Roberto Maffei Ultra light weight foldable sheltering systems

Steel Days - P6 Ultra light weight architecture: foldable and expandable shelter for humanitarian relief – Roberto Maffei

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P6: Ultra lightweight architecture: foldable and expandable shelters for humanitarian relief

From containers to kits: evolution of lightweight sheltering systems

Contents

INTRODUCTION

a. STATE OF THE ART 1. Definitions 2. Lightweight and ultra lightweight architecture 3. Foldable and expandable systems 4. Special structures: Tensegrity and Tensairity® 5. Structure in lightweight construction: materials and details 6. Two scenarios of application

b. APPLICATION IN EMERGENCY: advantages and drawbacks 7. Analysis of advantages and drawbacks of the application of lightweight structures in emergency 8. Foldable and expandable systems for emergency 9. Tensegrity and emergency 10. Inflatable and tensairity® 11. Details and materials 12. Building processes: design, stocking, delivery and mounting phase

c. CONCLUSIONS 13. Key words 14. Innovation


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INTRODUCTION

This article explains how and when lightweight architecture has developed, how it works and which are its basic principles. Structures that come ready to assemble, that can be erected and disassembled in a matter of hours and those that have the last impact on the natural environment while providing adequate shelter and modern amenities, are the preoccupation of several architects whose ambitions are not only toward the micro but the autonomous. Anyway, most of these features are not known and that’s why, in this dissertation, foldable and expandable architecture are shown and their features are highlighted (part a.). The article continues explaining how these kind of solutions can be adapted to suit the needs of victims in case of emergencies and some of the few applications are presented (part b.). The conclusion (part c) focuses on the weak points about the application of such structures in emergency to foreseen possible fields of improvement. A detailed bibliography about the topic is provided in annex. After reading this paper you will: 1) learn the meaning of lightweight, foldable, expandable architecture, their basic principles and their evolution in history; 2) have in mind a series of examples of lightweight architecture and you will be able to understand their properties in terms of weight, transport, assembling and sustainability; 3) understand the advantages and disadvantages of the application of these kinds of structures in emergency; 4) be able to identify the role of steel elements in these kinds of sheltering systems; The goals of this paper are: 1) to show the potential of lightweight structures in the field of emergency; 2) to highlight the role of steel in these kind of systems; 3) to focus on the weak points that have to be improved and can be fields for further researches;


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a. STATE OF THE ART

1. Definitions

To better understand the topic of this dissertation, five concepts related to lightweight architecture are presented. These concepts are complex and can’t be covered in few paragraphs. Anyway, they are strictly related with lightweight architecture and that’s why they will be used to describe the projects presented later on in this article, focusing on their applications in emergency. 1.1. Concept of portability

Portable architecture consists of structures that are intended for easy erection on a site remote form their manufacture. There are three different levels of portability: container, kit and compactable systems.

The container strategy is the simplest portable method and consist of buildings that are transported in one piece, fully equipped and already assembled, for instant use once they arrive at their location. Some incorporate their transportation method into their permanent structure and may be built on a chassis or a hull. Such buildings are generally restricted in size due to the limitation of transport (standard size of container (ISO) are two: 244 (h)*259 (w)*610 (l) or 244(h)*259 (w)*1220 (l)). In this case, the volume transported is the same as the volume in use.

Fig 1: Container Fig 2: Container houses

Extra expandable devices like concertina walls or moveable parts can be applied to further enlarge the volume once on site. Advantages of these solutions derive from the incredibly short set up time and the integration of furniture and sanitary systems. Transportation, on the contrary, can take more time compared to other strategies and, sometimes, can generate issues, for example, if the structures have to be provided in remote sites. Caravans are examples out of this category.

Fig 3: Diy, Japanese mobile home Fig 4: Opera mobile home by Axel Enthoven Fig 5: Bob by Andrew Maynard (2006)

To overcome the limit of the container solution and considering the possibility to have several options and layouts,

ready to be adapted according to the surrounding and the boundary conditions a crucial advantage, the aggregation of smaller modules was developed. That was the concept of “Micro dwellings” (2005) by N55. It is a system for making low-cost dwellings of variable sizes for any number of persons consisting of movable housing modules that can form different configurations on land, water and underwater. Micro dwelling are modular, which allow them to be stacked up, rearranged or gathered together with other systems into small communities.


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Fig. 6: Micro dwelling configuration 1 (2005) Fig. 7: Micro dwelling configuration 2 Fig. 8: Micro dwelling prototype

The opposite method, that enables a larger variety of forms, is based on a kit approach. In this case, the building is constructed from factory-made elements transported as single elements and then quickly assembled on site. These building kits can be packed and stored in a small volume: in this case, volume transported is several times less than the volume of the shelter in use. According to number of elements of the kit, the shelter can improve and/or enlarge its final configuration. This strategy needs workforce on site to assemble the kits into the final shelter. Advantages of this solution comes from the optimization of the shipping methods and the possibility to access any sites; drawbacks derive from the waste of time on the construction site and the level of know-how required for the assembling phase. The shorter and the easier the set up is, the more effective the solution will be. Elements are usually simple and standardized thus expansions or additions of the kit are possible and fast. Tents are well know solutions out of this category.

