Let's consider the picture Mackey has provided. Mackey is asking us to believe, without evidence, that all of the cross bracing of the core structure which is observed in this photo, was meticulously removed after the cranes were not needed anymore. Why would they do this? Because they needed it for another job! Absent the detailed engineering drawings, which are "missing", observation must rule over assertion. The floor trusses were cross-braced as well, BTW, contrary to the hilarious cartoons produced for the NOVA show.
You need to be much more careful, with that attitude. I've provided
no pictures, nor asked for any.
I don't deal in pictures. Pictures are too subjective for the precision I require. Your claim, bolded, is wrong. That's yet another mistake for you, a clumsy one this time.
It appears you are in such a hurry to "discredit" me that you've lost track of whom you're speaking to.
I have "asked you to believe" nothing. I asked
you to show me that there was additional cross-bracing that neither I, Ross, nor Greening knew about. If you can do that, please do. So far what you've shown me is a terrible picture that may or may not represent temporary bracing during construction. It may also represent bracing well down in the structure that is irrelevant for purposes of collapse initiation.
I don't know what your picture represents. I'm asking you. Seems you don't know either, though you think you do.
You did attempt to answer my questions about it, finally, so that merits a response:
Mackey wanted some answers
1) "It is clear from photographs, such as the one on the right, that the core columns were abundantly cross-braced."
http://911research.wtc7.net/wtc/arch/core.html
I asked you to point out exactly what looks like cross-bracing to you, not to give someone else's inexpert opinion that there is cross-bracing. Please point it out.
2) Observe the construction picture here
http://nomoregames.net/911/trouble_with_jones/core_2.jpg
Would they really use cross bracing as thick and heavy as shown here, only to tear it out after the floor assembly was in place? What evidence do you have that this horizontal and diagonal cross bracing was temporary? Last I knew, the actual drawings for WTC were secret. Have they now been released? A lot of people have been very anxious to see them for a long time.
Oh joy, another picture.
You haven't answered my question. They very well might use "thick and heavy" cross-bracing. I don't know. You've answered my questions with more questions.
I'm still waiting for an answer from you on this, most important question. If you don't know whether those elements stayed in place, just say so.
3) They are made of structural steel. Notice how they are identical in color and appearance to the structural steel elements.
Useless. Color isn't a good determination, though I would also guess they are steel. What I
wanted was more exact -- what size are they? I-beams? Shapes? What thickness? Alloy?
This is why I don't ask for, or use, pictures in quantitative analysis. They just don't contain what I need except in rare examples.
How do you know that?
I would expect them to be bolted, not welded. And yes, it makes a difference.
