Re fundamental principles of collapse:
NIST suggests PE > SE = global collapse (of both WTC 1 and 2) as only cause of global collapses in both cases.
One: Read Architect's post on this, above.
Two: You are full well aware that the correct collapse model is that the failures in the impact and fire zones leads the upper segment fall and create a dynamic stress that overwhelms the structural supports of the floor immediately below it, adds that mass, and continues.
To make the argument you're trying to make, you must demonstrate that the upper block is significantly slowed by the lower section. You never do this; you argue entanglement, you argue all sorts of other silliness (remember your argument that elements of the upper block would outright miss vertical supports of the lower block and therefore not transfer strain to them? Utterly imbecilic argument), but you never establish that the upper block is slowed enough. The important thing is that once the upper segment compromises the first floor of the lower one, mass accrues and acceleration is not significantly impacted, as with more mass and continued acceleration, the next floor is not able to resist. And so on.
You want energetics? You know where the other energy calculations lay. You go out of your way to mischaracterize Bazant and Zhou's argument to try to disprove it, so I know you've seen calculations establishing the energetics exist. You should also be aware that Gregory Ulrich has independently reached the same conclusion. The NIST report establishes collapse
events, Bazant, Zhou, Greening, and others are the ones who deal with energetics.
You contribute - so to speak - by establishing inapplicable analogies. At any rate, you don't establish the same level of rigor compared to the work you claim is flawed. And you don't see why we don't take your analysis seriously? Especially when you have to miscast the oppositional arguments to make your case?
Pls advise where NIST calculates PE and how.
Pls advise where NIST calculates SE and how.
Again, re: Architect's note on NIST's computer analyses on this. And in turn, please establish where
you determine rigorously where the upper block is significantly slowed by the lower floors.
Pls advise where PE > SE = global collapse is established as a fundamental principle of collapse.
Pls advise why the individual floors of the lower block is able to resist the increasingly accreting mass and increasing acceleration of the upper block. Again, you don't consider the collapse as it occurred.
BTW - do you know what structural damage analysis really is?
Perhaps not. Forgive me for taking the term literally
. So, how is NIST's work on the impact damage and separate subreports on the fire damage not a damage analysis?
Architect, and any other engineers, feel free to sound off on this too. If there's something specific about that term that I'm missing, feel free to correct me. But I'm at a loss as to how an analysis of the damage from the two largest, complementing causes of failures in the towers is not a "damage analysis".
Re FoS=5 for perimeter columns means that static compressive stress = 0.2 of critical stress.
And this means what? This is supposed to tell me how a static load rating indicates it's ability to resist dynamic loads?
Architect and any other engineer here: Do you get what he's trying to say here? And whether that actually translates into a significant resistance to a falling load the size of the upper blocks? Furthermore, if he's discussing purely compressive stresses, given the lack of lateral support when the floors give, and given the impossibility for a chaotic collapse to maintain a purely vertical force with absolutely no off axis or completely horizontal forces, how does this matter? Because to me, to discuss the pure vertical axis loading is to ignore the complete lack of lateral support and the fact that many impacts were not purely vertical. Am I wrong about this?
Pls advise how any upper segment can apply a blow to a column.
Pls advise why you continue to misstate the events. Pls advise as to why the blow has to be direct and strictly vertical, and cannot compromise lateral support and remove the vertical columns' ability to stand on their own, let alone as a group resist the force of the upper segment falling on it when they don't have any ability to resist whatever horizontal forces will manifest in the complexity of the collapse.
To start with!
BTW Who is your God? Expert of structural damage analysis?
It's certainly not you. It's all the other posters here that you end up on the short end of the argument against, from Architect to Ryan Mackey, from Dave Rodgers to rwguinn, from old time posters like tsig and Brainache to new posters with architectural or engineering training like Grizzly Bear, Ratas, and Bluesky.
I full well realize my limitations as far as engineering concepts, math, or architectural knowledge lies. But the fact that someone like me, massively untrained and absolutely inexperienced at engineering and architectural concepts, can with help spy the errors you make should indicate the inadequacy of your arguments.
Everyone else (no, not you Heiwa; I've laughed enough today): Feel free to confirm or correct anything I've argued in this post. I believe I have the arguments correct because that is what has been pointed out in the past, but if something needs clarification or correction, have at it. The important thing is to establish correct information.