Fig. 9: Bubble kit by studio MMASA (2009) Fig. 10: Mounting phase Fig. 11: Bubble prototype

A third type of portable building is something in between the first two options and it is based on a fully integrated

but compactable system, easy to transport and usually deployed or dry assembled on site. This option offer a larger variety in forms and typologies compared to containers and tries to minimize the drawbacks of the previous solutions combining the advantages of both. Volume to be transported is lower compared to container systems but higher than simple kits. In this case, the assembling phase plays the key role but it is simplified and speed up compared to the kit solution. On the other side, personalization is possible but it is quite limited. Some transitional shelters, but also some prefabricated modules, are from this category.

Fig. 12: MoMi tent by Future systems (1992) Fig. 13: Airclad by Inflate (2006) Fig. 14: Cellular compartment by Andreas

Zittel (2001)

To summarize, both containers and compactable systems are fast to be set up but personalization and implementation in time are usually quite difficult. On the contrary, kit approach is much more “open” and allows different arrangements according to different applications. The former ones are “ready to use” solutions: definition of the foundations and deployment are the only actions required on site; the latter ones require time and effort in the construction phase but they are much easier to be transported.


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1.2. Concept of flexibility

Flexible architecture respond to today’s living problems and predict the architecture of tomorrow. Flexible building are intended to respond to changing situations in their use, operation or location. This kind of architecture adapts rather than stagnates, transform rather than restricts; it is motive rather than static, interacts with the users rather than inhibits1.

Flexible architecture is not a new phenomenon but a form of building that has evolved alongside human being developing creative skills. Even if most of people is used to architecture that is essentially composed of statics, solid objects, the possibilities of completely flexible buildings are limitless. Extreme possibilities consist in a house that is design for one person during the week and change into a six people house for the week-end to host relatives and friends. Or a home that can be folded and took with you in your business trip. Or a building that fits your individual needs now but you can invest in over the course of your life and divide up between your children to give them each a starter home when they need it.

Fig. 15: Muscle by ONL (2003) Fig. 16: Trans_port by ONL (2001) Fig. 17: GucklHupf by Hans Peter Wörndl (1992) Therefore flexibility is not only related with volume but with performances too and it acts in time. What makes a

building successful is the number of possible transformations during time and its adaptation to the external environment and boundary conditions. The changing of climate conditions and lifestyle, for example, requires adaptation during time and that’s way flexible architecture should modifies its components as fast and easy as possible.

Modern camper trailers use a number of devices to enlarge space once they have arrived at their location, such as rising roof or pop up rooms. The simplest system is a roll-up awning that can be extended from the side of the trailer to cover a space that forms an external living room. Dutch architect Eduard Boehtlingk’s “Markies” camper trailer uses this strategy: once you arrive in place the walls fall down and became floors while the new space is enclosed by a concertina-like membrane.

Fig. 18: Markies: deployment (1985): Fig. 19: Open configuration Fig. 20: Closed configuration at night

1.3. Concept of temporality

Temporary architecture is designed and built for a specific and short period of time. Temporary architecture refuses monumentality. It is essential, efficient and fast: it avoids unnecessary elements.

Temporary architecture is designed to be set in one place for a limited period of time and then to be easily dismantle. Crucial feature of temporary architecture are the design of joints and connections that guarantee the fast assembling and disassembling of the whole structure. Any elements should be designed thinking about the packaging and transportation phase too.

The concept of temporary architecture derives from the shelter of nomadic tribes of the past. Problems of transportability (limitation in size and weight) and durability of the materials and connections are the main boundary conditions in the design of temporary structures. If centuries ago, structures were transported by animals and erected by men, nowadays airships or trucks can easily transport much larger structures that can be assembled using machines: 1 Kronenburg R. 2007


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large temporary structures are, thus, now available. From the durability point of view, stronger materials and smart construction systems have been developed: the faster and the easier the structure can be set up, the better it is.

Fig. 21: Serpentine gallery: OMA (2006) Fig. 22: Cavalia, Circus by Canobbio (2003) Fig. 23: Tree home

Circuses, showrooms and pavilions are modern temporary shelters: an incredible variety of materials can be used in

temporary architecture and several building systems have been developed producing a long series of astonish examples. 1.4. Concept of minimum

Minimum means optimum, lightness and efficient. The concept of minimum lies at the basis of any lightweight construction. Minimal structures are not only the ones that use the minimum amount of material. From the design point of view, concept of minimum plays the key role in the definition of the shape and forces within a lightweight construction. Since the form of lightweight structures derives from the forces that are acting in the structure itself, controlling the forces, it is possible to control the shape of the whole structure and to optimize the final design. Moreover, minimizing the forces, sections of materials can be reduced. That’s why, applying specific load cases and restrictions, the behavior of the whole structure can be improved and therefore, it can minimized.

