Reply #1: Still dealing with that fundamental mistake

[Bolo Boffin]

Essentially that is what we are dealing with - steel and glass.

What, Bolo Boffin? The lower section wasn't made out of steel!!!!!

No, it wasn't. But the lower structure was brittle when compared to the force that hit it from above. Whether it was still bound together into a structure or torn apart into its several pieces, the mass of the upper section remained the mass of the upper section.

And when it crashed down, it only had to break through this, floor after floor:



It had to tear these joints loose. That's all. Whether it was on the side of the core columns or the side of the perimeter columns (as shown here), the joints you see here had a choice when the falling mass of the upper section began to deliver its force to them: redistribute every bit of that force to the rest of the structure or snap before doing so. If they snapped or tore loose, then the mass kept going down.

What Bazant showed in several papers was that the upper section had enough force after falling a single story to have done exactly this SEVEN TIMES OVER. There was no way for these joints to have redistributed that much dynamic load. They snapped, and the relatively brittle structure tore apart all the way down.

Sledgehammer, meet Stubben glass.