In the high rises of Tokyo, Osaka, and Yokohama, skyscrapers dominate the cityscapes that surround them. These towers give a powerful impression of being immovable and steadfast, as human-made structures can be, fixed to the backdrop of urban daily life in Japan, just as they are in any other developed city in the world. While they stand tall, the city moves around them; people and traffic bustle, and they stand still as the pieces that tie the hectic town together. If you’ve ever experienced an earthquake swaying the world around you, you might know what it’s like to feel like your world has grown chaotic. The perspective and perception of the immovable object are simply an illusion. An object that cannot be moved cannot stay that high if the ground beneath it wants to shake it down to its core. In Japan, these skyscrapers have to move.
Building Skyscrapers in Japan: Resilience against Earthquakes
Today, we’re going to take a look at how skyscrapers in Japan are built and how they withstand the tournament of earthquakes that come through the area. Wood is considered safe in an earthquake zone. The Japanese islands rest along the Pacific Ring of Fire and the Eurasian, Philippine, and Pacific tectonic plates. It sits on the margin where one plate is forced beneath the other, which causes a buildup of extraordinary pressures. An earthquake releases such pressures, which send strong vibrations that can sometimes raze an entire city to the ground. In 2011, the Tohoku earthquake occurred, still known as one of the most devastating seismic events of recent times. However, it was just one of many that strike Japan each year. For this reason, all buildings, even smaller temporary structures, have to be resilient against earthquakes across the country.
There are two primary levels of resilience that these engineers work towards. One is to withstand more minor earthquakes, like the one that Japan may see several times throughout its lifetime. For this magnitude, any damage is unacceptable, as they want the building to be so well designed that these earthquakes can pass, and the building is left unscathed. The second level of resilience is the ability to withstand extreme earthquakes. These are rarer, and the bar was set by the Great Kanto earthquake of 1923. It was so large, a magnitude of 7.9, that it not only devastated Yokohama and Tokyo but killed more than 140,000 people in the process. These earthquakes and the resilience mean there is a little more leeway than before. Preserving buildings ideally is no longer the goal. Instead, any damage that does not cause human casualty is acceptable, and the designs are meant to protect lives. That is actually the minimum requirement in places plagued with an onslaught of earthquakes like Japan; protect people.
Seismic Isolation and Motion Dampers: How Skyscrapers in Japan Withstand Earthquakes
But how do they do it? To withstand these incredible forces, buildings have to be made to absorb as much of the seismic energy as possible so they will not collapse. The process that mainly happens is called seismic isolation. Buildings or structures are set supports of shock absorption, which are sometimes as simple as blocks of rubber that are about 12 to 20 inches thick. This shock absorption works to resist the motions of the earthquake and take the pressure off of the buildings. They sit on rubber pads wherever they build columns down to the foundation. Adaptations to the base of the buildings are just one of the ways that buildings are made to withstand earthquakes. Motion dampers throughout the height, however, can also improve resilience. If you put dampers throughout at certain levels, like every other floor, you can reduce the overall motion of the building during an earthquake to a much smaller amount and prevent widespread structural damage.
Those dampers look a little like bicycle pumps but are filled with liquid rather than air. Compressing the pump pushes against the fluid, moving it slightly and reducing the vibrations. Often, designers of spectacular skyscrapers are reluctant to make the compromises needed to meet the seismic standards required by engineers. These complex devices that excessive tension are not the only way to make buildings resistant, though. Many involve the overall layout and design of the building. For example, the more regular the building is, the better. Keeping all the floors a standard height and an even grid for the columns helps the buildings perform better in an earthquake. However, designers often have conflicts with engineering as these standard designs often don’t match their lofty architectural visions. Using mesh structures, for instance, is another way that they help prevent the building’s supports buckling. If one part buckles, having that close neighbor helps stop ending and helps to fortify the building by distributing the energy evenly.
Reinforcing Buildings with Carbon Fiber: A New Solution for Earthquake-Prone Areas?
Instead, one Japanese textile firm turned to carbon fiber rope. They developed a high tensile twine from a carbon fiber composite. They sought to reinforce the structure of its new showroom and laboratory in Nomi. They worked together with Japanese architects Kengo Kuma and Associates to use rods of this material to help anchor it. They use the combined 1031 rods attached to the roof. They essentially tethered them to the ground in a straightforward sort of way to help stabilize it, with 2778 rods inside. This may be the first time that carbon fiber has been used in this way. Still, the way they see it, it could be applied to flexible structures like wooden buildings that sway horizontally.
