They are in conflict with the same people---far more credentialed architects and engineers agree with the established case---so that they assert they know the truth by reason of a contrived "theory" is in the same ballpark as the "climate scientists" (who are also credentialed) who serve up a contrived theory. I focus on the theory, not on the argument from authority. When the leading members of this organization say "I knew from the beginning that something was wrong," their bias is unmistakable. So, they go on a quest to confirm their bias---just like a lot of people on this page.
What problem do I have with credentials? I have a bachelor of science, a master of science, and a master's of aeronautics and astronautics from the University of Washington (Seattle). I worked for 40 years at was began as the Boeing Aerospace Company and ended as its Defense and Information Division, interacting from time to time with Boeing Commercial Airplanes. I became an Associate Technical Fellow and had the highest performance ratings throughout my career. A key accomplishment was to edit and re-write what became the winning proposal for the YAL-1A airborne laser system, the most powerful military directed weapon yet constructed. I have 9 patents and preceded by about 5 year's NASA's invention of an afterburning nuclear thermal rocket engine. I had Secret, Top Secret, SCI, NATO Cosmic Top Secret, and Classified Nuclear Weapon Design Information clearances. That's just skimming the record.
I'm good with evidence, as reflected by the fact that I always refer to it. I give no credence to interpretations that are inconsistent with the evidence (e.g., that the Pentagon crash was a "cruise missile."
I'm fine with one issue at a time, but we were not originally discussing WTC7.
As for the video, their own argument is self-refuting. Free fall for 7 seconds at an acceleration of ~32.2 feet/second/second results in a distance of 789 feet. The building itself was 610 feet tall. If one only accounted a distance of 100 feet in 7 seconds, then the acceleration would have been 4 ft/sec/sec or 12.7% of free fall. So, they are cherry-picking the data to find a spot where it was in free fall.
I have already explained repeatedly that, in an environment where the supporting columns have their strength reduced to below structural margins, the time taken for a column to fail in compressive shear is essentially instantaneous and that the interval for the next column to fall is on the order of a millisecond, so that the whole failure process for each floor amounts to about a tenth of a second at most. That would be 4.7 seconds for the whole building, if even that much. No, when the shear failures are happening as fast as a floor can fail, it will look like free fall when the process is running. Reading the data as best I can from the grainy image of the curve plot, it appears that the linear part of the velocity/time trace starts at 1 m/sec @ t = 0.8 second and ends at 26 m/sec at t = 3.2 second (they annotate 3.18 second). This gives an acceleration of 10,4 m/sec2 which is 12% higher than free fall. I'm not saying that is the true acceleration, since it can never be higher than 9.8 m/sec2. What it tells me is that the reconstruction is in error by as much as +/- 12%.
All the self-assured talk about "that's why we have all this structural steel in this building" comes apart once you take into account that high temperatures short of melting will reduce the column strength of the steel to practically nothing, and compressive sheer failures will occur at the speed of sound in the steel.
Structural steel loses 70% of its room-temperature strength at a temperature of 600 C (1,112 F). (It gains about 35% in strength by a temperature of 225 C / 437 F, but slides downhill from there.) I don't have knowledge of other examples, except to note that the same dynamic undoubtedly happened with the Twin Towers. It is a question of whether a fire can proceed to attain such temperatures. As I understand from a past reading of the WTC7 event, the fire fighting systems were initially disabled by shock.
The examples before us are the Twin Towers and WTC7. The Twin Towers were anomalous from the standpoint of a lot of fuel being available to feed the fires, along with the potential of burning aluminum vapor, which is far more exothermic. WTC7 did not have burning airplanes to deal with, but it did have internal carbon-based fuel and a disabled extinguishing system, and took a prolonged time to develop a crisis.
I'm not a skyscraper architect, so I am unacquainted with other cases, but these are quite unique. It does open up a significant vulnerability in the way we construct skyscrapers. There may be no practical defense. (Or we build tall buildings as ziggurats or pyramids.) I think it would be rational to make sure that approach and departure corridors to airports do not go over urban high-rise building districts.
So this new theory of office fires causing structural steel to lose its strength so catastrophically that it resulted in the building falling straight down into the path of most resistance at free fall speed (for a few seconds) should have a major effect on the field of architecture. Given this new information architects must have studied this and changed how they design buildings so they don’t just collapse during an office fire.
What has the industry done with this new information?
There may not be much to do. The special case is aluminum catching fire. It is extremely energetic (used for rocket fuel) and would ordinarily not be present---unless an airplane crashes into your building. I don't see that there is much that can be done. The materials in use are arguably suitable and well-performing.
https://www.engineeringtoolbox.com/metal-temperature-strength-d_1353.html
“ I'm not a skyscraper architect, so I am unacquainted with other cases,”
Nor am I, but I have listened to lectures by architects looking precisely at this issue. There are a couple of other examples of modern concrete and steel high rise building burning for extended periods of time. No collapse. No loss of structural integrity.
Not burning with a profusion of aviation fuel and the prospect of burning aluminum vapor. The flame temperature of kerosene is 2,093 deg C. But the flame temperature of aluminum (vapor, in oxygen) is 3,732 deg C. That ups the ante considerably.
