Some Misunderstandings Related to WTC Collapse Analysis

[Tony Szamboti]

The perimeter would be pulled inward and fail causing the upper section to descend and impact the next story down and arrest. A one or two story fall does not produce enough kinetic energy to continue the collapse as it is significantly less than the column energy absorption.

Jeffrey thinks his ROOSD can begin right away but it can't as the floors could take 29 million lbs. of force, which is a static load of about five additional full floors with their live load. The dynamic load of one floor assembly would be nowhere near 5g's so ROOSD needs to wait until a sufficient number of floors have broken loose and gained momentum.

But this is a deficient model. In your model the flange effect caused by the perimeter frame being pulled in would then cause the falling section to wedge the lower section's perimeter frame outward. As it did this it would pull the fasteners for the floor pads to the inner core outward causing, once again, a misalignment of the core columns causing instant load failure. As I've repeated in several posts your model is fatally flawed because it fails to involve the necessary lateral forces that would necessarily be involved by physical design.

But that isn't what happened in my opinion. As I said, the pneumatic blast pressure from the falling concrete floor pads exited both outward and inward driving the floor pads off their mounts and downward in an accelerated dynamic that undercut the static resistance of the core columns as it progressed in a wave just ahead of that static resistance form.

Uh, I thought 12 floors fell above the collapse zone in the North Tower?

12 floors did not immediately fall onto one floor. Jeffrey is talking about floors assemblies falling onto each other when he usues the term ROOSD (runaway outside office space destruction).