12-04-2011, 02:07 PM
Mr. Lewis,
I believe you are not familiar with the facts and observations. The collapse time is difficult at best to nail down because it began for example, in the case of WTC 1 with the top section of about 14 or so stories being destroyed from about the 96 floor up to the top. If you observe the many videos it appears as if those stories are being "crushed" (destroyed) at the bottom and the ones above descend. This sequence takes approximately 4 seconds. The motion of the roof line does wobble about, both before the actual descent and as it comes down. This is not easily or perhaps impossible to see with the naked eye, but scientists have analyzed the motion with "trace" software and determined its motion. The antenna atop WTC1 also clearly tilts to the east and south in ADVANCE of any obvious to the naked eye motion of the roof line.
We can conclude from the antenna motion that parts of the structure supporting the antenna were failing in ADVANCE of the roof decent or visible destruction and hence the antenna's motion. We don't know what caused this motion and it could be incendiaries or explosive or weakened steel. Whatever it was it occurred inside the core and out of our view.
Once the entire 15 or so stories came apart (whatever the mechanism) they represented about 30,000 tons of material which had descended over the 4 seconds onto the top floor(s) of the lower section below the "crush" (crash) zone of the building up at the mid 90s. Some material from the destruction of the top went over the side. Nothing was shot up. Study the videos. The top section experienced a gravity driven... collapse of unknown cause... onto /into the lower section of the tower.
The the destruction phase which I refer to as ROOSD - runaway open office space destruction occurred. The appears to travel at about 60 mph or 100 feet per second destroying 8 floors in one second. Obvious the collapse begins at 0 mph accelerates up to 60 or so mph and then no faster. This part of the destruction is 1100 feet and therefore tool about 10+ seconds. So the total elapsed time of visible collapse was about 14 seconds. We could not see the "end" of the collapse and we can't tell precisely when it began except to use the first downward motion of the roof or the antenna, but clearly the "collapse" was already happening as structure was failing unseen behind the facade before the facade and the roof moved.
The collapse elapse times might be ascertained from seismic records but it is yet to be determined when that began as well. There are delays in the seismic waves and correlating them to the videos is imprecise. Plus the early movement likely would not have a seismic signature. That would begin only after there was significant crashing of heavy material on the ground... and we know that something in free fall from 1300 feet wouldn't show up for 9 seconds after it began falling.
So the collapse time is quite imprecise and given as a range since we can truly only know when it ended. And there's the Spire which stood for perhaps 15 seconds AFTER the global collapse of the floors and facade. It's likely and possible that parts of the spire were falling in the period when the global collapse obscured or view until we could see the Spire when most of the dust was blown to the SE and then it too collapsed.
So what was the total collapse time for WTC 1? When did it literally begin? When do we start the clock when we observe the first motion? And when does the collapse end... when the Spire falls?
Finally, the 60+ mph is quite fast.. the velocity of a free falling object after about 3 seconds. However it is not an unreasonable speed considering that the tower was 96% air, and the floors themselves were on 4" thick no-stone aggregate lightweight and very brittle concrete and these floors and the 88 trusses which supported them would offer very little resistance to 10's of thousands of tons of falling debris... and they would "fail" almost instantly from the impact.
Larry Silverstein is reported to have said he made the decision to "pull" it and this has been interpreted to mean that someone in the FDNY or NYC DOB indicated to him that the building was un able to be saved... and that explosives were placed to "take it down" and -pull it- was the technical term for taking a building down. That sounds fishy doesn't it?
However consider the following. Two huge buildings had collapsed in the morning and this was quite a shock. Though they were hit by plans and showed massive fires for a while, there were also reports of explosions. The officials could have suspected a massive terrorist attack with planes AND bombs. They couldn't possible know for sure in the madness. Thousands of people had been killed in the twin towers including hundreds of fire fighters, police and first responders. Don't you think the officials would have been spooked and think that 7 was going to go as well? There are reports that the city had an engineer sight the building with a transit after it was damaged by debris from WTC 1. This, if true, and it likely is, was prudent. If a huge building showed even a few inches of distortion, it would mean that the structure has twisted, joints stressed and this mean that the structure was not at full "strength capacity". Would you go into a building that was distorted by 2-3 inches... after it had been struck by debris and had fires and huge tanks of diesel fuel stored there?
Perhaps the officials decided it was necessary to get everyone out of the building... and they did in the AM and not fight the fires and let them self extinguish or just see what happened, believing that unfought fires WOULD weaken steel and it MIGHT collapse. Steel has fire protection for 2 hrs. After that it is unprotected and will begin to lose strength. We don't know how long the fires raged, what was burning and so forth. Some have claimed they only burned 20 minutes consumed the flammable material and move on. But haven't we see a building in Madrid burn for many hours... it did not collapse. But it was a different design and included a concrete core I believe.
YES all three collapses could have been caused by explosives. But we don't have proof of this and the collapses were gravity driven (one started) and did not defy any laws of physics.
Careful observations informed by technical knowledge of structural engineering, physics, material science and even optics will lead to understanding what happened. All of these are key to understanding.
