So happens that bin Laden had a degree in engineering, so he'd likely have known quite well that the buildings collapse was very likely. At least we can say one good thing about bin Laden...he's dead. Good!

Two planes, full of passengers, in flight crew & fully loaded with aviation fuel were bound to decimate buildings.

yes. They studied engineering etc

No.

I know some people may think this question is stupid, but I am curious. Did Al Qaeda know that by crashing the planes into the World Trade Center that the towers would fall, or was that just a "bonus" for them?