As the second anniversary of the 9/11 disaster approaches, federal investigators have revealed that early tests on steel beams from the World Trade Center show they met or were stronger than design requirements, ruling them out as a contributing cause of the twin towers collapse.
Engineers of the National Institute of Standards and Technology have run preliminary tests on 236 pieces of steel from ground zero, according to the Associated Press, which quoted Frank Gayle, the man leading the investigation.
Tests showed the steel beams could bear in excess of 36,000 pounds per square inch and often could bear around 42,000 pounds per square inch.
Lead investigator Shyam Sunder said: What that is showing us is that the steel that was applied certainly met the specifications, but was also significantly higher in some instances.
The Skyscraper Safety Campaign, a group of families of 9-11 victims, had complained about the governments rapid removal of steel from the site. The beams were shipped off and reprocessed into new beams before they could be examined.
Sunder said if the test results continue, they would rule out weak steel as a factor in the WTC collapse.
The two-year probe is designed to create a model of the fire and collapse, allowing NIST to draft recommendations for improved fire and safety codes in building construction.
James Quintien, professor at the University of Maryland, said key questions about the steels strength under intense heat, and the overall building design remain unanswered. Release of transcripts of tapes made of firefighter transmissions from inside the towers on 9-11 disclosed there was no prolonged intense fire.
In coming months, investigators will recreate sections of the WTC floor trusses and will carry out large-scale fire endurance tests to see how they react.