WASHINGTON — The twin towers of the World Trade Center sustained enormous structural damage after two hijacked jets crashed into the 110-story buildings Sept. 11, and the steel eventually buckled under the tremendous heat generated by fires caused by spreading jet fuel, a federal team of engineers has concluded in a report to be released today.
Saying it was “remarkable” that the towers remained standing as long as they did, the engineers warned that it “may not be technically feasible” or cost-effective to design structural safeguards to protect other skyscrapers from toppling in similar attacks.
“Resources should be directed primarily to aviation and other security measures rather than to hardening buildings against airplane impact,” stated the report by the Federal Emergency Management Agency and American Society of Civil Engineers.
Although the report found that the World Trade Center met building standards, it urged a national study to examine broader issues such as the quality of fireproofing materials, placement of emergency-exit stairwells, evacuation procedures and firefighter response. New standards might be needed to evaluate fire resistance along with changes in building codes, the report said. Specialists also should look for feasible design changes to limit or stop collapses that have begun, it said.
The towers, designed in the 1960s, were unique because they were built to withstand the impact of the largest jet at the time, a Boeing 707. But the design plan did not take into account the consequences of jet fuel and a massive fire, engineers said.
“There’s no smoking gun where we could say there was a terrible design feature here,” said Jonathan Barnett, a professor of fire-protection engineering who helped write the report. “We went into this to study the buildings and how they performed and what lessons could be learned to make the world a safer place.”
