The only WTC7 on 9/11 question which satisfies that criterion of 'what it is ll about' is the big question of 'demolition or not?' and the answer to that question is 'not'. So if achimspok wants to tackle that real big question then he should stop wasting his time in technical detail. There is a lot of 'no demolition' evidence awaiting rebuttal which is not in the domain of micro technical details. So much that no matter what this detailed technical exploration comes up with it will not shift the weight of 'no demolition' evidence.
In fact, this is the root of why all this discussion is futile.
Achimspok, however much he may deny it, is trying to construct a proof that WTC7's collapse was due to means other than fire and impact damage. Now, if he were serious about doing so rigorously, here's a set of steps he might like to follow.
(1) Construct viable hypotheses for collapse due to fire and impact damage, and collapse due to explosives or incendiaries.
(1a) If possible, identify known examples of both and compile observations on them.
(2) Analyse both hypotheses, and identify key differences between them that will result in specific observables.
(3) Look for key observables in the dataset from WTC7, and determine which hypothesis is a better fit.
Part (1) is pretty well done for the fire and impact scenario; the NIST report is a good enough starting point. No truther has made the slightest attempt to generate a hypothesis in anything approaching the same level of detail for collapse by other means. This should be, yet never is, the focus of effort for anyone wanting to challenge NIST. Part (1a), though optional, is one rarely approached by truthers too; very little work has been done by truthers on identifying even the key characteristics of the explosive demolitions they claim WTC7 to have resembled.
Part (2) is, of course, impossible without having carried out part (1). One cannot draw conclusions from a model that does not exist.
Part (3) is only worth doing, in any detail, when informed by part (2). Without any idea of what key observables differentiate between scenarios, there is absolutely no point in refining, to an ever-increasing level of detail, the interpretation of the motion of the building from the dataset available. If we have no idea which effects are necessary to one hypothesis and excluded by the other, no amount of observation will ever be of value in choosing the better hypothesis.
So, achimspok, by addressing (3) in greater detail - given that there is already a dataset of reasonable quality in existence - is putting the cart before the horse. Without hypotheses and prediction of specific observables, no amount of refinement of understanding the details of the dataset is of any value whatsoever in assigning causes.
In other words, come back when you have a fully formed hypothesis.
Dave