Got to give the Scholars credit, though, for publishing Greening's piece. Peer review may not be all you like it to be, but they do publish dissenting views.
Hey Brumsen, welcome back. I was just going to comment on this issue.
Back in
this post I outlined some problems I found with Ross's analysis. I was gratified to see Greening take Ross to task on several of the same issues, while at the same time playing by Ross's rules, and still refuting his conclusions.
I also see that Ross has a rebuttal... talk about evading questions, check this beauty out. (Both Greening's refutation and Ross's response are found at
http://www.journalof911studies.com/.)
Ross's whole argument is to siphon off as much of the initial collapse energy as possible. He postulates a "kinetic energy" sink of lower floors springing away from the collision of upper and lower floors, while utterly disregarding the additional structural damage that would be caused by transmitting that energy through the support columns, or explaining where it goes immediately afterwards. He stops his energy balance equation with the 20+ floors below impact moving downward at various speeds up to 4 meters per second, but
clearly this is not the end state of a building that remains standing. (Ross's original paper can be found at the same URL, in "Volume 1, July 2006.")
Greening's main counterpoint (there are other adjustments that, on their own, also refute Ross's conclusion) is that Ross has grossly overestimated the number of floors that
could recoil, not to mention the number that
did recoil according to the video evidence:
Dr. F. R. Greening said:
WTC 1's collapse also involved a tilting of the upper section of the Tower and was therefore asymmetric. Thus the downward collapsing force had a significant angular component. Why is this important? Because the longitudinal compression wave induced by the initial rotational (tilting) action and free fall collapse of the upper sections of WTC 1 & 2 was not propagated down the central vertical axis of the columns. Lateral and even torsional compression waves were created. This means that most of the initial impact kinetic energy was expended in destroying the first impacted floor as proposed in Greening’s Energy Transfer in the WTC Collapse report. In addition it is well known that an elastic compression wave in a spliced column system such as the WTC will not propagate efficiently, but dissipate, at each splice. Thus there is no justification for the assumption that the initial elastic deflection would propagate 24 storeys below the impact floor. This is an idealized concept that was not satisfied in the collapse of the Twin Towers.
Certainly, if Ross’ suggestion that 24 floors below about the 95th floor moved downward after the impact of the upper section, the videos and photographs of the collapse of WTC should show a noticeable downward displacement of floors between the 70th and 94th levels immediately after the impact. In fact, no such movement was observed. It is significant, however, that ejections of dust and debris were observed at a few locations several floors below the impacted floors. This observation suggests that the fast moving compression wave did inflict some damage to floors a few storeys below the directly impacted floors. However, and this is an important point, such “pre-damage” to lower floors should not be considered as “lost” kinetic energy but rather as energy that facilitated the later total collapse of the affected floors. Thus we suggest that, instead of 24 floors, a maximum of four floors would have shown any significant downward movement after impact of the upper block of floors.
Terrific. Case closed. The reactive mass is smaller, so even if accelerating those floors completely dissipates that part of the energy budget (also false, but let's roll with it), the amount of energy is far smaller than Ross would have us believe. Ergo, collapse is initiated when the upper block hits the lower structure.
Along comes Ross. What does he say?
Gordon Ross said:
Let us assume for a moment that Dr. Greening is correct. What would be the result of an analysis which allows all of Dr.Greening's assumptions to be held valid, all his figures to be utilised and all his reasoning to be used, but then simply allow the clock to tick over for a few more tenths of a second? Dr. Greening shows an energy excess at a point in time some 13 milliseconds into the collision.
(Paraphrasing, "OK, you got me, but what about...")
Gordon Ross said:
The falling upper section, according to Dr. Greening's analysis, remains able and equipped to continue to progress the collapse, and it will do so by continuing to accelerate the tower downwards and deforming the support columns. The most immediate task that it will face in doing so will be to continue the acceleration of those floors identified by Dr. Greening as being first affected by the collapse as it attempts to reconcile and satisfy the laws of conservation of momentum and energy. The upper section will also continue to act on the first impacted and impacting column sections by moving these through the remainder of their elastic strain phase and into the plastic phase range. This will consume energy and take time. Again assuming a continued constant velocity of 8.5m/sec the further movement through the plastic deflection of four storeys 444mm will take another 50 milliseconds.
(emphasis added)
But, Ross argues, if you just wait another 50 milliseconds,
then -- according to my model -- the structure could transmit still more energy to the four lower floors, and it wouldn't collapse! It has to in order to conserve momentum and energy!
Need I point out how specious this reasoning is? Oh heck, I'll do it anyway:
- After 13 milliseconds -- starting from the upper block hitting the lower block -- the two contact floors have been destroyed, and thus collapse has already been initiated. No point continuing the calculation, as it is moot.
- Ross's "energy balance" had already accounted for the pillars being compressed to their plastic limit, with a much lower energy cost. Any further compression means total failure -- they have no more shock to absorb!
- Ross needs the pillars to further compress a remarkable 444 millimeters, or roughly a foot and a half! This is a LOT of distortion, roughly enough to destroy four-floor sections on its own (3% strain is roughly maximum for steel).
- Ross needs to get it through his head that he is basically assuming his conclusion. He is insisting that his model, in which the building stays up, conserves momentum and energy. If you force those to be true, as he has, of course your numbers will say it stays up. Your numbers will also have no bearing on reality...
I really have to hand it to Dr. Greening for putting up with such pretenders to science. I eagerly await his thorough destruction of Ross once again.
In my opinion, Steven Jones and his little circle of lunatics have done a grave disservice by
not following the standards of peer review. Ross could learn a great many things from the process if they had. Unfortunately, it seems Ross hasn't yet learned anything, and will suffer needless ridicule, perhaps permanently damaging his employment potential, as a result.
