(September 12, 2016 at 11:36 pm)Thumpalumpacus Wrote: The fires that caused the collapse were obviously lower than the 12th and 13th floors:
Additionally, the color of the smoke tells the canny fireman that petrochemicals (most likely plastics, in this case) were highly involved. Those burn are very high temperatures.
We have a hot fire on the lower floors of a large heavy building that burned unabated for hours. Steel loses 50% of its load-strength after 30 minutes exposed to 1300°F heat. The steel in the lower part of the building failed.
Dude, that picture is taken half way through it's near free-fall.
Here's a better one...
Do you know how many blocks away it was taken? You can definitely see the burnt out floors and that looks fairly high....look at all those street lamps going off into the distance...
And this is the official NIST report:
https://www.nist.gov/engineering-laborat...estigation
According to the report's probable collapse sequence, heat from the uncontrolled fires caused thermal expansion of the steel beams on the lower floors of the east side of WTC 7, damaging the floor framing on multiple floors.
Eventually, a girder on Floor 13 lost its connection to a critical column, Column 79, that provided support for the long floor spans on the east side of the building (see Diagram 1). The displaced girder and other local fire-induced damage caused Floor 13 to collapse, beginning a cascade of floor failures down to the 5th floor. Many of these floors had already been at least partially weakened by the fires in the vicinity of Column 79. This collapse of floors left Column 79 insufficiently supported in the east-west direction over nine stories.
Excuse me I was in error, it was in free fall for 2.25 seconds.
http://www.europhysicsnews.org/articles/...6-47-4.pdf
The total collapse of WTC 7 at 5:20 PM on 9/11, shown
in Fig. 2, is remarkable because it exemplified all the signature
features of an implosion: The building dropped
in absolute free fall for the first 2.25 seconds of its descent
over a distance of 32 meters or eight stories [3]. Its
transition from stasis to free fall was sudden, occurring
in approximately one-half second. It fell symmetrically
straight down. Its steel frame was almost entirely dismembered
and deposited mostly inside the building’s
footprint, while most of its concrete was pulverized into
tiny particles. Finally, the collapse was rapid, occurring
in less than seven seconds.
Given the nature of the collapse, any investigation
adhering to the scientific method should have seriously
considered the controlled demolition hypothesis, if not
started with it. Instead, NIST (as well as the Federal Emergency
Management Agency (FEMA), which conducted a
preliminary study prior to the NIST investigation) began
with the predetermined conclusion that the collapse was
caused by fires.
Trying to prove this predetermined conclusion was
apparently difficult. FEMA’s nine-month study concluded
by saying, “The specifics of the fires in WTC 7 and how
they caused the building to collapse remain unknown at
this time. Although the total diesel fuel on the premises
contained massive potential energy, the best hypothesis
has only a low probability of occurrence.” NIST, meanwhile,
had to postpone the release of its WTC 7 report
from mid-2005 to November 2008. As late as March 2006,
NIST’s lead investigator, Dr. Shyam Sunder, was quoted as
saying, “Truthfully, I don’t really know. We’ve had trouble
getting a handle on building No. 7.”
All the while, NIST was steadfast in ignoring evidence
that conflicted with its predetermined conclusion.
The most notable example was its attempt to deny thatWTC 7 underwent free fall. When pressed about that matter during a technical briefing, Dr. Sunder dismissed it by saying, “[A] free-fall time would be an object that
has no structural components below it.” But in the case
of WTC 7, he claimed, “there was structural resistance
that was provided.” Only after being challenged by high
school physics teacher David Chandler and by physics
professor Steven Jones (one of the authors of this article),
who had measured the fall on video, did NIST acknowledge
a 2.25-second period of free fall in its final report. Yet
NIST’s computer model shows no such period of free fall,
nor did NIST attempt to explain how WTC 7 could have
had “no structural components below it” for eight stories.