When I first started back to school in 2006, I was studying Engineering. I was in a materials class when they did strength testing of various materials. I remember the noise that the breaking I-Beam made when it snapped. It did not just go “Ping” like many people think, but rather sounded like a combination of an explosion and a breaking mirror (a BIG mirror).
We had a short discussion at this point about 9/11 and the reported “explosions” hear within the building. The professor asked what those noises might have been (nodding at the tiny I-Beam we had just broken and mentioning that the I-Beams in the WTC where hundreds of times larger).
It did not take us long to get the clue that the “explosions” hear were large structural members breaking under incredible strain, and that the stored up energy in these members was then released further along the member’s length (so, you get this recursively adding structural failure that generates louder and louder “BANGs” as the buildings falls).
The pancaking of the floors is just a part of that process. Also, as you mention below… The fire did not need to melt anything, all it needed to do was to remove just enough strength from one portion of the building to have that fail, and have the other supporting redundant members have just enough strength sapped from them as well to begin a catastrophic failure. If the fire did melt things (as is possible when you have a hot firing burning in an oxygen deprived environment, it will heap up to huge temperature and then if a hole were to suddenly appear that allowed in oxygen. It will act like a blowtorch—we got to do this in class too) then that would just make the failure all the more spectacular...
When I first started back to school in 2006, I was studying Engineering. I was in a materials class when they did strength testing of various materials. I remember the noise that the breaking I-Beam made when it snapped. It did not just go “Ping” like many people think, but rather sounded like a combination of an explosion and a breaking mirror (a BIG mirror).
We had a short discussion at this point about 9/11 and the reported “explosions” hear within the building. The professor asked what those noises might have been (nodding at the tiny I-Beam we had just broken and mentioning that the I-Beams in the WTC where hundreds of times larger).
It did not take us long to get the clue that the “explosions” hear were large structural members breaking under incredible strain, and that the stored up energy in these members was then released further along the member’s length (so, you get this recursively adding structural failure that generates louder and louder “BANGs” as the buildings falls).
The pancaking of the floors is just a part of that process. Also, as you mention below… The fire did not need to melt anything, all it needed to do was to remove just enough strength from one portion of the building to have that fail, and have the other supporting redundant members have just enough strength sapped from them as well to begin a catastrophic failure. If the fire did melt things (as is possible when you have a hot firing burning in an oxygen deprived environment, it will heap up to huge temperature and then if a hole were to suddenly appear that allowed in oxygen. It will act like a blowtorch—we got to do this in class too) then that would just make the failure all the more spectacular...
I’ll shut up now...