Jed Rothwell wrote: > Harry Veeder wrote: > >> I suspect the WTC towers were designed with a structural weakness >> to make any future demolition easy. > > ABSOLUTELY NOT! That would be insane. The WTC Towers were one of the > strongest structures made up to the 1970s. They withstood the effects > of the crashing airplanes and fire far longer than any previous > structure could have, or than most would today. > > They collapsed because millions of tons of steel and concrete fell > about 6 meters when one of the floors finally collapsed. The force > from that immediately sheered the next floor supports, and the ones > below that, one after the other. This was obvious from the metal > recovered from the wreckage. It is easy to tell the difference > between metal that was melted and broken from heat, and metal that > was broken by the force of falling weight. In any case, putting > explosives in the lower floors would be pointless. They would not be > needed. The energy of the falling building was roughly equivalent to > a small nuclear bomb. It far exceeded the force you could achieve > with conventional explosives.
That is my point. The building was designed to withstand a severe _horizontal_ blow, but it was not designed to withstand a severe _downward_ blow. The inability of the structure to withstand a vertical shock would make its future demolition a breeze. > Along the same lines, having the > airplanes fire missiles into the building before they struck would be > ridiculous. The energy release from a missile is trivial compared to > the kinetic energy from an airplane, and that kinetic energy is far > smaller than the energy release from the burning jet fuel. The fuel > has enough potential energy to drive the aircraft for hours at close > to the speed of sound! Firing a missile first would be like hitting > someone with a pillow first and then hitting him with a Mack Truck > going at 60 mph. Why bother with the pillow? > > A missile is effective that it can be guided to the target and it > causes intense damage to the machine it strikes. > > - Jed > Harry
