On Sat, 09 Feb 2008 10:38:10 -0800, Stephen Trapani
wrote:

Everything always falls straight down. That is the direction the force
of gravity acts. What do you think fall means?

Do you have any idea how much trouble demolition experts have to go to
to make buildings "fall in their footprint?" Tall buildings don't
crumple straight down. No one on earth, including all the designers of
the building knew that you could cause an explosion and fire that high
up in the towers and they would collapse, let alone collapse roughly
straight down and take out the rest of the building as it collapses.

The design of the WTC almost certainly had an effect on the mode of
collapse. Almost all of the vertical support for the structures was
concentrated in the outer perimeter. The interior spaces were very
open and had very little structural steel with the exception of the
elevator core. The unusually strong perimeter walls helped to focus
the the falling floors inward. All it took was one floor to collapse
to set off the whole chain reaction. I saw the towers go up over the
course of several years back in the late 60s when I was working two
blocks away on Wall Street, and I saw them come down from acoss the
river in New Jersey.