What problem do I have with credentials? I have a bachelor of science, a master of science, and a master's of aeronautics and astronautics from the University of Washington (Seattle). I worked for 40 years at was began as the Boeing Aerospace Company and ended as its Defense and Information Division, interacting from time to time with Boeing Commercial Airplanes. I became an Associate Technical Fellow and had the highest performance ratings throughout my career. A key accomplishment was to edit and re-write what became the winning proposal for the YAL-1A airborne laser system, the most powerful military directed weapon yet constructed. I have 9 patents and preceded by about 5 year's NASA's invention of an afterburning nuclear thermal rocket engine. I had Secret, Top Secret, SCI, NATO Cosmic Top Secret, and Classified Nuclear Weapon Design Information clearances. That's just skimming the record.
I'm good with evidence, as reflected by the fact that I always refer to it. I give no credence to interpretations that are inconsistent with the evidence (e.g., that the Pentagon crash was a "cruise missile."
I'm fine with one issue at a time, but we were not originally discussing WTC7.
As for the video, their own argument is self-refuting. Free fall for 7 seconds at an acceleration of ~32.2 feet/second/second results in a distance of 789 feet. The building itself was 610 feet tall. If one only accounted a distance of 100 feet in 7 seconds, then the acceleration would have been 4 ft/sec/sec or 12.7% of free fall. So, they are cherry-picking the data to find a spot where it was in free fall.
I have already explained repeatedly that, in an environment where the supporting columns have their strength reduced to below structural margins, the time taken for a column to fail in compressive shear is essentially instantaneous and that the interval for the next column to fall is on the order of a millisecond, so that the whole failure process for each floor amounts to about a tenth of a second at most. That would be 4.7 seconds for the whole building, if even that much. No, when the shear failures are happening as fast as a floor can fail, it will look like free fall when the process is running. Reading the data as best I can from the grainy image of the curve plot, it appears that the linear part of the velocity/time trace starts at 1 m/sec @ t = 0.8 second and ends at 26 m/sec at t = 3.2 second (they annotate 3.18 second). This gives an acceleration of 10,4 m/sec2 which is 12% higher than free fall. I'm not saying that is the true acceleration, since it can never be higher than 9.8 m/sec2. What it tells me is that the reconstruction is in error by as much as +/- 12%.
All the self-assured talk about "that's why we have all this structural steel in this building" comes apart once you take into account that high temperatures short of melting will reduce the column strength of the steel to practically nothing, and compressive sheer failures will occur at the speed of sound in the steel.
High temperatures resulting in loss of a steel columns ability to load bear would be a significant event.
Is there an example of this happening anywhere else in the world? Or is this the first time it had happened to your knowledge?
Structural steel loses 70% of its room-temperature strength at a temperature of 600 C (1,112 F). (It gains about 35% in strength by a temperature of 225 C / 437 F, but slides downhill from there.) I don't have knowledge of other examples, except to note that the same dynamic undoubtedly happened with the Twin Towers. It is a question of whether a fire can proceed to attain such temperatures. As I understand from a past reading of the WTC7 event, the fire fighting systems were initially disabled by shock.
https://www.engineeringtoolbox.com/metal-temperature-strength-d_1353.html
Shock of what?
Somehow, I can't get back to the original thread and have lost the stream of consciousness. I don't know how to answer.
The examples before us are the Twin Towers and WTC7. The Twin Towers were anomalous from the standpoint of a lot of fuel being available to feed the fires, along with the potential of burning aluminum vapor, which is far more exothermic. WTC7 did not have burning airplanes to deal with, but it did have internal carbon-based fuel and a disabled extinguishing system, and took a prolonged time to develop a crisis.
I'm not a skyscraper architect, so I am unacquainted with other cases, but these are quite unique. It does open up a significant vulnerability in the way we construct skyscrapers. There may be no practical defense. (Or we build tall buildings as ziggurats or pyramids.) I think it would be rational to make sure that approach and departure corridors to airports do not go over urban high-rise building districts.
So this new theory of office fires causing structural steel to lose its strength so catastrophically that it resulted in the building falling straight down into the path of most resistance at free fall speed (for a few seconds) should have a major effect on the field of architecture. Given this new information architects must have studied this and changed how they design buildings so they don’t just collapse during an office fire.
What has the industry done with this new information?
There may not be much to do. The special case is aluminum catching fire. It is extremely energetic (used for rocket fuel) and would ordinarily not be present---unless an airplane crashes into your building. I don't see that there is much that can be done. The materials in use are arguably suitable and well-performing. https://www.engineeringtoolbox.com/metal-temperature-strength-d_1353.html
“ I'm not a skyscraper architect, so I am unacquainted with other cases,”
Nor am I, but I have listened to lectures by architects looking precisely at this issue. There are a couple of other examples of modern concrete and steel high rise building burning for extended periods of time. No collapse. No loss of structural integrity.
Not burning with a profusion of aviation fuel and the prospect of burning aluminum vapor. The flame temperature of kerosene is 2,093 deg C. But the flame temperature of aluminum (vapor, in oxygen) is 3,732 deg C. That ups the ante considerably.