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Reason for
selection:
The Kamihirai Flood
Gate is the largest such facility against high tides in Tokyo, located at the
confluence of the Ayasegawa River and the Nakagawa River running through the
eastern part of the 23 wards of the city. As it was built more than 50 years ago
and became antiquated with its deteriorating earthquake resistance, seismic refurbishment
was performed. As the flood gate is situated in the middle of residential areas,
it was anticipated that repainting maintenance in the future would be difficult
and consequently, all-stainless steel gate leaves have been adopted. With the
need for repainting eliminated, lower life cycle costs and lighter
environmental burdens, the material selection has provided advantages to the owners
as well.The four gate
leaves measure 30 meters wide and 11.1 meters high and are of a structure named
Pipe Vierendeel – the only one such structure in Japan and rather unique even in
the word. The construction with stainless steel has been made possible with the
applicant’s high-end techniques in manufacture and installation pursuing
accuracy on the order of millimeters, including its welding technique for large
diameter pipes called Uranami welding.Duplex
stainless steel is used for the gate leaves, which works to improve the
functions of the flood gate and at the same time to lessen maintenance and
operating costs with the metal’s high strength and high corrosion resistance.
In particular, taking advantage of the metal’s high strength, the height of the
opening section of each gate leaf is raised by two meters on the average and
this improves the safety and convenience of ships navigating under the facility.As a stainless
steel structure of unrivaled scale in the world symbolizing Japan’s advanced civil
engineering techniques, the flood gate is highly evaluated overseas, has
received a Gold Medal of worldstainless Awards and is attracting many visitors
from other countries.
It has an attractive exterior appearance with conspicuous curved lines and serves as a popular landmark of the Katsushika Ward. In addition, a scale model of the flood gate is displayed in the disaster prevention corner of the administration building, which is included in the course of field trips for grade school and junior high school students of the locality, and keeps on exhibiting beneficial points of stainless steel structures to visitors.
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