You seem to be hung up that NIST omitted "studs" in the simulations they ran. Husley left out fire and damage on other floors. He also did not simulate "real world" fire behavior.
You statement of "Certainly not the ones illustrated on the above drawing.........." is an opinion.
See post 40 in
https://www.metabunk.org/wtc-towers-core-columns-what-held-them-together.t9256/
D. Friedman (Contract Engineer during clean up).
"I had misgivings about the core columns I was seeing. I was sure the dunnage design would work—Kyle and Chris know their stuff—but I was unhappy that the columns I saw lying on West Street seemed to be in too-good condition. These huge columns—the largest weighed more than one ton per running foot—were almost all straight, with clean edges at both ends. There were some dents here and there, but I expected a piece of steel that had been wrenched out of a building to be bent. I examined the ends of the columns every chance I got. Every welded splice at the column ends I saw had failed the same way: by ripping out of the steel. The plates that had been assembled into boxes for the core columns varied from a couple of inches at the top to five inches at the bottom. The top and bottom ends of each column were flat and had been spliced with a partial-penetration groove weld: the upper column’s four sides were beveled about an inch and a half. When the upper column was erected over the already in-place column below, the bevel and the flat top surface of the lower column formed a lopsided “V” shaped groove, which was then filled with weld. Partial penetration welds are not as strong as full-penetration welds, where the groove is the same depth as the steel is thick, but they are far stronger than is needed for most purposes. Under the extraordinary loads imposed during the collapse, the columns were free to buckle after the the welds ripped off of the flat surface of the groove. Like a lot of the structural damage I saw, this was not a normal phenomenon and it was hard to accept. I spent a lot of time noting such issues and trying not to learn too much from them. It would be easy to stop trusting my knowledge of building design, and weld performance, and steel strength, and so on. I felt that by understanding what had physically happened on September 11, I could contrast it with the ordinary engineering problems I dealt with on my projects.]
https://play.google.com/store/books/details?id=7EYjl-f3DhAC
