FREE node for a single layer free-form envelope subjected to bending moment

•The spherical node with optimized weight was successfully developed and evaluated.•The moment capacity of FREE node satisfied the requirements.•A spherical node system has an excellent usability for single layer free-form envelope.

For free-form structures with a single layer envelope, the node is subjected to axial load, as well as moment. The purpose of this paper is to develop and evaluate a new hollow spherical connector, termed the FREE (Flexible, Resilient, Efficient, Economic) node, for single layer free-form spatial envelopes. Reducing material and efficient shape are important points in the space structure node. Therefore, hollow spherical node sections with different holes were proposed and finite element analysis was performed, to determine the prototype among these parameters. The parameters are the size and shape of the hollow sphere. Bending experiments were also performed, to evaluate the structural capacities of the proposed node; and the corresponding test results were compared with finite element analysis. As a result, it may be said the proposed FREE node satisfied the required capacities.

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