Japanese Pagodas

Japanese Pagodas are somewhat a contradiction in Architecture. Tall towers with large overhanging roofs that are known to survive well over 1000 years in an earthquake prone country. The tallest surviving pagoda in Japan, at Toji, is 41 metres tall. The key to the Pagodas earthquake resistance is in its flexibility, much of which can be attributed to the Shinbashira; a hexagonal pillar running up the centre of the tower. The Shinbashira is free standing inside the tower and sits on the buildings foundation, supporting the top level of the pagoda. The pillar is usually made from a single tree trunk, and the fibres allow the Shinbashira to act as a tall vertical leaf spring. The floors can move independently of one another, so when seismic activity occurs the floors move side to side in a snake like pattern (referred to as the snake dance), and the Shinbashira counteracts the movement of each floor. In addition to the Shinbashira, the floors are connected by complex wooden joinery consisting of many separate components. The many faces of the timber joints experience a lot of friction as they move over each other, serving to dissipate the energy of the earthquake and preventing damage to the structure. During an earthquake the whole tower essentially becomes a shock absorber.

Trees and the timber they provided were a core resource in Japan, and so the fact that they used the tallest and straightest trees for the Shinbashira of these structures shows their religious significance, and their importance to Japanese people. Pagodas are also intricate pieces of mechanical art on a huge scale, requiring the skill and effort of carpenters using closely guarded techniques, usually passed down only from master to student. The technology has been adapted for use in modern skyscrapers, allowing for buildings of a size that would otherwise have been impossible due to the risk of earthquakes, such as the Tokyo Sky Tree, which features a Shinbashira consisting of Four enormous steel beams, surrounded by a dampening system on each floor.87-fogong_temple_corner_dougongshnaisndasdtoji pagoda

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