Reply #331: So-- [View All]

[spooked911]

do you agree that a one story (12 foot) free-fall drop for the upper block leads to a larger downward force than a half story (6 foot) free-fall drop of the upper block?

"You haven't demonstrated that the simple analysis appreciably favors a progressive collapse."

I assume you mean Bazant's simple analysis? Can you rephrase that, as I am not sure what you are asking?


As far as the alternatives, I started with the floor sections because that is the obvious weak link for fire-induced weakening of structural steel. I haven't seen any evidence that the perimeter or core columns actually got hot enough to fail on their own and start the collapse.


""The natural reaction is to think of a huge weight gaining so much speed that is (sic) smashes down through all lower floors, in a 'pile-driver' type of reaction.""

My point was that the natural reaction is not always right, and that is something the OCTists have pointed out when it suits their argument.

In any case, it is still true that the columns get progressively stronger down the tower, and there is major loss of material from the floors at each collision-- both are complicating factors for your fillet.