A Strategy for Complex-Curved Building Design Design Structure with Bi-Lateral Contouring as Integrally Connected Ribs

This paper presents an algorithmic approach to design rationalization that supports physical production as well as surface production of design models. Our approach is an alternative to conventional rapid prototyping that builds objects by assembly of laterally sliced contours from a solid model. We explored an improved product description for rapid manufacture as bi-lateral contouring for structure. Infrastructure typically found within aerospace, automotive, and shipbuilding industries, bi-lateral contouring is an organized matrix of horizontal and vertical interlocking ribs evenly distributed along a surface. These structures are monocoque and semi-monocoque assemblies composed of structural ribs and skinning attached by rivets and adhesives. Alternative, bi-lateral contouring discussed is an interlocking matrix of plywood strips having integral joinery for assembly. Unlike traditional methods of building representations through malleable materials for creating tangible objects, this approach constructs with the implication for building life-size solutions. 1.0 Introduction Shapes in designs created by architects such as Gehry Partners (Shelden, 2002), Foster and Partners, and Kohn Peterson and Fox rely on additional computational processes for rationalizing complex geometry for construction. Unfortunately, for many architects the rationalization is limited reducing solid models to surfaces or spreadsheet data for contractors to follow. Rationalized models produced by such digital fabrication. For the physical production and construction of CAD description, an alternative to the rationalized description is needed. This paper examines the coupling of digital rationalization and digital fabrication with physical mockups (Rich, 1989). Our aim is to explore complex relationships found in early and mid stage design phases when digital fabrication is used to produce design outcomes. Results of our investigation will aid architects and engineers in addressing the complications found in the translation of design models embedded with precision to constructible geometries. The approach undertaken in this research investigates a method of creating a bidirectional free-form surface designs. Three algorithms are presented as examples of rationalized design production with physical initial 2D curved form into ribbed slices to be assembled through integral connections constructed as part of the rib solution. The second algorithm deconstructs curved forms of greater complexity. The algorithm walks along the surface extracting surface information along horizontal and vertical axes saving surface information resulting in a ribbed structure of is expressed as plug-in software for Rhino that deconstructs a design to components for assembly as rib structures. The plug-in also fabrication. The software demonstrates the full scope of the research exploration. 2.0 Objectives In this study, the aim was to investigate bilateral contouring as a set of algorithms for deconstructing form for fabrication using a twodimensional cutting device. Lateral slicing is the process of slicing an object parallel to a chosen axis. Horizontal slicing therefore connotes laterally slicing parallel to the X and Y axes, whereas vertical slicing is parallel to the Z axis. The concurrency of slicing happens in both the horizontal and vertical directions which create perpendicularity. The relation of the A Strategy for Complex-Curved Building Design SiGraDi2006 / Arte y Cultura Digital 466 bidirectional slicing of the object denotes the term bi-lateral contouring. Studies published by Dodgson argued that innovation technology (IvT) (Dodgson, Gann, Salter, 2004) helped in solving projects like the Guggenheim in Bilbao, the leaning Tower of Pisa in Italy, and the Millennium Bridge in London. Similarly, the method discussed in this paper looks at innovative methods of solving complex design forms with the use of computational methods that derive physical artifacts during the stages of design. The design processes have focused on different computational methods for constructing digitally representation of design artifacts, but remain stagnant when deriving more generic solutions to address fabrication procedures. Although, there have been many approaches for materializing design, the solutions are more prescriptive than generic, which makes the result a project-based solution. This paper examines a general approach that can be used in multiple design disciplines for materializing a design that has been created by means of CAD applications. The product of this research is a plug-in tool for Rhinoceros that facilitates the creation of physical artifacts from a surface object that has been produced by computation technologies. 3.0 Development 3.1 Structure and Assembly Three parameters contribute to the structural strength of the assembly: density, thickness, and friction. In order to optimize the structure, each of these parameters must be considered to resist the live and dead loads with the least possible ultimate goal for a complete understanding of the structural performance of a bi-laterally contoured assembly would include mathematical each of these three parameters. 3.1.1 Density The strength of a bi-laterally contoured structure may imply a direct relationship to the amount of vertical and horizontal ribs comprising the structure. However, each of these two types of structural members does not perform the same task in the assembly and thus does not increase the total strength of the assembly at the same rate. As the vertical members resist the majority of the load force under typical loading conditions, an incremental augmentation of strength can be perceived with each addition of another vertical rib to the assembly. However, as the primary direction of the live and dead loads of a building wall (under typical loading, where wind loads are not a crucial issue) is parallel to the gravitational constant (Schodek, 2001), we found that increasing the amount of horizontal ribs beyond a certain threshold does little to augment the overall strength of the assembly system and, in fact, performs the inverse effect of adding extraneous dead load with little-to-no structural purpose. Through physical testing of various densities [Figure 1.0] of bi-laterally contoured walls, we have found that, while the assembly process is quicker when the wall is composed of very few elements, assemblies requiring a larger magnitude of member density (for structural reasons) can in fact be easier to assemble. The reason for this phenomenon is the following: while time of assembly is increased in an incremental fashion with each new rib, the a higher resolution (denser) grid. From this, factor also acts to equalize the number of horizontal ribs relative to the number of vertical ones. In all other respects, however, the desire laterally contoured wall, in the case of higher relative magnitudes of loading, will act contrary that of structural strength. 3.1.2 Thickness The strength of short or braced structural members in compression, as well as all members in tension, is directly related to their crosssectional area. (Schodek, 2001) Thus, increasing the width of a bi-laterally contoured wall has the effect of augmenting its structural strength. However, more material is used when the ribs are wider, and therefore wall thickness ought to be optimized such that the width of the members [Figure 2.0]: are not over-engineered to Figure 1.0