| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that when a core of a light-weighted rib structure of a plate constitution body is processed, a risk of breakage of the core is high and it is difficult to make a mirror large-size and to shorten the construction period.SOLUTION: A base (core) that a plate constitution body has includes a first surface to which a plate is joined and a second surface on the opposite side from the first surface, and also includes a first opening portion 13 formed for each of a plurality of first recessed holes from the first surface toward the second surface 15 and a second opening portion 16 formed for each of a plurality of second recessed holes from the second surface 15 toward the first surface, the first recessed holes and second recessed holes being arranged at mutually different positions. Further, the plurality of second recessed holes are arranged on the second surface in one of cross and concentric circle shapes, and the first surface includes planes at parts corresponding to the plurality of second recessed holes arranged in the cross or concentric circle shape. |
