... I'm less sure that I could bring them together to form a coherent model of the collapses in my mind. Maybe one day I'll try.
But I want to be clear that no one should be looking for a "definitively proven" model of the "exact" collapse sequence. All we need is the most probable model (or, if there are close contenders, several such models) of the approximate sequence. I think it's important to tell the public if the collapses cannot be explained without reference to "illegal alterations", "disrepair", or construction "errors"). If those need to be hypothesized for the collapses (as observed) to make sense, then that's important. (And of course grist for the CT mill.) I don't think that's the received view in the engineering community, though. I think the collapses make sense to them even if the buildings were in perfect working order.
Short question:
In your mind, are you clear about distinguishing between explanations for collapse
initiation and collapse
progression?
I.e. why did the collapses get started in the first place - damage to which columns, trusses, connections, caused by fire, impact, explosives, death ray, platoons of midgets with saws... vs. why did the collapse, once started, not arrest and instead accelerate and go all the way to the ground?
I think the latter is easier to understand, if properly explained. One could discuss is under an auxiliary hypothesis that all/some columns/trusses/connections were broken/removed by "magic", such that a top "block" starts moving downward. What will happen with that moving block next? How and where will it meet static structure, what resistance will this incur, how will that resistance be overturned?
Once you understand that collapse progression indeed is inevitable, regardless of what initiated the collapse, you know that it would have been unnecessary for imaginary demolition villains to help the collapse progress.
Bazant, Stassorek (was that the name?) and some others only look at this - and get it (partially) wrong by focusing on column buckling, when the evidence clearly shows that hardly any column buckled.
NIST did not really look into this, except for one item in their FAQ, where they explain how the floor truss seats would necessarily shear under the dynamic load of more than 6 floors. This is a back-of-the-envelop that ignores most details of how floors truss systems actually got loaded during the collapse, but it should be convincing nevertheless.
NIST, in contrast, was concerned with collapse
initiation (and may, or may not, have gotten this partially wrong, too). I think it is unrealistic, and unnecessary, to expect that the actual detailed collapse sequence could ever be found and be agreed upon by a solid consensus. What can be shown is that that several failure modes could plausibly explain the collapses as observed, be they "floor-led" (i.e. failing floor trusses cause column buckling), "perimeter-led" (i.e. perimeter columns buckle before any floor trusses detach) or "core-led" (i.e. core columns buckle before any floor trusses detach).
As a general lesson to be included in the book would speak of the facts that steel-framed buildings are destroyed by fire all the time everywhere, and that firefighters, structural engineers and authorities everywhere understand that, if and when steel frames fail in a fire, they often fail suddenly and quickly. It's just that the vast majority of steel frame structures are not supertall highrises. Most are warehouses, factories, bridges, lowrise buildings.
The second lesson to learn is that building tall is more difficult than building low, which is why only the best structural engineers are tasked to do this: There is no magic that confers invulnerability to steel frame structures once they exceed some (never explicitly stated) height. Yes, they are stronger absolutely than less tall buildings, but actually tend to get more fragile relative to their own size and load. A 415 meter skyscraper is about as sturdy as a delicate bottle made of super-thin, brittle glass - a bottle that would break immediately if you tried to grab and lift it, that would shatter if you dropped it from a height of just millimeters. The book would need to explain the perils of scale.
A chapter coming late in the book might discuss possible differences between more conventional skyscraper designs, the WTC designs, and contemporary and future designs as regards their susceptibility to plane crashes and multi-floor fires. How in conventional structures, with their grids of columns, collapses may more likely be limited in their lateral and vertical progression to just one or few bays, where the open-office-space of the WTC towers essentially creates just one huge bay that goes down all at once.