverse 'inputs' should have given 'mixed boundary-areas' effects on all materials/processes over the many weeks....so one could 'pick out' SELECTIVELY almost anything to show a 'different' exposure to a 'neighbour' thing, hehehe. Take your pick and attach an 'interpretation' and favourite 'conspiracy' to almost every thing to come out of that pile....if that is your 'bag', hehehe.
So let's keep those 'hypotheses' within the realms of 'falsifiability', heh?....or else you'll have jay hpward coming at you at a rate of knots and screaming "falsifiability!", falsifiability!......" ad nauseum! hehehe.
Cheers!
RC.
.
HI all!
Does anybody know whether the CITY MAINS water was CHLORINED for killing bacteria/parasites?
Also, was it FLUORIDED (the usual anti-tooth decay additive) drinking water quality as well?
And what was the chemical composition of all the various FIRE-suppression FOAMS/FLUIDS pumped onto the pile?
All those separate streams of diverse 'inputs' should have given 'mixed boundary-areas' effects on all materials/processes over the many weeks....so one could 'pick out' SELECTIVELY almost anything to show a 'different' exposure to a 'neighbour' thing, hehehe. Take your pick and attach an 'interpretation' and favourite 'conspiracy' to almost every thing to come out of that pile....if that is your 'bag', hehehe.
So let's keep those 'hypotheses' within the realms of 'falsifiability', heh?....or else you'll have jay hpward coming at you at a rate of knots and screaming "falsifiability!", falsifiability!......" ad nauseum! hehehe.
Cheers!
RC.
.
QUOTE (newton+Feb 28 2008, 12:05 AM)
i already showed various metal failure modes, and what we see in the picture is not one of them.
Newton where can I find this photo on line what independent sites I am puzzled by the strait lines in the pixels, of the bolt holes like the picture was a cut and paste composite?
IS there a large photo of this piece?
Newton where can I find this photo on line what independent sites I am puzzled by the strait lines in the pixels, of the bolt holes like the picture was a cut and paste composite?
IS there a large photo of this piece?
QUOTE (Chainsaw,+Feb 28 2008, 01:54 AM)
Newton where can I find this photo on line what independent sites I am puzzled by the strait lines in the pixels, of the bolt holes like the picture was a cut and paste composite?
IS there a large photo of this piece?
it's the only one i know of. i got it from photobucket or whatever. it says "mike walker" in the file name. i tried to find more pics based on that, but failed.
sorry.
IS there a large photo of this piece?
it's the only one i know of. i got it from photobucket or whatever. it says "mike walker" in the file name. i tried to find more pics based on that, but failed.
sorry.
QUOTE (newton+Feb 27 2008, 09:20 PM)
it's the only one i know of. i got it from photobucket or whatever. it says "mike walker" in the file name. i tried to find more pics based on that, but failed.
sorry.
newton produces a picture from an unknown source, taken at an unknown time of a piece of the WTC structure for which there is no known as built location,
but
based on what he can see in that over-exposed photo,
his conclusion is:
Are any of you ever going to summarize your FINDINGS and post your CONCLUSIONS?
You know, for those of us who have been skipping past your smearogram posts for some time now.
Arthur
hahaha, all I can do is laugh. Good point and thanks for the continued smile on my face.
Crushing tinkertoy structures in my garage in an enclosure with a pneumatically-driven piston (with load cell and displacement transducer) at the top is placing very great demands on my time. The crushing goes rather quickly, but the assembly is another matter. It does not help that I'm confounded by the bizarre and alien manner with which pieces connect to each other. I hope you can be patient during this time and content in the understanding that all of your questions will be answered in due time.
Traditional, the towers were NOT, otherwise they would not have been so tall.
Traditional, the towers were NOT, otherwise they would not have been so tall.
Astaneh-Asl says that the reason for undertaking his studies is not to implicate the designers, but rather to look into the design and answer the basic question that has bothered him since September 11: “Why did these towers collapse so quickly and so completely while other steel structures, including skyscrapers, under intense fire for hours, have not failed?”
He says that he feels he is closing in on the answer. “These structures were so unique that their collapse does not represent the performance expected of any other existing steel high-rise structure subjected to the same scenario,” he says.
This brief video is a good example of a top-down progressive collapse. The falling mass at the beginning was too much for the floor below to withstand. Notice that the main floors collapse via failure of their connections to the columns, leaving the columns standing at the end of the collapse.
http://s134.photobucket.com/albums/q91/sha...nt=collapse.flv
sorry.
newton produces a picture from an unknown source, taken at an unknown time of a piece of the WTC structure for which there is no known as built location,
but
based on what he can see in that over-exposed photo,
his conclusion is:
QUOTE (newton+)
that one photo is pretty damning.
newton, can you understand why no one takes you seriously?
Arthur
newton, can you understand why no one takes you seriously?
Arthur
i can understand why you would say no one takes me seriously.
can you show me the results of the gallup poll so i will know exactly how many people i need to convince to start taking me seriously?
perhaps it's a picture of the washington monument, and i was mistaken that it might represent events at ground zero.
i thought you were going to tell me where it came from? you said you knew.
can you show me the results of the gallup poll so i will know exactly how many people i need to convince to start taking me seriously?
perhaps it's a picture of the washington monument, and i was mistaken that it might represent events at ground zero.
i thought you were going to tell me where it came from? you said you knew.
QUOTE (newton+Feb 27 2008, 11:57 PM)
can you show me the results of the gallup poll so i will know exactly how many people i need to convince to start taking me seriously?
No, but I' can look at your feedback.
Arthur
No, but I' can look at your feedback.
Arthur
QUOTE (adoucette+Feb 28 2008, 05:02 AM)
No, but I' can look at your feedback.
Arthur
yes.
and you can see what could be the work of one or two people with a fat three letter agency cheque in their pocket.
just sayin'. it's meaningless, the feedback. there are DEFINITELY tons of sock puppets, here.
however, you arthurs, are the opposite. a team of people assigned to one avatar.
prove you're not, shneibster, LOL!
when you look at my feedback, do you see the nice things people said?
oh, yeah, and so it's not off topic of the off topic, ummmm, what floor did that spandrel tree come from? you said you knew.
Arthur
yes.
and you can see what could be the work of one or two people with a fat three letter agency cheque in their pocket.
just sayin'. it's meaningless, the feedback. there are DEFINITELY tons of sock puppets, here.
however, you arthurs, are the opposite. a team of people assigned to one avatar.
prove you're not, shneibster, LOL!
when you look at my feedback, do you see the nice things people said?
oh, yeah, and so it's not off topic of the off topic, ummmm, what floor did that spandrel tree come from? you said you knew.
QUOTE (NEU-FONZE+Feb 27 2008, 01:11 PM)
OneWhiteEye:
Yes, what I call "drop" is any downward apparent vertical motion, usually determined from the roof line or the window washing machine line.
What I call "tilt" is any angular motion which I derive from lateral motion of a reference point near the top of the antenna. I convert this to degrees of tilt by taking some initial vertical line as my reference "zero degrees" line.
Now obviously if the upper block is tipping to the south and we are viewing from the north, the "drop" includes tipping motions. For the South Tower it is much easier to separate the dropping and tipping motions because the available viewing angles show the tilt very well and you can follow the tilt out to at least 25 degrees. For the North Tower the tipping is more subtle and some of the best videos for measuring the drop are almost useless for measuring the tilt.
One more point: I may have posted some contradictory data on the tilt because I have attempted, (from time to time), to make perspective corrections, and these can easily double the estimated angle! Sorry if this has caused any confusion!
OK.
I typed a whole bunch of stuff here but erased it. There's nothing more I can say except I'm going to examine some different videos and see what I see.
Yes, what I call "drop" is any downward apparent vertical motion, usually determined from the roof line or the window washing machine line.
What I call "tilt" is any angular motion which I derive from lateral motion of a reference point near the top of the antenna. I convert this to degrees of tilt by taking some initial vertical line as my reference "zero degrees" line.
Now obviously if the upper block is tipping to the south and we are viewing from the north, the "drop" includes tipping motions. For the South Tower it is much easier to separate the dropping and tipping motions because the available viewing angles show the tilt very well and you can follow the tilt out to at least 25 degrees. For the North Tower the tipping is more subtle and some of the best videos for measuring the drop are almost useless for measuring the tilt.
One more point: I may have posted some contradictory data on the tilt because I have attempted, (from time to time), to make perspective corrections, and these can easily double the estimated angle! Sorry if this has caused any confusion!
OK.
I typed a whole bunch of stuff here but erased it. There's nothing more I can say except I'm going to examine some different videos and see what I see.
QUOTE (newton+Feb 27 2008, 09:25 PM)
...bedazzled and confused by the high science of OWE and benson.
Thank you, I'm sincerely flattered.
Thank you, I'm sincerely flattered.
Extracting bitmaps= no high science, but what they do with it is of course!
Re tilt.
Taken from the Sauret video:
roofline to NW corner lowest rupture floor (14? floors down): 202px
roofline to NW corner nominal rupture floor (12? floors down): 173px
dark band to roofline: ~ 85px
The real situation is more complicated than what follows. Technically, these measurements correspond to degrees in the field of view, but if I don't treat them as real vertical distances, I'll never get through this. The argument is not diminished by this small error. I'll use the higher rupture location for the hinge location at the NW corner, directly below the washer. With 18 floors = 258.67px and 1 floor = 3.78m, the distances between features and rupture become:
roofline to NW corner hinge: 45.5m
dark band to NW corner hinge: 67.9m
Now, antenna centerline to wall is 32m (I was sorely tempted to convert this to pixels instead of the others to meters) and the radius of the antenna at that location is roughly 2m or more, so the angle formed by the dark band and roofline with hinge at vertex is approximately 24 degrees and the radial distance, hinge to dark band, is 74m.
Ratio of radii for the two features: 1.6
If the antenna were contained in the wall plane and the optic axis zero, camera at infinity, the dark band would have half again the displacement of the roof and both would have zero vertical displacement at t_0. It has been suggested that the roofline would not appear to move at all initially because of the perspective yielding a zero derivative. The dark band, while at a 24 degree angle to the wall plane, does not have that initial angle wrt the camera, and neither is the roofline zero. The camera is aimed at a vertical location about 61m below the roofline which, along with other assumptions, leads to an elevation angle of at least 13 degrees. Further assumptions about view angle (field of view) gives a VERY rough:
roofline camera angle: 14 deg => 14 deg initial angle (> 0)
dark band camera angle: 15 deg => 39 deg initial angle (>> 0)
The roofline has a substantial initial angle, but notice the dark band is starting out very near the maximum possible apparent travel -- 45 deg. The zero derivative at zero degrees idea is useful as a first approximation, and gets the idea across, but it's not strictly true. Between the radial differences and initial angles, the dark band will appear to move quite a bit more than the roof, but both would begin moving together at t_0 in this video if the upper block were a perfect rigid body.
Is there sufficient resolution to see the antenna motion at 1-2px, but not the roofline at <1px? Is deformation of the entire upper block responsible for some of the earliest tilt of the antenna?
