No the planes didn't disintegrate when they hit the building. They melded into the building and then there was an explosion. Planes don't just disintegrate upon impact into a building or anything else. You should go back and watch the footage.
Jim
Originally Posted by Mr MojoRisin
So... A plane that hits the ground at 600 mph doesn't disintegrate? Really?
And it wasn't an explosion. It was a conflagration, technically.
"The steel columns were covered with insulation, and were designed to maintain their strength for 2 to 3 hours of burning. However, the material that burned was not office furnature and paper documents. The wings, with their fuel load, probably remained in the building, where they provided fuel for the subsequent burning. The fierce burning that took place over the next hour was slowly fed by the fuel leaking out of the remains of the tanks.
At high temperatures, steel will melt. At much lower temperatures, it weakens. The jet fuel created a holocaust far hotter than planned for in the building. When the columns weakened, they became vulnerable to buckling. When buckling takes place, it takes place quickly. When one column buckles, it puts more weight on the others, and they buckle too. The columns for an entire floor (maybe for several floors) buckled at one time. The upper floors then slammed into the lower floors. The impact multiplied the force on these lower floors, and they buckled. The process continued as each lower floor continued to buckle in turn. In a few seconds, the entire building had collapsed.
Did the terrorists know this would happen. No. This was a new mode for the collapse of a tall building that was completely unanticipated. I can't rule out that some engineer, sometime, didn't write a memo pointing out this failure mode, but it was not well known. If it were, the building would not have had 300 firemen in the building at the time of collapse.
It is the fire that eventually caused the buildings to collapse. It was not the impact of the plane; it was not the explosion."