Fig. 24: Kapoor, Tate Modern Gallery,

minimal surface (2002) Fig. 25: Lucy Orta: refuge wear, minimal

shelter (1996) Fig. 26: Rakowitz, paraSITE minimal habitat

(2007) Minimum means also natural. Minimal surfaces, volumes and distances are present in nature too. Bubbles or drops

are just two examples of a well know phenomena of equilibrium. 1.5. Concept of sustainability

Sustainability is a complex topic. For this dissertation sustainability is only described in relationship with the idea of lightweight construction, focusing on three aspects: the amount of material used, the energy consumption of the structures and the reuse or recycle of the materials.

Sustainability is definitely related with the amount of material used for building a structure. “Less is more” is, from the sustainability point of view, fundamental. The less material is used, the less energy is required, the less pollution and less waste material is generated. In the case of lightweight constructions the amount of material used is strictly the one required to support the loading conditions, nothing more. Moreover, lightweight structures are designed to react to external forces in the most efficient way. Only tension and compression forces are present and bending moment or torque are mostly avoided. That’s the reason why structural elements can be thin and slender (cf. 4).

From the energy consumption point of view, lightweight constructions can’t be compared to traditional structures. To provide indoor quality, mass matters. Thus, lightweight solutions and systems have to be applied in specific climate conditions. Well designed shading systems have to be taken into account and special attention should be given to natural ventilation. A good example is the “Desert seal” by Andreas Vogler: inflatable tent for extreme environments that make use of temperature curves in hot arid regions where the air gets considerably cooler the more distant is from


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earth’s surface. This effect is used by many desert animal, not least by the camel. That’s why an electric fan constantly blows cooler air from the top of the tent into the body of the liveable space within. The tent consist of an “airbeam” structure made of yellow polyurethane-coated polyethylene fibre and its awning is a silver coated high-strength textile that reflects heat and protect form direct sunshine. The beauty of this configuration derives from its functionality and efficiency.

Fig. 27: Desertseal concept, Vogler (2004) Fig. 28: Desertseal prototype Fig. 29: Desertseal details From the material point of view, lightweight structures are, most of the time, dry assembled and, therefore, they can

be easily dismantled. For this reason, materials can be easily separated and shorted to be prepared for recycling or to be re-use for new purposes.

2. Lightweight and ultra-lightweight architecture

The definition of lightweight structures can be wide. Lightweight implies a comparison between different things: one is heavier than another one thus, the latter is lightweight. It is clear how, this definition, can’t be considered sufficient. In architecture, this definition has to be better addressed: any structures that can carry much more load than the weight of the structure itself it is generally considered “lightweight”. This is in contrast with traditional structures (such as bricks, concrete or steel structures) in which the load bearing capacity is less than the weight of the supporting structure.

Fig. 30: Lightweight structures by Vincenzo Pinto Lightweight structures are special. Their components (i.e. membrane, struts, poles, cables, turnbuckles etc.) are

visible both from outside and inside in a composition that is defined by their function: namely, the transmission of forces. This is in direct contrast to “ordinary” structures, where structural components are usually hidden behind finishing elements and whose textures and forms are considered more comfortable to the human eyes and tactile senses. Although light structures may be painted galvanized or plated, the structure itself, being clearly visible, become the architecture of both form and space.

Fig. 31: Konsberg Jazz Festival (2006) Fig. 32: Chianciano conference center (2007) Fig. 33: Solo recital pavilion by Studio Dre

Wapenaa (2008)


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Tensile structures, in particular, are definitely a challenge for structural engineers. In fact, the stability of conventional building made of concrete, steel, wood or masonry is based on two main structural properties: gravity and rigidity. These properties make them stable and capable of transmitting load. If masonry walls stay in place because of their bulky weight, steel frames carry load by means of their rigid strength and resistance to bending. In tensile structures gravity and rigidity are not available at all. Fabric structures, in particular, are so light that their weight is almost negligible. Moreover, the materials of which they are made, such as fabric and cables are highly flexible. Other means have to be harnessed, therefore, to give stability and strength to a structural system consisting of flexible members. Their components require arrangement in a specific geometric form (surface shape), while being subjected to a specific pattern of internal stresses (pre-stressed pattern). The geometry of tensile structure is, therefore, not arbitrary, but follows strict engineering rules2 (cf. 5).

