Originally posted by thedman
Yes the towers were strong - as long as the steel work was intact.
More than 85% of the columns were still intact on the impacted floors. 100% of the columns were still intact on all other floors (allegedly).
This is according to NIST and the FEMA report chapter 184.108.40.206 and 220.127.116.11. They counted the perimeter columns. NIST modeled worst case scenarios for
the core, assuming both engines knocked out core columns (the engines would have been the only things dense enough at that point according to NIST).
The counter perimeter columns severed were something like 11% on the impacted floors in one tower and 13% in the other, and then when you factor in
the % of core columns it still conservatively comes out less than 15% columns severed on those floors.
A safety factor of 2 means that at least 50% of the columns' capacities would have to be compromised to reach the yield strength of the remaining
columns, which is the force at which deformation first starts. Again this is at 50% compromised integrity with a FoS of 2, and the impacts only
accomplished less than 15% compromised integrity on those floors. And not only that, but the WTC Towers most likely had even greater safety factor
ratings than 2 (we don't know for sure because NIST never released all the necessary data). It is ILLEGAL for a skyscraper in NYC to have a rating
of less than 2, and actually in the NIST report it outlines how all NYC skyscrapers are required by law to pass a number of rigid tests and that the
WTC Towers passed all of them and was in accordance with building code.
WTC one of the first buildings to use
engineered steel in its structural support.
Source please. Seriously, I am asking you for a source for this. If you cop-out and don't post one then this statement is as good as refuted,
because it is based on nothing but your wild fancy.
The Empire State Building used steel and it was built in the 1930s.
Built during the Depression between 1930 and 1931...The Empire State Building is composed of 60,000 tons of steel
Another thing. Engineers would not design such a massive project if they were unfamiliar or had uncertainties about the materials they were using.
That is not how modern engineering works, especially in multi-million dollar firms. Sorry.
Problem with steel is heat - when exposed to heat steel will
1) expand 2) lose structural strenght 3) undergo plastic deformation or "creep" under load
1) See the Cardington tests. Expansion in steel-framed structures is studied there and it has never been shown to lead to run-away collapses.
2) Loss of structural integrity due to excessive heating has NEVER been an accepted theory of why the buildings collapsed. FEMA rejected it, and
NIST rejected it, and anyone who looks at how much heat would be required to elevate enough steel to 600 C or above realizes how ridiculous the idea
is, and why NIST and FEMA both dismissed it immediately as a possibility.
3) Creep is a very gradual phenomenon (thus the name "creep", not "snap" or "boom") and does not cause skyscrapers to collapse within 2 hours.
Especially when the necessary overloading and heating was also not realistic, as discussed above.
The aircraft impacts severed many structural support members
Discussed in detail at the start of this post.
Structural members were pulled out of alignment weakening them further . heat the steel enough will
lose its load bearing strenght and cause the structure to collapse
According to only you, and no one else. Well at least no one who has actually read the reports or taken the time to educate themselves about this
theory. NIST and FEMA both disagree with you.
And I'll definitely be waiting for a source for your claim, that the WTC Towers were one of the first buildings to use steel.