Sunder described them as normal office fires.
The impacts of debris? Then you're left with core column failure due to normal office bldg fires.
And that's basically correct. There is no reason to suppose that ordinary office fires cannot cause column failure, provided they burn long enough. We still have debris impacts ventilating the fire, and possibly (I'm speculating now) knocking down internal partitions that should have contained the fires, so the impacts may have contributed to the fire but not structurally.
But I don't know this for sure. It is possible the impacts also reduced the system capacity directly. It is also possible that the impacts did so, but the actual failure mode that happened first didn't depend on the impacts. There could be more than one way for the structure to fail.
"Normal" Class A fires are quite dangerous. The WTC 7 fires were normal, except for being large, well ventilated, long lasting, and unfought. Kind of like how the role of jet fuel in the Towers was only as an accelerant, and once started, the fires there were "normal" as well.
Bolding to emphasize that it matters entirely how and where the collapse was initiated. It appears collapse hypotheses are being reduced to a very improbable single column, comprehensive central failure, that appears similar if not characteristic of a controlled demo.
You need to be careful with that "probability" thing. If the design was such that, as Mr. Scheuerman suggests, a single core column failure could take down the entire structure, then it's not improbable at all. There were many columns and many floors exposed to fire, and if it only takes one failure, then the "odds" go up substantially. It also may be that WTC 7 was unlucky. Arguments from probability are of little value here.
Regarding being like a controlled demo, most CD's don't involve only blowing a single column. I'm unaware of any that don't induce a systematic structural failure. I would agree that an uncontrolled demo hypothesis is helped by this, since only a single large placement would be required, but this only helps slightly. You still have the problem of explosives in a fire, absence of sound and shock, absence of shrapnel, and the basic question "why." Occam's Razor is still in effect.
Ah, I get you.My observation might not have come across clear. I was quoting Ron who was proposing the position of some conspiracy theorist.
I appreciate that. I'm not responsible for any other researcher here, regardless of position. And I wouldn't hold incivility and inaccuracy coming from some leading voices here against your thorough and persuasive research.
I look forward to more productive discussions when NIST does release their final report on 7.
If you were responsible for one or two particular posters here, I'd have to sue you!
Yes, the WTC 7 Report will be interesting.