Intentionally engineering structural weaknesses into a building can prevent catastrophic collapse. This counterintuitive strategy successfully limited damage to a two-storey concrete building in its first real-world experiment.
The innovation was inspired in part by the way lizards will sacrifice their tails to escape the clutches or jaws of predators. In this case, segments of the building’s connective structure are designed to break when stressed beyond a certain point instead of pulling down the rest of the structure. Researchers say such structural engineering could have prevented the fall of the Champlain Towers South beachfront condominium that killed 98 people in Florida in 2021, or the multistorey parking garage collapse following a van bomb explosion that killed two and injured 58 at the Madrid-Barajas Airport in Spain in 2006.
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“We want to prevent collapse, but if we cannot prevent collapse, we want to minimise the collapse,” says at the Technical University of Valencia in Spain.
Setiawan and his colleagues first studied catastrophic building failures – where a structure completely collapses – by compiling a database with dozens of examples. The prevailing design philosophy assumes structural elements must be strongly connected to mutually support a building’s weight if a column or load-bearing wall is knocked out. This principle has shaped modern building codes since the collapse of the 22-storey Ronan Point tower, which killed four and injured 17 in London in 1968.
“This approach works very well if the initial damage affects a limited number of elements only,” says at the Polytechnic University of Turin in Italy, who was not involved in the study. “If, on the other hand, the initial damage affects a larger number of elements, this over-connection between parts is counterproductive and causes the entire structure to collapse.”
The new study overturns this design philosophy by adding “zones of calibrated weakness” in the structure. These zones can still support a building experiencing limited damage, but in cases of catastrophic destruction, they can crumple while preventing a chain reaction of structural collapse, says De Biagi.
Setiawan and his colleagues used computer simulations to find the right balance between strong and weak structural connectivity. They also drew inspiration from unintentional engineering success, such as the US Department of Defense’s Pentagon building in Virginia, which survived partial collapse after a hijacked civilian airliner crashed into it on September 11, 2001.
Simulations set the stage for a full-scale test with a two-storey building made of precast concrete. A first testing phase involved sequentially removing two edge columns on either side of one corner of the structure, which showed the new design could prevent any collapse following a small structural malfunction.
The second phase tested a much larger structural failure by suddenly removing the corner column between the two previously removed columns. That corner of the building subsequently crumbled, but thanks to the new design, the rest of the structure remained standing.
This strategy may work especially well for preventing a horizontal style collapse in low- and medium-rise facilities with large floor footprints, such as hospitals, shopping malls, auditoriums and sports stadiums, says Setiawan. As part of the 2.5 million euro Endure project funded by the European Research Council, the researchers plan to test the innovation in two more buildings made from cast-in-place concrete and steel, respectively.
Nature
