Zero-Waste, Flat Packed, Tri-chord Truss: Continued Investigations of Structural Expression in Parametric Design

The direct and rapid connections between scripting, modeling and prototyping allow for investigations of computation in fabrication. The manipulation of planar materials with two- dimensional CNC cuts can easily create complex and varied forms, volumes, and surfaces. However, the bulk of research on folding using CNC fabrication tools is focused upon surfaces, self-supporting walls and shell structures, which do not integrate well into more conventional building construction models.

This paper attempts to explain the potential for using folding methodologies to develop structural members through a design-build process. Conventional building practice consists of the assembly of off-the-shelf parts. Many times, the plinth, skeleton, and skin are independently designed and fabricated, integrating multiple industries. Using this method of construction as an operative status quo, this investigation focused on a single structural component: the truss.

Using folding methodologies and sheet steel to create a truss, this design investigation employed a recyclable and prolific building material to redefine the fabrication of a conventional structural member. The potential for using digital design and two-dimensional CNC fabrication tools in the design of a foldable truss from sheet steel is viable in the creation of a flat-packed, minimal waste structural member that can adapt to a variety of aesthetic and structural conditions. Applying new methods to a component of the conventional ‘kit of parts’ allowed for a novel investigation that recombines zero waste goals, flat-packing potential, structural expression and computational processes.

This paper will expand (greatly) upon previous research into bi-chord truss designs, developing a tri-chord truss, which is parametrically linked to its structural moment diagram. The cross section of each truss is formed based on the loading condition for each beam. This truss design has been developed through a thorough series of analytical models and tests performed digitally, to scale and in full scale. The tri-chord truss is capable of resisting rotational failures well beyond the capacity of the bi-chord designs previously developed. The results are complex, and elegant expressions of structural logics embodied in a tightly constrained functional design. 


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