Notes | Architectural Geometry(AG) as Design Knowledge by Helmut Pottmann

注1：AA建筑联盟学院DRL（Design Research Lab）Term 2 Constructed History (Tutor: Shajay Bhooshan) Reading List

注2：原文见2010年Architectural Design期刊《Architectural geometry as design knowledge》，作者Helmut Pottmann

Pottmann, Helmut. "Architectural geometry as design knowledge." Architectural Design 80.4 (2010): 72-77.

Mindmap of AG

建筑师通常将用在automotive和aeroplane industries的digital techenology作为tool，但这些tech很难解决建筑问题，如美学、结构、建造技术上的问题。

1 Aims of the research in AG

- 形态与设计过程：meet the requirements in the shape creation and design phase

- 实际建造与结构：incorporate basic aspects of the actual construction including materials, manufacturing technologies and structural properties

- 完整workflow从设计到制造：enabling a completely digital workflow from design to manufacturing, especially for highly complex geometries

- rationalization：把digital model转化为适合应用在建筑和fabrication上：transfer standard digital models into a form suitable for architectural application and fabrication – a process referred to as ‘rationalisation’

2 Construction-Aware Geometric Design vs Rationalisation

Construction-Aware Geometric Design

- 需要了解材料，panel types，分布装配：incorporates knowledge of the material used, panel types, subconstruction and so on in the shape creation process via customised geometric modelling tools

- Combining subdivision and optimisation (centre) provides construction-aware geometric design, a direct approach to modelling free-form surfaces which are composed of single- curved strips.

AG Rationalization

- need redesign phase, recompute the geometry

- rationalization解决非线性和优化问题：From a mathematical perspective, rationalisation amounts to the solution of often highly non-linear and computationally expensive optimisation problems

- AG research的challenge-算法优化和user-friendly的软件：The development of efficient optimisation algorithms and the incorporation into user-friendly rationalisation software tools are substantive research challenges in AG

- architectural education上的影响：requires further knowledge of geometry

3 Architectural Free-Form Structures from Single-Curved Panels

Frank Gehry has been one of the first to employ free-form surfaces in architecture.

Guggenheim Museum in Bilbao (1997), the Experience Music Project in Seattle (2000) and the Walt Disney Concert Hall in Los Angeles (2004)

Gehry used mostly developable surfaces(可展曲面)

- also known as single-curved surfaces, can be unfolded into the plane without stretching or tearing

- characterised by a family of straight lines, along each of which they possess a

constant tangent plane

- implies various positive properties for fabrication

- A technique composed of subdivision (refinement) and optimisation towards developability provides a direct (construction- aware) modelling approach

- The process of rationalisation of a given free-form surface with developable panels (strips) follows related ideas

4 Rationalisation by Ruled Surfaces and Relation to Manufacturing Technologies

Ruled surfaces 直纹曲面

- formed by a family of straight lines and therefore possess advantages in fabrication

- To give an example, ruled panels from glass-fibre-reinforced concrete can be produced more efficiently than general double-curved panels, since the rapid and inexpensive hot wire cutting technique can be used to manufacture their styrofoam moulds.

Ruled surfaces possess negative Gaussian curvature(K)负高斯曲率, which means that they are locally saddle shaped(马鞍面); they may also be single-curved (K=0)

Designs which contain large areas with non-positive K are promising candidates for rationalisation with ruled panels 非正曲率的曲面最适合rationalisation with ruled panels

Zaha Hadid’s Cagliari Contemporary Arts Centre in Sardinia (2007)

- Software: Evolute

- 右上图：This design contains large areas which can be covered by ruled surfaces

- 左下图：more complicated saddle-shaped parts may be rationalised by a smooth union of ruled strips

- The asymptotic curves渐进曲线 (curves with vanishing normal curvature) depicted lower right are partially nearly straight and thus indicate the potential for rationalisation with ruled surfaces

- The algorithmic techniques employed in this rationalisation study by Evolute are linked to manufacturing geometry (CNC machining) and hot wire cutting of moulds

- On this surface, three curve families which are close to geodesics (shortest paths) are arranged in a trihexagonal（三角+六边形的）pattern. Geodesic curve families are preferred for cladding with wooden planks

- The trihex arrangement of three such families is especially useful for the construction of timber grid-shells.

- this is the pure result of AG, but future research will aim at combining geometric and structural optimisation

5 Panel Layout

- double-curved metal panel的制造技术意味着更大尺度的free form metal facade也可以被建造出来 Recent developments in manufacturing technology for double-curved metal panels suggest that large-scale free-form metal facades will be buildable in the near future

- 这种技术可以简化金属外壳的rationalization，但仍然需要将surface分成最大可被建造尺寸的技术：This technological advancement will eventually simplify the rationalisation of a metal facade surface, but splitting the surface into panels of maximum manufacturable size is still required.

- 当前的软件工具还不能足够支持这种复杂free form曲面的panel layout的设计 State- of-the-art design tools do not yet efficiently support the design of such panel layouts for complex free-form surfaces.

经常在早期使free form曲面被简单的参数化的曲面代替：often leads to free-form surfaces being replaced by simple parametric surfaces at an early stage

- 现在的研究尝试把这些free form surface处理为单独的参数：Recent research therefore tries to close these gaps, treating arbitrary free-form surfaces as parameters themselves and fully parametrising their panel layouts

6 Future Research

- Architectural geometry constitutes a new and challenging research area which aims at providing construction-aware design tools and enabling a completely digital workflow from design to manufacturing, especially for highly complex geometries

- Future academic developments will need to address these new challenges in order to recognise the emerging significance of geometry as architectural knowledge.