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 (G(1) 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.