The thin-shell concrete dome topping the Sundome in Yakima, Washington, has 24 wedge-shaped segments arranged in a radial pattern like the pieces of a pie. But only six wood forms were needed to cast the 24 segments because of an innovative rotating forming and shoring system. The Sundome roof has a rise of 40 feet and a maximum clear height above the floor of 80 feet. Its 24 identical wedge-shaped segments arch to a compression ring at the crown of the roof and their bases are stabilized by a post-tensioned concrete tension ring supported on 24 reinforced concrete columns. Each segment is doubly curved like a saddle to increase the stability of the dome.
