Design and fabrication of smooth poly-hypar timber gridshells

Abstract

This paper introduces the timber gridshell designed and fabricated as smooth poly-hypar surface structure, a new type of doubly curved freeform shell which is combined smoothly (G¹ degree) from hyperbolic paraboloids (hypars). It is locally ruled, while globally appears to be a doubly curved freeform. Compared to the elastic timber gridshell designed through form-finding method, smooth poly-hypar timber gridshells have more advantages in terms of structural behaviour and construction method. Structurally, smooth poly-hypar gridshells are able to resist different loading cases with mainly membrane actions. In terms of construction, as a locally ruled surface, it can be prefabricated in modules with straight components, which effectively reduces the construction cost. In this paper, an open theatre, Hypar Wave, is presented as a case study to show the structural and constructional advantages of smooth poly-hypar gridshell in timber. Advances made in this research have added to the knowledge of gridshell behaviour and construction, thereby making the design and construction of future timber gridshells a more viable option.

KEYWORDS:

• timber gridshell
• smooth poly-hypar surface structure
• hyperbolic paraboloid
• form-making
• doubly curved freeform shell
• prefabrication and assembly

Acknowledgements

The authors would also like to thank Dr. Pierluigi D’Acunto, and Wang Yan for their supports and contributions to the design and fabrication of Hypar Wave. The fabrication test of Hypar Wave is financed by ETH Zurich and the architectural company GOA (Group of Architects). All images are by the authors unless otherwise noted.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.