Sometimes great innovations happen when you step out of your comfort zone. We verified this when we decided to test a new system to prevent the collapse of buildings with a full-scale experimental building. The new building design we propose, surprisingly, prevents it from completely collapsing in the event of any extreme event, such as a large impact, an explosion or a terrorist attack. It even prevents chain falls after a natural disaster such as an earthquake or a landslide.
Also, sometimes, great innovations come from imitating what happens in nature. In this case, the system we developed is a defensive strategy against catastrophe that imitates the behavior of lizards when they lose their tail.
The result of our work has had enormous international echo. Magazine Nature (one of the ones with the greatest scientific impact) included it on its cover, something worth highlighting if we take into account that it is the first time that research in the field of construction and building design occupies its cover.
The process to get here has been quite an adventure. Seven years of work and two seconds to finish tearing down a building.
Haengju Bridge and Champlain Towers
Wikimedia commons
Eleven spans of the Haengju Bridge, South Korea, completely collapsed after the initial failure of one of them during construction. The Champlain Towers in Miami collapsed in a domino effect after a local structural failure. The Disaster and Emergency Management Agency noted that in Turkish territory alone, at least 5,606 buildings collapsed during and after the earthquake on February 6, 2023.
Human casualties are often caused not by external action, such as an earthquake, but by the collapse of buildings.
The disasters that occurred between 2000 and 2019 have caused 1.23 million deaths and 2.97 trillion dollars in economic losses. Many of these losses can be attributed to building collapses.
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why they fall
Collapses occur due to an “initial failure” located in a specific part of a building. From that failure, a chain of failures begins that propagate to the rest of the structure, as if it were a domino effect.
The initial causes can be diverse: earthquakes, floods, storms, landslides, explosions, vehicle impacts, the aging of the structure itself or even construction or design errors.
Current methods of designing building structures focus on preventing the onset of collapse following a small local failure. It is achieved by making all the elements of the structure closely connected, so that the load supported by any element that fails is redistributed to the rest of the structure. But if the initial failure is large, the system does not work and the bridge or building falls.
In these situations, the application of designs based on high connectivity between elements can even be harmful, because the parts of the building that collapse can pull on the rest of the structure, generating a chain collapse that can affect the entire structure. the structure. The fact that the most catastrophic collapses have been due to large initial failures raises concerns about the effectiveness of current designs.
How we approach it
The article that we have published in Nature It includes a new design, which meets the requirements of current codes, but prevents a collapse from propagating after a small initial local failure. The design introduces a new approach, analogous to how “lizards lose their tail when faced with an external threat.” We make the initial collapse isolated and… “lost.”
The trick lies in the implementation of structural fuses, which allow the building to be segmented in case of failure. That is, we lose a part of the building to preserve the rest.
The columns and tail of lizards
The most important components for a building to remain standing are the columns. If the columns fail, everything they support collapses. To prevent successive failure of columns, our design ensures that beam and slab connections to columns are designed to fail before they can transmit sufficient forces to successively break columns.
Our design is inspired by how lizards protect themselves from predators when threatened, releasing their tail to do so. This tactical sacrifice prevents them from being devoured.
Under normal conditions, lizards retain and use their tail. In the case of buildings, our design ensures a high level of connectivity between elements in normal and accidental situations defined in the design codes. However, when a large initial failure is going to propagate to the rest of the building, the collapse is isolated, protecting the rest.
We put it to the test
The design was tested and implemented in a single trial on a full-scale prefabricated concrete building. The test revealed that the design is effective and can be applied at very low cost, using techniques and elements that are already commonly used in the construction sector.
The building that remains standing suffers only minor damage, allowing safe rescue and evacuation operations to be carried out, saving lives in the event of an extreme situation.
In future work within the framework of the project Endure We will test this design in two other buildings: with a concrete structure executed on site and with a steel structure.
We will also develop simplified design methods to facilitate their use in the daily practice of engineering and architecture. These measures should help us build robust buildings for a more resilient society.
