And in other news...
Here is the Abstract from a Keynote Speech and Paper written by one of the guys who first proposed the Pancake Theory. See if you can find any problems with it.
Learning from World Trade Center and Building Demolitions
ZdenÃÂ·ek P. BaÃÂ·zant, F. ASCE, and Mathieu Verdure
Abstract: Progressive collapse is a failure mode of great concern for tall buildings, and is also typical of building demolitions. The most infamous paradigm is the collapse of World Trade Center towers. After reviewing the mechanics of their collapse, the motion during the crushing of one
floor (or group of floors) and its energetics are analyzed, and a one-dimensional continuum model of progressive collapse is developed. Rather than using classical homogenization, it is found more effective to characterize the continuum by en energetically equivalent snap-through. The collapse,
in which two phases crush-down followed by crush-up must be distinguished, is described in each phase by a nonlinear second-order differential equation for the propagation of the crushing front of a compacted block of accreting mass. Expressions for consistent energy potentials are formulated
and an exact analytical solution of a special case is given. It is shown that progressive collapse will be triggered if the total (internal) energy loss during the crushing of one story (equal to the energy dissipated by the complete crushing and compaction of one story, minus the loss of gravity potential
during the crushing of that story) exceeds the kinetic energy impacted to that story. Regardless of the load capacity of the columns, there is no way to deny the inevitability of progressive collapse driven by gravity alone if this criterion is satisfied (for the World Trade Center it is, with an order-
of-magnitude margin). The parameters are the compaction ratio of a crushed story, the fracture of mass ejected outside the tower perimeter, and the energy dissipation per unit height. The last is the most important, yet the hardest to predict theoretically. Using inverse analysis, one could identify
these parameters from a precise record of the motion of floors of a collapsing building. Due to a shroud of dust and smoke, the videos of WTC are useless here. It is proposed to obtain such records by monitoring the precise time history of displacements in different modes of building demolitions.
The monitoring could be accomplished by real-time telemetry from sacrificial accelerometers, or by high-speed optical camera. The resulting information on energy absorption capability would be valuable for the rating of various structural systems and for inferring their collapse mode under
extreme fire, internal explosion, external blast, impact or other kinds of terrorist attack, as well as earthquake and foundation movements.
OK, just for simplicity let us look at the proposed method of acquiring the information which will be used as the base values for; validating events previously theorized to have been progressive collapses, figuring out if an event is a progressive collapse, and predicting the likelihood of any progressive collapse in the future.
It is proposed to obtain such records by monitoring the precise time history of displacements in different modes of building demolitions.
Using inverse analysisis, (backwards scientific methodology?) these guys will utilize information gathered at controlled demolitions to extrapolate the likelihood of a completely disimilar event. Not, mind you, to contrast the differences, but to equate the similarities of the events even though one of them has explosives and the other one does not. I assume that the variable, blew up/ did not blow up, will be a major factor and not just a control group.