This is a rather silly response and parsing of words. It sounds more like you have a bone to pick with Tom than with his work.
Words have meaning. Major_Tom's acronym falsely leads actual industry professionals astray. That's a problem born because he's ignorant of actual industry standards. It's not a silly parsing of words, it's reading the words for what their actual definitions are.
The twin towers design at the time was very unique in that the engineers removed the interior columns... placing them in a structure facade creating column free rentable space outside the core.
Oh geez. The engineers didn't
remove columns. There is no rulebook that describes "how to lay out framing in a skyscraper". There is no building code rule that states these interior columns you think were
removed were required. And most importantly, there is no
engineering principle in existence now, or when the towers were designed, that stated that such columns are necessary for any reason.
The engineers didn't
move the columns to the exterior, either. A small column spacing in a moment frame makes the frame stronger and the building stiffer. This is common practice in tall construction (especially today).
The engineers of WTC1&2 engineered a system (correctly) with long spans. One of the primary structural virtues of using long span flooring is that it added additional dead load to the lateral force resisting system. That in turn reduces the amount of steel required in the LFRS, the strength of connections required, and mostly importantly it reduces the amount of uplift the foundations are required to resist. It's a good system. A conventional framed system, like say the Empire State Building, requires interior moment frames.
Now the reason why such long spans are uncommon is that it is generally uneconomical. The strength required for the trusses is directly related to the square of the length, the stiffness required increases with length^4. However, the WTC contractors were assembling large sections of floor before craning it into place. This offset much of the economic penalties.
It has nothing to do with collapse propagation.
Any interior partitions or office landscape (which originated at the time) played no role in structural integrity of the building and were simply superimposed dead loads.
Do you enjoy parroting other peoples remarks?
The acronym is fine for anyone who can understand how this "hull and core" concept differs from a standard high rise frame with a grid of columns.
The acronym is fine so long as the people using it describe how the words in the acronym don't actually mean what everyone in the industry thinks they mean.
A collapse in a standard frame would likely be prevented from propagating laterally and be confined with the bay where it occurred. In the WTC design without bays to limit the lateral propagation the collapse is prone to spread and involve the entire column free floor area outside the core. I believe this is a key element of ROOSD... and something that the term "progression floor collapse" does not reflect.
That's BS.
You want to play like an expert and make these wild ass claims, then
prove that the null hypothesis is false. Show, using rigorous engineering analysis, that a building framed with more conventional spans, would not collapse under the same conditions.
Now, I've read thoroughly read the building code, the AISC Manual of Construction (including the lovely sections after the Specification) and the AISC Design Guides. Nothing in them states anything about this supposed problem you've identified. I've also polled all the structural engineers I've worked with (and a fair number of additional ones) about the WTC collapses. Every single one of them was amazed at how long the buildings stood.
Every. Single. One. They attribute this remarkable feat to the unusual design, the same design you claim led to the towers demise. Now, who am I going to believe? Dozens of my own peers or a guy on the internet who claimed to know how to calculate a radius of gyration, but did so in a laughably incorrect manner?
Yea, I'm gonna go with my peers.
