Also, I think you need to take care about tossing around the "many times redundant" claim. That may be true for lateral loads, but too many times, it's cited to support the claim that the TWin Towers were exceptionally robust, and that's not been demonstrated to be the truth.
Not demonstrated to be the truth... by the collapse, right?
For example, NDBoston is a poster here who actually worked in the building, and has flatly stated that he's never seen any sort of project that can remotely be tied into such explosives installation.
Right. Next thing you know is you'll have a different witness reporting suspicious activity and explosions here with the same sort of credibility.
Furthermore, the characteristics of explosives demolitions are missing from 7 World Trade's collapse.
lol wut
Which leads into my next point: If you want to argue the possibilty of CD, you'd also have to account for the lack of signature characteristics of such.
What? Massive dust clouds, macroscopic debris scattered all over the place, reported explosions, spontaneous vertical implosion at nearly free fall speed.
For example, the seismographic evidence argues against this.
Right, but the massive dust clouds, macroscopic debris scattered all over the place, reported explosions, the spontaneous vertical implosion at nearly free fall speed speak for it. The lack of seismographic evidence may speak against CD, but then again the fact that the windows were blown in in many buildings around the WTC speaks against the absence of CD.
So does the state of the steel; no components investigated show any fragmentation consistent with explosives use.
Steel does not fragment unless the explosion applies enough force to overcome the steel's tension. Which is why fragmentation grenades, bombs and shells usually contain a prefragmented casing and often shot too. Since it requires the explosion to overcome the tension of the steel to actually rupture it, demolition teams do not usually destroy with high explosives (to which steel is very resilient to) but instead using cutter charges, for example thermite to pre-fragment the steel, and then simply blow it away with a small charge not capable of overcoming the steel's tension.
How do I know this? Because I'm a demolitions guy in the army, and I've worked with C1, TNT and blasting cord. I wouldn't call me an expert as the army training is more pragmatic than theoretical in nature, but I'm trained to know how to bring things down - be it buildings, bridges, steel, concrete or wood structures.
On top of that, comparison with the sounds of known explosives demolitions do not match; any reports from witnesses of supposed "bombs" going off have universally been shown to not coincide with the collapses themselves, and in some cases, not coinciding on the order of hours, not mere minutes or seconds.
Proving what?
Saying that any of the buildings' collapses "matches a CD signature far better than anything else" is erroneous. It in fact is a claim that even many CD advocates, like Jim Hoffman, have discarded a long time ago. Explosives demolitions do not explain the bowing of columns, nor the tilt of the upper section as well as the initiation of the collapse at those upper sections of the main towers.
It is trivial to start the collapse at the upper section of the tower. The way you bring a tall building down is that you weaken its structure in the entire lenght. If you just blow up the basement alone with sufficient force, the building may topple over, or remain standing after falling a floor or two. That's why you need to bring down the entire length of the building's structure. Also, in CD, you do not normally fire all charges at once, nor do you apply the "more is better" philosophy of the army when it comes to the amount of explosives, the simple reason being that you only want to destroy the building, and not everything next to it too. For that reason too, you avoid blowing all explosive charges at once. Professional CD works are timed shortly after each other, avoiding the creation of an explosive shockwave that would damage nearby buildings or scatter debris all over the place.
However, that all being said, it's trivial to start the explosion at the top. The reason why you normally don't is because it takes more explosives (where with a bottom-up CD you let gravity do most of the work) and is more prone to scattering debris all over the place.
While the WTC was professional work, the twin tower's collapses both also show signatures of being a military rather than a civilian demolition team. But there should not be too much interpreted into that statement, I'm sure the reason for the top-down nature of the CD was rather to make the collapse seem more natural to the untrained eye, instead of being solely caused by pragmatically trained military agents. The enormeous dust cloud and the large area of scatter however suggests that a rather large amount of explosives was used, which suggests that there was some hurry when they were applied.
Rule of thumb for explosives: If you're in a hurry, you use more explosives to make up for the fact that you don't have the time to properly install the charges. You can get by with very small amounts of explosives if you apply them well, compared to just randomly duct taping (No, I'm not kidding) a large pile of plastic to whatever it is you want to destroy.
The collapses simply do not look like explosives demolitions.
I disagree. It looks 100% like a regular controlled demolition to me. Wait, what you say? I'm an expert and thus your own opinion is rendered obsolete? Neato!
But they do fit failure modes put forth by NIST; NIST constructed those models from actual observations, after all.
"It collapsed, so lets just modify the computer simulation until our model collapses too" and then they end up with a virtual simulation of a hollow tube made from paper machee.
And further on top of all of that, the matter of opportunity is still unaddressed.
Indeed, that is the biggest mystery. Who did it. What's clear however is that there have been months of preparations gone into this.
