Independents like professor bazant also get a lions share of the criticism, for good reason. Aside from the facile use of block mechanics, a major shortcoming of his 'piledriver' hypothesis is that he envisions a uniform crush front propagated by an intact 'upper block', which pulverises floors and columns at an equal rate. We now know that this is untrue, and that bazants specification of a two phase collapse (crush down followed by crush up, rather than both occurring simultaneously) may well violate newtons 3rd law of motion. These errors have escaped the notice of the public, and most attempts to understand the towers collapse are still dominated by these 1D concepts.
So, in place of these fragmented and often spurious allegation of how the towers fell, the author of sharpprintinginc attempts to provide an accurate collapse history of the three towers. Relying mostly on direct observation (and not on abstract mathematical models which use random assumptions to come to conclusions about factor x or y), he does an admirable job at establishing a causal chain of events for the twin towers, which are addressed here and here. Both provide an adequate description of where various instabilitys and failures took place, and other pages also explain how they led to a massive progressive floor collapse.
The problem with this compilation, however, is with the arrangement of the details. The account for WTC 2 is nothing like the account for WTC 1: It almost looks like a completely different process is being explained. For the earliest detected movement, we have a sagging roof vs a flexing of the perimiter columns. With WTC 1, we have ejections followed by descent of the upper block, then tilting. With WTC 2, we have ejections followed by more perimiter column flexing, then tilting of the upper block that precedes its descent! One wonders why the process of instability leading to collapse is so different for each building.
Such contrasting accounts give off the aura of incompetence: If you are attempting to sell a theory for how the towers fell to the public, there should be as much commonality as possible in the features of both collapses, otherwise they will not be convinced. If the characterisation for how WTC 1 fell is completely different from how WTC 2 fell, your explanation will rightly be looked upon with suspicion. Thats something that needs work. Another shortcoming of his compilation is that it still doesn't provide an answer to the key questions about the twin towers collapse, a list of inquires that might go like this:
-Were gravity loads redistributed after the plane impacts (and if so, where, when, how)?
-When did the downward acceleration of the twin towers peak, and what was the key factor in determining its fall rate?
-What kind of structural damage was being done inside the buildings after collapse initiation?
-How does the debris flow accumulate during collapse? When a floor system is destroyed, how much of the resultant debris is ejected from the building?
-Why did the perimiter walls peel away in large sections, and why were lone spandrel plates ejected at high velocity?
-How should we categorise each section of the twin towers, based on the role they played in the collapse? Is professor bazants a, b, and c designation adequate?