Fig. 34: Lightweight structures’ behavior

Lightweight structures are more than light materials3. The essence of engineering lightweight structures is a careful

design of the force flow within the structure such that minimal material required for a specific task is used. From a structural point of view, cables under tension are extremely efficient, since the cable strength is independent of the length of the cable and solely given by the material strength. However, whenever there is tension, there is compression too. And for compression length matters. The risk of buckling demands larger cross sections and, thus, more material. As a result, columns are heavier and thicker than cables as it is obvious in the case of suspension bridges.

Constructive separation of tension and compression is a major goal of good lightweight engineering. The principle is fully adapted in tensegrity structures4-5. Astonishing sculptures were built according to the tensegrity principle of discontinuous compression and continuous tension but structures solely based on this principle are not so common in architectural applications (cf. 4).

Starting from all these considerations and this background, ultra-lightweight constructions are a step further: considering the previous analysis and looking at the example of tensegrity, ultra-lightweight constructions are structures where materials, design, layout and arrangement of the elements collaborate towards lightness: the equilibrium of forces is optimized and materials are carefully chosen and dimensioned. Moreover, ultra-lightweight constructions are systems that perfectly fits all five concepts defined at the beginning of this essay without any compromises.

History of lightweight construction is full of controversial structures: some of them are lightweight from the material point of view but require huge anchor systems to resist withstand wind loads: as result, the temporality concept is failed due to the fixed foundations. Some other, are incredibly light but, from the flexibility point of view, require additional structures/elements that, at the end, double the total mass. Considering transportability, some inflatable domes, for example, are lighter, in terms of kg/m2, than any other arch-supported tent available but, being the whole dome one element only, transportation can require machines and special devices. Set up systems should be also considered to define the total “weight” of the structure. Moreover, the sustainability of the solution provided, in terms of performances, reusability but also energy consumption “weights” a lot. Therefore, ultra lightweight constructions can be considered light not only because of their mass but mainly because of their design.

2 Berger H., 1996 3 Luchsinger R. H. et all, 2004 a

4 Fuller R. B., 1975 5 Pugh A., 1976


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Fig. 35: Oympiastadium, Monaco, Frei Otto

(1971) Fig. 36: Velodromo Aigle, 2004 Fig. 37: Frame supported tensile structure

One of the most famous example of “tricky” lightweight structure is the Fuji pavilion built during the expo of

Osaka, Japan, 1970. It was based on 16 arch shaped tubes of 4m diameter and 72m in length. Each tube was 4 tons in weight and the inflation and setting time was 5 days per tube. Total set up time took five months and total weight was 65 tons (about 35 Kg/m2). To have a comparison, modern air halls easily weight 2 Kg/ m2 and the set up of a structure of a comparable size to the Fuji pavilions is, nowadays, a matter of one of two days.

Fig. 38: Fuji pavilion, 1970, side view Fig. 39: Fuji pavilion, 1970, top view Fig. 40: Fuji pavilion, erection phase

2.1 Weight VS lightness

To have the concept of lightness more clear, one should have in mind numbers and data about the weight of architectural elements or materials and investigate examples where weight is crucial. In case of emergency, as we said, weight is a key issue and that’s why solutions are usually shorted according the transportation systems or the required workforce for mounting (number of men, machines etc.). The following overview offers eight out of the several examples of sheltering used in humanitarian relief.

UNHCR - Lightweight emergency

tunnel UNHCR - Standard version -

center pole tent UNHCR - Family tent (5 people) UNHCR - Ridge type tent

(5 people)

W/l/h: 3/5,5/2,1 m

Area: 15,18 m2 Weight:42 kg

W/l/h: 4/4/2,75 m Area: 16 m

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Weight: 115 kg

W/l/h: 4/6,6/2,2 m Area: 23 m2

Weight: 55 kg

W/l/h: 4/4/2 m Area: 16 m2

Weight: 85 kg

Protezione civile – Familiy 16 sqm Protezione civile – Montana 19fr Protezione civile – Montana Pneu tex fr 3 arches

Protezione civile – Fast set up 6x6

W/l/h: 5,5/3,1/2 m

Area: 17 m2 Weight: 55 kg

W/l/h: 5,1/3,9/2,65 m Area: 19,8 m2 Weight: 101 kg

W/l/h: 5,1/5,1/2,6 m Area: 26 m2

Weight: 150 kg

W/l/h: 5,9/5,9/2,8 m Area:34,6 m2

Weight: 327 kg


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A comparison between products is not the task of this essay (also because one should take into consideration not only dimensions but also materials, structural and thermal performances) anyway, it is clear how, even basic tents can vary in terms of weight. UNHCR focused its solutions on lightness. On the contrary, Protezione Civile offer heavier solutions that should assure higher performances. The model called “Fast set up 6x6” should be considered more into detail.

