Visualization of simulated attack to benefit structural engineers

Why — and how, exactly — did the Twin Towers collapse the way they did? An animated visualization created by researchers at Indiana’s Purdue University will help structural engineers understand exactly what happened during the attacks on the World Trade Center in 2001. Christoph Hoffmann, a professor of computer science and director of Purdue’s Rosen Center for Advanced Computing, said that the animation reveals more information than could be conveyed through a scientific simulation alone.

The simulation depicts how a plane tore through several stories of the World Trade Center north tower within a half-second, and found that the weight of the fuel acted like a flash flood of flaming liquid, knocking out essential structural columns within the building and removing fireproofing insulation from other support structures. The simulation used lines and dots to show the aircraft and building during the event. To develop the new animated visualisation, Voicu Popescu, an assistant professor of computer science, developed a translator application which creates a link between computer simulations and computer visualization systems to automatically translate simulation data into a 3D animation scene.

In the animation, elements that were not part of the scientific simulation, such as flames and smoke, are clearly rendered, although the visualization does not show the subsequent effects of the fire. Still, the visualization has a realism never seen before.

Purdue researchers have developed a scientifically based video animation of the 9/11 attacks on the World Trade Center. Their research has found that it was the weight of the fuel (some 10,000 gallons on impact), combined with the fire, and not the aircraft itself, that caused the most damage to the buildings. “It is the weight, the kinetic energy of the fuel that causes much of the damage in these events,” Hoffmann said. “If it weren’t for the subsequent fire, the structural damage might be almost the same if the planes had been filled with water instead of fuel.”

The animation is the latest in a series of projects by the Purdue team that arose after 9/11 to determine the structural damage that occurs when an airplane collides with a building. One goal was to develop structures that can withstand a terrorist attack, but the team also has used this research to investigate other scenarios, such as an airplane inadvertently crashing into a building located near an airport.