There is simply no way to break the floor below with a falling beam and girder assembly from one floor above. The eight floor cascade could not have happened. It is pure fiction. There is a reason the WTC 7 report does not provide a supporting analysis for this.
“… a falling beam & girder assembly from one floor above.”
Well, I’m pretty DAMN certain that you’re wrong about this. Because you’re ignoring the fact that the girder that it is falling onto has no bolts retaining it, and the dynamics of the impact are virtually certain to knock it off its tenuous perch on its seat.
But, regardless of what I think, NIST never says that the collapse resulted from “[one] falling beam & girder assembly.”
Here’s what it does say, Tony.
NIST said:
The floor framing structure was thermally weakened at Floors 8 to 14, with the most substantial fire-induced damage occurring in the east region of Floors 12, 13, and 14.
…
After the fire-induced ANSYS damage was applied, floor sections surrounding Columns 79 to 81 on Floors 13 and 14 collapsed to the floors below, as shown in Figure 12–42. The LS-DYNA analysis calculated the dynamic response of the structure to the floor failures and resulting debris impact loads on the surrounding structure. The thermally weakened floors below Floors 13 and 14 could not withstand the impact from the collapsing floors, resulting in sequential floor collapses. The floor systems progressively failed down to Floor 5, where the debris accumulated, as shown in Figure 12–43.
pg. 572
Can you read, Tony.
Portions of TWO fire-weakened floors (13 & 14) collapsed onto one lower, fire-weakened floor (12) below.
From Fig 11-36, it shows 17 beams & 2 girders have lost their vertical support on floor 14, and fallen two stories onto Floor 12.
From Fig 11-35, it shows 24 beams & 2 girders have lost their vertical support, on floor 13, and fallen one story onto Floor 12.
And all of the above is falling onto Floor 12, which Fig 11-34 shows has 22 beams & 2 girders that have lost their vertical support. And have substantial damage to all the connections that remain in this quadrant of the building.
The collapse would have happened in one of 2 ways, depending on whether Floor 13 or Floor 14 collapsed first.
Let's assume Floor 13 collapses first.
Then a large portion of floor 13 falls one story onto a fire damaged Floor 12. Let's assume the (highly unlikely) circumstance that Floor 12, in its significantly weakened state, can support twice its static live load, plus one floor's dead load, plus the dynamic overload of the impact. THEN it must withstand 1 extra floor (13) live load plus one extra floor (13) dead load, PLUS one more floor's (14) live load, One extra floor's dead load (14), and the dynamic impact of the last two component's falling thru 2 stories. All onto massively weakened beams & girders.
Your representation of it being just A2001 (one girder & 6 attached beams) falling onto a relatively pristine floor 12 represents about 1/8th the mass and about 1/10th the energy imparted on the 12th floor by the partial collapses of the two floors above.
Your representation is a bad joke.
__
Finally, it’s ALWAYS hilarious when some Truther invokes a real engineer’s data & contradicts his conclusions.
You use Nordenson’s analysis, ostensibly to bolster your “the collapse couldn’t progress a multifloor collapse”.
There is simply no way to break the floor below with a falling beam and girder assembly from one floor above. The eight floor cascade could not have happened. It is pure fiction.
Let’s see what Nortenson has to say about that, shall we?
Nordenson said:
Upon failure of Girder 44-79’s connection to Column 79 on Floor 13, the southern end of the girder is unseated and falls toward Floor 12. As it falls, the composite beams framing into the girder as well as a portion of the concrete slab are also pulled down, and the collapsing partial floor section impacts Floor 12 below.
Using principles of energy conservation, it was determined that the impact energy of Floor 13 falling on Floor 12 is sufficient to fail the floor, causing the propagation of floor collapse on lower floor levels. Using the same methodology, it was determined that the propagation of the floor collapse on lower levels could not be arrested, even on Floors 5 and 7, which are thicker and more highly reinforced than the typical floors. The analysis methods outlined in the following section demonstrate that the failure of the Girder 44-79 connection to Column 79 on Floor 13 initiated a sequence of partial floor collapses that propagated until reaching the base of the structure.
page B1
Note that, unlike NIST, Nordenson is invoking only the A2001 girder & its attached beams.
And only a drop of 1 floor.
But his analysis is not as incompetent as yours, Tony.
In fact, the main difference is that you simply assert your nonsense.
Nordenson actually did an FEA.
You?
... not so much …
