Researchers at Purdue University have created a computer-based 3-D simulation to study in detail the cause of the World Trade Center (WTC) collapse on Sept. 11, 2001, local media reported Wednesday.

A report on the first part of the simulation concludes that the fuel of the hijacked airplanes, when ignited, stripped away crucial fireproofing material and produced a flood of flaming liquid that knocked out columns within the twin towers.

The weakened buildings then collapsed under their own weight.

The simulation research, funded by the National Science Foundation, was carried out by a team made up of the same Purdue researchers who in 2002 created a similar simulation of the Sept. 11 attack on the Pentagon.

"We have finished the first part of the simulation showing what happened to the structure during the initial impact. In the coming months, we will explore how the structure reacted to the extreme heat from the blaze that led to the building's collapse, and we will refine the visual presentations of the simulation," said Christoph M. Hoffmann, co-director of the Computing Research Institute at Purdue.

It took about 80 hours using a high-performance computer containing 16 processors to produce the first simulation, which depicts how the plane tore through several stories of the structure within a half-second.

The two-year study was the first to use 3-D animation to provide visual context to the attacks.

Researchers on the study say the work shows that it is essential to fireproof steel structures.

When the WTC was built, codes did not require steel beams to be fireproofed.

Source: Xinhua