Researchers at Purdue University have created a computer simulation of what likely happened (engineering-wise) when an airplane crashed into the World Trade Center's North Tower on 9/11/01:
The simulation could be used to better understand which elements in the building's structural core were affected, how they responded to the initial shock of the aircraft collision, and how the tower later collapsed from the ensuing fire fed by an estimated 10,000 gallons of jet fuel, said Mete Sozen, the Kettelhut Distinguished Professor of Structural Engineering in Purdue's School of Civil Engineering.
So far, the scientists and engineers had used the simulation to analyze how many columns were destroyed initially in the building's core:
The researchers are analyzing how many columns were destroyed initially in the building's core, a spine of 47 heavy steel I-beams extending through the center of the structure, Sozen said.
"Current findings from the simulation have identified the destruction of 11 columns on the 94th floor, 10 columns on the 95th floor and nine columns on the 96th floor," he said. "This is a major insight. When you lose close to 25 percent of your columns at a given level, the building is significantly weakened and vulnerable to collapse."
Link (includes video of the simulation in action) - Thanks Another Jake!