Taken from the Sauret video:
roofline to NW corner lowest rupture floor (14? floors down): 202px
roofline to NW corner nominal rupture floor (12? floors down): 173px
dark band to roofline: ~ 85px
The real situation is more complicated than what follows. Technically, these measurements correspond to degrees in the field of view, but if I don't treat them as real vertical distances, I'll never get through this. The argument is not diminished by this small error. I'll use the higher rupture location for the hinge location at the NW corner, directly below the washer. With 18 floors = 258.67px and 1 floor = 3.78m, the distances between features and rupture become:
roofline to NW corner hinge: 45.5m
dark band to NW corner hinge: 67.9m
Now, antenna centerline to wall is 32m (I was sorely tempted to convert this to pixels instead of the others to meters) and the radius of the antenna at that location is roughly 2m or more, so the angle formed by the dark band and roofline with hinge at vertex is approximately 24 degrees and the radial distance, hinge to dark band, is 74m.
Ratio of radii for the two features: 1.6
If the antenna were contained in the wall plane and the optic axis zero, camera at infinity, the dark band would have half again the displacement of the roof and both would have zero vertical displacement at t_0. It has been suggested that the roofline would not appear to move at all initially because of the perspective yielding a zero derivative. The dark band, while at a 24 degree angle to the wall plane, does not have that initial angle wrt the camera, and neither is the roofline zero. The camera is aimed at a vertical location about 61m below the roofline which, along with other assumptions, leads to an elevation angle of at least 13 degrees. Further assumptions about view angle (field of view) gives a VERY rough:
roofline camera angle: 14 deg => 14 deg initial angle (> 0)
dark band camera angle: 15 deg => 39 deg initial angle (>> 0)
The roofline has a substantial initial angle, but notice the dark band is starting out very near the maximum possible apparent travel -- 45 deg. The zero derivative at zero degrees idea is useful as a first approximation, and gets the idea across, but it's not strictly true. Between the radial differences and initial angles, the dark band will appear to move quite a bit more than the roof, but both would begin moving together at t_0 in this video if the upper block were a perfect rigid body.
Is there sufficient resolution to see the antenna motion at 1-2px, but not the roofline at <1px? Is deformation of the entire upper block responsible for some of the earliest tilt of the antenna?
QUOTE (newton+Feb 28 2008, 02:20 AM)
it's the only one i know of. i got it from photobucket or whatever. it says "mike walker" in the file name. i tried to find more pics based on that, but failed.
sorry.
Newton the photo is cut and paste, a cleaver deception as noted by the enlarged pixel data, it is not even a good cut and paste.
To many Squares where there should be rounded edges.
User posted image: User posted image
That pattern appears all over the outside of the metal that is eroded but no where else.
sorry.
Newton the photo is cut and paste, a cleaver deception as noted by the enlarged pixel data, it is not even a good cut and paste.
To many Squares where there should be rounded edges.
User posted image: User posted image
That pattern appears all over the outside of the metal that is eroded but no where else.
QUOTE (newton+Feb 28 2008, 12:13 AM)
what floor did that spandrel tree come from? you said you knew.
No, I never said I knew.
I said if you knew more about the pieces in the picture THEN you could figure out ~ what floor it came from.
My actual point is that you JUMPED TO CONCLUSIONS based on this picture even though you knew almost nothing about it and even though obvious features, such as the drip patterns not being vertical, are a good indication that the minimal visual corrosion seen occured AFTER the towers fell.
Arthur
No, I never said I knew.
I said if you knew more about the pieces in the picture THEN you could figure out ~ what floor it came from.
My actual point is that you JUMPED TO CONCLUSIONS based on this picture even though you knew almost nothing about it and even though obvious features, such as the drip patterns not being vertical, are a good indication that the minimal visual corrosion seen occured AFTER the towers fell.
Arthur
This is apparently the original image. Image number 148.
http://bocadigital.smugmug.com/gallery/270..._aaPUV/Original
http://bocadigital.smugmug.com/gallery/270..._aaPUV/Original
QUOTE (shagster+Feb 28 2008, 03:48 PM)
This is apparently the original image. Image number 148.
http://bocadigital.smugmug.com/gallery/270..._aaPUV/Original
good find. how'd you do that?
i don't think it's a cut and paste job, chainsaw. what you're seeing are just normal digital imaging algorithms. i zoomed in on the whole picture(from shagter's source), and the whole picture has the same type of artifacts.
http://bocadigital.smugmug.com/gallery/270..._aaPUV/Original
good find. how'd you do that?
i don't think it's a cut and paste job, chainsaw. what you're seeing are just normal digital imaging algorithms. i zoomed in on the whole picture(from shagter's source), and the whole picture has the same type of artifacts.
QUOTE (shagster+Feb 28 2008, 10:48 AM)
This is apparently the original image. Image number 148.
http://bocadigital.smugmug.com/gallery/270..._aaPUV/Original
Based on this, its pretty clear that the column in question came from pretty low in the towers.
Observe the size of the number 2 plates (perpendicular to tower face) in those columns.
Note their size in relation to the bolt holes.
Now check out NIST NCSTAR 1-3C Fig 3-44 pg 168.
This is a column from the lowest fire/impact set of floors (74-77)
So, where the #2 plates are clearly much larger than the bolts in the column in question, on ~ 77th floor they don't appear to be even HALF the size of the bolt holes.
I agree, the photo is not a cut/paste, but the photo info also shows that the Flash fired on this shot. I believe its responsible for some of the strange colorations of the material that is close to the camera as that area is over-exposed.
Arthur
http://bocadigital.smugmug.com/gallery/270..._aaPUV/Original
Based on this, its pretty clear that the column in question came from pretty low in the towers.
Observe the size of the number 2 plates (perpendicular to tower face) in those columns.
Note their size in relation to the bolt holes.
Now check out NIST NCSTAR 1-3C Fig 3-44 pg 168.
This is a column from the lowest fire/impact set of floors (74-77)
So, where the #2 plates are clearly much larger than the bolts in the column in question, on ~ 77th floor they don't appear to be even HALF the size of the bolt holes.
I agree, the photo is not a cut/paste, but the photo info also shows that the Flash fired on this shot. I believe its responsible for some of the strange colorations of the material that is close to the camera as that area is over-exposed.
Arthur
QUOTE (adoucette+Feb 28 2008, 02:42 PM)
No, I never said I knew.
I said if you knew more about the pieces in the picture THEN you could figure out ~ what floor it came from.
My actual point is that you JUMPED TO CONCLUSIONS based on this picture even though you knew almost nothing about it and even though obvious features, such as the drip patterns not being vertical, are a good indication that the minimal visual corrosion seen occured AFTER the towers fell.
Arthur
sorry, when you typed, "(will tell you ~ what floor its from)", i thought you meant you would tell me, not the thickness of the spandrel would tell me. it was a little ambiguous.
I said if you knew more about the pieces in the picture THEN you could figure out ~ what floor it came from.
My actual point is that you JUMPED TO CONCLUSIONS based on this picture even though you knew almost nothing about it and even though obvious features, such as the drip patterns not being vertical, are a good indication that the minimal visual corrosion seen occured AFTER the towers fell.
Arthur
sorry, when you typed, "(will tell you ~ what floor its from)", i thought you meant you would tell me, not the thickness of the spandrel would tell me. it was a little ambiguous.
QUOTE (newton+Feb 28 2008, 03:58 PM)
good find. how'd you do that?
i don't think it's a cut and paste job, chainsaw. what you're seeing are just normal digital imaging algorithms. i zoomed in on the whole picture(from shagter's source), and the whole picture has the same type of artifacts.
I agree now Newton that I know the source and after running it though some enhancement programs that clearly show it was not photo shopped cut and paste.
That is why I asked for the original, it was just a low resolution Jpg.
The photo also shows tearing not cutting of the steel, notice the force to sever the steel came from above and vectored to the right, and that the Bolt holes were deformed by considerable tension, that help shear the bolts from the sides like a pear of bolt cutters do.
That plate of steel was cold when those bolts were sheared, probably less than 600c.
Few people actually look for the recorded motion in the system, but the steel always tells you the forces that acted upon it.
Bolt holes deforming in high tension cutting bolts is common around heavy equipment often a reason for failure.
There is also considerable chemical corrosion on the plate however it only occurred on exposed torn fresh steel where the oxide layer was exposed, it appears to be common edge corrosion after breakage however a better photo would be necessary for me to say for sure but I have seen similar, from just hours of exposure to salts or especially molten salts.
i don't think it's a cut and paste job, chainsaw. what you're seeing are just normal digital imaging algorithms. i zoomed in on the whole picture(from shagter's source), and the whole picture has the same type of artifacts.
I agree now Newton that I know the source and after running it though some enhancement programs that clearly show it was not photo shopped cut and paste.
That is why I asked for the original, it was just a low resolution Jpg.
The photo also shows tearing not cutting of the steel, notice the force to sever the steel came from above and vectored to the right, and that the Bolt holes were deformed by considerable tension, that help shear the bolts from the sides like a pear of bolt cutters do.
That plate of steel was cold when those bolts were sheared, probably less than 600c.
Few people actually look for the recorded motion in the system, but the steel always tells you the forces that acted upon it.
Bolt holes deforming in high tension cutting bolts is common around heavy equipment often a reason for failure.
There is also considerable chemical corrosion on the plate however it only occurred on exposed torn fresh steel where the oxide layer was exposed, it appears to be common edge corrosion after breakage however a better photo would be necessary for me to say for sure but I have seen similar, from just hours of exposure to salts or especially molten salts.
Correcting for the tilt of WTC 1 appears to be quite difficult. If I knew the tilt over the full period of observations, of course I could correct for that. But I'll have to estimate, at least past the 1.6 seconds of data Greening measured. It may well be I will have to actually use Bayesian (subjective) priors. If so, I'd like to have a good guess as to what happens to the angular momentum of the top portion after the north wall hinge is broken.
I'll state that it ought to decrease, since the top portion impacts the south edges of floors before sweeping to the north, floor by floor. I'm looking for estimates, based on a 33,200 tonne top portion and a floor mass of about 1530+ tonnes. Thanks.
I'll state that it ought to decrease, since the top portion impacts the south edges of floors before sweeping to the north, floor by floor. I'm looking for estimates, based on a 33,200 tonne top portion and a floor mass of about 1530+ tonnes. Thanks.
QUOTE (David B. Benson+Feb 28 2008, 10:53 PM)
Correcting for the tilt of WTC 1 appears to be quite difficult. If I knew the tilt over the full period of observations, of course I could correct for that. But I'll have to estimate, at least past the 1.6 seconds of data Greening measured. It may well be I will have to actually use Bayesian (subjective) priors. If so, I'd like to have a good guess as to what happens to the angular momentum of the top portion after the north wall hinge is broken.
I'll state that it ought to decrease, since the top portion impacts the south edges of floors before sweeping to the north, floor by floor. I'm looking for estimates, based on a 33,200 tonne top portion and a floor mass of about 1530+ tonnes. Thanks.
David, for wtc2 it should be possible to give a good tilt(time) function because there is a good video around. that's something for later, there is no hurry...
