Prefabrication experiments - 263 - Connectors - 04 - Geodesic dome hubs

First explored in the 1940s, every generation of educators, architects, designers and DIYers seems to rediscover the pleasure and structural enlightenment that comes from assembling a geodesic dome. Associated with R. Buckminster Fuller and his Fuller Research Foundation, the geodesic dome is a segmented reticulated framework, which forms a spherical shape. Established from the study of an icosahedron, a platonic solid of twenty identical equilateral triangle faces, points (vertices) are extended outward toward a great circle according to a predetermined number of divisions or segments. This division of each composing triangular face is the dome’s frequency or its capacity to approach the sphere’s radius as closely (greater frequency) or as loosely (lower frequency) as desired. 

 

It seems at first glance relatively simple as the segments follow a repeating pattern. This is the case for the equilateral triangles, however each segment and angular deformation within the triangle are dimensionally nuanced and modulated as they spread toward the curve. The hubs, intersections or connector points are fundamental to the dome’s assembly as they define at once the angle and the number of struts splitting from each vertex. Connectors are the secret to the domes’ perceived simplicity. Along with their numerical and mathematical importance to the domes’ geometry, structurally the hubs react to both tensile (parallel, hoop) and compressive (meridional, arch) stresses. Composing triangles and their connection points push and pull against one another, under uniform loading. 

 

Sonostar connectors, is one of many companies offering options to construct a dome based on a configuration that is determined on-line through the company’s website. A construction kit of parts from made to stock pieces and connectors is then delivered to any context. Connectors include five or six appendages regardless of the dome’s frequency as combining the triangles forms a skeletal network of hexagons (6 points) or pentagons (5 points). Geodesic domes are experimental structures, rarely massively applied, that garner fascination through the satisfaction that comes with seeing geometry and structural assembly in action. Sonostar’s dome kits propose standard PVC piping for the struts, which makes for a simple female to male fastened or bonded connection.

Two connector scales (standard and mega hub) form the company website