[ExI] Fascist America, in 10 Easy Steps

[Jordan Hazen]

On Sat, Oct 06, 2007 at 02:25:48PM -0700, David Masten wrote:
> On Sat, 2007-10-06 at 10:50 -0700, Samantha Atkins wrote:
> > Yes.  Here is a small sampling of some of the official story things  
> > requiring much better explanation.
> 
> Actually they don't require better explanation, but better understanding
> of thermal dynamics and structural design is required of the Truthers.
> 
> > 1) No steel framed buildings in history before this have ever fallen  
> > due to heat softening the infrastructure;

Some have partially collapsed, though nothing so complete or sudden as
at WTC.  The Windsor Tower fire in Madrid is often brought up for
comparison:

 http://www.mace.manchester.ac.uk/project/research/structures/strucfire/CaseStudy/HistoricFires/BuildingFires/default.htm

That was a smaller building, but the fire was more widespread,
eventually engulfing all of it.

After three hours ablaze, parts of the upper facade started falling
off.

After another two hours, Windsor's upper floors started to collapse. 

That collapse left the building's core intact, though, and stopped at
the first reinforced "technical floor" (itself surrounded by fire)
whereas the WTC's much more rapid collapse front didn't even slow down
when passing through intact, reinforced floors at the 78th and 45th
storeys.


> And how many modern high-rise structures have been struck by modern wide
> body airliners? Or putting it another way - how many buildings with
> modern elevator shafts and modern HVAC systems have had thousands of
> gallons of kerosene burning inside them?

WTC's HVAC included a damper system, to help slow the spread of fire
between floors, and its two-tiered express elevator / local elevator
system limited the number of floors served by each elevator shaft. 

Only one freight elevator served all of the floors directly.

In WTC 1, other shafts present on the plane impact floors descended
only to the 77th level sky-lobby.

 
> > 2) The buildings fell is free fall time which is inconsistent with  
> > pancake collapse theories;

A little slower than free-fall, actually.  Compare the fall times of
steel beams ejected horizontally for each building to the advancing
collapse wave, which moves a bit slower (still at a tremendous speed,
which remains constant even when traversing the heavily-reinforced
mechanical floors).

> What is "free fall" time? Please show accelerations and terminal
> velocity, please. Also please show the assumptions for determining
> coefficient of drag of debris. 

Those making this argument usually start with a "free fall in vacuum"
figure, e.g.

 1355 ft = 1/2 (32 ft/s^2) t^2

 9.2 sec = t

Oversimplified as it is, this is still a conservative lower bound,
since the neglected air resistance would act only to increase the
free-fall time, never to decrease it.

In comparison, the observed collapse time was between 12 and 15
seconds.  The huge volumes of pulverized material enveloping each
tower's base towards the end make it it difficult to pinpoint an exact
time.

 
> Despite that, typical demolitions practice for tall buildings is to cut
> the structure at key points and allow the upper stories to bring down
> the stories below it, i.e. the collapse should be nearly identical
> whether it was a demolition job or weakening from a kerosene fire. 

But achieving a straight-down, symmetrical collapse (implosion)
requires precise control over the timing at which individual supports
are cut.

Demolition companies would never attempt to bring a building down by
setting fires.  Even at temperatures high enough to assure complete
column failure, the sequencing would just be too unpredictable, likely
causing the building to topple over onto an adjacent structure.

Conventional demolitions are also done bottom-up (like WTC 7);
top-down would be much harder.

-- 
Jordan.