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Parametric Modelling of Architectural Developables Roel Van De Straat Scientific Research Mentor: Dr MSc thesis: Computation & Performance parametric modelling of architectural developables Roel van de Straat scientific research mentor: dr. ir. R.M.F. Stouffs design research mentor: ir. F. Heinzelmann third mentor: ir. J.L. Coenders Computation & Performance parametric modelling of architectural developables MSc thesis: Computation & Performance parametric modelling of architectural developables Roel van de Straat 1041266 Delft, April 2011 Delft University of Technology Faculty of Architecture Computation & Performance parametric modelling of architectural developables preface The idea of deriving analytical and structural information from geometrical complex design with relative simple design tools was one that was at the base of defining the research question during the early phases of the graduation period, starting in September of 2009. Ultimately, the research focussed an approach actually reversely to this initial idea by concentrating on using analytical and structural logic to inform the design process with the aid of digital design tools. Generally, defining architectural characteristics with an analytical approach is of increasing interest and importance with the emergence of more complex shapes in the building industry. This also means that embedding structural, manufacturing and construction aspects early on in the design process is of interest. This interest largely relates to notions of surface rationalisation and a design approach with which initial design sketches can be transferred to rationalised designs which focus on a strong integration with manufacturability and constructability. In order to exemplify this, the design of the Chesa Futura in Sankt Moritz, Switzerland by Foster and Partners is discussed. From the initial design sketch, there were many possible approaches for surfacing techniques defining the seemingly freeform design. The key to controlling the form was to make use of a polar grid association. Generally, the polar grid is a well applicable way of locating elements, such as windows, whose positions are based on a radial geometry. The geometric definition was based on four sectors and a number of subdivisions within each sector. This provided flexibility and control as well as a convenient coding and referencing system1 and additionally, based on this definition, parametric relations were defined, providing smooth transitions between the sections, Figure P1. The example of the Chesa Futura project shows how a logic of radial geometry within a parametric environment is used to generate plans and sections and as such defines a globally rationalised surface definition. 1 Lenz, Chesa Futura Computation & Performance Fig. P1. From sketch design to geometric description based on parametric radial rationalisation of the Chesa Futura in Sankt Moritz, Switzerland by Foster and Partners [http://www.daapspace.daap.uc.edu, March 2011] parametric modelling of architectural developables This thesis focuses on discussions related to definitions of digital rationalised surface geometry. As such, it is an integral part of the graduation project of the research group Computation & Performance of the department of Building Technology of the Delft University of Technology, Faculty of Architecture. The thesis describes the research and background studies in rational design methods and parametric descriptions of surface definitions and describes a design approach based on digital design tools which allow for the analysis and generation of developable surfaces. The .gha assembly which allow access to these tools in Grasshopper for Rhinoceros is provided including a installation manual, see Appendix C. The content of the research is presented on 8 April 2011. Computation & Performance parametric modelling of architectural developables acknowledgements A number of people took time and effort to assist in working on this thesis. It is underlined here that their input is much appreciated and they are thanked accordingly. The members of the graduation committee in general are thanked for their advice and feedback given during the process of writing this thesis and being available for questions related to the research. In particular, dr. ir. R.M.F. Stouffs, for his contribution to the Computation & Performance research group which provides for research topics as discussed in this thesis at the Faculty of Architecture of the Delft University of Technology and his insightful and valuable comments regarding the scientific approach taken in this research. Ir. F. Heinzelmann for sharing his insights from the architectural practice and for the fruitful discussions on digital design, complex geometry and utilisation of design tools in the design process. Ir. J.C. Coenders for his sharp and to the point feedback on a technical and scientific level and for sharing his knowledge on tool development related to, on one hand, the programming aspects, and on the other hand, deployment and implementation. Colleagues at Arup Amsterdam are thanked for their positive feedback and their interest in the progress of the thesis. Especially, Anke Rolvink for assisting in setting up the code for the development of the Grasshopper components and helping with issues related to programming the tools. Joost Lauppe, who showed a great enthusiasm and interest regarding the development of the tools and the content of the research and was a great support on a personal level throughout the graduation period. Computation & Performance parametric modelling of architectural developables summary general introduction Over the last decades, the advances in digital surface modelling seemingly grew ahead of possibilities to follow the design intention in analysis and construction. This especially in relation to the control over the geometry and the costs of fabrication and assembly of non-standard elements. The lack of control over the geometry, in relation to both structural analysis and construction, in some cases proves to be a hurdle in realising a design. And although the current state of technology allows computation-driven design processes to incorporate tools and machines that automatically fabricate structural elements, formwork and building components, the costs of employing digital fabrication are not always exceeded by the profit. As such, geometrically complex design can put the relationship between design and realisation under pressure when manufacturing and construction methods cannot follow the envisioned design or when they result in a disproportionate increase of costs. One general aspect in reducing the complexity of translation from modelling to construction is the rationalisation of geometry informed by manufacturing and construction characteristics. Two world renowned structures have been used to present notions of form and surface rationalisation. Firstly, the design process of the Sydney Opera House shows how the initial designed forms needed to be rationalised into spherical elements simply to be describable using contemporary drafting and engineering methods and to positively affect the constructability of the structure. Secondly, the Guggenheim Museum of Bilbao is presented as an exemplary project for the design of architectural surface geometry based on the principles of single-curved surfaces, also known as developable surfaces. Related to the surface descriptions of these projects, it is exemplified that rationalisation can greatly simplify the surface definition of a design, positively affecting the engineering and construction of a design. This, ideally, whilst still allowing for a vast design freedom. Based on the above, this thesis tries to provide an answer to the question of how restrictive design conditions of rational surfaces be taken into account within a parametric environment to inform the design process which is focussed on the translation from design to realisation. As such, the goal is to embed the use of digital tools in a design process which on one hand deals with the boundary conditions related to rational surface description and on the other hand provides the designer possibilities in choosing parameters allowing for a design freedom within these restrictions. Computation & Performance rationalisation of surface definitions Along with the digital possibilities in fabrication and construction, focusing on decreasing the complexity of the design by rationalising surface definitions can narrow the gap between digital modelling, fabrication and construction. Shaping the geometry based on rational surface classes, such as developable surfaces, allows designers to influence the buildability along with positively affecting the level of complexity in structural analysis. Shelden denotes that rationalisation serves as the resolution of rules of constructability into project geometry2. In this sense, rationalisation may allow for full and precise control over the structural dimensions, may avoid having to deal with limitations in CAD/CAM machinery and related software and may force a design to be constructed out of elements from a limited number of moulds. parametric definitions of developable surfaces In the field of surface rationalisation, developable surfaces play a specific role as they allow for expressing an overall sculptural appearance in R3 space while being conform definitions of single-curvature geometries. In the words of Huffman: “Developable surfaces offer a complexity that is midway between a completely general surface and a plane surface”. Developable surfaces have the advantage that they can be
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