The future of earthquake-proofing is not going to be a static process. Researchers estimate how earthquakes might impact a structure in the future by continuing to observe activity at faults. 2021 has seen two 7.0 or higher earthquakes so far, even as we close out the year in February. One was at Fukushima, which was intense and deadly at 7.1, and then in March at Miyagi at around 7.0. This level of earthquakes is becoming more and more frequent, and seismologists will be tasked with the increasingly difficult job of predicting the unpredictable.
The answer, it seems, lies in their gradual testing of the known technologies used to stabilize buildings. They continue to trail with creative designs such as the mesh mentioned above. Sometimes the testing is in smaller, more experimental structures, like the one with an elaborate polyhedral mesh designed to resist buckling entirely, designed by Sou Fujimoto. Perhaps looking at the past of earthquake-proofing will provide a glimpse into the future. Japan has been struck by 7.0 or higher magnitude earthquakes a staggering 61 times since the Horiuji Temple was built in 607AD. But how did this 122-foot-tall structure stay upright through all of that shaking? Since the 6th century, they’ve had multi-story pagoda technology in Japan, coming along with Buddhism from China. Pagodas were traditionally built from stone on the mainland, but with Japan’s seismic instability, the design wouldn’t last long. Japanese eventually found out how to adapt them to the unstable condition through three design changes: the use of wide and heavy eaves, disconnected floors, and shock-absorbing shinbashira.
Skytree Tower: Blending Neo-Futuristic Design with Traditional Japanese Architecture for Seismic Resilience
One good example of blending the old with the new is the Skytree Tower in Tokyo, the second-tallest building globally, only losing at tallest after the Burj Khalifa in Dubai opened in 2012. The style incorporates a neo-futuristic style with some elements of the traditional Japanese pagoda, which includes a central pillar attached to its seismic dampers. This blend helps absorb the energy of an earthquake, as shown by its performance through earthquakes in recent years.
The shinbashiro was developed to help keep the floors from flexing too far. It works as a load-bearing column, but it doesn’t support the building’s weight. These may originally have been built from a large pine trunk. It is strung from the underside of the roof, hung down a shaft in the center of the structure. Sometimes it would be buried into the earth, but sometimes it was rested lightly on top of the ground. Sometimes it even freely hangs. It works in that case, swaying to the point of collapse and absorbing the momentum of the floors as they strike against it. It’s a giant pendulum with enough mass to help absorb the movement and shocks caused by earthquakes.
To this day, this same dampening technology is still in use. The Taipei 101 uses its own massive four-story, 730-ton pendulum made of steel that hangs from the 92nd floor to prevent the building from swaying in high winds. In New York City, it is used in the Citicorp Center as a 500-ton concrete block that helps to keep hurricanes from moving the building.
Exceptional innovations continue to push technology to its outer boundaries and desire safer technologies. The underlying promise from engineers and architects alike to help preserve human life will continue to do just that. We’ll have to see how they continue to push the boundaries of design aesthetics and ancient technologies going forward. For now, we can just enjoy the fantastic structures they’ve created so far.
The Reality of Earthquakes in Skyscrapers: A Perspective from Japan’s Urban Landscape
Have you ever been through an earthquake in a skyscraper? An earthquake anywhere can be a terrifying experience, but having the ground shake when you’re hundreds of feet in the air can feel almost reality bending. When you’re in the high rises of Tokyo, Osaka, and Yokohama, you’re dominating the cityscapes that surround you. These towers give a powerful impression of being immovable and steadfast, as human-made structures can be. Fixed to the backdrop of urban daily life in Japan, just as they are in any other developed city in the world, while they stand tall, the city moves around them. People and traffic bustle, and they stand still as the pieces that tie the hectic town together.
If you’ve ever experienced an earthquake swaying the world around you, you might know what it’s like to feel like your world has grown chaotic. The perspective and perception of the immovable object is simply an illusion. An object that cannot be moved cannot stay that high if the ground beneath it wants to shake it down to its core. In Japan, these skyscrapers have to move.
In conclusion, Japan’s skyscrapers are a testament to human innovation and our ability to adapt to our environment. They serve not only as marvels of architecture and engineering but as symbols of resilience and hope. In the face of natural disasters and the constant threat of earthquakes, the buildings in Japan have been built to withstand the tremendous forces of nature. The engineers and architects who designed these buildings have drawn on a variety of techniques, from the use of seismic isolation and motion dampers to the integration of traditional Japanese designs, to create structures that can withstand even the most extreme earthquakes. As Japan continues to experience seismic activity, these innovations will continue to be refined and improved, ensuring that these buildings remain safe and stable for generations to come.