Wrong, as MarkLindeman has idicated above. Onset of 'global collapse' is not synonymous with beginning of FFA. Except, perhaps, in your mind.
1-9 Vol II states that all exterior columns had buckled "within approximately 2 seconds" of onset of collapse. This matches almost precisely the beginning of Stage 2, as per their graphs.
While you're here - when will you open a thread to tell us your ideas on why, when and how WTC7 was CD'd?
So Glenn, Mark,
I still have questions about what Chris7 is bringing up here. First of all, it is still my understanding that NIST's
draft document on Building 7 did not acknowledge freefall at all. That came into the final report, and Chris7 asserts that NIST did not change their model when they acknowledged freefall. From what I can see, Chris 7 is correct when he says this.
However, Glenn quotes NIST 1-9 (above) saying complete buckling had happened within 2 seconds of the collapse, so if I understand correctly here, the original unchanged model could allow for freefall at that point.
Now Glenn, here is where I get really confused: when you said, "And for a column to break anywhere other than a connection would be a very strange event as connections are easily the weakest link. If your stick had a groove cut around it that's where the eventual break would occur, as it were. Chris7 prefers to insist on plastic buckling of the column material itself, as this allows him to claim "2% retained support" (or something) which would result in slightly < g acceleration. It's just more C7 straw-grasping to support his CD delusion." The reason this is confusing to me is because all the NIST modeling, especially figure 12-62, shows precisely what Chris7 says happened in the NIST model, which is plastic buckling of the column material itself. Isn't that exactly what I am seeing when I look at Figure 12-62?. Look at the computer model of the view from the south around the 11th floor or so. That looks like severe, extreme, plastic buckling of the column material to me.
Lest you think I am agreeing with Chris7, I am also looking at his own post 4121 at the top of page 104. There C7 shows another set of four NIST diagrams. In these model diagrams, at 13 and 14 seconds I see plastic buckling globally in floors 7-14 and columns snapping all over the place along the east side where the penthouse has collapsed. At 15 seconds, I see columns beginning to snap along the right side. One second into the global collapse, at 16 seconds, I see more columns snapping along the right side. Two seconds into the global collapse, which would be the 17th second, there is no diagram shown by Chris7, but that may be the point at which the buckling columns are globally snapping like, dare I say it, sticks. I don't know for sure. I'm just observing what I see in these two sets of NIST computer simulations.
So the to things that seem inaccurate to me at this point are: 1) saying that Chris7 is holding onto the plastic deformation of columns assertion when in fact that is exactly how NIST modeled the collapse onset and 2) Chris7's apparently inaccurate timing of the NIST models in relation to the 2.25 seconds of freefall rates. Am I wrong here?
