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Component-Based Adaptive Shell StructureHaruna Okawa, Keio Universityhttp://harunaokawa.com/

2. Concept-A Pop-up Shell, Self-Optimized Shape The idea is to create a Pop-up Shell that can appear and disappear in a relatively short time. The pop-up process consists of three steps:

(1) Transport, (2) Placement, and (3) Stressing. Firstly, the units are stacked and transported to the site. There, they are placed to form a

hexagonal grid. By adding pressure, it will eventually pop-up and form a self-optimized shell structure. The significance of this outcome is

in the non-linear shell-forming process that takes place in the final stage. Components can go through three different structural modes:

flat, tensioned, and pressured. The method is non-linear in that the shape does not form slowly as forces are applied, but rather takes

place suddenly after a threshold is reached. When combined together, it behaves like a cloth.Yet, thanks to the component system, the

number of components can be incremental and literally infinite variations in shape is available.

4. Materialization-CNC-milling, Folded Urethane Sheet Several scale models were made before the full-scale shell was built in order to test fabrication methods and to explore the effect of changed

parameters of the individual components, including materiality and connecting details. The final material used to build the 1:1 scale model is a

hard urethane sheet (Achilles Board ALN/PE Non-CFC), with an aluminum sheet bonded to its top surface and waterproof paper on its bottom.

A sheet is 910mm by 1820 mm and 15mm thick. In this case 10 sheets were used to make the model. In terms of fabrication, the shapes were

cut with Shopbot and each piece then folded manually. Usually, hard urethane cannot be folded because it will easily crack, however the

addition of aluminum to the front face resolves this issue, so that a folded structure could be produced.

6. Future Development-Accurate Simulation, Integrated Fabrication The simulation process be improved in the next stage of this research. Instead of

regarding the body as a single surface, collisions between multiple three dimensional

objects will be detected as force is applied. In this way the structural transition process

and stress lines can be simulated more precisely. This will also enable structural

sophistication of the component. Also, better fabbication methodology should be explored

as there is inevitable inefficiencies of nesting irregular shapes on flat sheets for CNC

cutting. Possible solutions include but not limited to create frames, inflatable baloons, and

so on by hand, 3d printer, moulding, et cetera.

3. Component Design and Simulation

-Surface Morphology, Hex Block with Three Legs The component is a hexagon with three legs attached. Each component can be

connected to six adjacent parts with ribs that prevent them from separating. As an

aggregate it can move as a cloth, and under the right conditions it becomes a shell

structure. In the pseudo-simulation, the aggregate of hexagonal units is replaced by

a single surface (and in this way is not a full simulation). The surface is transformed

to simulate the physical form making process. Its four corners are set as anchor

points which give the surface a three dimensional form when moved. The centroids

of each unit are located on this surface and move as the surface is transformed.

The height and overall shape correspond with the distance the anchor points have

moved. Finally, the surface is evaluated at each point and normal vectors are

acquired. Following the position of the points and direction of the vectors, the

components are placed, creating a shell shape based on the simulation. Depending

on the length of the legs, the stretch of the surface is ditermined.

1. Introduction-The Scaffold Problem and Non-Linear Assembly Shell-structured buildings have been explored by many architects and structural engineers, each of them constructed in a different way.

For example, L’ Oceanogràfic (2003), designed by Félix Candela used a wooden mould to cast its concrete shell. Although this method is popular

for concrete shell construction it leaves a lot of waste once the concrete is cured and the formwork is removed. Another example, Mannheim

Multihalle(1974) by Frei Otto is more efficient because it does not require a formwork. Instead a wooden lattice was built on the ground and the

application of specific pressure to the total form created a complex three-dimensional curve. However, its formal transformation depended on the

application of stress on the structure, making the material structurally weaker. These works are traditional examples of static shell structures. By

looking at the relationship between the shell design and its construction method, a critical point is noticed in the transformation strategy that turns

a 2D shape to one that is three dimensional. Thus, this research explores the development of an adaptable non-static shell structure utilizing

advances in computational design and digital fabrication technology. The goal is to overcome the issues inherent in the traditional examples,

namely that the creation process weakens the materials, and that the need for an intermediate support structure can be wasteful.

7. Conclusion-Adaptive Shell The chained block structural system enabled the creation of an adaptive shell that moves

between different structural state. The range of each component’ s movement is controlled

by multiple parameters such as length of the legs and height of the component. The

allowance of this movement resulted in flexibility in form. By increasing the accuracy of the

simulation and exploring new ways of fabrication, further development in the shape is

expected. This will allow to get feedbacks and reflect them in deisign more frequently.

5. Results and Feedbacks-Lightness vs Hardness The self-supported shell is composed of 34 individual pieces. The simulation was

useful as a tool during the design process, giving an indication of the final shape of

the shell structure. As a responsive system, changes made to the surface and the

components revealed different shapes. Criteria that had significant impact included the

placement of the components, changes in the shape of the initial surface, as well as

the direction and amount of anchor points. In scaling up the shape, the lightness and

hardness of the material were crucial elements and the urethane sheet was found to

perform best in terms of rigidity and strength. The precision of fabrication and gap

between the individual components were key factors to take note of in the built model

as they defined how smoothly the components moved and how strongly the friction

connection worked to maintain the final shape under real-world conditions.

Component Design Simulation FabricationComponents Formation

Abstract

Shell structures have a long lineage. At the beginning of architectural history shell structures were made from bricks that interlocked with their own weight. Later,

structures made from concrete and lattices were explored, as can be seen in the work of Félix Candela and Frei Otto. These were created through a process that is

time-consuming and labor-intensive with many waste materials left over at the end. Searching for an alternative method, this research aims to connect shell design

with non-linear construction techniques, making use of a rapid prototyping process based on computational design and digital fabrication. It uses components whose

movement is restrained to a certain range and attempts to simulate the structural state in order to confirm the forms will not collapse, partially, or as a whole.

The resulting work is shown here. The self-standing shell was assembled using composite boards created from aluminum sheets attached to urethane boards.

34 individual components interact with each other to create a three-dimensional shell when force was applied to the system. In future development of the model,

more accurate collision detection system between each of the individual parts and their adjacent members will be implemented and new fabrication process will be

explored.

Keywords: shell structure, non-linear construction, aggregate architecture, collision simulation

References

Garlock, Maria E. Moreyra., and Billington, David P. 2008. Félix Candela : engineer, builder, structural artist. Princeton, N.J. :

Princeton University Art Museum ; New Haven : Yale University Press

Nerdinger, Winfried. 2005. Frei Otto : complete works : lightweight construction natural design. Basel : Birkhäuser

Fig.1 Closeup view of the pavilion

Fig.2 Construction Process of L’ Oceanogràfic

(Garlock and Billington 2008, 149)

Fig.3 Construction Process of Mannheim Multihalle

(Nerdinger 2005, 287)

(1)Transportation of the Units (2)Hexagonal-Grid-Based Placement (3)Stressing

Fig.4 Workflow of Pop-up Shell

Fig.9 Achilles Board Processed by ShopbotFig.8 Scale Model Printed by Projet4500 Fig.10 Fabrication Process of the Component

Fig.6 Pseudo Simulation Fig.7 Interaction between the Components

(1) Cutting (2) Folding (3) Glueing (3) Combining

Fig.5 Three Types of Structural State

(a) Flat (b) Tensioned (c) Pressured

Fig.13 Ideal Process of Design and Fabrication

Fig.12 Possible Form of the Component

Fig.11 Completed Work