Re: One Structural Engineer's Professional 9/11 Opinion
posted at 12/31/2010 10:16 AM EST
In Response to Re: One Structural Engineer's Professional 9/11 Opinion
[QUOTE]Interesting generalities. The near free fall I like. There is no evidence produced for this assertion and video shows this not to have happened. So why do troofers keep saying it? The strength factor has nothing to do with the collapse. Once started it clearly overwhelmed the design spec what ever the actual spec was. The strength factor, as any engineer worth the label would clearly de rate during an intense fire in a structure designed to use sprinklers, could not be relevant in this situation. I really like the exploding "upward" statement. That is a first. Mostly because it did not happen and it undercuts the demolition argument. Demo experts would never see such a thing happen. Cutting charges are designed to focus toward the object to be cut not outward and certainly not upward. The charges alleged to have been used are very bulky and very slow burning. Less than 1/4 the velocity of C4. Thermite burns more like black powder than C4 and would not have a large quick blast. I geuss this guy did not read the engineering report. If he had he might have had facts in his statement instead of vague general arm waving. So how close to free fall was the collapse? Not very. Faster than a paper airplane, slower than the large lightweight extenal cladding sheets and glass that easily hit the ground before the rest of the building.
Posted by topaz978[/QUOTE]
“Interesting generalities. The near free fall I like. There is no evidence produced for this assertion and video shows this not to have happened. So why do troofers keep saying it? “
Because NIST has said it – I keep posting this, and you keep ignoring it. Then you make uneducated, idiotic, unfounded statements like “There is no evidence”
So, one more time, here is the “evidence”
The following 3 paragraphs are excerpted verbatim (that means an exact, unedited, not-out-of-context copy) from the NIST NCSTAR report from page 602
In Stage 1, the descent was slow and the acceleration was less than that of gravity. This stage corresponds to the initial buckling of the exterior columns in the lower stories of the north face, as seen in Figure 12-62. By 1.75 s, the north face had descended 7 ft.
In Stage 2, the north face descended at gravitational acceleration, as exterior column buckling progressed and the columns provided negligible support to the upper portion of the north face. This free fall drop continued for approximately 8 stories (105 ft), the distance travelled between times t = 1.75 and t = 4.0s.
In Stage 3, the acceleration decreased somewhat as the upper portion of the north face encountered resistance from the collapsed structure and the debris pile below(3). Between 4.0 s and 5.4 s, the northwest corner fell an additional 130 ft.
(Highlight color added) As you can see, NIST has admitted to real, honest to goodness free fall of the massive WTC7 to the tune of 8 full stories, an incredible amount equal to over 17% of the total height of the 47 story structure.
Follow the link provided above, and satisfy yourself that this is the actual NIST report, on the actual government site. Scroll down to page 602 and satisfy yourself that the excerpt above is exactly as I have posted. Then tell me once again that there was no admission of, no evidence for, FREE FALL
This is not a contest of “gotchas” – I have no ego vested in being right about this – I sincerely wish I were wrong because it is so disgusting – but I’m not wrong, because there was free fall of a massive steel frame structure, a free fall equivalent to 8 full stories, each one the size of a football field, and that is physically impossible without enormous amounts of added energy – that’s right… EXPLOSIVES