Lizard defense strategy inspires system for collapse-proof buildings

Extreme situations such as earthquakes, floods or terrorist attacks require more resistant buildings. These events cause severe damage to structures and can cause a building to collapse like a house of cards. To address the challenge of minimizing human and material losses, science and engineering have come together in a work carried out by researchers from the Polytechnic University of Valencia (UPV) in Spain.

The authors sought inspiration in the animal world, and their project imitates the ability of lizards to detach their tails to escape from predators. “We released a part to save 10,” explains José Adam, engineer and leader of the research. On Wednesday, the researchers published their results in the Nature. What’s more, the work made the front cover of the prestigious journal — a historical milestone, since it is the first time that research in the field of building design and construction has made the cover of Nature.

The team has devised a new construction system that can prevent the collapse of an entire building by ensuring that, in the event of a catastrophe, the failure is localized to the damaged region without spreading. The method is intended for application in critical buildings such as hospitals, shopping malls and bus terminals, where there are large concentrations of people. In addition, this technique does not increase construction costs. The project, called Endure, has been funded by the European Research Council with a Consolidator Grant of more than €2.5 million ($2.72 million). It initially came about thanks to a Leonardo Grant that Spain’s BBVA Foundation awarded to Adam in 2017.

When a building is affected by severe weather conditions or accidents, the impacted part causes a domino effect that ends up affecting the rest of the building. Current designs attempt to prevent the collapse from spreading by connecting the structure to compensate for the damage. However, this idea, although effective in the first instance, can end up causing the entire structure to completely collapse. But what if there was a way to stop the domino effect? This is the question that the researchers asked themselves.

A unique opportunity to test the results

The team of scientists and engineers has devised a hierarchy-based collapse isolation system, the key to which lies in the implementation of structural fuses, which allow the building to be segmented in the event of a failure. According to Adam, this design philosophy is similar to fuse-based protection of electrical networks. His technique has been validated by a test on a real building — 15 by 12 meters in plan, with two 2.6-meter-high floors — using prefabricated reinforced concrete. It is the first solution of its kind to be tested and verified at full scale.

To do this, they put the building through two phases of testing in June 2023. In the first, they removed two columns that were not adjacent to each other at the same time. In the second phase, they removed a corner column that was among those removed in the first phase. This initiated a collapse in all areas directly supported by the missing columns, but not in the rest of the building. In other words, they successfully prevented the entire structure from collapsing.

“It’s like preparing for the Olympic Games,” says Adam regarding the tests, comparing the long preparation stage required for a single test that only lasts a few moments: “Four years of work are summed up in two seconds. The collapse of a building lasts only that, two seconds,” he explains. The team will be able to carry out two more tests to test the system’s effectiveness with other materials such as in situ concrete and steel.

Antoni Cladera, professor of Construction Engineering at the University of the Balearic Islands in Spain, has celebrated the results. “It seems simple and logical, but it means turning around the usual practices in construction,” says Cladera, who did not take part in the study. “There is research that is not as visible as others, but it also helps save lives.”

The challenges ahead

While celebrating his team’s achievements, Adam is aware of the long road ahead. The technique is far from being implemented, since construction is a highly regulated sector and modifying regulations is complex. Cladera agrees: “A lot of work awaits them to convince researchers and construction companies.” However, both engineers remain positive about the future and argue that the method could even go further: “Surely the same principle can be applied to other structures such as bridges. We all need and want to feel safe,” reflects Cladera.

Now, seven years after the start of the project, it will continue to develop in the structures laboratory of the Institute of Concrete Science and Technology of the UPV until 2026. The research represents a significant step forward towards building safer buildings and saving human lives in extreme situations. Nature says that the approach will make buildings more resilient and therefore “meets the primary goal of structural engineering, which is to protect the safety of the public.”

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