...simulation that actually visually appeared similar to the event even
Agonist insinuates that Hulsey's simulation (presumably the one where he removes ALL columns at once) actually visually appeared similar to the event. But is that true?
I think this is as good a time as any to list the visual characteristics of the real event, as are known from the video record, and check which of those are or aren't replicated by Hulsey's model (and would not be visible in the sim videos released so far). Perhaps let's also do an appraisal of which visual clues are significant, which aren't, and why. Because, you see, Hulsey argues this(page 2, Executive Summary, my bolding):
External Quote:
This conclusion is based primarily upon the finding that the simultaneous failure of all core columns ... followed ... by the simultaneous failure of all exterior columns ... produces almost exactly the behavior observed in videos of the collapse
Here are the details of the "behavior observed" that Hulsey mentions:
- "collapse of the east penthouse approximately 7 seconds prior to the collapse of the rest of the structure" (p. 5)
- "straight-down collapse" (p. 5)
- "2.25 and 2.5 seconds of free fall (i.e., gravitational acceleration) during its collapse" (p. 11)
- "The debris pile of WTC 7 was contained mostly inside the building's footprint. ... (see Figure 1.7)" (p. 11)
- "it did not have large pieces of concrete flooring or intact structural framing that would be expected in a building collapse (see Figure 1.7)." (p. 11)
- "[Key Feature 1.]The collapse of the east penthouse, which begins approximately 6.9 seconds prior to the descent of the north face roofline" (p. 91)
- "[Key Feature 2.]The collapse of the screenwall and west penthouse, which begins approximately 0.5 to 1 second prior to the descent of the north face roofline" (p. 91)
- "[Key Feature 3.] The descent of the north face roofline, which progresses at a rate of free fall for approximately 2.25 to 2.5 seconds over a distance of approximately 105 feet or 8 stories," (p. 91)
- "[Key Feature 3., continued] during which the building's sheathing remains attached to the exterior steel framing and does not experience visible differential movements" (p. 91)
- "window breakage, cracking of the facade, and exterior deformation, none of which were observed" (p. 91)
- "the minimal differential movement of the exterior seen in videos of the collapse" (p. 91)
1. and 6. are the same feature
2. and 4. overlap greatly
3. and 8. are the same feature
9. and 11. are the same feature, and 10. is closely related
So this boils down to 6 distinct features, which Hulsey thought worthy of a mention:
i) EPH descends several seconds before the rest - no details given, such as that it kinks
ii) Screenwall and WPH start descent 0.5 to 1 s prior to north wall - no further details given
iii) Collapse staight down, largely into the footprint
iv) 2.25 to 2.5 s of FFA of the north face roofline
v) minimal differential movement of the exterior, resulting in no window breakage, no cracking of the façade, and no exterior deformation
vi) no large pieces of concrete flooring or intact structural framing in the debris pile post-collapse
Hulsey notes (page 91):
External Quote:
While NIST's progressive collapse simulation does show the three key features listed above, it also predicts significant differential movements in the exterior, both before and during the fall of the roofline, that were not observed in the video (see Figures 4.1a and 4.1b).
So...
- Feature i) is covered by NIST. What's more, in the NIST analysis, this is a result (output) of the simulation of the damage accumulation, while in the Hulsey model, it is a premise (input) of the simulation: The EPH drops a few seconds before the rest because Hulsey artifically forces it to. NIST's model explains, Hulsey's doesn't
- Feature ii) is covered by NIST. What's more, in the NIST analysis, this is a result (output) of the simulation of the damage accumulation, while in the Hulsey model, it is a premise (input) of the simulation: The west core drops a moment before the perimeter because Hulsey artifically forces it to. NIST's model explains, Hulsey's doesn't
- Feature iii) is FALSE - as I showed in post #29, the building did NOT collapse into its own footprint, and NOT (entirely) straight down, instead it had major parts hitting buildings across two different streets. In addition, Hulsey FAILS to show that this feature is replicated by his preferred simulation (all columns removed).
- Feature iv) is covered by NIST (according to Hulsey - I am not aware that NIST, or Hulsey, or anyone, ever actually analysed the acceleration of the north wall roofline in NIST's global collapse simulation). What Hulsey misses is the few tens of seconds before FFA is reached. He again forces the FFA, by artificially, and without explaining (stating a cause), removing all perimeter columns at once, thus making free fall a premise (input) of his model.
- Feature v) is FALSE - there was deformation of the facade observed, there was differential movement, there was window breakage. See below.
- Feature vi) is a bare assertion, not supported by a proper citation nor by own study. The only reference, Figure 1.7, actually DOES show very large pieces of still-connected structural framing. In addition, Hulsey FAILS to show that this feature is replicated by his preferred simulation (all columns removed).
In effect, we see that Hulsey replicates NO actual, real feature that NIST doesn't - none anyway that he cared to mention himself.
Worse yet:
The few true features that he replicates arise not as a result (output) of the model from actual physical causes, but as a direct result of assuming (inputting) these features: Making the EPH fall seconds before the WPH, making the WPH descend moments before the perimeter, making the perimeter fall freely by removing all columns at once. This has zero explanatory value.
I note with interest that nowhere in the report, Hulsey claims the collapse was "symmetric". He says at one point (page 11): "
WTC 7 would be expected to experience a combination of axial rotation and bending of members, resulting in a disjointed, asymmetrical collapse. Asymmetrical, tipping behavior is especially likely because WTC 7 did not have planar symmetry", but falls short of making "symmetry" a feature to look for. He writes these two sentences in an explanation of why he thinks FFA is relevant.
Now of course there are more major visual features of the collapse that Hulsey does NOT mention:
- The kink in the north face that forms as the EPH disappears
- The counter-clockwise motion of the entire structure (north-east corner falls to the north, south-west corner to the south)
- The east part of the north wall lags behind the center and west parts after a few seconds
- Numerous windows do break after the EPH, later the WPH, start to descend
- The eastern facade bulges dynamically as the EPH falls
For visual references, see Mick's
post #54.
Also, prior to the rapid collapse of the EPH
- The building was observed to bulge etc, show signs of distress
- The roofline was already observed to move (up and down) for as much as 30 seconds.
Hulsey of course replicates none of these, nor are any of these plausible as results of his "all core columns at once, then all perimeter columns at once" scheme.
Edited to add:
I asked, at the beginning of this post:
"Agonist insinuates that Hulsey's simulation (presumably the one where he removes ALL columns at once) actually visually appeared similar to the event. But is that true?"
The answer now is:
Hulsey's simulation "
visually appeared similar to the event" only with respect to those features that he explicitly forced on the model by making columns disappear at opportune time, without explanation why they would, how they could disappear like that.
Hulsey fails to replicate any other features.