by Major_Tom on Sun Oct 18, 2009 8:51 am
femr2, the video is a nice start.
I think the contrast between the NIST model and reality is mind-blowing.
If I did videos this would be a huge theme in my work.
The good posters raised the following issues:
1) What does the model show which can explain what was happening during the near freefall phase of collapse? (Wouldn't we all be curious how the structural resistance fell to near zero for about 8 floors of falling and then was magically restored?)
2) How does the model explain the initial lateral failure progression leading to what appears to be near simultaneous column failure. (I've never been able to visualize the chain of events that leads to rapid symmetrical collapse)
3) How does single column failure lead to global collapse (the type of collapse witnessed?)
4) Comparing the penthouse fall in the model and in the real world (i.e. the freefalling) penthouse).
5)Contrast the unevenness of the roofline in the NIST model to the obvious symmetrical straightness of the roofline in reality. Model actually shows: "at least initially, a slow displacement resulting from folds developing across the major portion of remaining structure." (OWE)
On the model itself:
"This, according to NIST, is simulation of an unprecedented scope (guess they hadn't heard about Extreme Loading, eh?) requiring thousands of hours of computation. Anyone in the least familiar with simulation techniques must be immediately skeptical of simulation without precedent and actual physical examples, since this is the means by which simulation is developed and verified, and must also call foul when the results of the simulation bear only passing resemblance to the event being simulated.
The nature of most physical simulations, even of very simple systems composed of only a few free bodies, present the opportunity to diverge rapidly from actual system evolution as the result of only small initial deviation from the system state at any given step. While it would be quite a miracle if the entirety of the physical simulation matched the observed dynamics and would lead me to suspect data-fixing, the alternate result - that of a poor match and the one that was actually presented - leaves little room to conclude that the dynamics have been adequately captured. Only if your institutional standards absolutely suck can you claim this simulation reflects the actual dynamics. It is merely a solution which leads to global collapse, from among the innumerable other outcomes which could lead to similar or entirely different results, and completely distinct from a solution that matches the observables." (OWE)
Reality check: How would we expect the building to react to the loss of a single column?
"WTC7 has 24 core columns. Removing one column = no. 79 between floors 11/13 does not produce overload of adjacent two core columns (or perimeter wall columns). You can evidently continue to remove (adjacent) core columns at floors 11/13 to see when an adjacent core column becomes overloaded and will buckle by itself and then you should check it it means that further, adjacent columns just fail/buckle by themselves ... and how much of the load drops down (or out = does not contribute to further actuion) and how much is transmitted to still intact structure to assist further destruction.
Or in other words - arranging local failures as suggested above will probably result in serious local failures, e.g. one part of the structure/tower collapses due to bottom supports having been removed and the load drops off the structure, while the remainder structure still stands." (Heiwa)
The 4 points above with the two quotes contrasted with the NIST simulation can be the basis of a good one hour documentary. Much better than this NOVA crap, or National Geographics.
Someone like you or Achimspok can produce powerful material on this theme.
If you were to contrast the NIST model carefully highlighting any and all of these points I'd put that at the very top of a comprehensive WTC7 collapse features list.
Powerful potential.
