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Reply #66: Good examples... [View All]

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William Seger Donating Member (1000+ posts) Send PM | Profile | Ignore Sat Nov-07-09 11:46 AM
Response to Reply #60
66. Good examples...
... of exactly what I called "bogus" and "lame attempts to refute Bazant."

I suppose that we'll have to go through your list, but please let's start with a very important quote from the article that Gourley attempted to respond to. There is no point in going on until you understand the significance of this:

Inabsorbable Kinetic Energy

First, let us review the basic argument (Bazant 2001; Bazant and Zhou 2002). After a drop through at least the height h of one story heated by fire (stage 3 in Fig. 2 top), the mass of the upper part of each tower has lost enormous gravitational energy, equal to m0gh. Because the energy dissipation by buckling of the hot columns must have been negligible by comparison, most of this energy must have been converted into kinetic energy K = m0v2/2 of the upper part of tower, moving at elocity v. Calculation of energy Wc dissipated by the crushing of all columns of the underlying (cold and intact) story showed that, approximately, the kinetic energy of impact K > 8.4 Wc (Eq. 3 of Bazant and Zhou 2002).

It is well known that, in inelastic buckling, the deformation must localize into inelastic hinges (Bazant and Cedolin 2003, sec. 7.10). To obtain an upper bound on Wc, the local buckling of flanges and webs, as well as possible steel fracture, was neglected (which means that the ratio K/Wc was at least 8.4). When the subsequent stories are getting crushed, the loss m0gh of gravitational energy per story exceeds Wc exceeds 8.4 by an ever increasing margin, and so the velocity v of the upper part must increase from one story to the next. This is the basic characteristic of progressive collapse, well known from many previous disasters with causes other than fire (internal or external explosions, earthquake, lapses in quality control; see, e.g., Levy and Salvadori 1992; Bazant and Verdure 2007). {emphasis added.}

Merely to get convinced of the inevitability of gravity driven progressive collapse, further analysis is, for a structural engineer, superfluous. {emphasis added.} Further analysis is nevertheless needed to dispel false myths, and also to acquire full understanding that would allow assessing the danger of progressive collapse in other situations.

Do you understand what Bazant is saying there? No, you do not -- you apparently do have not the first clue. Otherwise, you would understand that if you want to criticize Bazant's paper, this is where you need to start -- not a handful of insignificant details -- and if you can't do that, then as Bazant said "further analysis is superfluous" to overcome your invincible ignorance. You clearly don't understand what Bazant is saying in that paragraph, but you think you can parrot a bunch of insignificant details that you picked up from websites that, like you, desperately need to disbelieve Bazant's conclusions, to protect delusions that you have developed for perfectly irrational reasons. Then, you feel justified in smearing and slandering not only Bazant but the huge number of people who do understand what Bazant is saying in that paragraph. It's beyond pathetic, and you don't seem to understand it well enough to understand why that's so.

So, eomer, prove me wrong and talk to me like you understand what that paragraph says, or please do everyone a favor and stop wasting our time.

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