Even if? Of course the upper part is destroyed
No.
After all, what do you even mean when you say "destroyed"? With a structure like WTC? Columns are bent? Broken? Welds broken? Floors cracked? Shattered? Reduced to dust?
What? Some of these happen to some degrees in some circumstances, but it all depends on the circumstances.
and the interface upper part/lower structure changes and the load it applies to the lower structure is redistributed, local pressures at contact points are reduced and further destruction is arrested.
No. You've demonstrated yourself why you cannot claim this.
You always reason as if the upper part remains unchanged after contact.
I never said anything of the sort.
What I said was that it doesn't matter.
Yeah.
You are reasoning exactly as Bazant!
What we know, and you are having trouble with, is that it's not that important.
In the real world the upper part could not have remained unchanged, and when it starts to change after contact you have to look again what happens.
Yes.
And it might be that the top of the structure crumbles, leaving the rest of the structure standing.
Or it might be that the entire structure collapses.
You pointed out yourself that the rest of the structure undergoes deformation. You said that.
If the rest of the structure is not strong enough to withstand that deformation, it will collapse. The precise sequence of events depending on a huge variety of factors, of course, all of which you have chosen to ignore.
That's why the videos, topic of this thread, are wrong showing the upper part intact all the time.
No.
It doesn't matter.
Whether it's a single perfectly rigid million-ton structure, or a million tons of concrete kibble, it's still a million tons coming down on a weakened structure not designed to support that load in that way.
But the videos are still quite good. If the upper part for any reason would have remanied intact, the destruction that follows would have taken much longer time than seen in reality.
And what is the basis for this claim? You just said that it couldn't happen at all.
So the destruction seen including horizontal ejections of big chunks of wall sections cannot be due to energy provided by gravity.
Utter nonsense.
Take a normal drinking glass. Drop it on a tiled or concrete floor. Bits of it will fly all over the room.
That's your "horizontal ejection of big chunks of wall sections" right there.