Computer clues to Pentagon crash

Orange shows fuel onboard as the plane crashed

A computer simulation of the attack against the Pentagon last September could be used to design buildings that can withstand terrorist attacks.

The software used principles of physics to show how the plane's huge mass of fuel and cargo impacted the building.

It could help design buildings such as hospitals and fire stations that would be more resistant to similar attacks.

It was designed by engineers and computer scientists at Purdue University in the US state of Indiana.

Mathematical model

At that speed, the plane itself is like a sausage skin

Professor Mete Sozen, Purdue University

Computer science professor Christoph Hoffmann said the simulation could play a vital role in future.

"We hope that through such simulation we can learn from this tragic event how to protect better the lives of our citizens and the civil infrastructure of the nation," he said.

The model shows that it was not the plane's structure that caused the damage to the building.

"At that speed, the plane itself is like a sausage skin," said Professor of Structural Engineering, Mete Sozen.

"It doesn't have much strength and virtually crumbles on impact."

Instead the combined mass of everything inside the plane, particularly the fuel, that had the effect of a huge river crashing into the Pentagon.

Lengthy process

Professor Sozen first created a mathematical model of the reinforced concrete columns which supported the Pentagon building.

This was turned into a simulation, representing the plane as thousands of small squares containing specific physical characteristics.

It was a laborious process. Creating just one-tenth of a second of the simulation took about 95 hours of computation time on a supercomputer.

It was important to the scientists to represent both the plane and the Pentagon realistically as well as being true to physics.

The result has pleased all involved in the project.

"This is going to be a tremendous asset," said Professor Sozen.

"Eventually, I hope this will be expanded into a model that we can use to help design structures to resist severe impact loads."