I'll state that it ought to decrease, since the top portion impacts the south edges of floors before sweeping to the north, floor by floor. I'm looking for estimates, based on a 33,200 tonne top portion and a floor mass of about 1530+ tonnes. Thanks.
David, for wtc2 it should be possible to give a good tilt(time) function because there is a good video around. that's something for later, there is no hurry...
You had to search for a while but finally you found it in this obscure thread in an obscure forum from an obscure website:
THE END OF THE INTERNET
THE END OF THE INTERNET
OneWhiteEye discovered a (serious) error in my pixels2metersDrop code. Soon it will be fully corrected and I'll once again ask OneWhiteEye to post the graphs.
Maybe this coming weekend?
Maybe this coming weekend?
I think this LONG discussion is winding down.
While there is some interest in a better understanding of what happened during the first few seconds of collapse (because we can measure that part to a fairly accurate degree) there seems to be not much enthusiasm for steadfastly repeating the tired Twoofer mantras of Squibs, melted pools of steel, thermite and Explosions before the collapse etc etc. since they have all been so resoundingly debunked.
You can see it in the decline in page activity at "Truther" sites and the lack of any growth of any groups that have been created around these issues.
I think some of this was from the fact that the Democrats took control over both houses of Congress in 06 and yet, for all the bluster about this being a Bush/Cheney driven conspiracy, the Democrats did nothing to push for a new investigation into 9/11.
With Bush/Cheney leaving in less than a year, the clock is running down on almost all of their targets for anger. If people didn't care while they were in power, they certainly aren't going to get all worked up about them when they aren't.
So, while there will ALWAYS be a level of CONSPIRACY lovers who will support this idea till the end, the VAST majority of the people are not at all concerned that the true cause of the collapse of the towers has not been found.
Arthur
While there is some interest in a better understanding of what happened during the first few seconds of collapse (because we can measure that part to a fairly accurate degree) there seems to be not much enthusiasm for steadfastly repeating the tired Twoofer mantras of Squibs, melted pools of steel, thermite and Explosions before the collapse etc etc. since they have all been so resoundingly debunked.
You can see it in the decline in page activity at "Truther" sites and the lack of any growth of any groups that have been created around these issues.
I think some of this was from the fact that the Democrats took control over both houses of Congress in 06 and yet, for all the bluster about this being a Bush/Cheney driven conspiracy, the Democrats did nothing to push for a new investigation into 9/11.
With Bush/Cheney leaving in less than a year, the clock is running down on almost all of their targets for anger. If people didn't care while they were in power, they certainly aren't going to get all worked up about them when they aren't.
So, while there will ALWAYS be a level of CONSPIRACY lovers who will support this idea till the end, the VAST majority of the people are not at all concerned that the true cause of the collapse of the towers has not been found.
Arthur
Arthur, you think that conspiracy theories are completely politically driven ? I think it's save to say that not all features of the collapse are explained. The squibs are not modeled, the amount of mass (parabolic tracks of the chunks) ejected in air is not modeled, not explained. They are unable to give a full explanation, not because of the complexity of the situation but because they cannot explain it or they knew what the real reason is, they avoid to burn their fingers. It's a scary world and a big shame.
QUOTE (einsteen+Mar 6 2008, 03:57 PM)
Arthur, you think that conspiracy theories are completely politically driven ?
No, there's also money to be made fleecing those gullible enough to buy a CD/book/T-shirt.
Those things you ask about though, there has been no significant SCIENTIFIC effort to TRY to explain these issues.
Why?
Because the scientists doing the work can see intuitively that these are perfectly reasonable effects from a CHAOTIC system that is releasing tremendous amounts of energy in a short a period of time, and the fact that there is NO particular value to the engineering community to even attempting to solve what are MINOR issues about the collapse.
Its, after all, only those who can't seem to understand the basic physics involved, who after reading the NIST report, still think it required MORE than a fueled 767 at ~ 500 mph to cause the level of destruction that day, or think there was any possible way the lower part of the structure could withstand the forces involved when the top block started moving downward.
Arthur
No, there's also money to be made fleecing those gullible enough to buy a CD/book/T-shirt.
Those things you ask about though, there has been no significant SCIENTIFIC effort to TRY to explain these issues.
Why?
Because the scientists doing the work can see intuitively that these are perfectly reasonable effects from a CHAOTIC system that is releasing tremendous amounts of energy in a short a period of time, and the fact that there is NO particular value to the engineering community to even attempting to solve what are MINOR issues about the collapse.
Its, after all, only those who can't seem to understand the basic physics involved, who after reading the NIST report, still think it required MORE than a fueled 767 at ~ 500 mph to cause the level of destruction that day, or think there was any possible way the lower part of the structure could withstand the forces involved when the top block started moving downward.
Arthur
QUOTE (adoucette to einsteen+Mar 6 2008, 10:39 PM)
No, there's also money to be made fleecing those gullible enough to buy a CD/book/T-shirt....
...
Hehehe. Putting aside any political-gain aspects, I wonder what the GROSS income was for those peddling books/T-shirts/lectures etc etc about alleged US govt "so-called conspiracies" re 'ET/Alien' UFOs and "fake' Moon Landings?
In the millions/billions of dollars over the decades to date?
Man, if I had easy ethics I could make a good living writing/performing for that 'suckers market'!
Pity I've got scientific/personal scruples......darnit, I'm doomed to stay poor! hehehe.
RC.
.
...
Hehehe. Putting aside any political-gain aspects, I wonder what the GROSS income was for those peddling books/T-shirts/lectures etc etc about alleged US govt "so-called conspiracies" re 'ET/Alien' UFOs and "fake' Moon Landings?
In the millions/billions of dollars over the decades to date?
Man, if I had easy ethics I could make a good living writing/performing for that 'suckers market'!
Pity I've got scientific/personal scruples......darnit, I'm doomed to stay poor! hehehe.
RC.
.
QUOTE (einsteen+Mar 6 2008, 01:57 PM)
I think it's save[sic] to say that not all features of the collapse are explained. The squibs are not modeled, the amount of mass (parabolic tracks of the chunks) ejected in air is not modeled, not explained.
I have explained the so-called squibs and there is really nothing to model. Some time back NEU-FONZE pointed out that the air ejection speed on the so-called squibs agreed closely to the speed of the descending main mass. End of story.
shagster modeled the ejection of the exterior wall sections falling freely outside the towers. He posted on this several weeks, even months, ago. What is left to explain?
I have explained the so-called squibs and there is really nothing to model. Some time back NEU-FONZE pointed out that the air ejection speed on the so-called squibs agreed closely to the speed of the descending main mass. End of story.
shagster modeled the ejection of the exterior wall sections falling freely outside the towers. He posted on this several weeks, even months, ago. What is left to explain?
QUOTE (David B. Benson+Mar 6 2008, 07:00 PM)
OneWhiteEye discovered a (serious) error in my pixels2metersDrop code. Soon it will be fully corrected and I'll once again ask OneWhiteEye to post the graphs.
Maybe this coming weekend?
David B. Benson discovered a (serious) error in my correction. So there.
This weekend for sure.
Maybe this coming weekend?
David B. Benson discovered a (serious) error in my correction. So there.
This weekend for sure.
Did I say this weekend? I meant this weekend.
Hypotheses -
H1: Sef-K+Z+ZSS-F-exp-pow-stretch
H2: Sef-const-F-const-stretch
Graph legend for calculated values -
Hypothesis <=> color (H1 green, H2 blue)
Dataset <=> shape (S2D square, C44789 circle)
Calculated values: http://i26.tinypic.com/32zjswn.jpg
Calculated values zoom on beginning: http://i30.tinypic.com/28armnn.jpg
Calculated values zoom on end: http://i28.tinypic.com/291j8uf.jpg
(will do another calculated values using lines soon)
Residuals next.
Hypotheses -
H1: Sef-K+Z+ZSS-F-exp-pow-stretch
H2: Sef-const-F-const-stretch
Graph legend for calculated values -
Hypothesis <=> color (H1 green, H2 blue)
Dataset <=> shape (S2D square, C44789 circle)
Calculated values: http://i26.tinypic.com/32zjswn.jpg
Calculated values zoom on beginning: http://i30.tinypic.com/28armnn.jpg
Calculated values zoom on end: http://i28.tinypic.com/291j8uf.jpg
(will do another calculated values using lines soon)
Residuals next.
Graph legend for residual values -
Dataset <=> color (S2D red, C44789 blue, C447 green, C448 magenta, C449 aqua)
H1: http://i29.tinypic.com/2ajrlgy.jpg
H2: http://i31.tinypic.com/23mofx1.jpg
This is a process that needs to be automated, if only to reduce the potential for error.
Dataset <=> color (S2D red, C44789 blue, C447 green, C448 magenta, C449 aqua)
H1: http://i29.tinypic.com/2ajrlgy.jpg
H2: http://i31.tinypic.com/23mofx1.jpg
This is a process that needs to be automated, if only to reduce the potential for error.
The calculated H1 and H2 values graph from the first post with lines added, same legend:
http://i27.tinypic.com/2h2plpe.jpg
With the measured values from the two datasets added to the above, large diamond markers only, S2D magenta and C44789 aqua:
http://i30.tinypic.com/x98r5.png
Zoom of beginning: http://i31.tinypic.com/11w8vo5.png
Zoom of end: http://i29.tinypic.com/50scvc.png
Crush front drop:
http://i27.tinypic.com/zx5eee.jpg
Crush front speed:
http://i30.tinypic.com/i595is.jpg
Stretch:
http://i28.tinypic.com/2cfb3mr.jpg
No warranty against mistakes. (and edited to correct one - gray line in last series changed to green)
http://i27.tinypic.com/2h2plpe.jpg
With the measured values from the two datasets added to the above, large diamond markers only, S2D magenta and C44789 aqua:
http://i30.tinypic.com/x98r5.png
Zoom of beginning: http://i31.tinypic.com/11w8vo5.png
Zoom of end: http://i29.tinypic.com/50scvc.png
Crush front drop:
http://i27.tinypic.com/zx5eee.jpg
Crush front speed:
http://i30.tinypic.com/i595is.jpg
Stretch:
http://i28.tinypic.com/2cfb3mr.jpg
No warranty against mistakes. (and edited to correct one - gray line in last series changed to green)
For good measure; the house of cards. An example of top-down progressive collapse where the failure mode is connection only - for there are no connections, only the friction between card surfaces and edges. No buckling or deformation of members, or at least it can be neglected. It's 18 stories; crushing begins at the top story and propagates downward. There is mass shedding. The collapse is almost arrested at one point, but then restarts and goes to completion.
The raw data from a new 1DxN routine:
http://i30.tinypic.com/a0a0cw.png
Zoom on interesting part: http://i27.tinypic.com/15y9hle.png
The raw data from a new 1DxN routine:
http://i30.tinypic.com/a0a0cw.png
Zoom on interesting part: http://i27.tinypic.com/15y9hle.png
QUOTE (OneWhiteEye+Mar 13 2008, 06:11 PM)
H2: http://i31.tinypic.com/23mofx1.jpg
This is quite telling.
Thanks for all the work. I'm pleased that the two data collection methods appear to be giving essentially the same results now.
This is quite telling.