I believe you are not familiar with the facts and observations. The collapse time is difficult at best to nail down because it began for example, in the case of WTC 1 with the top section of about 14 or so stories being destroyed from about the 96 floor up to the top. If you observe the many videos it appears as if those stories are being "crushed" (destroyed) at the bottom and the ones above descend. This sequence takes approximately 4 seconds. The motion of the roof line does wobble about, both before the actual descent and as it comes down. This is not easily or perhaps impossible to see with the naked eye, but scientists have analyzed the motion with "trace" software and determined its motion. The antenna atop WTC1 also clearly tilts to the east and south in ADVANCE of any obvious to the naked eye motion of the roof line.
We can conclude from the antenna motion that parts of the structure supporting the antenna were failing in ADVANCE of the roof decent or visible destruction and hence the antenna's motion. We don't know what caused this motion and it could be incendiaries or explosive or weakened steel. Whatever it was it occurred inside the core and out of our view.
Once the entire 15 or so stories came apart (whatever the mechanism) they represented about 30,000 tons of material which had descended over the 4 seconds onto the top floor(s) of the lower section below the "crush" (crash) zone of the building up at the mid 90s. Some material from the destruction of the top went over the side. Nothing was shot up. Study the videos. The top section experienced a gravity driven... collapse of unknown cause... onto /into the lower section of the tower.
The the destruction phase which I refer to as ROOSD - runaway open office space destruction occurred. The appears to travel at about 60 mph or 100 feet per second destroying 8 floors in one second. Obvious the collapse begins at 0 mph accelerates up to 60 or so mph and then no faster. This part of the destruction is 1100 feet and therefore tool about 10+ seconds. So the total elapsed time of visible collapse was about 14 seconds. We could not see the "end" of the collapse and we can't tell precisely when it began except to use the first downward motion of the roof or the antenna, but clearly the "collapse" was already happening as structure was failing unseen behind the facade before the facade and the roof moved.
The collapse elapse times might be ascertained from seismic records but it is yet to be determined when that began as well. There are delays in the seismic waves and correlating them to the videos is imprecise. Plus the early movement likely would not have a seismic signature. That would begin only after there was significant crashing of heavy material on the ground... and we know that something in free fall from 1300 feet wouldn't show up for 9 seconds after it began falling.
So the collapse time is quite imprecise and given as a range since we can truly only know when it ended. And there's the Spire which stood for perhaps 15 seconds AFTER the global collapse of the floors and facade. It's likely and possible that parts of the spire were falling in the period when the global collapse obscured or view until we could see the Spire when most of the dust was blown to the SE and then it too collapsed.
So what was the total collapse time for WTC 1? When did it literally begin? When do we start the clock when we observe the first motion? And when does the collapse end... when the Spire falls?
Finally, the 60+ mph is quite fast.. the velocity of a free falling object after about 3 seconds. However it is not an unreasonable speed considering that the tower was 96% air, and the floors themselves were on 4" thick no-stone aggregate lightweight and very brittle concrete and these floors and the 88 trusses which supported them would offer very little resistance to 10's of thousands of tons of falling debris... and they would "fail" almost instantly from the impact.
Larry Silverstein is reported to have said he made the decision to "pull" it and this has been interpreted to mean that someone in the FDNY or NYC DOB indicated to him that the building was un able to be saved... and that explosives were placed to "take it down" and -pull it- was the technical term for taking a building down. That sounds fishy doesn't it?
However consider the following. Two huge buildings had collapsed in the morning and this was quite a shock. Though they were hit by plans and showed massive fires for a while, there were also reports of explosions. The officials could have suspected a massive terrorist attack with planes AND bombs. They couldn't possible know for sure in the madness. Thousands of people had been killed in the twin towers including hundreds of fire fighters, police and first responders. Don't you think the officials would have been spooked and think that 7 was going to go as well? There are reports that the city had an engineer sight the building with a transit after it was damaged by debris from WTC 1. This, if true, and it likely is, was prudent. If a huge building showed even a few inches of distortion, it would mean that the structure has twisted, joints stressed and this mean that the structure was not at full "strength capacity". Would you go into a building that was distorted by 2-3 inches... after it had been struck by debris and had fires and huge tanks of diesel fuel stored there?
Perhaps the officials decided it was necessary to get everyone out of the building... and they did in the AM and not fight the fires and let them self extinguish or just see what happened, believing that unfought fires WOULD weaken steel and it MIGHT collapse. Steel has fire protection for 2 hrs. After that it is unprotected and will begin to lose strength. We don't know how long the fires raged, what was burning and so forth. Some have claimed they only burned 20 minutes consumed the flammable material and move on. But haven't we see a building in Madrid burn for many hours... it did not collapse. But it was a different design and included a concrete core I believe.
YES all three collapses could have been caused by explosives. But we don't have proof of this and the collapses were gravity driven (one started) and did not defy any laws of physics.
Careful observations informed by technical knowledge of structural engineering, physics, material science and even optics will lead to understanding what happened. All of these are key to understanding.