所泽市西武体育场，日本
SEIBU DOME, TOKOROZAWA, JAPAN, 1999

  Today, heavily equipped domed stadiums are being constructed all over the country. The goal here was to go bock to fundamentals and to provide the sort of comfort offered by the cool shade of o tree through a simple design for a bright, open ecological space that utilizes natural energy ; i.e. a dome in a symbiotic relationship to the natural environment. 
  A patented construction method——what might be called a " renewal method of construction" for a "subsequently installed dome"——was developed, The existing stadium did not have to be closed, and the management of the stadium was minimally affected because construction took place during two off--seasons.
  The roof structure is supported on V-shaped steel tube columns located on the periphery of the existing structure. Openness and ventilation were enhanced by not building walls along the columns. The stainless folded plate roof in the shape of a donut on top of the spectator seats solves problems of heat insulation, prevention of condensation, sound absorption and sound insutation. In the first off-season, the three-dimensional stepped truss was constructed from the outside in, in a ring configuration, without any temporary supports among the seats, and further roofing was accomplished by a circumferential sliding method of construction.
  The central membrane roof makes maximum use of the translucency of the membrane material. The simple gridded frame has no diagonal or auxiliary members. making it easy to see baseballs and helping to make the roof structure lightweight. This was constructed on the ground during the second off--season and lifted up to complete the dome.