Thanks for all the work. I'm pleased that the two data collection methods appear to be giving essentially the same results now.
QUOTE (David B. Benson+Mar 14 2008, 01:54 PM)
This is quite telling.
Are any of you ever going to summarize your FINDINGS and post your CONCLUSIONS?
You know, for those of us who have been skipping past your smearogram posts for some time now.
Arthur
Are any of you ever going to summarize your FINDINGS and post your CONCLUSIONS?
You know, for those of us who have been skipping past your smearogram posts for some time now.
Arthur
QUOTE (adoucette+Mar 14 2008, 12:15 PM)
Are any of you ever going to summarize your FINDINGS and post your CONCLUSIONS?
Yes. The conclusion is that H2 is at least substantially disconfirmed in favor of H1.
Thinking about the physics of the situation and the properties of the materials involved, this is not surprising. But the difference is that the conclusion arises strictly from the data, some of which was obtained by using einsteen's smear-o-gram method.
What perhaps is surprising is that it does appear that WTC 1 fell more slowly than most have stated: NIST's time estimate is much too small, even BLGB's 12.74 seconds for crush-down appears to be a bit too small; the structure [assuming the force and stretch functions used are correct] attained terminal speed (about 20--25 m/s) after about 8--10 seconds.
Yes. The conclusion is that H2 is at least substantially disconfirmed in favor of H1.
Thinking about the physics of the situation and the properties of the materials involved, this is not surprising. But the difference is that the conclusion arises strictly from the data, some of which was obtained by using einsteen's smear-o-gram method.
What perhaps is surprising is that it does appear that WTC 1 fell more slowly than most have stated: NIST's time estimate is much too small, even BLGB's 12.74 seconds for crush-down appears to be a bit too small; the structure [assuming the force and stretch functions used are correct] attained terminal speed (about 20--25 m/s) after about 8--10 seconds.
I don't believe NIST estimates the time of collapse.
From the FAQs
NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A).
...
From video evidence, significant portions of the cores of both buildings (roughly 60 stories of WTC 1 and 40 stories of WTC 2) are known to have stood 15 to 25 seconds after collapse initiation before they, too, began to collapse. Neither the duration of the seismic records nor video evidence (due to obstruction of view caused by debris clouds) are reliable indicators of the total time it took for each building to collapse completely.
Arthur
From the FAQs
NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A).
...
From video evidence, significant portions of the cores of both buildings (roughly 60 stories of WTC 1 and 40 stories of WTC 2) are known to have stood 15 to 25 seconds after collapse initiation before they, too, began to collapse. Neither the duration of the seismic records nor video evidence (due to obstruction of view caused by debris clouds) are reliable indicators of the total time it took for each building to collapse completely.
Arthur
QUOTE (adoucette+Mar 14 2008, 07:15 PM)
Are any of you ever going to summarize your FINDINGS and post your CONCLUSIONS?
You know, for those of us who have been skipping past your smearogram posts for some time now.
Arthur
hahaha, all I can do is laugh. Good point and thanks for the continued smile on my face.
Crushing tinkertoy structures in my garage in an enclosure with a pneumatically-driven piston (with load cell and displacement transducer) at the top is placing very great demands on my time. The crushing goes rather quickly, but the assembly is another matter. It does not help that I'm confounded by the bizarre and alien manner with which pieces connect to each other. I hope you can be patient during this time and content in the understanding that all of your questions will be answered in due time.
You do realize that if the neighbors see you "Crushing tinkertoy structures in my garage in an enclosure with a pneumatically-driven piston " you are likely to be visited by the men in white coats with the suggestion that a 'rest' might be in order.
Don't you?
Arthur
Don't you?
Arthur
QUOTE (adoucette+Mar 14 2008, 01:37 PM)
I don't believe NIST estimates the time of collapse.
Thanks for the correction. I should have said others.
I would be quite interested if anybody had actually estimated the interval from the beginning of the collapse of WTC 1 until the massive, ground level dusts appear. That is (approximately) the end of crush-down, all I care about just now.
Thanks for the correction. I should have said others.
I would be quite interested if anybody had actually estimated the interval from the beginning of the collapse of WTC 1 until the massive, ground level dusts appear. That is (approximately) the end of crush-down, all I care about just now.
QUOTE (OneWhiteEye+Mar 13 2008, 06:11 PM)
Graph legend for residual values -
Dataset <=> color (S2D red, C44789 blue, C447 green, C448 magenta, C449 aqua)
H1: http://i29.tinypic.com/2ajrlgy.jpg
H2: http://i31.tinypic.com/23mofx1.jpg
The first of these is what is expected from well-fitting curves: the residuals form a band above and below zero, about the same width from beginning to end (modulo additional shaking in the latter portion).
The second demonstrates two aspects: the band waves up and down, indicating some aspect of the behavior is not captured by the H2 equation; the S2D (short red) line is poorly correlated with the others.
Together, and plugging in the numbers, this gives about 13.3 decibans down for H2, odds against greater than 10 to 1.
Dataset <=> color (S2D red, C44789 blue, C447 green, C448 magenta, C449 aqua)
H1: http://i29.tinypic.com/2ajrlgy.jpg
H2: http://i31.tinypic.com/23mofx1.jpg
The first of these is what is expected from well-fitting curves: the residuals form a band above and below zero, about the same width from beginning to end (modulo additional shaking in the latter portion).
The second demonstrates two aspects: the band waves up and down, indicating some aspect of the behavior is not captured by the H2 equation; the S2D (short red) line is poorly correlated with the others.
Together, and plugging in the numbers, this gives about 13.3 decibans down for H2, odds against greater than 10 to 1.
I forgot to mention that the argument given at the end of the previous post is due to James Hawthorne, the author of
Inductive Logic --- Stanford Encyclopedia of Philosophy
Inductive Logic --- Stanford Encyclopedia of Philosophy
QUOTE (David B. Benson+Mar 14 2008, 11:45 PM)
I forgot to mention that the argument given at the end of the previous post is due to James Hawthorne, the author of
Inductive Logic --- Stanford Encyclopedia of Philosophy
Nice link. Thanks.
Inductive Logic --- Stanford Encyclopedia of Philosophy
Nice link. Thanks.
The first data out of a DVD dump instead of internet copy.
Dark band and window washer: http://i27.tinypic.com/jgt7pd.jpg
The method yields 0.5 pixel accuracy, one point per frame unless the feature can't be found. There are such drop outs in the washer data due to smoke. In this graph, the antenna hits 3 pixels (~ three-fourths meter) downward motion before the washer registers any motion.
I'm not entirely happy with the conversion process from DVD but it's good enough for now, especially since it's much clearer than the previous copy, which I will no longer be using. I haven't checked yet but, tentatively, it looks like the frame numbers are the same, or close, and the horizontal pixels will have 20 added to them.
The new automated method used to obtain this data I am quite happy with. It has produced the most accurate transcription of motion from the Sauret video anywhere, to the best of my knowledge. If anyone knows of better data I'd be much obliged if you'd point me to it.
Edit: some corrections plus a note -
there are two sets for the dark band in the graph, most likely corresponding to 447 and 448 from the old video, and both will suffer from the same systematic distortion that affected the smearogram data, particularly with the dark band. Being 1D, the same limitations apply to individual columns but this method produced much more data on the band that what I presented and the net result is I can (eventually with a little more programming) correct for the error entirely.
The substance of the correction to the dark band will be to increase the early travel, not sure with the washer but I suspect there will be little or no change.
Dark band and window washer: http://i27.tinypic.com/jgt7pd.jpg
The method yields 0.5 pixel accuracy, one point per frame unless the feature can't be found. There are such drop outs in the washer data due to smoke. In this graph, the antenna hits 3 pixels (~ three-fourths meter) downward motion before the washer registers any motion.
I'm not entirely happy with the conversion process from DVD but it's good enough for now, especially since it's much clearer than the previous copy, which I will no longer be using. I haven't checked yet but, tentatively, it looks like the frame numbers are the same, or close, and the horizontal pixels will have 20 added to them.
The new automated method used to obtain this data I am quite happy with. It has produced the most accurate transcription of motion from the Sauret video anywhere, to the best of my knowledge. If anyone knows of better data I'd be much obliged if you'd point me to it.
Edit: some corrections plus a note -
there are two sets for the dark band in the graph, most likely corresponding to 447 and 448 from the old video, and both will suffer from the same systematic distortion that affected the smearogram data, particularly with the dark band. Being 1D, the same limitations apply to individual columns but this method produced much more data on the band that what I presented and the net result is I can (eventually with a little more programming) correct for the error entirely.
The substance of the correction to the dark band will be to increase the early travel, not sure with the washer but I suspect there will be little or no change.
OneWhiteEye --- That's impressive. Are you really getting straight lines towards the end of the data?
QUOTE (David B. Benson+Mar 15 2008, 03:29 PM)
OneWhiteEye --- That's impressive. Are you really getting straight lines towards the end of the data?
Thanks. Pretty close to straight. Curious, isn't it? Here's what the pixel rate of change looks like:
http://i25.tinypic.com/64lz84.png
so they're not entirely straight. After tooting my horn, I have to back off a bit and caution that the half-integral resolution of the method means it's not ready for prime time. Think of it as analogous to quantum states. There are only so many values possible - in this case, not enough for a decent analysis. There are two ways I'm going to address this and I'm expecting some pretty good results from it, very soon. That's when I'll have numbers instead of graphs, and I believe some curvature will be evident then.
Thanks. Pretty close to straight. Curious, isn't it? Here's what the pixel rate of change looks like:
http://i25.tinypic.com/64lz84.png
so they're not entirely straight. After tooting my horn, I have to back off a bit and caution that the half-integral resolution of the method means it's not ready for prime time. Think of it as analogous to quantum states. There are only so many values possible - in this case, not enough for a decent analysis. There are two ways I'm going to address this and I'm expecting some pretty good results from it, very soon. That's when I'll have numbers instead of graphs, and I believe some curvature will be evident then.
QUOTE (David B. Benson+Mar 15 2008, 03:29 PM)
OneWhiteEye --- That's impressive. Are you really getting straight lines towards the end of the data?
Terminal velocity ? F_netto=0 N .....
Terminal velocity ? F_netto=0 N .....
QUOTE (einsteen+Mar 18 2008, 05:22 AM)
Terminal velocity ?
F_netto=0 N .....
Yes. With the current data and the vertical avalanche resistive force, about 25 m./s after about 9 seconds.
;huh: Don't understand.
F_netto=0 N .....
Yes. With the current data and the vertical avalanche resistive force, about 25 m./s after about 9 seconds.
;huh: Don't understand.
QUOTE (metamars+Oct 23 2007, 04:30 AM)
I've taken a look, in the last couple of days, at a paper called Experimental and Theoretical Studies of Columns Under Axial Impact by Ari-Gur, Weller and Singer (pub. in Int. J. Solids Structures Vol. 18 No. 7 pp619-641 1982)
This paper has relatively simple derivations of displacements due to buckling of columns under a dynamic load. Theory was tested by means of a drop hammer device (similar to Calladine and English). Simple, that is, compared to the derivations in the book Impact - The Theory and Physical Behaviour of Colliding Solids by Werner Goldsmith. Agreement with experiment is good.
