Openable dome-shaped roof structure

An openable dome-shaped roof structure for covering an enclosure defined by a side wall constructed on the ground, said roof structure comprising:

• an annular stationary roof section having a central opening and fixedly secured along an outer periphery thereof to said side wall;
• a movable roof section comprising a plurality of roof units having substantially the same shape and corresponding to the shape of each of a plurality of equal divisions of said central opening, each of said roof units being radially movable between an open position where said roof unit is supported on said stationary roof section, and a closed position where said roof unit is supported in said central opening;
• and
• a plurality of retractable beams for supporting respective said roof units in said central opening, each said retractable beam being connected to said stationary roof section and extending toward the center of said central opening, each said retractable beam being provided at the inner end thereof with an interlocking head, and said interlocking heads of adjacent of said retractable beams engaging with each other at the center of said central opening when said retractable beams are fully extended.