Fig. 41: Fast set up 6x6 tent: mounting phase Its structure is a foldable aluminum frame with shock-corded poles. Set up is fast (four people in three minutes) but it weights much more compared to other similar solutions (like Montana Pneu). Total weight reaches 327kg. It is clear how lightness is therefore, relative: sometimes, weight can be counterbalanced by special features that make the solutions better for a specific application. That sometimes happens in the case of expandable and foldable solutions: it can be that “foldable” versions of a shelter, result heavier compared to a standard, not foldable, solution: in this case, the increasing of weight is counterbalanced by the easiness of transport. Anyway, in most of the cases, foldable structures give a strong contribution in the reduction of weight, these are the cases discussed in the following paragraphs.

3. Expandable and foldable systems

Usually structures became be lighter if they incorporate systems and devices that can modify their volume or configuration on site according to the changing of needs (transport) or other externalities (climate). Therefore, expandable and foldable systems are subsets of lightweight constructions. They can enlarge and reduce their space in different ways using rollers, hinges or other mechanisms: sliding or rotating walls or floor, one structure can expand its volume or can compact itself. To offer the tools of analysis of part b. of this essay, features of expandable and foldable systems are now presented.

Lightweight systems are usually a combination of rigid parts and flexible elements. Sometimes, the main structure relies on rigid elements like poles or struts; in other cases structure is only made of flexible elements stabilized by tension: that’s the case of pneumatic structure; in the most common case, both rigid and flexible parts collaborate to the structural integrity of the system. According to the structural role of the elements of a construction, limits of packaging and folding strategies can be defined.

Fig. 42-43-44: Foldable canopy mounting phase by LSU University of Dundee

The rigid elements of structures usually fold through hinges, rollers or a telescopic arrangement. Expandable bar

structures based on the concept of scissor hinges have been studied since long time, initially only as two-dimensional, lazy-tong-type structures that extend linearly. More recently, curved structures, that expand in three dimensions, have been developed. In the case of flexible elements (e.g. membranes) folding pattern deriving from the origami approach have been applied in architecture too. Rigid two dimensional elements (cardboard plates) can be also folded using this strategy.


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Concerning the folding process of bar structures, detailing of connections and movement control are fundamental to obtain an efficient structure. Weight of each element and stability during the folding phase should be also taken into account. Internal forces like frictions, torque or bending moment should be minimized and reduced because a deformation of any of the elements of the mechanism can damage the whole system.

Fig. 45: Foldable envelope, Accordion

ReCover shelter by Mattew Malone (2008) Fig. 46: Foldable rigid structure by Grupo Estran Fig. 47: Folded membrane, retractable roof

Considering membrane materials, the bending stiffness of standard PVC coated polyester fabric is basically

neglected when large surfaces are involved. That’s because the stiffness of a membrane is much smaller than traditional construction material such as steel or wood. Anyway, considering the transporting and the packaging phases, bending stiffness and elasticity of material in use has to be considered from the very beginning of the design phase. As consequence of good design, some structures can be packed in a well defined volume; in some other cases, structure can’t be nicely folded and the material itself can be damaged. The control of the folding process and the packaging of the structure are, therefore, crucial.

4. Special structures: Tensegrity and Tensairity®

Two new interesting concepts have been developed recently. The first is the Tensegrity one. It consist in an innovative construction concept that, thanks to the development in material occurred in the last decades, could be finally applied and used in architecture. The second one is the well known Tensairity® principle, a combination of some of the advantages of Tensegrity together with pneumatics, in an easy way. Both principles show clearly that structural and material innovation play the key role in the developments and applications of lightweight structures.

4.1. Tensegrity systems

Tensegrity is: “a structural principle based on the use of isolated components in compression inside a net of continuous tension, in such a way that the compressed members (usually bars or struts) do not touch each other and the pre-stressed tensioned members (usually cables or tendons) delineate the system spatially”6. Tensegrity is a developing and relatively new system (barely more than 50 years old) which creates impressive, lightweight and adaptable figures, giving the impression of a cluster of struts floating in the air. It is not a commonly known type of structure, so knowledge of its mechanism and physical principles are not widespread among architects and engineers7. Three men have been considered the inventors of tensegrity: Richard Buckminster Fuller, David Georges Emmerich and Kenneth D. Snelson.

Fig. 48: Tensegrity tetrahedron by Snelson Fig. 49: Needle tower by Snelson Fig. 50: Needle tower by Snelson

6 Valentín Gómez Jáuregui, Tensegrity structures and their application to architecture, 2004 7 Valentín Gómez Jáuregui, Tensegrity structures and their application to architecture, 2004


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Considering the structural behavior, tensegrity structures doesn’t work like traditional structures where elements are held in place by weight. Instead of the “weight and support” strategy, they are stablized thanks to a “system of equilibrated omni-directional stresses”8. Furthermore, they do not have to be supported as they are self-equilibrated and pre-stressed, so they are not depending on gravity factors for their own equilibrium: the tension created by the attraction of the Earth is replaced by the multidirectional tension of their members.