I took a look at the Ari-Gur paper to try and quantitatively determine energy dissipation due to elastic vs. non-elastic dissipation.
The following is inexact - I am eyeballing a graphs to derive figures from it. I hope somebody else will follow up by studying the Ari-Gur paper, then giving either one of the authors a call, or else somebody else who actually works in the field of impact studies. I make assumptions that I'm not really sure about, so take with a grain of salt. I would appreciate it if other people studied this paper....
p. 622 of their paper (which I have uploaded) gives 2 compressive strain vs. time plots (side-by-side). The peak strain for the first plot is about 1000 mu, and the peak strain for the second plot is about 1500 mu. I'm not sure which test sample this is for. A pair of graphs on the bottom of p. 633 show experimental and theoretical graphs for one of the steel samples. Oddly enough, the theoretical graph seem to match the experimental graphs on p. 622 better (ignoring the inversion about the time axis.)
In any event, I referred to the theoretical graph, since I am eye-balling things, and this is the easiest to eyeball.
From the graph, the main elastic pulse is (very) roughly equal in area to a box 1000 mu high by .35 msec wide. Since the speed of sound in steel is 5,100 m/s, that means that the initial "pulse" is felt over a length of about 1.5 m. Since all the steel specimens were under 1 meter (max 380 mm), I take this to mean that it's a good approximation to consider the strain as being representative of the specimen as a whole, and furthermore that the rod can transfer elastic energy (to be calculated below) through the rod in an amount equal to 1.5 m/ 230 mm = 6.5 times the elastic strain energy corresponding to a 230 mm rod, compressed 1000 microns, statically. (Actually, this can't be correct, as I will show.)
Please note that I had previously thought that the pulses were smaller than the sample. Thus, I thought the pulses were mostly exiting out the bottom of the impacted rod, never to return.
Now, that seems to be definitely wrong! The fact that nobody ever questioned me on this point just shows, I think, why we need to talk to experts in the field. I don't know that anybody is looking at the relevant studies, besides myself, and I am clearly not a domain expert.
Anyway, rolling right along....
p. 623 has dimension and measurements of the various steel specimens being impacted. Using a middling one, Y5, I have a length of 230 mm, width 19.05 mm, and thickness 1.6 mm.
From Hooke's Law, using a constant of 10^9 N/m^2, I find that the elastic static strain energy is
(19.05 x 10^-3 m) * ( 1.6 x 10^-3 m ) (10^9 N/m^2) * (1,000 / 1,000,000) * (2.3 x 10^-1 m)
= 7.01 Newton
However, the Kinetic Energy is just 1/2 m v^2, where the striking mass has mass 180 grams and velocity 10.05 m/s
so KE = .5 * .18 kg * 100 m^2/s^2
= 9 Newton
Earlier, we saw that the "pulse" would have exceeded the length of the struck object. If we interpret this as meaning that 6.5 x the static strain energy is passing through this object, we end up with an energy sink greater than the energy source! Obviously, a contradiction.
That being the case, it seems unintuitive that the strain energy would "sit around" in the struck rod until after (9 Newton - 7.01 Newton) got dissipated in plastic strain, and then leave through the bottom of the rod. The plastic strain begins after the elastic loading begins, and it's oscillations "of consequence" continue after the main elastic pulse has terminated.
If the main elastic pulse had lasted about as long as the plastic strain oscillations, I would think it likely that all of the 'extra' (i.e., exceeding the static case) elastic energy goes into plastic strain. However, this isn't the case.
All of which means, I'm really not sure what becomes of the elastic energy.
As we are discussing energy dissipation in a collapse, and we want to try and get a handle as to how much elastic strain energy can pass through the bottom of the building via the columns, I would hope that I'm not the only one interested in quantitative experiments which can shed light on this.
This paper has relatively simple derivations of displacements due to buckling of columns under a dynamic load. Theory was tested by means of a drop hammer device (similar to Calladine and English). Simple, that is, compared to the derivations in the book Impact - The Theory and Physical Behaviour of Colliding Solids by Werner Goldsmith. Agreement with experiment is good.
I took a look at the Ari-Gur paper to try and quantitatively determine energy dissipation due to elastic vs. non-elastic dissipation.
The following is inexact - I am eyeballing a graphs to derive figures from it. I hope somebody else will follow up by studying the Ari-Gur paper, then giving either one of the authors a call, or else somebody else who actually works in the field of impact studies. I make assumptions that I'm not really sure about, so take with a grain of salt. I would appreciate it if other people studied this paper....
p. 622 of their paper (which I have uploaded) gives 2 compressive strain vs. time plots (side-by-side). The peak strain for the first plot is about 1000 mu, and the peak strain for the second plot is about 1500 mu. I'm not sure which test sample this is for. A pair of graphs on the bottom of p. 633 show experimental and theoretical graphs for one of the steel samples. Oddly enough, the theoretical graph seem to match the experimental graphs on p. 622 better (ignoring the inversion about the time axis.)
In any event, I referred to the theoretical graph, since I am eye-balling things, and this is the easiest to eyeball.
From the graph, the main elastic pulse is (very) roughly equal in area to a box 1000 mu high by .35 msec wide. Since the speed of sound in steel is 5,100 m/s, that means that the initial "pulse" is felt over a length of about 1.5 m. Since all the steel specimens were under 1 meter (max 380 mm), I take this to mean that it's a good approximation to consider the strain as being representative of the specimen as a whole, and furthermore that the rod can transfer elastic energy (to be calculated below) through the rod in an amount equal to 1.5 m/ 230 mm = 6.5 times the elastic strain energy corresponding to a 230 mm rod, compressed 1000 microns, statically. (Actually, this can't be correct, as I will show.)
Please note that I had previously thought that the pulses were smaller than the sample. Thus, I thought the pulses were mostly exiting out the bottom of the impacted rod, never to return.
Now, that seems to be definitely wrong! The fact that nobody ever questioned me on this point just shows, I think, why we need to talk to experts in the field. I don't know that anybody is looking at the relevant studies, besides myself, and I am clearly not a domain expert.
Anyway, rolling right along....
p. 623 has dimension and measurements of the various steel specimens being impacted. Using a middling one, Y5, I have a length of 230 mm, width 19.05 mm, and thickness 1.6 mm.
From Hooke's Law, using a constant of 10^9 N/m^2, I find that the elastic static strain energy is
(19.05 x 10^-3 m) * ( 1.6 x 10^-3 m ) (10^9 N/m^2) * (1,000 / 1,000,000) * (2.3 x 10^-1 m)
= 7.01 Newton
However, the Kinetic Energy is just 1/2 m v^2, where the striking mass has mass 180 grams and velocity 10.05 m/s
so KE = .5 * .18 kg * 100 m^2/s^2
= 9 Newton
Earlier, we saw that the "pulse" would have exceeded the length of the struck object. If we interpret this as meaning that 6.5 x the static strain energy is passing through this object, we end up with an energy sink greater than the energy source! Obviously, a contradiction.
That being the case, it seems unintuitive that the strain energy would "sit around" in the struck rod until after (9 Newton - 7.01 Newton) got dissipated in plastic strain, and then leave through the bottom of the rod. The plastic strain begins after the elastic loading begins, and it's oscillations "of consequence" continue after the main elastic pulse has terminated.
If the main elastic pulse had lasted about as long as the plastic strain oscillations, I would think it likely that all of the 'extra' (i.e., exceeding the static case) elastic energy goes into plastic strain. However, this isn't the case.
All of which means, I'm really not sure what becomes of the elastic energy.
As we are discussing energy dissipation in a collapse, and we want to try and get a handle as to how much elastic strain energy can pass through the bottom of the building via the columns, I would hope that I'm not the only one interested in quantitative experiments which can shed light on this.
QUOTE (metamars+Mar 19 2008, 11:50 AM)
As we are discussing energy dissipation in a collapse, and we want to try and get a handle as to how much elastic strain energy can pass through the bottom of the building via the columns, I would hope that I'm not the only one interested in quantitative experiments which can shed light on this.
My guess is you are one of the very few who thinks that the amount of energy that could "pass through the bottom of the buildings" is a significant factor in the collapse of the towers.
Since the foundation WAS coupled to bed rock and the seismic energy WAS tracked, I'd say there is already a pretty good estimation of the amount of energy that eventually left via the foundation.
IIRC it was mentioned in one of the Seismic reports.
Arthur
My guess is you are one of the very few who thinks that the amount of energy that could "pass through the bottom of the buildings" is a significant factor in the collapse of the towers.
Since the foundation WAS coupled to bed rock and the seismic energy WAS tracked, I'd say there is already a pretty good estimation of the amount of energy that eventually left via the foundation.
IIRC it was mentioned in one of the Seismic reports.
Arthur
Metamars:
There is something wrong with your calculation!
Energy is in Joules. Force is in Newtons.
Also Hooke's Law constant, k, should have units of Newtons/meter.
There is something wrong with your calculation!
Energy is in Joules. Force is in Newtons.
Also Hooke's Law constant, k, should have units of Newtons/meter.
metamars --- I worked out the transmission coefficient into the bedrock many, many posts back. About 1/3, if I remember correctly. Note that is compression/rarefaction signal. Square that for energy.
QUOTE (NEU-FONZE+Mar 19 2008, 08:51 PM)
Metamars:
There is something wrong with your calculation!
Energy is in Joules. Force is in Newtons.
Also Hooke's Law constant, k, should have units of Newtons/meter.
Sorry, this actually is N-m, not N.
From Hooke's Law, using a constant of 10^9 N/m^2, I find that the elastic static strain energy is
(19.05 x 10^-3 m) * ( 1.6 x 10^-3 m ) (10^9 N/m^2) * (1,000 / 1,000,000) * (2.3 x 10^-1 m)
is
(19.05 x 10^-3)m * ( 1.6 x 10^-3)m * (10^9 N)/m^2 * (1,000 / 1,000,000) * (2.3 x 10^-1) m
= 7.01 Newton-m
(10^9 N/m^2) is the Young's modulus constant for steel (A36, iirc)
1,000 / 1,000,000 is (or should be) the dimensionless strain
KE is 9 Joules
There is something wrong with your calculation!
Energy is in Joules. Force is in Newtons.
Also Hooke's Law constant, k, should have units of Newtons/meter.
Sorry, this actually is N-m, not N.
