Here are a few quotes from past exchanges I have had with David Benson which give a good idea of how he was interpreting the visual evidence available in 2008 just after BLGB was published:
"Better to call the section cushed, rather than compressed, as it is inelastic. It did contain, for the most part, the core columns; only a few were bypassed." from
http://the911forum.freeforums.org/p...wers-and-collapse-mechanisms-t62-30.html#p857
"In situations like this, there is no guarentee of a least energy solution being actually used. The fact that both towers had a standing spire of some core columns after crush down shows that eventually the collapse did move out towards the periphery."
"On another matter, we ordinarily start with the simplest hypothesis and stik with it until some evidence shows the hypothesis must be modified. In the case of the top portion, the simplest is that it stayed on top most of the way down; say with the roof at around floor 25. Until someone develops some actual evidence to the contrary, I'll stick with that rather than unending speculation and new simulations of the resulting hypothesis." from
http://the911forum.freeforums.org/p...wers-and-collapse-mechanisms-t62-30.html#p833
The top portion stayed on with the roof until around floor 25. This was the simplest hypothesis?
"Albert Einstein once said something to the effect that a model should be as simple as possible, but no simplier. The B&V crush-down equation meets that criterion as long as one only considers measurements taken on the antenna mast. With your careful observations of perimeter wall sections breaking off at and above floor 98 and OneWhiteeEye's observation earlier on this thread to the effect that this led to a inhomogeneity in the structure, I then, as reported earlier on this thread, in effect moved zone C up to start at floor 102. That fits the antenna tower measurements and also (approximately) the additional observation that OneWhiteEye posted earlier on this thread, regarding the SW corner of WTC 1."
"So, the simplest possible model for WTC 1 collapse works very well even though I now conclude that some 4+ floors of early crush-up occurred due to the inhomogeneity introduced by missing perimeter wall sections. But not more early crushup than that. Once those were crushed, the homogeneity is re-introduced so that Bazant & Le then applies. I think. It's a point that needs checking."
It certainly does.
"More complex equations simply are not required. Parsimony suggests the B&V crush-down equation with vertical avalanche resisting force together with starting the crushing front around floor 102, being good enough for the data in hand, is indeed good enough." from
http://the911forum.freeforums.org/list-of-all-scientific-research-9-11-papers-t106-105.html#p4886
Good enough?
"Assuming homogeneity, Bazaant & Le show thaqt zone C is almost industrucible. That's mechincs for you. The sturcture obviiously was not homogeneous and you have, in other threads, shown some distruction along the west and north walls. In of itself that mass loss is not important, but it does mean the floor trusses in those areas have been weakened. So an average of about 4--6 stories above floor 98 do not come close to satisfying the homogeneity condition. Fine. consider then that zone C is from floor, say, 102 up. To keep the equation simple, assume crush-down begins from there. As I mentiioned in this thread yesterday, this works well enough to match the additional observations by OneWhiteEye.
" from
http://the911forum.freeforums.org/list-of-all-scientific-research-9-11-papers-t106-90.html#p4881
That's mechanics for you.
"Zone C simply disappears into the obscuring dusts. Not sufficient reason to assume it is being crushed first. If sufficiently close to homogeneous, then from Bazant & Le it is not being crushed at all." from
http://the911forum.freeforums.org/list-of-all-scientific-research-9-11-papers-t106-90.html#p4863
If sufficiently close to homogeneous?
"OneWhiteEye --- I've been thorugh all this before. Homogenization is fine when the tilt is taken into account; crushing proceeded on 3+ floors simultaneaously which is surely better represented by homogenization that by stepwise floor-by-floor model. However, both give essentially ythe same results; shagster actually went to the effort of running his own version of Greening's ideas using minifloors to demonstrate this; although, after some study, this is analytically obvious.
"The issue of early crush-up never seems to die, does it? The problem is that it would have to proceed against the force of gravity, not with it. Instead what you seem to have noticed in frame 1007 is a lack of one dimensionality, with zone C west perimeter wall going outside the lower portion, yes? That actually does not trouble me, yet.