Several advantages derive from the application of such kind of systems. Due to the ability to respond as a whole, it is possible to use materials in a very economical way, offering a maximum amount of strength for a given amount of building material9. Moreover, tensegrity structures don’t suffer any kinds of torque or torsion and buckling is very rare due to the short length of their components in compression. In addition, tensional forces naturally transmit themselves over the shortest distance between two points, so the members of a tensegrity structure are precisely positioned to best withstand stress. The fact that these structures vibrate readily means that they are transferring loads very rapidly, so the loads cannot become local. This is very useful in terms of absorption of shocks and seismic vibrations10. Thus, they would be desirable in areas where earthquakes are a problem. From a modular approach, the spatial definition of individual tensegrity modules, which are stable by themselves, permits an exceptional capacity to create systems by joining them together. This conception implies the option of the endless extension of the assembled piece. In case of large tensegrity constructions, the process would be relatively easy to carry out, since the structure is self-scaffolding. This can be of great advantages in remote areas where machines and scaffolds are difficult to be transported. Last but not least, the kinematic indeterminacy of tensegrity is sometimes an advantage. In foldable systems, only a small quantity of energy is needed to change their configuration because the shape changes with the equilibrium of the structure. Consequently, several researchers have explored the use of tensegrity structures as sensors and actuators11 and these are definitely two of the most promising and interesting application of these structures.

Fig. 51: Tensegrity skyscraper by Block and Kilian

On the other hand, disadvantages are relevant too. First of all, tensegrity arrangements need to solve the problem of

bar congestion. As some designs become larger (thus, the arc length of a strut decreases), the struts start running into each other. Moreover, in order to support critical loads, the pre-stress forces should be high enough, which could be difficult in larger-size constructions12. Furthermore, tensegrity suffer of relatively high deflections and low material efficiency, as compared with conventional, geometrically rigid structures”13. The fabrication complexity is also a barrier for developing this kind of systems: some arrangements are complex, which can lead to problems in production14. In addition, inadequate design tools have been a limitation until now: it is clear how a lack of design and analysis techniques for these structures is present.

Since the introduction of the tensegrity concept in the 1940’s, many models have been built. However, as Motro notes: “[…] there has not been much application of the tensegrity principle in the construction field. […] examples have generally remained at prototype state for lack of adequate technological design studies15”. This is not to say that there have been no practical structures built using the tensegrity principal. Effective use of tensegrity principles has been made by Geiger Fuller and Levy to design roofs which cover large areas.

8 Kenner, 1976 9 Ingber 1998 10 Smaili, 2003 11 Tibert, 2002 12 Schodek, 1993 13 Hanaor, 1987 14 Burkhardt, 2004 15 Motro, 1992

Steel Days - P6 Ultra light weight architecture:

Fig. 52: Tensegity domes

However these approaches result in essentially composite structures where a substantial portion of the structure is

fabricated using non-tensegrity technologies. Thus these structures do not take complete advantagtensegrity technique has to offer. The resulting light weight allows tensegrity structures to encompass very large areas with minimal support at their perimeters, obviating the “heavy anchorage devices”cable-based technologies, or extensive support structures needed by the composite structures discussed above.Moreover another issue should be mentionedEnvelope components, closing the space to protect htherefore joints and detailing should be investigated structure (cf. 11-12) 4.2. Tensairity principle

“A Tensairity® beam consists of a simple air beam and a compression element which is connected with two cables running in helical form around the air beam. At the end of the compression element the cables are connected. Due to the connection of the cables with the compression element, the cable force is transferred to the compression element, acting here as a compressive force P. […] The key principle of Tensairityelements against buckling”17.

In fact, the compression element becomes prone to buckling. In general, the buckling load is much smaller than

the yield load meaning an inefficient use of the material and extra weight for the compression element. In Tensairitythe air tube plays a key role. The compression elTherefore it is continuously supported by the membrane. In fact, the membrane acts as a continuous elastic support for the compression element. The stiffness of this support is determined by the proportional to the overpressure inside the membrane tubebuckling in truss and in Tensairity® are shown in figure 46

Fig 56: Buckling behavior

16 Motro 1987 17 Luchsinger et all, 2004b 18 Luchsinger et all, 2004c

P6 Ultra light weight architecture: foldable and expandable shelter for humanitarian relief

Fig. 53: Geiger dome Fig. 54: Olympic

However these approaches result in essentially composite structures where a substantial portion of the structure is tensegrity technologies. Thus these structures do not take complete advantag

The resulting light weight allows tensegrity structures to encompass very large areas with minimal support at their perimeters, obviating the “heavy anchorage devices”16

needed based technologies, or extensive support structures needed by the composite structures discussed above.

