By "structurally sound" I mean, "not unsound, structurally."
I don't mean that the engineer who built the house out of playing cards didn't use superglue to hold the house together. I meant that he though any kind of house of playing cards was structurally worth anything other than show.
It doesn't matter that what you have just posted does not make sense. Phrases like "structurally sound" have very specific meanings.
Put it this way - If I was an investor and had that kind of money and was looking at Building 7, no to buying it. It just plain looked kind of shakey.
It would be nice if the things that I posted made sense to you. You could be quite a fantastic person for explaining things that made sense, if you only understood some sense.
At the base of it, the things that apply to Bulding 7, apply to the Twin Towers as well. The fires didn't weaken the Towers enough that they could have come close to falling from them. But, if they fell from some fires, they wouldn't have fallen into their own footprint in 11 to 14 seconds as they did. They would have toppled.