The 9/11 Attacks Changed How Engineers Design Buildings

September 16, 2015 | Kelly Tatera

Ground zero, New York City. World Trade Center
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Following the tragic collapse of the Twin Towers on 9/11, engineers were compelled to redesign the structure of buildings to prevent such rapid downfall from occurring again.

The attacks on 9/11 in New York took a devastating amount of innocent lives as the Twin Towers quickly collapsed after being struck. In order to maximize preparation and minimize loss in the case of a similar emergency in the future, architectural engineers have transformed their building techniques.

The towers quickly collapsed despite having heat protection surrounding their internal steel beams, which was pretty shocking to engineers. It turns out that the World Trade Center’s rapid collapse was largely due to its ultra-stiff, long steel beams holding up each floor. To avoid wasting floor space, there were no internal columns in between the beams that stretched from the elevator’s core (in the center of the building) and the building’s perimeter.

While this design allows for an incredibly stable building with the capacity for tens of thousands of workers, it largely contributed to the rapid collapse after the buildings were hit. The beams were so rigid that, upon impact, the fire protection was immediately knocked off. Then, as a result of the extreme heat following the explosion, the beams expanded and pushed against the perimeter. Tragically, this caused the entire structure to swiftly collapse.

The day after 9/11, J. Paul Beitler, a Chicago developer who once aspired to build the world’s tallest building, told The Chicago Tribune that governments would no longer pass plans for skyscrapers in fear that they’d become “magnets for future terrorism.”

However, over a decade later, skyscrapers are still popping up around the globe. But it’s undoubtedly become part of the architect “mantra” to ensure security at any cost, and many have managed to accomplish the goal in aesthetically-pleasing and environmentally conscious ways. In fact, the One World Trade Center will not only be one of the safest skyscrapers in the world, but also one of the most environmentally sustainable, featuring biological and chemical air filters, green cooling and irrigation systems, and blast-resistant glass.

In order to give people more time to evacuate buildings in case of emergency, researchers at the University of New South Wales (UNSW) in Australia developed a high performance concrete that’s twice as strong and 200 times tougher than regular concrete. This means the new material can absorb 200 times more energy than standard concrete and continue to stand, allowing more time for people to evacuate.

In addition to safer building structure and materials, researchers are now testing bombs to analyze how the blasts behave in city environments, and relying less on the results collected by computer modeling data in open spaces.

Check out the latest episode of Catastrophic Science created at UNSW to get some more insight on how terrorist attacks have refashioned building methods:


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