mentioned: tensegrity are beautiful structure but architecture is not only structure. closing the space to protect human life, should be designed and attached to the structure,

oints and detailing should be investigated carefully, without destroying the beauty

beam consists of a simple air beam and a compression element which is connected with two cables running in helical form around the air beam. At the end of the compression element the cables are connected. Due to the

ection of the cables with the compression element, the cable force is transferred to the compression element, acting here as a compressive force P. […] The key principle of Tensairity® is to use low pressure air to stabilize compression

element becomes prone to buckling. In general, the buckling load is much smaller than the yield load meaning an inefficient use of the material and extra weight for the compression element. In Tensairitythe air tube plays a key role. The compression element is tightly connected with the membrane of the airbeam. Therefore it is continuously supported by the membrane. In fact, the membrane acts as a continuous elastic support for the compression element. The stiffness of this support is determined by the membrane stress, which itself is proportional to the overpressure inside the membrane tube18. The different cases of a compressed element prone to

are shown in figure 46.

behavior Fig. 57: Comparison between a Tensairity® beam and a truss

Fig 55. Tensairity basic elements

foldable and expandable shelter for humanitarian relief – Roberto Maffei

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Olympic gymnastic center, Seoul

by Geiger (1988)

However these approaches result in essentially composite structures where a substantial portion of the structure is tensegrity technologies. Thus these structures do not take complete advantage of what the

The resulting light weight allows tensegrity structures to encompass very large areas needed for support with some

based technologies, or extensive support structures needed by the composite structures discussed above. : tensegrity are beautiful structure but architecture is not only structure.

d and attached to the structure, the beauty and integrity of the

beam consists of a simple air beam and a compression element which is connected with two cables running in helical form around the air beam. At the end of the compression element the cables are connected. Due to the

ection of the cables with the compression element, the cable force is transferred to the compression element, acting is to use low pressure air to stabilize compression

element becomes prone to buckling. In general, the buckling load is much smaller than the yield load meaning an inefficient use of the material and extra weight for the compression element. In Tensairity®,

ement is tightly connected with the membrane of the airbeam. Therefore it is continuously supported by the membrane. In fact, the membrane acts as a continuous elastic support for

membrane stress, which itself is . The different cases of a compressed element prone to

Comparison between a Tensairity® beam and a truss


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The combination of compressed air, fabrics, struts and cables in Tensairity® is new in structural engineering. Thus a structural analogy is very helpful for the understanding of Tensairity®. The analogy to a truss was suggested in the case of a Tensairity® cylinder. For the symmetric spindle under homogenous load, the situation is shown in figure 57. The Tensairity girder has an upper compression element and a lower tension element. Both these elements can be found in the truss (on the right) with the same functionality. Assuming a parabolic shape of the tension element and the compression element in the truss model, half of the homogeneous load needs to be transferred to the tension element by the vertical struts, while the force in the diagonal struts vanishes. In Tensairity®, the vertical and diagonal struts are missing. Thus this transfer has to be fulfilled by the fabric and the compressed air. As an interesting feature of Tensairity® and other pneumatic structures, compressive forces are transmitted by fabrics under tension. Obviously, this transfer depends on the pressure and thus a relation between load and pressure can be established. As for the cylinder, the pressure is proportional to the load per area and independent of the length or slenderness of the beam. Consequently, for a given snow load, the necessary pressure in the Tensairity® girder is the same for a small roof as for the covering of a huge stadium. This is an interesting property of Tensairity® and especially important for wide span applications.

5. Structure in lightweight constructions: materials and details

Structures are designed to stand two forces (and their combinations): compression and tension. In lightweight constructions, the response to these forces should be optimize. Membrane may be connected directly to the supporting structure at its edges or it can have an edge-cable system that is then connected at discrete points to the boundary system supporting structure that equilibrates the tensile forces from the membranes and transmits them to the ground under both pre-stress and applied loading conditions. This primary structure may consist of compression loaded masts and tie-back cables in their simplest form, or reinforced concrete ring-beam or arches, till complex assemblage of beam, strut and cables elements.

Fig. 58: Forces distributions in basic lightweight constructions Lightweight construction can be divided into three main categories according to the structural system: membrane

supported construction, structure supported construction and inflatable linear elements construction. The first one is the typical system of air supported structures or air halls. In this case, stability is provided by the

balance between the tension in the membrane and the compression in the air of the enclosed inner space. This system is characterised by the strict relation between form and structural behaviour. Membrane form is the transfer of loads to the foundations thus equilibrium shape is the only form possible. Natural shape of pneumatics is bubble’s shape. A combination of different bubbles is also possible thanks to the use of cables or rigid rings. These kinds of structures are the most easy to build and fast to set up. However the form is not appealing and flexible and that’s one of the reasons why they are not widely used in architecture. Details and joints of this kind of constructions are mainly in the foundations: the connection between membrane and ground and its air tightness under pressure is the main task. Usually, a metal bar is insert into a pocket at the edges of the membrane and it is than connected through metal rings to the stakes sunk in the concrete kerb all along the perimeter of the structure.