QUOTE
From Hooke's Law, using a constant of 10^9 N/m^2, I find that the elastic static strain energy is
(19.05 x 10^-3 m) * ( 1.6 x 10^-3 m ) (10^9 N/m^2) * (1,000 / 1,000,000) * (2.3 x 10^-1 m)
is
(19.05 x 10^-3)m * ( 1.6 x 10^-3)m * (10^9 N)/m^2 * (1,000 / 1,000,000) * (2.3 x 10^-1) m
= 7.01 Newton-m
(10^9 N/m^2) is the Young's modulus constant for steel (A36, iirc)
1,000 / 1,000,000 is (or should be) the dimensionless strain
KE is 9 Joules
I was curious and manually tried to determine the south tower's tilt as function of time, the kink is ignored and the angle of the part under the kink is used. The extracted bitmaps had a height of 23 px and x1-x2 is the difference in x-axis of a line that has been added on a couple of frames.
frame , x1-x2 , arctan[(x1-x2)/23]
0 , 0 , 0
6 , 0 , 0
12 , 1 , 2.5
26 , 2 , 5.0
32 , 2 , 5.0
36 , 3 , 7.4
40 , 3 , 7.4
47 , 4 , 9.9
54 , 5 , 12.3
60 , 7 , 16.9
64 , 8 , 19.2
68 , 10 , 23.5
75 , 13 , 29.5
82 , 19 , 39.6
88 , 23 , 45.0
92 , 25 , 47.4
96 , 27 , 49.6
101 , 30 , 52.5
This leads to this plot
South Tower's tilt (in degrees) as function of frame
The framerate of the movie was 30, but it could also be converted from 29.97, but the behavior in the beginning is interesting, I see that we need more data points in the beginning. It is a typical function which for which the 2nd derivative is zero at frame 70 because the derivative has a peak there (I forgot the name of such a function), there is also more data in the movie somewhere at the end but I only extracted some frames in the beginning
frame , x1-x2 , arctan[(x1-x2)/23]
0 , 0 , 0
6 , 0 , 0
12 , 1 , 2.5
26 , 2 , 5.0
32 , 2 , 5.0
36 , 3 , 7.4
40 , 3 , 7.4
47 , 4 , 9.9
54 , 5 , 12.3
60 , 7 , 16.9
64 , 8 , 19.2
68 , 10 , 23.5
75 , 13 , 29.5
82 , 19 , 39.6
88 , 23 , 45.0
92 , 25 , 47.4
96 , 27 , 49.6
101 , 30 , 52.5
This leads to this plot
South Tower's tilt (in degrees) as function of frame
The framerate of the movie was 30, but it could also be converted from 29.97, but the behavior in the beginning is interesting, I see that we need more data points in the beginning. It is a typical function which for which the 2nd derivative is zero at frame 70 because the derivative has a peak there (I forgot the name of such a function), there is also more data in the movie somewhere at the end but I only extracted some frames in the beginning
einsteen ---- Very nice! Is there a way to do this for WTC 1?
Of course if there is a proper video around that
- has sufficient resolution and framerate
- has a good camera angle
- doesn't start after the collapse started already
But I don't know such a video
ps. it is interesting that after my post the hits went from
268009 to 268244 although you only replied, I guess a lot of
people like to know that!
- has sufficient resolution and framerate
- has a good camera angle
- doesn't start after the collapse started already
But I don't know such a video
ps. it is interesting that after my post the hits went from
268009 to 268244 although you only replied, I guess a lot of
people like to know that!
einsteen --- I believe NEU-FONZE knows of one.
Some of those hits might be one of more scarfers. For example, Google caches lots. Some of the others might be attempted attacks by hackbots attempting to get into the site.
Some of those hits might be one of more scarfers. For example, Google caches lots. Some of the others might be attempted attacks by hackbots attempting to get into the site.
Einsteen + DBB:
Yes, there are at least two videos of WTC 1 showing the drop AND tilt reasonably well. There is a set of frames from one of them at:
http://wtc.1accesshost.com/blast.html
Yes, there are at least two videos of WTC 1 showing the drop AND tilt reasonably well. There is a set of frames from one of them at:
http://wtc.1accesshost.com/blast.html
thanks but I already have that one I think, it would be nice to have one that is perpendicular.
Einsteen:
Ever hear the saying "beggars can't be choosers"?
Ever hear the saying "beggars can't be choosers"?
You mean (as we say here) you don't look in a given horse's mouth...
Einsteen:
Oui, or is that neigh?
Oui, or is that neigh?
Is that French Canadian?
back to business.. I hope I can make one for wtc1 later. The wtc2 movie was interesting because it was, hi-res (or better suff-res) hi-framerate, it was perpendicular, i.e. the axis of rotation was aligned with that of the camera.
I would like to repeat it again for that movie and then use two smearograms (I already posted one without extracting the data), the only problem is that we get similar effects as described by OneWhiteEye, if we have this shape for example (the left edge of the top section)
|| ||
and it rotates then the smearograms (which is a range of dark and lighter values) get an additional error because the colour is not uniform, the width of the band changes with rotation, smoke sometimes appears etc. The perfect case is a two coloured movie of a single line rotating, but we don't have that. In this case the manual method has the advantage that the human eye is able to recognize the wall and draw a line on it. The problem I had with the few chosen frames is that when measuring the difference for small rotations it is a matter of measuring the difference in the following line
x
x
x
.x
.x
.x
..x
..x
..x
because that is how (added) lines look on bitmaps, sometimes it is even a difference of one pixel, in that case the smearogram method could provide more info.
If we finally have the function tilt(angle) then one could calculate the energy that is lost in the drop of the block, one could assume it stays intact and then that energy value includes the complex effects due to rotation. An additional difficulty then is the amount of mass "added" to the top section, it is obvious that the floors don't nicely pancake in the beginning.
I would like to repeat it again for that movie and then use two smearograms (I already posted one without extracting the data), the only problem is that we get similar effects as described by OneWhiteEye, if we have this shape for example (the left edge of the top section)
|| ||
and it rotates then the smearograms (which is a range of dark and lighter values) get an additional error because the colour is not uniform, the width of the band changes with rotation, smoke sometimes appears etc. The perfect case is a two coloured movie of a single line rotating, but we don't have that. In this case the manual method has the advantage that the human eye is able to recognize the wall and draw a line on it. The problem I had with the few chosen frames is that when measuring the difference for small rotations it is a matter of measuring the difference in the following line
x
x
x
.x
.x
.x
..x
..x
..x
because that is how (added) lines look on bitmaps, sometimes it is even a difference of one pixel, in that case the smearogram method could provide more info.
If we finally have the function tilt(angle) then one could calculate the energy that is lost in the drop of the block, one could assume it stays intact and then that energy value includes the complex effects due to rotation. An additional difficulty then is the amount of mass "added" to the top section, it is obvious that the floors don't nicely pancake in the beginning.
ps. forgot about my latest plot, I made some major mistake
Thanks Einsteen. Yes, I was wondering about your plot... the angles appear to be much larger than I have previously estimated for WTC 2. I think the tilt was certainly less than 35 deg before it was obscured by smoke and debris..... although there is a perspective correction required for the video I was using.
I created that plot, posted it and even didn't check the values because it was a trivial operation, stoopid me, I think I divided x by y or something like that (even DBB's sharp eyes missed it...) , forgot about it, sorry, next try later. A quick look at the video says it must be about < 30 degrees
Engineer society accused of cover-ups
...
In 2002, the society's report on the World Trade Center praised the buildings for remaining standing long enough to allow tens thousands of people to flee.
But, the report said, skyscrapers are not typically designed to withstand airplane impacts. Instead of hardening buildings against such impacts, it recommended improving aviation security and fire protection.
Abolhassan Astaneh-Asl, a structural engineer and forensics expert, contends his computer simulations disprove the society's findings that skyscrapers could not be designed to withstand the impact of a jetliner.
Astaneh-Asl, who received money from the National Science Foundation to investigate the collapse, insisted most New York skyscrapers built with traditional designs would survive such an impact and prevent the kind of fires that brought down the twin towers.
...
news.yahoo.com/s/ap/20080325/ap_on_re_us/embattled_engineers
Hm. hm... so, most other steelbuildings would survive a plane impact... but the only building which was specificially designed to whithstand B707 impact... could not !!
Hm..hm...hm...
...
In 2002, the society's report on the World Trade Center praised the buildings for remaining standing long enough to allow tens thousands of people to flee.
But, the report said, skyscrapers are not typically designed to withstand airplane impacts. Instead of hardening buildings against such impacts, it recommended improving aviation security and fire protection.
Abolhassan Astaneh-Asl, a structural engineer and forensics expert, contends his computer simulations disprove the society's findings that skyscrapers could not be designed to withstand the impact of a jetliner.
Astaneh-Asl, who received money from the National Science Foundation to investigate the collapse, insisted most New York skyscrapers built with traditional designs would survive such an impact and prevent the kind of fires that brought down the twin towers.
...
news.yahoo.com/s/ap/20080325/ap_on_re_us/embattled_engineers
Hm. hm... so, most other steelbuildings would survive a plane impact... but the only building which was specificially designed to whithstand B707 impact... could not !!
Hm..hm...hm...
The reference is to the use of SFRM and the lightweight Truss design for the floors.
TRADITIONAL, in his reference is use of concrete and post and beam type construction.
Use of both might have prevented collapse.
Of course its a moot point, since you couldn't build the WTC towers using post & beam and concrete.
There was a reason the WTC towers were the tallest building in the world when built, and part of that had to do with the how LIGHT its structure was.
Oh, and in case you missed it, the buildings DID survive the impacts of both the planes.
It was the unfought fires that brought the buildings down.
Arthur
TRADITIONAL, in his reference is use of concrete and post and beam type construction.
Use of both might have prevented collapse.
Of course its a moot point, since you couldn't build the WTC towers using post & beam and concrete.
There was a reason the WTC towers were the tallest building in the world when built, and part of that had to do with the how LIGHT its structure was.
Oh, and in case you missed it, the buildings DID survive the impacts of both the planes.
It was the unfought fires that brought the buildings down.
Arthur
QUOTE (adoucette+Mar 27 2008, 11:38 AM)
The reference is to the use of SFRM and the lightweight Truss design for the floors.
TRADITIONAL, in his reference is use of concrete and post and beam type construction.
Use of both might have prevented collapse.
Of course its a moot point, since you couldn't build the WTC towers using post & beam and concrete.
There was a reason the WTC towers were the tallest building in the world when built, and part of that had to do with the how LIGHT its structure was.
Oh, and in case you missed it, the buildings DID survive the impacts of both the planes.
It was the unfought fires that brought the buildings down.
Arthur
Isn't that a matter of definition, when a plane crashes you expect fire + fuel + damage, they didn't survive then. If you say it was only the fire then it looks like you mean it could also occur with fire only.
TRADITIONAL, in his reference is use of concrete and post and beam type construction.
Use of both might have prevented collapse.
Of course its a moot point, since you couldn't build the WTC towers using post & beam and concrete.
There was a reason the WTC towers were the tallest building in the world when built, and part of that had to do with the how LIGHT its structure was.
Oh, and in case you missed it, the buildings DID survive the impacts of both the planes.
It was the unfought fires that brought the buildings down.
Arthur
Isn't that a matter of definition, when a plane crashes you expect fire + fuel + damage, they didn't survive then. If you say it was only the fire then it looks like you mean it could also occur with fire only.
No one ever expected a plane flying at that speed doing that much damage to the structure.
And, NO, I didn't say it was fire only.
NIST showed that a fire alone would not have brought the towers down.
The fire was an issue because the SFRM was widely disloged and because of the amount of structural damage sustained.
Both of which were directly related to the impact energies of a plane flying at ~500 mph.
