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Explosion impact, burning fuel caused WTC collapse

Astaneh-Asl, Professor of Civil Engineering at the University of California, Berkeley, who was involved in a study to examine pieces of the steel structure and to train workers unloading steel for recycling to look for tell-tale signs of destruction, told Khaleej Times yesterday that the impact of the explosion and burning of fuel perhaps gradually weakened the steel structure to the point of collapse.

Astaneh-Asl, who hopes to construct a computer model of the Trade Centre buildings and how they fell, uncovered during investigation pieces of structural steel that bear gouge marks — material removed as the Boeing 767s tore through the buildings. One column shows the impact of what he believes to be an airplane wing slicing through the steel; another, the curve of a plane's nose.

These marks, Astaneh-Asl explains, could be made only by a sharp object moving very fast.

Astaneh-Asl was speaking after delivering a lecture on high-rise buildings in Abu Dhabi.

The lecture was organised by the Municipalities and Agriculture Department to discuss the structural design of buildings to resist tremors and other disasters.

Elaborating on the theory of the collapse, Prof Astaneh-Asl said if the wings of the planes fell outside the building, the twins towers would partially collapse and sustained the explosion.

He said that due to the collapse of the twin towers, a massive amendment had been brought in on the standards of constructions in the US such as the code which was issued recently by the American Assembly of Civil Engineers which issued a new complete chapter about the load as a result of the explosion which did not exist before the September 11 events.

Professor Astaneh-Asl said regarding the high costs of construction after the new theories which have come after 9/11, the cost of protection of any building is about five per cent of the total amount of the cost of construction of the building.

He said in fact, not all buildings needed this kind of protection where most of the buildings followed the normal style in construction.

He said the main targets of such measures was to prevent the complete collapse of the building and confine the damage to the site of the explosion.

He denied that the new measures will make the construction a kind of military buildings.

Professor Astaneh warned that there were many companies which were trying to market expensive packages to make unbelievable profits.

He explained that the rate of death due to earthquakes or hurricanes in some countries were high when compared to US such as in the recent incidents in the US where a few hundreds died in Katrina Hurricane due to the strict measures and standards in the US in construction.

Regarding the system and structures of buildings and roads in UAE, Professor Astaneh said it would require a thorough study to arrive at any conclusion. But he said that after meeting with some experts and engineers, he found that safety measures and standards which were adopted in UAE gave him a good impression that these buildings would be able to resist earthquakes and overloads which follow as a result of explosions.

The forum was attended by Khalfan Ghaith Al Muhauirbi, Chairman of Municipalities and Agriculture Department and Engineer Juma Mubarak Al Junaibi, Under-Secretary of the department.

The forum was presented by Dr Abdul Rahim Al Saboni, Technical Affairs Consultant at the department.

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