Located in East Asia, Japan is a group of islands in the Pacific Ocean and has 126 million people who suffer through multiple earthquakes every year. The Japanese archipelago is situated in an area where several continental and oceanic plates converge, which is why it experiences earthquakes and tsunami waves frequently. Over the past decade, more than 200 thousand people have died, 500 thousand have been injured, and thousands of families have lost their homes in three devastating earthquakes in Japan. Many cities have been extensively damaged and destroyed.
In 2011, one of the strongest earthquakes ever recorded hit Japan. The quake caused a tsunami wave along the Pacific Coast that killed thousands and seriously damaged the Fukushima nuclear power plant. The earthquakes that hit Japan everyday forced buildings to be built to be resilient. Thus, new techniques and methods are being developed for strengthening Japanese structures, walls, and doors to withstand earthquakes.
Japan and Earthquakes: An untold story
Several of Japan’s buildings are among the world’s most durable – and their secret lies in their ability to dance as the ground moves beneath them. High-rises dominate the cityscapes of Tokyo, Osaka, and Yokohama. The towers resemble the immovability and steadfastness of fabricated structures. Every large and developed city in the world has these towers as the backdrop to its daily urban life. While the rest of the city bustles around them, they remain fixed and still – the anchors that hold it all together. It takes an earthquake to reveal the illusion of that perspective. In Japan, skyscrapers have to be movable.
As a result, all buildings in Japan must have an earthquake-resistant structure, so new construction can only be approved if it meets rigorous earthquake-proof standards set by the government.
Building Resilience into Architecture
The concept of ‘resilience’ is defined as the interplay between rigidity – a system’s ability to resist stress – and ductility – its ability to absorb pressure through its own deformation. A tower block in Japan is not an ordinary building. There are two primary levels of resilience for engineers: the first is to tolerate more minor earthquakes, the type that a building might be exposed to three or four times in its lifetime in Japan. Damage of this magnitude cannot be repaired. This building should be well-designed enough to withstand earthquakes without damage.
Earthquake-resistant buildings can survive a level two earthquake, which is rare. Japan’s Great Kanto Earthquake of 1923 sets the standard for earthquake resistance. This magnitude 7.9 earthquake devastated Tokyo and Yokohama, killing more than 140,000 people. It is no longer possible to preserve buildings perfectly in earthquakes larger than this benchmark. There ought to be no human casualties caused by damage below this threshold. A seismic specialist at University College London, Ziggy Lebowski, says building designers design buildings to protect people. “That’s the minimum standard.”
An Earthquake-Proof design
A building must absorb as much seismic energy as possible to withstand the devastating forces of an earthquake. A structure can absorb all the energy from an earthquake and not collapse. The process is called seismic isolation. Buildings and other structures in earthquake-prone areas are built on bearings or shock absorbers – sometimes as simple as blocks of rubber about 30-50cm (12 to 20in) thick – to resist the motions of an earthquake. Whenever the building columns come down to the foundation, they sit on rubber pads. Compared to earthquake-resistant structures, seismic isolation structures reduce seismic intensity by 13% to 15% (less than half).
Buildings designed to withstand earthquakes usually have their bases adapted. Adapting the height of a building with motion dampers can also increase its resilience. “Tall buildings may move 1.5m (5ft), but by putting dampers at certain levels – every two floors up to the top – you can minimize that motion and prevent damage to the superstructure,” Lubkowski says. Generally, dampers look like bicycle pumps, except they are filled with liquid instead of air. As the pump is compressed, it pushes against the liquid. Although it compresses only slightly, there is a small amount of movement. As a result, vibrations in the building are reduced.
Integrating structures with Earthquake Concepts
In addition to complex devices that absorb earthquake energy and ease shaking, there are other ways to make a building earthquake-resistant. This may involve the layout and design of the building. Ideally, the building should be as regular as possible. When all the columns are evenly spaced and each floor is exactly the same height, the building will perform better in an earthquake.
Japan’s Sky Tree Tower is the world’s second tallest building. In a ‘neo-futuristic’ style incorporating elements of the traditional Japanese pagoda, this structure has seismic dampers attached to a central pillar that can absorb the energy of an earthquake. Among Sato’s accomplishments is developing earthquake-engineering solutions that are both functional and elegant. It intends to harmonize seismic elements into the overall design of the building. The use of mesh structures prevents the supports of a building from buckling, for example. Mesh structures are a great way to fortify buildings, as they are also attractive.
Implications towards conclusions
Will tomorrow’s buildings be able to withstand large earthquakes?
It is certainly possible to achieve this. It starts to withstand the future with base isolation systems, bearings, braces, and damped outrigger systems. Building stability requires the evaluation of all known technologies and testing creative designs, like mesh structures. Experimental structures, such as those designed by Sou Fujimoto to resist buckling at the Naoshima Pavilion in Kagawa can enhance an engineer’s abilities. Added to the progress of technology that has brought earthquake-resistant buildings to the fore, Japan’s efforts to make earthquake-resistant buildings have encouraged Japanese citizens to have a sense of security even in the areas of their city that are considered high-risk but are also considered to be good residential areas.
Natural disasters are unpredictable, so it is impossible to know whether a design will withstand the next large earthquake until after it occurs. Relative to their designs, engineers, and architects can only be certain of their resilience in retrospect.
“Japan’s Earthquake and Tsunami adheres to how flimsy and sophisticated the modern world is!”
– Author (Neha Lad)
References:
- issuu.com. (n.d.). Earthquake Resilient Architecture in Japan – Team Kukan Hatten by wirkonas.agn – Issuu. [online] Available at: https://issuu.com/wirkonas.agn/docs/earthquake-resilient-architecture
- Plaza Homes Ltd (2018). Earthquake resistance of buildings in Japan – PLAZA HOMES. [online] PLAZA HOMES. Available at: https://www.realestate-tokyo.com/news/earthquake-resistance-of-buildings-in-japan/.
- Buildings Can Be Designed to Withstand Earthquakes. Why Doesn’t the U.S. Build More of Them? (2019). The New York Times. [online] 4 Jun. Available at: https://www.nytimes.com/interactive/2019/06/03/us/earthquake-preparedness-usa-japan.html.
- Ltd, P.H. (n.d.). Earthquake Resistant Rental Properties in Tokyo. [online] PLAZA HOMES. Available at: https://www.realestate-tokyo.com/rent/seismic-isolation/
