Structural idea of retractable loop-dome

The author proposes a 3-dimensional multi-angulated scissor element as the main structural element of a new type of dome called 'Retractable Loop-Dome'. It allows the dome to continuously change its shape according to changes in the diameter of the oculus. This paper describes 1) the geometry of the 3-D multi-angulated scissor element determined by cutting a sphere with a plane passing through the apex 2) a proposal for a rational structural system with expandable circular rings for a large span and 3) a numerical simulation of the changing shape and the trial construction of an aluminum model with a 10 m base diameter.