" from
http://the911forum.freeforums.org/list-of-all-scientific-research-9-11-papers-t106-90.html#p4847
No, it did eventually die, except for the cult following.
"No sign of zone C falling aprat as long as it can be seen. Unlike the case of WTC 2." from
http://the911forum.freeforums.org/wtccs-asynchronous-impact-crush-down-model-t178-30.html#p4824
As long as you don't bother looking too carefully.
"Major_Tom ---
Do you doubt Newton's Laws?
Do you doubt
http://en.wikipedia.org/wiki/D'Alembert's_principle?
Do you doubt the applicability of the four simplifying assumptions in B&V?
If not, the conclusion of little early crush-up of zone C follows.
Further, the timing studies in BLGB show that most of zone C mass must have stayed on top most of the way down." from
http://the911forum.freeforums.org/wtc-1-offered-no-resistance-t168-60.html#p3497
It is just that simple. How could I have doubted those assumptions?
"As for the core punching through the roof, I conjecture this occurred when the upper mechanical floors and up to the roof encountered the greater resistance offered around floors 75--79, about 30 stories (about 110 meters) down. No air escaping through such a puncture will be separately observable in any of the photos, IMO." from
http://the911forum.freeforums.org/wtc-1-offered-no-resistance-t168-30.html#p3392
A pretty air-tight puncture of that roof from the "spire".
MT: "Can you please explain how such tall surviving sections of the core can exist with horizontal bracing still attached without the need the debris to go around it, not through it (hence a gaping hole up the middle of the debris distribution)?
DBB: "The west and north walls peeled away sufficiently rapidly that deebris tended to move west and north near the spire. Similarly, but to a lesser extent, to south and east. There actually wasn't a gaping hole, just less density and in particular no structural steel to break connections."
A huge homogeneous piston.
"OneWhiteEye --- B&L show little inital crush-up, not none at all. Since it is so small, the argument is that the crush-down only in B&V is a valid approximation." from
http://the911forum.freeforums.org/crush-down-models-t145-135.html#p2619
"Major_Tom --- B&V have four simplifying assumptions which lead to the crush-down ODE. These assumptions are reasonable for WTC 1 but not, by video timing, for WTC 2 after a few seconds. In the case of WTC 2 it is clear from the ABC video of the collpase proceeding down to the Mariott rooftop level that the collapse was proceeding much too slowly; the inference is that the top section broke apart and fell off rather early on.
But as BLGB indicates, this could not have happened to WTC 1 or the timing would be off."
from
http://the911forum.freeforums.org/crush-down-models-t145-75.html#p2476
"OneWhiteEye --- I'm not the one with any doubts about the matter: there can be no significant early crush-up.
" from
http://the911forum.freeforums.org/crush-down-models-t145-30.html#p2406
"Read Bazant & Le to understand why zone C can be consired to be essentially rigid during crush-down.
I offered to start a thread about how to build a table-top demonstrator that will allow one to see that,
indeed, zone C remains intact during crush-down. I didn't bother when I realized that nobody here would bother to actually build it, test it, and in the process dicover that the application of Newton's laws and
d'Alembert's principle in Bazant & Verdure agrees with reality." from
http://the911forum.freeforums.org/a-question-to-david-b-benson-t144.html#p2315
"See Bazant & Le for a further exposition of why early crush-up is very small. It is, I admit, a difficult
point. But it is similar to a house riding down a landslide for which many examples have occurred in southern California." from
http://the911forum.freeforums.org/a-question-to-david-b-benson-t144.html#p2296
>>>>>>>>>>>>>>>>>>>>>>>>>>
We could talk about any of these ideas in the context in which he was describing them at the links provided.
The moral of the story is neither he nor Bazant were very good at observing the events directly. The written record shows they were pretty crappy observers.
Smart minds, no doubt, but crappy observational skills.
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