Inspired by lizards, scientists design earthquake-resistant buildings →

In the face of the power of nature, humans always seem very small. Earthquakes, as one of the most common natural disasters on Earth, are often shocking in their destructive power. Traditional building structures are often unable to withstand the impact of large earthquakes, resulting in frequent collapse, serious damage, and a large number of casualties.

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These tragedies continue to remind us that it is urgent to improve the earthquake resistance of buildings. Next, let us unveil the mystery of the new earthquake-resistant building!

Lizard-Inspired New Building System Design

On May 15, 2024, Chinese scientists published an article in the journal Nature about a lizard-inspired building system. The advent of this type of building is expected to avoid the risk of building collapse caused by external impacts such as earthquakes , and build a solid line of defense for our life safety!

The research results were published in Nature magazine. Image source: Reference 1

When an earthquake occurs, seismic waves will produce periodic vibrations. When these seismic waves are close to the natural vibration frequency of a building, resonance will occur, causing the building to vibrate more and aggravate the damage to the building. In building design, a common challenge is how to prevent the damage from spreading further to the entire structure when the building is initially damaged, thereby avoiding catastrophic total collapse. Therefore, in building design, the key issue is how to react quickly like a lizard when the building is subjected to external impact, preventing the damage from spreading further and avoiding greater damage.

There are many predetermined breaking points in the cartilage tissue of the lizard's tail. When the lizard feels danger, it will contract the tail muscles to quickly break the tail at these predetermined points. After the tail is broken, the lizard's body will secrete a kind of mucus to cover the fracture to prevent infection and reduce blood loss. This mucus can also confuse predators, giving the lizard more opportunities to escape. Inspired by this behavior, scientists will propose the concept of "collapse isolation" and apply it to the design of new building systems.

Application of the “collapse isolation” concept

In order to prevent the further spread of damaged parts in buildings in the event of earthquakes or external impacts, scientists apply the concept of "collapse isolation" to isolate the collapse caused by initial large failure by controlling the failure level of the structural system.

Scientists set specific fracture point structures at key parts of the building. When the building is damaged, these parts will break in a predetermined way, ensuring that specific elements fail before the most critical components fail. In this way, the entire building will be isolated into different units, thereby enhancing its damage resistance. At the same time, the different units of the new building system have sufficient connectivity to redistribute loads to each other, further isolating the spread of collapse.

Collapse isolation design based on hierarchical structure (a, beam-column connection based on hierarchical optimization; b, partial collapse isolation simulation of building based on hierarchical structure; c, conventional building collapse scenario simulation) Image source: Reference 1

Field testing and result verification

To verify the anti-collapse effect of this "hierarchical collapse isolation" design in an actual earthquake, the researchers built a two-story building with a length of 15 meters and a width of 12 meters using concrete, which is similar to the current standard floor height of buildings, and each floor of the building on both sides is 2.6 meters high. The researchers conducted a double test, first verifying the ability of the interlocking structure to prevent collapse after a small-scale impact, and then verifying the collapse isolation effect of the building.

In the first round of tests, the researchers removed one of the two columns at the corner of the building and found that the building did not collapse on a large scale and was still able to provide traditional structural support. In the second round of tests, the researchers used a more extreme initial damage and removed the remaining column at the corner. The results showed that the building manufactured based on the "hierarchical collapse isolation" design concept successfully avoided the collapse of the entire structure, and only part of the building along the loading path collapsed. This proves that this type of building design can limit collapse to a limited area.

Building design and testing (a, full-scale precast concrete and column structures removed at different stages of testing; b, first-floor connections during construction; c, second-floor connections after precast beam placement during construction; d, two-column setup for quasi-static removal during first-stage testing; e, three-hinged mechanism for corner column removal) Image source: Reference 1

Conclusion

With the rapid development of science and technology, new earthquake-resistant building technologies have emerged. These technologies have not only overturned the design concept of traditional buildings, but also achieved revolutionary innovations in materials, structures, construction and other aspects. They can not only significantly reduce the damage to buildings caused by earthquakes, but also provide safer shelters after disasters, building an important barrier to protect our lives. I believe that in the near future, new technologies will be widely used in various types of buildings, making our cities safer and stronger!

References

[1]Makoond, N., Setiawan, A., Buitrago, M. et al. Arresting failure propagation in buildings through collapse isolation. Nature 629, 592–596 (2024).

[2] Dong Bingjun. Study on tail amputation and regeneration in lizards[J]. Bulletin of Biology, 2009, 44(1):24-25.

[3] Zheng Jianguo, Xu Jian, Qian Chunyu, et al. Research on several key technologies for earthquake resistance and vibration control of ancient buildings[J]. China Civil Engineering Journal, 2023.

[4] Jin Bo, Zhang Minzheng, Guo Xun, et al. Structural integrity analysis and construction measures of earthquake-resistant buildings[J]. World Earthquake Engineering, 2009(2):4.

Planning and production

Source: Science Popularization China

Author: Shi Wuyao, PhD in Biology

Producer丨China Science Expo

Editor: Yinuo

Proofread by Xu Lai and Lin Lin