Kumamoto station
Structural Awards 2010
Japan Structural Design Award 2010
location : Kumamoto-shi, Kumamoto
year complete : 2010
usage : Forecourt shelter
site area : 6037 m2
gross floor area : 1054 m2
structure : Steel structure (PC structure)
architect : Office of Ryue Nishizawa
contractor : Tekken construction company
—
As part of the redevelopment of Kumamoto Station, new forecourts structures were required to the east and west exits to provide a sheltered path from the station to onward transport stops. With the tram track planned to run under the eastern exit of the canopy. The architect Nishizawa Ryue won the commission through a competition in 2008. The curved, gourd-shaped flat roof was designed with concrete surfaces as a vital part of the architectural concept.
The concrete roof was designed to be continuously exposed to the elements and was required to be waterproof and have almost zero maintenance needs. Post-tensioned prestressed concrete was used to form a 400mm thick flat slab, spanning up to 14m between the 13 column arrangement. The columns are vertical cantilevers embedded in large ground beams. They have pinned tops, achieved using a bespoke insert-type connection. The columns themselves are spun-cast steel, with wall thicknesses up to 90mm to keep the diameter to a minimum.
Extensive earthquake modelling was performed during the structural design stage, including the development of a man-made seismic record based on the precise site ground conditions and seismic statistics. The structure can resist about 1.4g horizontal load applied continuously. It was used as a refuge during the Kumamoto double earthquake of 2016.
