The exterior walls were mostly glass. That is the style of modern skyscrapers. They were not significantly concrete. The exterior wall had steel columns...among all the others in the core, which were holding up all that weight. There is utterly no mystery about this and I don't understand why I have to explain this to you like you are a child. Did I not give you the reference to the B-25 collision with the Empire State Building?---which was a much less serious event.
As for the building "still standing," I didn't catch that except on second reading. What possibly can that prove? We normally expect (for example) that automotive head-on collisions are terrible affairs with loss of life and mangled vehicles. But I was in one where I was essentially unhurt and my car had mainly cosmetic damage. So also, the other party. You can't draw rules from discrete events. There was nothing else like the Twin Towers event so far as I am aware. And the "still standing" building was only about 20-25 stories. The photo shows the fire department working to abate the fire. No possibility of that at the height of the Twin Towers collision. You are not making a logical comparison. The majority of professional opinion was that the collapse was understandable. As an engineer, I find it understandable. What more do you want? You don't seem to be approaching this as an engineer, or as one familiar with structures.
WTC7 also collapsed from columnar failure from an internal fire (innards first and walls last).
Thanks for the photo. Very interesting. I had thought the building used the heretofore standard curtain wall approach. The windows (dark spaces) comprise about 50% of the wall and are non-structural. I presume the rest are columns (light-colored surfaces), which are structural, and carry vertical loads---along with the interior columns. They are not designed to withstand lateral loads (an airliner crash).
In any case, the collapse of the building was the result of failure throughout the column array, not just from the exterior columns.
Have you looked at the vast expanse of glass in WTC1 and WTC2?
Thought not.
As for the 110 floors, something was holding up all that weight. Whatever it was was not trivial in the strength department.
The exterior walls were mostly glass. That is the style of modern skyscrapers. They were not significantly concrete. The exterior wall had steel columns...among all the others in the core, which were holding up all that weight. There is utterly no mystery about this and I don't understand why I have to explain this to you like you are a child. Did I not give you the reference to the B-25 collision with the Empire State Building?---which was a much less serious event.
As for the building "still standing," I didn't catch that except on second reading. What possibly can that prove? We normally expect (for example) that automotive head-on collisions are terrible affairs with loss of life and mangled vehicles. But I was in one where I was essentially unhurt and my car had mainly cosmetic damage. So also, the other party. You can't draw rules from discrete events. There was nothing else like the Twin Towers event so far as I am aware. And the "still standing" building was only about 20-25 stories. The photo shows the fire department working to abate the fire. No possibility of that at the height of the Twin Towers collision. You are not making a logical comparison. The majority of professional opinion was that the collapse was understandable. As an engineer, I find it understandable. What more do you want? You don't seem to be approaching this as an engineer, or as one familiar with structures.
WTC7 also collapsed from columnar failure from an internal fire (innards first and walls last).
But you also said:
Sounds mysterious to me. Structural or not structural?
I am still trying to find all that glass: https://en.wikipedia.org/wiki/File:WTC-Perspektive.jpg
Thanks for the photo. Very interesting. I had thought the building used the heretofore standard curtain wall approach. The windows (dark spaces) comprise about 50% of the wall and are non-structural. I presume the rest are columns (light-colored surfaces), which are structural, and carry vertical loads---along with the interior columns. They are not designed to withstand lateral loads (an airliner crash).
In any case, the collapse of the building was the result of failure throughout the column array, not just from the exterior columns.
What is your point?
My main point now is that you do not seem to know what you are talking about!
Another thing you seem to have missed: The buildings WERE stressed to combat collisions with planes.