Consider that they were not assuming a terrorist attack and thus the only reason for a plane to be at the height of the WTC would be landing (at take off a jet reachs altitudes above the WTC before leaving the airport boundary), and thus would be flying UNDER 200 mph, and you can see that the energy of the impact would be significantly smaller.
Arthur
And, NO, I didn't say it was fire only.
NIST showed that a fire alone would not have brought the towers down.
The fire was an issue because the SFRM was widely disloged and because of the amount of structural damage sustained.
Both of which were directly related to the impact energies of a plane flying at ~500 mph.
Consider that they were not assuming a terrorist attack and thus the only reason for a plane to be at the height of the WTC would be landing (at take off a jet reachs altitudes above the WTC before leaving the airport boundary), and thus would be flying UNDER 200 mph, and you can see that the energy of the impact would be significantly smaller.
Arthur
The engineering study conducted at the University of Edinburgh, on the other hand, concluded that sufficient (unfought) fire would collapse an unimpacted WTC tower, eventually.
QUOTE (adoucette+Mar 27 2008, 02:31 PM)
No one ever expected a plane flying at that speed doing that much damage to the structure.
But most other (if not all) skyscrapers in NY would survive such an impact.
"Astaneh-Asl, who received money from the National Science Foundation to investigate the collapse, insisted most New York skyscrapers built with traditional designs would survive such an impact and prevent the kind of fires that brought down the twin towers."
WTC was much stronger than other skyscrapers in all the world. The first skyscrapers in all the history designed to survive a large jetliners impact.
Understand ?
It makes no sense. It holds no water.
Something is rotten in Denmark !
When years goes by it will only be more and more obvious that explosives was involved.
But most other (if not all) skyscrapers in NY would survive such an impact.
"Astaneh-Asl, who received money from the National Science Foundation to investigate the collapse, insisted most New York skyscrapers built with traditional designs would survive such an impact and prevent the kind of fires that brought down the twin towers."
WTC was much stronger than other skyscrapers in all the world. The first skyscrapers in all the history designed to survive a large jetliners impact.
Understand ?
It makes no sense. It holds no water.
Something is rotten in Denmark !
When years goes by it will only be more and more obvious that explosives was involved.
Daru, do you think Astaneh-Asl really KNOWS that statement is true?
Here's a hint.
NO.
What he is saying though is that the more tradiitional POST AND BEAM construction along with the use of reinforced concrete would withstand an aircraft impact better than a lightweight steel tube in tube design that used even lighter weight truss framing to provide lateral stabality and where the majority of the insulation was SFRM or sheetrock.
Its this LIGHTWEIGHT construction (about the first to dispense with reinforced concrete) that shows that the WTC was not "much stronger than other skyscrapers in all the world" nor was it DESIGNED to withstand a high speed impact of a large jet.
Daru, it has BEEN years, and the many feeble attempts by halfwits to show that explosives were involved have been shown to be beyond silly.
As time goes by the attempts get more feeble and the wits drop below the halfway mark.
Like yours.
Arthur
Here's a hint.
NO.
What he is saying though is that the more tradiitional POST AND BEAM construction along with the use of reinforced concrete would withstand an aircraft impact better than a lightweight steel tube in tube design that used even lighter weight truss framing to provide lateral stabality and where the majority of the insulation was SFRM or sheetrock.
Its this LIGHTWEIGHT construction (about the first to dispense with reinforced concrete) that shows that the WTC was not "much stronger than other skyscrapers in all the world" nor was it DESIGNED to withstand a high speed impact of a large jet.
Daru, it has BEEN years, and the many feeble attempts by halfwits to show that explosives were involved have been shown to be beyond silly.
As time goes by the attempts get more feeble and the wits drop below the halfway mark.
Like yours.
Arthur
QUOTE
"Astaneh-Asl, who received money from the National Science Foundation to investigate the collapse, insisted most New York skyscrapers built with traditional designs would survive such an impact and prevent the kind of fires that brought down the twin towers."
Traditional, the towers were NOT, otherwise they would not have been so tall.
QUOTE (->
| QUOTE |
| "Astaneh-Asl, who received money from the National Science Foundation to investigate the collapse, insisted most New York skyscrapers built with traditional designs would survive such an impact and prevent the kind of fires that brought down the twin towers." |
Traditional, the towers were NOT, otherwise they would not have been so tall.
Astaneh-Asl says that the reason for undertaking his studies is not to implicate the designers, but rather to look into the design and answer the basic question that has bothered him since September 11: “Why did these towers collapse so quickly and so completely while other steel structures, including skyscrapers, under intense fire for hours, have not failed?”
He says that he feels he is closing in on the answer. “These structures were so unique that their collapse does not represent the performance expected of any other existing steel high-rise structure subjected to the same scenario,” he says.
QUOTE (David B. Benson+Mar 27 2008, 11:11 AM)
The engineering study conducted at the University of Edinburgh, on the other hand, concluded that sufficient (unfought) fire would collapse an unimpacted WTC tower, eventually.
Sorta.
What they said:
But their 2-D analysis was rather primitive and not very realistic as to the way fires would spread in a typical office fire (burning out in one area as they moved on).
They DID show, that the fundmental design weakness of the WTC towers was to widespread multi-floor fires and the reliance on the diaphram like floor trusses to provide lateral support to the slender external columns.
Now toss in structural damage from the plane impact and the resulting widespread multi-floor fires and their work does show how the buckling of one of the long truss supported perimeter walls was a LIKELY outcome.
They also showed that the result did not rely on either the perimeter columns or the floor trusses to have been heated significantly.
Still, they in no way tried to model the spread of an actual fire in an actual building, as NIST did, so the NIST conclusions in NIST NCSTAR 1-5 about this hypothetcial event is still based on a more rigourous approach than the Edinburgh work.
Arthur
Sorta.
What they said:
QUOTE
It can therefore be provisionally concluded that these buildings could have collapsed as a result of a major fire event.
But their 2-D analysis was rather primitive and not very realistic as to the way fires would spread in a typical office fire (burning out in one area as they moved on).
They DID show, that the fundmental design weakness of the WTC towers was to widespread multi-floor fires and the reliance on the diaphram like floor trusses to provide lateral support to the slender external columns.
Now toss in structural damage from the plane impact and the resulting widespread multi-floor fires and their work does show how the buckling of one of the long truss supported perimeter walls was a LIKELY outcome.
They also showed that the result did not rely on either the perimeter columns or the floor trusses to have been heated significantly.
Still, they in no way tried to model the spread of an actual fire in an actual building, as NIST did, so the NIST conclusions in NIST NCSTAR 1-5 about this hypothetcial event is still based on a more rigourous approach than the Edinburgh work.
Arthur
DBB, you have a small PM
This brief video is a good example of a top-down progressive collapse. The falling mass at the beginning was too much for the floor below to withstand. Notice that the main floors collapse via failure of their connections to the columns, leaving the columns standing at the end of the collapse.
http://s134.photobucket.com/albums/q91/sha...nt=collapse.flv
That's great Shagster. This is indeed the classical domino effect but that was not what happened with the top section, the man should still lie in his bed and the core columns (not there) have to buckle in order to get his bed moved downwards as an intact whole.
einsteen
Actually, the tilt of the top sections could have snapped the welds on the core columns(especially in two) and displaced the ends so they no longer bore upon each other. Previous calculations in this thread indicate as little as 7 degrees to snap those welds.
Grumpy
QUOTE
This is indeed the classical domino effect but that was not what happened with the top section, the man should still lie in his bed and the core columns (not there) have to buckle in order to get his bed moved downwards as an intact whole.
Actually, the tilt of the top sections could have snapped the welds on the core columns(especially in two) and displaced the ends so they no longer bore upon each other. Previous calculations in this thread indicate as little as 7 degrees to snap those welds.
Grumpy
I have a question.
If this is where the plane hits the building:
________
|-----------|
|-----------|
|----\-/----| <----plane
|-----------|
|-----------|
|-----------|
|-----------|
Assume that the plane completely destroys the inner column at this point. Now, the part of the building above where the plane hit will fall onto the building under it. (Under where the plane hit, the building would obviously stand if the chunk above where the plane hit was immediately removed after impact). Now as the top falls on the rest of the building, the top piece would have an equal force acting on it (Newton's 3rd law). If this top part of the building can crumble the rest of the building under it, then wouldn't this top piece also crumble? If you watch the footage of the tower falling, this upper block stays intact until the building hits the ground. This either means that Newton was wrong, or the top block's momentum was not the culprit on the rest of the building's collapse. Clearly, this is more of a freefall than how a building would collapse according to physics, no?
________
|-----------|
|-----------|
|\/\/\/\/\/\/\/\| <-----The separation of the 'upper block' from the 'lower block'
|-----------|
|-----------|
|-----------|
|-----------|
If this is where the plane hits the building:
________
|-----------|
|-----------|
|----\-/----| <----plane
|-----------|
|-----------|
|-----------|
|-----------|
Assume that the plane completely destroys the inner column at this point. Now, the part of the building above where the plane hit will fall onto the building under it. (Under where the plane hit, the building would obviously stand if the chunk above where the plane hit was immediately removed after impact). Now as the top falls on the rest of the building, the top piece would have an equal force acting on it (Newton's 3rd law). If this top part of the building can crumble the rest of the building under it, then wouldn't this top piece also crumble? If you watch the footage of the tower falling, this upper block stays intact until the building hits the ground. This either means that Newton was wrong, or the top block's momentum was not the culprit on the rest of the building's collapse. Clearly, this is more of a freefall than how a building would collapse according to physics, no?
________
|-----------|
|-----------|
|\/\/\/\/\/\/\/\| <-----The separation of the 'upper block' from the 'lower block'
|-----------|
|-----------|
|-----------|
|-----------|
QUOTE (Fusilli_Jerry89+Apr 3 2008, 03:06 AM)
I have a question.
If this is where the plane hits the building:
________
|-----------|
|-----------|
|----\-/----| <----plane
|-----------|
|-----------|
|-----------|
|-----------|
Assume that the plane completely destroys the inner column at this point. Now, the part of the building above where the plane hit will fall onto the building under it. (Under where the plane hit, the building would obviously stand if the chunk above where the plane hit was immediately removed after impact). Now as the top falls on the rest of the building, the top piece would have an equal force acting on it (Newton's 3rd law). If this top part of the building can crumble the rest of the building under it, then wouldn't this top piece also crumble? If you watch the footage of the tower falling, this upper block stays intact until the building hits the ground. This either means that Newton was wrong, or the top block's momentum was not the culprit on the rest of the building's collapse. Clearly, this is more of a freefall than how a building would collapse according to physics, no?
________
|-----------|
|-----------|
|\/\/\/\/\/\/\/\| <-----The separation of the 'upper block' from the 'lower block'
|-----------|
|-----------|
|-----------|
|-----------|
Two points.
You can't (AFAIK) see the top block "until the building hits the ground" in any video I've ever seen.
If you have such video please post a link to it.
Still, the concept that presumes that that is what happened is known as "Crush Down/Crush Up"
You can read about it here:
http://www.civil.northwestern.edu/people/b...d%206-22-07.pdf
The short version:
(Use the upper block as C, \/\/\/\/\/\/\/\ = B and the lower tower as A)
During crush-down, the moving upper part of tower (C in Fig. 1 bottom), having a compacted layer of debris at its bottom (zone B), is crushing the lower part (zone A) with little damage to itself. During crush-up, the moving upper part A of tower is being crushed by the compacted debris B resting on the ground.
