Pursuant studies of the shinbashira structure, and its utility in quake-resistance has made it to be used anew in structures including the Tokyo Skytree. A central feature of the tower is a system to control swaying used for the first time, has been dubbed "shinbashira" after the central pillar found in traditional five-story pagodas. The 375-meter-long, steel-reinforced concrete shinbashira is not directly connected to the tower itself and is designed to cancel out the swaying of the needle-like tower during an earthquake.[2]
https://en.wikipedia.org/wiki/Shinbashira
During our visit, I had the opportunity to observe numerous of the distinctively Japanese five-story pagodas. They appear across Asia and seem to have been imported to Japan, along with Buddhism, from China in the 6th century. We saw them at the Bannaji Buddhist temple in Ashikaga, at the temple complex at Nikko, at Asakusa and again at the Toshogu temple in Ueno Park. At once solid, yet delicate, these structures soar to great heights, yet seem unsupported and top heavy. How have they endured for centuries in a land prone to earthquakes?*
There is a secret at the heart of the pagoda that explains their endurance and even provides a useful modern innovation. It is called the shinbashira, the central pillar at the core of a pagoda. The shinbashira is made from the straight trunk of the Japanese Cypress tree (hinoki), a tree so strong it is referred to as 'ironwood' locally. The central pillar extends beyond the roof of the pagoda becoming the finial and is usually buried three meters into the foundation of the structure. Since it is one organic piece, it provides incredible strength and stability to the whole structure. Instead of building progressive stories each supported by the one underneath, all of the five stories essentially are hanging off the central pillar. Because they are not entirely dependent on the structure beneath, they are to an extent free floating and have tremendous flexibility to sway or move independently in the event of an earthquake (jishin).
This idea was even incorporated in the construction of the Tokyo Skytree. A 375 meter long steel reinforced concrete shinabashira is suspended inside the tower as a counterbalance to reduce swaying throughout the structure during earthquakes. It is 8 meters across and weighs 11,000 metric tons.**
Although this is an interesting application of ancient technology to a modern problem, I was more intrigued by the shinbashira as a metaphor. Japan and its people have been subjected to numerous hardships and disasters over the years. Countless earthquakes and fires have afflicted its cities. Kyoto was said to have burned to the ground 49 times in the first hundred years of its founding. The great Kanto earthquake of 1923 leveled Tokyo. I saw some of the evidence of this in the temples at Ueno Park. Hiroshima and Nagasaki are still the only two cities in the world to have been destroyed by nuclear weapons. Many other cities were burned during the war. Recently the Tohoku earthquake of 2011, and the subsequent meltdown of nuclear reactors added to the list of devastating disasters to hit Japan. Yet, despite of these, Japan has a reputation of resilience, of a determination to overcome adversity and to stand firm. I wonder if there is some sort of cultural shinbashira, that provides Japan with a sense of calm acceptance of impermanence, coupled with an undaunted spirit. Whatever it may be, their perseverance and success in the face of adversity is a lesson to us all.
* Research shows that there are only records of two pagodas that have collapsed due to earthquake in the last 1,400 years! Unfortunately, being built entirely of wood, many more have succumbed to fire. (Some of the temples I saw had wave patterns and motifs carved under the eaves as a warding against fire.)
** Measurements cited in http://www.nippon.com/en/views/b01101/
the sumitomo highrise brought me here. :D
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