Does this give anyone any ideas? http://www.dump.com/2010/12/11/bullet-physics-engine-simulates-the-creation-and-destruction-of-keva-planks-video/

The area under the impact seems incredibly resistant to collapse, unlike WTC 1 & 2 ; (would've liked to see the ball hit higher up)

Someone contact these guys and get them to do a simulation of the WTC'ers!