Subsystems and Interactions:
Struts are the force members in a geodesic dome that act in compressive and tensile forces to resist loading. What exactly is geodesic? Geodesic is a Latin term meaning “earth dividing.” Imagine the earth as a perfect sphere, with its longitudinal lines dividing it into equal halves. These longitudinal lines are called great circles. The geodesic dome has members which follow three sets of principal sets of great circles intersecting at 60 degree angles, subdividing the dome surface into a series of equilateral spherical triangles. (Ching, Francis D.K.: A Visual Dictionary of Architecture). The more complex this system of triangles, the more spherical the dome becomes. The structure as a whole is subjected to bending moments, but the individual struts are rigid and only subjected to tension and compression forces. Applied loads are distributed through one strut to the pins. The pins transfer the loads to the next strut, and this process continues until the loadings reach the foundation. A diagram of the load distribution is shown below:
II. Pins:
The pins are used at vertices to hold the struts together. The pins must be able to resist the compressive forces transferred through the struts. All of the vertices must have a pin connection, which allows forces to be transmitted through to the foundation. The pins should be weather treated to resist damage due to environmental conditions.
III. Substructure:
The foundation transfers loads from the superstructure down into the earth. The applied loads consist of live, dead, wind, seismic, and gravitational. All of these must be withheld by the foundation. Although the geodesic dome is primarily a self-supporting structure, its foundation must carry the applied loads and anchor it into the earth. Typically, a circular concrete slab is poured onto the earth. The struts and piers are bolted and welded to the slab as shown in the diagrams below:
By: Yayuan zhang
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