The separation crush-down and crush-up phases is justified by the condition of dynamic equilibrium of compacted layer B;
Arthur
If this is where the plane hits the building:
________
|-----------|
|-----------|
|----\-/----| <----plane
|-----------|
|-----------|
|-----------|
|-----------|
Assume that the plane completely destroys the inner column at this point. Now, the part of the building above where the plane hit will fall onto the building under it. (Under where the plane hit, the building would obviously stand if the chunk above where the plane hit was immediately removed after impact). Now as the top falls on the rest of the building, the top piece would have an equal force acting on it (Newton's 3rd law). If this top part of the building can crumble the rest of the building under it, then wouldn't this top piece also crumble? If you watch the footage of the tower falling, this upper block stays intact until the building hits the ground. This either means that Newton was wrong, or the top block's momentum was not the culprit on the rest of the building's collapse. Clearly, this is more of a freefall than how a building would collapse according to physics, no?
________
|-----------|
|-----------|
|\/\/\/\/\/\/\/\| <-----The separation of the 'upper block' from the 'lower block'
|-----------|
|-----------|
|-----------|
|-----------|
Two points.
You can't (AFAIK) see the top block "until the building hits the ground" in any video I've ever seen.
If you have such video please post a link to it.
Still, the concept that presumes that that is what happened is known as "Crush Down/Crush Up"
You can read about it here:
http://www.civil.northwestern.edu/people/b...d%206-22-07.pdf
The short version:
(Use the upper block as C, \/\/\/\/\/\/\/\ = B and the lower tower as A)
During crush-down, the moving upper part of tower (C in Fig. 1 bottom), having a compacted layer of debris at its bottom (zone B), is crushing the lower part (zone A) with little damage to itself. During crush-up, the moving upper part A of tower is being crushed by the compacted debris B resting on the ground.
The separation crush-down and crush-up phases is justified by the condition of dynamic equilibrium of compacted layer B;
Arthur
QUOTE (Fusilli_Jerry89+Apr 3 2008, 01:06 AM)
If this top part of the building can crumble the rest of the building under it, then wouldn't this top piece also crumble?
Yes, for the first fraction of a second. After that, the crushed materials between the top part and the intact portion of the bottom part acts as a buffer, protecting the top part. The top part rides down on the every increasing crushed part.
Yes, for the first fraction of a second. After that, the crushed materials between the top part and the intact portion of the bottom part acts as a buffer, protecting the top part. The top part rides down on the every increasing crushed part.
QUOTE (David B. Benson+Apr 3 2008, 04:45 PM)
Yes, for the first fraction of a second. After that, the crushed materials between the top part and the intact portion of the bottom part acts as a buffer, protecting the top part. The top part rides down on the every increasing crushed part.
But this is assuming that the building is in freefall, no? If it fell they way a building should fall, wouldn't it few in a bunch of rapid successions rather than a smooth continuous fall? Rapid successions would mean that the top block would be repeatedly pounded to dust. There can't be a buffer if its in successions. Even if a piece between is protecting the upper block, the force from the lower part of the building will act on it with a force, and in turn that piece will act on the upper block with almost the same force (friction and sh!t may cause it to not exactly be equal). Anyways, the block should have crumbled before it hit the rubble at the bottom since it was wat was causing the collapse.
But this is assuming that the building is in freefall, no? If it fell they way a building should fall, wouldn't it few in a bunch of rapid successions rather than a smooth continuous fall? Rapid successions would mean that the top block would be repeatedly pounded to dust. There can't be a buffer if its in successions. Even if a piece between is protecting the upper block, the force from the lower part of the building will act on it with a force, and in turn that piece will act on the upper block with almost the same force (friction and sh!t may cause it to not exactly be equal). Anyways, the block should have crumbled before it hit the rubble at the bottom since it was wat was causing the collapse.
QUOTE (adoucette+Apr 3 2008, 01:14 PM)
Two points.
You can't (AFAIK) see the top block "until the building hits the ground" in any video I've ever seen.
If you have such video please post a link to it.
Still, the concept that presumes that that is what happened is known as "Crush Down/Crush Up"
You can read about it here:
http://www.civil.northwestern.edu/people/b...d%206-22-07.pdf
The short version:
(Use the upper block as C, \/\/\/\/\/\/\/\ = B and the lower tower as A)
During crush-down, the moving upper part of tower (C in Fig. 1 bottom), having a compacted layer of debris at its bottom (zone, is crushing the lower part (zone A) with little damage to itself. During crush-up, the moving upper part A of tower is being crushed by the compacted debris B resting on the ground.
The separation crush-down and crush-up phases is justified by the condition of dynamic equilibrium of compacted layer B;
Arthur
ill try to find a video a little later, but im extremely busy right now with exams and ***. Ill ask my physics prof about this next week...
You can't (AFAIK) see the top block "until the building hits the ground" in any video I've ever seen.
If you have such video please post a link to it.
Still, the concept that presumes that that is what happened is known as "Crush Down/Crush Up"
You can read about it here:
http://www.civil.northwestern.edu/people/b...d%206-22-07.pdf
The short version:
(Use the upper block as C, \/\/\/\/\/\/\/\ = B and the lower tower as A)
During crush-down, the moving upper part of tower (C in Fig. 1 bottom), having a compacted layer of debris at its bottom (zone
, is crushing the lower part (zone A) with little damage to itself. During crush-up, the moving upper part A of tower is being crushed by the compacted debris B resting on the ground.The separation crush-down and crush-up phases is justified by the condition of dynamic equilibrium of compacted layer B;
Arthur
ill try to find a video a little later, but im extremely busy right now with exams and ***. Ill ask my physics prof about this next week...
Fusilli_Jerry89
No, it is a smooth(relatively) process because the energy of the top block was at least 8.4 times that required to destroy the next undamaged floor. That floor failed long before it could bring the top section to a stop. Since acceleration due to gravity is progressive, it was even worse for each successive floor after that. While the floor could provide SOME resistance(therefore slowing the top to below free fall speed), it never had a chance of stopping the collapse.
No, it is a smooth(relatively) process because the energy of the top block was at least 8.4 times that required to destroy the next undamaged floor. That floor failed long before it could bring the top section to a stop. Since acceleration due to gravity is progressive, it was even worse for each successive floor after that. While the floor could provide SOME resistance(therefore slowing the top to below free fall speed), it never had a chance of stopping the collapse.
Anyways, the block should have crumbled before it hit the rubble at the bottom since it was wat was causing the collapse.
No, the top rode down on an ever increasing cushion of rubble, only when the bottom of that cushion contacted bedrock did the crush up of the top part begin.
Grumpy
QUOTE
But this is assuming that the building is in freefall, no? If it fell they way a building should fall, wouldn't it few in a bunch of rapid successions rather than a smooth continuous fall? Rapid successions would mean that the top block would be repeatedly pounded to dust. There can't be a buffer if its in successions
No, it is a smooth(relatively) process because the energy of the top block was at least 8.4 times that required to destroy the next undamaged floor. That floor failed long before it could bring the top section to a stop. Since acceleration due to gravity is progressive, it was even worse for each successive floor after that. While the floor could provide SOME resistance(therefore slowing the top to below free fall speed), it never had a chance of stopping the collapse.
QUOTE (->
| QUOTE |
| But this is assuming that the building is in freefall, no? If it fell they way a building should fall, wouldn't it few in a bunch of rapid successions rather than a smooth continuous fall? Rapid successions would mean that the top block would be repeatedly pounded to dust. There can't be a buffer if its in successions |
No, it is a smooth(relatively) process because the energy of the top block was at least 8.4 times that required to destroy the next undamaged floor. That floor failed long before it could bring the top section to a stop. Since acceleration due to gravity is progressive, it was even worse for each successive floor after that. While the floor could provide SOME resistance(therefore slowing the top to below free fall speed), it never had a chance of stopping the collapse.
Anyways, the block should have crumbled before it hit the rubble at the bottom since it was wat was causing the collapse.
No, the top rode down on an ever increasing cushion of rubble, only when the bottom of that cushion contacted bedrock did the crush up of the top part begin.
Grumpy
Fusilli_Jerry89 --- The tilt of the top part was enough, even for WTC 1, that about 3--4 floors were in various stages of being crushed simultaneously. So the progression was completely smooth, as careful measurements taken from videos show.
QUOTE (Grumpy+Apr 4 2008, 12:51 PM)
Fusilli_Jerry89
No, it is a smooth(relatively) process because the energy of the top block was at least 8.4 times that required to destroy the next undamaged floor. That floor failed long before it could bring the top section to a stop. Since acceleration due to gravity is progressive, it was even worse for each successive floor after that. While the floor could provide SOME resistance(therefore slowing the top to below free fall speed), it never had a chance of stopping the collapse.
No, the top rode down on an ever increasing cushion of rubble, only when the bottom of that cushion contacted bedrock did the crush up of the top part begin.
Grumpy
Don't u mean that acceleration due to gravity is relatively constant (We are close to the surface of the earth here). Also, your logic about it riding on top of a growing pile of rubble makes no sense... If the pile is growing, then that means that the building under the rubble is breaking and becoming part of the rubble. This rubble would therefore be slowed a bit and hit the block above... I'm a physics major so please tell me what I'm not seeing here...
No, it is a smooth(relatively) process because the energy of the top block was at least 8.4 times that required to destroy the next undamaged floor. That floor failed long before it could bring the top section to a stop. Since acceleration due to gravity is progressive, it was even worse for each successive floor after that. While the floor could provide SOME resistance(therefore slowing the top to below free fall speed), it never had a chance of stopping the collapse.
No, the top rode down on an ever increasing cushion of rubble, only when the bottom of that cushion contacted bedrock did the crush up of the top part begin.
Grumpy
Don't u mean that acceleration due to gravity is relatively constant (We are close to the surface of the earth here). Also, your logic about it riding on top of a growing pile of rubble makes no sense... If the pile is growing, then that means that the building under the rubble is breaking and becoming part of the rubble. This rubble would therefore be slowed a bit and hit the block above... I'm a physics major so please tell me what I'm not seeing here...
QUOTE (Fusilli_Jerry89+Apr 4 2008, 04:44 PM)
please tell me what I'm not seeing here...
Are you familiar with the construction of the towers?
Arthur
Are you familiar with the construction of the towers?
Arthur
QUOTE (Fusilli_Jerry89+Apr 4 2008, 02:44 PM)
This rubble would therefore be slowed a bit and hit the block above...
Yes, except that 'hit' ought to be replaced by 'slow down'. The inertial equation for crush down is published in ASCE J. Engg. Mechanics in a paper by Bazant & Verdure. A copy is available from Prof. Bazant's publication web pages.
Yes, except that 'hit' ought to be replaced by 'slow down'. The inertial equation for crush down is published in ASCE J. Engg. Mechanics in a paper by Bazant & Verdure. A copy is available from Prof. Bazant's publication web pages.
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