Femr,
I figured out exactly what's going on here.
I also figured out why I thought that there was more tilt than there really is.
And why we both misinterpreted the data.
(In an attempt at a spirit of congeniality, I'll do this without snark. As long as you reciprocate.)
It's perception. And the fact, femr, that you work with images, not with steel.
The source of the "misunderstanding" (for both of us) is the NIST report.
But NOT thru any deviousness or deception. In their attempt to clarify, they implanted a misimpression in everyone who read the report.
And "reading the report" is exactly the source of my (& yours, I suspect) misimpression that there was a lot more tilt to the towers than there really was.
I got my misimpression from here:
"Total displacements of WTC 2 above Floor 86 at 43 min of Case D conditions (deformed shape magnified 20 times). Note the tilt toward east and south."
Fig 1.
NIST image, NCSTAR1-6D, Fig 4-90, WTC2 tilt, 43 min.tiff
I've overlaid a fine cyan line onto the original shape & a red square on the top of the 20x tilted position.
That imprinted on me, without my even noticing, the impression that there was a lot more tilt than in reality. EVEN THO I RECOGNIZED that NIST plainly states that the deflection has been magnified 20x.
They magnify the deflection, NOT to deceive anyone, but to show clearly what is impossible to see otherwise.
I've got CAD software that allows me to ACCURATELY change the 20x tilt into 1x tilt.
I'll put the details at the end, but here are the results. And they explain ALL of your "missing tilt anomalies". And why there is no missing tilt. ("Holy Szamboti, Batman!!")
Fig 2 shows the NIST image (at 50% transparency, with 20x deflection) with blue lines overlaid on the original shape & red lines overlaid on the CORRECTED 1x deflected shape. This program was not a CAD program, but it allowed me to drop the intensity of the graphic, and show the results clearly. I was not certain of the absolute accuracy of the program, so I redid the results in the CAD program, Vellum Graphite. It is exact.
Fig 2.
NIST image (50% transparency), straight shape (blue), true (1x) deflection (red).
Below (fig. 3) is the original shape of the tower in cyan. (I've added extensions to the side walls for a specific purpose that will be obvious later.
Original shape.
Fig 3.
Fig 4, below is the ACCURATE (1x) tilted shape, as NIST reports it at this time. I've doubled the vertical length of the tower from the image shown above. The smoke was pouring out of the mid height of these figures.
Fig 4.
Tower 2 with NIST claimed tilt.
THE TILT IS THERE in fig 4, femr. The exact amount that NIST claims. Show it to me...
You can see exactly why the tilt is "invisible". I drew these on a high def screen computer screen. And yet, if it were not for couple of 1 pixel jogs, I'd see no difference.
Fig 5 shows both the straight (cyan) & tilted (blue) graphics superimposed. This is real scale. Show me the tilt on a video monitor.
Fig 5.
Straight & tilted WTC2
There is no mystery here. There is no conspiracy of deception.
When you show the real deformations of stressed parts in FEA programs, frequently you can see little difference between unstressed parts and parts stressed to their limit.
___
Finally, it is evident that you're right. Before collapse initiation, WTC1 tilted very little (less than 0.5°). And WTC2 less than 1°.
But even if there is some error in NIST's statements about tilt, that isn't going to make one iota of difference to my conclusion that there were no demolition techniques of any sort. Because there is still a mountain of irrefutable evidence that there was no demolition of any sort.
What it WILL mean is that I learn that a massively damaged, burning building built in a lattice structure like the towers can deform less than - well, less than I never really considered before now. And less than I fooled myself in imprinting the image & forgetting the NIST "20x" qualifier.
It does not change the fact that the columns were stressed well beyond their plastic limits. It doesn't change the fact that they underwent a huge amount of creep. Both of these factor are clearly shown in NIST's FEA analysis & graphs.
Here is the info that was important to me. This graphic shows the creep in WTC2 at 20 minutes & 43 minutes. (43 being the same time as the tilted images above.) Note that the creep was NOT progressing linearly, but accelerating.
Fig 6
Plastic strain & creep
Top (20 minutes). Bottom (43 minutes)
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In essence, you stumbled on something that appeared to be a giant "GOTCHA!" to you.
And you cajoled me into looking into it with persistent, insulting badgering. And it took all of about 45 minutes to figure out what was really going on. And about an hours to draw up the graphs to show it.
There is a lesson here, femr.
You work with graphics.
You don't work with steel. Especially steel buildings.
You thought that you had caught them (& me) in "a lie". A deception. And you thought that you had us "back-peddling". That you had your exposee of NIST's perfidy.
And the end result is "you didn't understand & the professional got it right".
You'd do well to learn a global lesson from this.
(I learned this lesson the hard way over my career.)
Tom
