GovernmentExecutive.com

Computer science and engineering professors at Purdue University used a 3-D simulation program to confirm that the impact of the jets flown by terrorist into the World Trade Center in New York City stripped away fireproofing that eventually brought the buildings down, according to an Associated Press article.

The findings support a National Institute of Standards and Technology report released in 2005. That report "recommended that cities raise fire standards for skyscrapers and develop new materials that can better protect tall buildings from fire," according to the AP. "That analysis did not blame the collapse on the steel or design of the towers, but instead focused on the damage to the fireproofing."

The professors say the simulation, funded by a grant by the National Science Foundation, indicates steel structures should be fireproofed. The towers were built before building codes required such fireproofing.