Wow, my first GQ thread… 
My question: Were the World Trade Center towers designed to “implode,” i.e., fall straight down as opposed to falling over in case of catastrophe? In a morbidly fascinating sort of way, the second tower to fall I thought was beautiful in the way it collapsed, but I noticed they both fell fairly smoothly straight down rather than falling over. If the planes had hit nearer the base, was there a chance the towers could have fallen over instead of down?
Esprix
I think compared to their enormous height, the buildings simply weren’t strong enough to be able to topple over whole; that would take unbelievable rigidity.
Large objects simply don’t behave in the same way as scaled down models.
The WTC would not have fallen over. How I have heard it explained is this:
Earlier skyscrapers (such as the Empire State Building)were steel-framed, which means that the steel infrastructure bore the load of weight of the building, and the outside walls weren’t needed for that.
The World Trade Center, however, was designed so that the outside walls were the load-bearing members. In other words, the slender columns on the outside of each tower, 39" apart from each other, were what held the whole thing up. So, when the planes hit and weakened those steel supports, the impact alone didn’t collapse the building; the steel had to melt under the intense heat created by the fire for the collapse to occur. When it did it collapsed everything inward.
I’m not an expert, but I’ve learned a few things from the news and from reading stuff here.
I’m not sure that the impact of a possible collapse was specifically planned for. However, the way the building was put together made sure that it fell pretty much straight down.
Unlike many ‘skyscrapers’ which build around a central steel core, the WTC towers had a steel skeleton around the outside. The weight of the building was borne by the outer walls. So, when the floors began to collapse, they naturally fell first at the weakest point: the center. The outside acted as a chute, funnelling the collapse down. As the center went down, it eventually pulled the walls in, which also went into the ‘pipe’ created by the walls that still stood.
Another thing: it isn’t really possible for a building to ‘fall over’. In order to fall to the side, the building would need to stay in one piece (which it isn’t going to do) and it needs to be pushed with enough energy to lift the center of gravity a bit (so that it can then be free to move to the side). Needless to say, the force needed to actually lift one of these structures would be beyond enormous. The closest to ‘falling over’ that such a building could do would be a sort of waterfall of debris pouring off to one side. Even so, most of that would go down, not to the side.
More stuff on the buildings:
http://www.cnn.com/2001/US/09/12/wtc.architect.cnna/index.html