The second category consist in the combination of membrane (tension) and a supporting rigid structure (tension and compression) usually made by a metal or wooden frame. In structure supported constructions membrane protects the inner space from rain and sun rays and, most of the time, it doesn’t have a structural function. As a consequence, membrane’s form is the result of the frame’s shape. Therefore, equilibrium shape of the membrane is not the only form possible anymore. The weight of the structure is, on the contrary, much higher than an air supported structure. Moreover, storage volume is much more than the one of an air supported structure of the same dimension. However, appealing shapes are possible and maintenance is easier too (to substitute membrane is easy and fast). That’s why these kinds of structures became much more common in architecture in the last decades. Supporting structure can be defined by masts, arches, ring elements and flying mast systems. Detailing of these systems and materials involved are countless. Wood, metal, plastic and composite elements are used. Specific details for these kinds of structures can be


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sorted in three main areas: detail for foundations, connections between membrane and supporting structures and connection between membranes and cables. Examples of the first group are metal hinges (single- double- or tri-hinge) and pin and anchor base plate with bolts for the connection to the concrete foundation plinth. Among joints between structure and membranes should be named: corner plate connection, eyelet systems, keder systems, clamped edge with plates, cannel and lacing edge system, bale rings (in case of conical structures) etc. Within the third group one should keep in mind: cable edge system with clamps, eye cables to strength the structure in specific areas, ridge and valley cable to shape the form of the membrane, tie back cables and stakes joints.

The inflatable linear elements construction case can be considered an hybrid category in which a set of inflatable components (air-beam or air-column) act as supporting rigid structure. Membranes or other finishing elements are supported by this structure and usually they don’t have any structural functions. Inflatable tubes are usually inflated with high pressure but low pressure systems are also possible (e.g. tensairity®). Details are similar to the ones of the first and second case. Specific details for tensegrity and tensairity® systems can be considered too.

Fig. 59: Air supported construction Fig. 60: Structure supported construction Fig. 61: Inflatable linear element construction

6. Two scenarios of applications

Lightweight and foldable structures can be thought and designed according to the definition of temporality. Temporary living can be “by choice”, for example, in case of camping, or “for necessity”, for example, in case of emergency19. Although, in this essay, the main focus is the second case, the first one can’t be neglected: both temporary living are strictly related and some technologies or devices, thought for the first use, can solve some of the problems that affect by the second one. The main risk of the application of the solutions designed for temporary “by choice” comes from the know how involved in the technology. In the first case, users are willing to live temporarily and they are prepared to face their status (that is limited in time). In the second case, users are forced to live in temporary dwelling and sometimes, they can’t predict how long that experience will last. Social and cultural acceptance are here crucial.

Together with the concept of temporality, as watershed between the two ways of temporary living are the other four concepts mentioned in paragraph one. First of all, the flexibility of the structures that is their ability to adapt to the different environmental requirements, changing of demands and climatic conditions. Secondly, portability of the solutions as fast as possible and efficient packing and shipping configuration in cases in which transportation is an issue. Thirdly, a minimum and efficient use of material able to offer the best performances for the larger number of people. Last, a sustainable design that foresees how materials/components could be recycled/reused when the emergency phase has passed: life time, availability and maintenance should be considered too.

6.1. Temporary use by choice

It represents the more sophisticated and elegant temporary solution, able to answer to new needs of housing and nomadic working. Hi-tech materials and systems are usually required and applied in this case. Two opposite solutions are possible. In the first one, several devices like caravans, tents or boats are already on the market and they are able to satisfy the desire of freedom in an efficient way. Solutions, can be similar to everyday dwellings but take inspiration from the word of cars, planes or other high-tech backgrounds. As a result, sometimes, dwellings are not only houses but they are a luxury concentrate of devices, comfort and innovative design. On the other hand, extreme houses are an answer too. Minimal shelter and habitat are required by users who are seeking for fun and adventure. Living in extreme weather conditions like in the desert or at the top of mountains need hi-tech material and devices to withstand the harsh

19 Giurdanella V., Zanelli A.: Lightweigth, adaptable and reversible construction: sustainable strategies for housing, Internation conference Adaptables, Eindhoven, 2006


climate conditions20. These solution are far to be comfortable or luxury: only efficiency matters.of the development in these kind of structures.

Fig. 62: Ski house by Horden R. 2004

6.2. Temporary use for necessity

It responds to an urgent need of protection and safety, following natural disasters or war emergencies, humanitarian and sanitary aid. Main goal is economical and technical issues. Solutions offered in this case should be fast to set up, easy to maintain and repair, product should provide the higher level of comfort in relation with the New materials or high-tech solution should be carefullyand social acceptance on site. They should be highVery important: these solutions should make people feel safe and homes”. Big issues derives from the fact that with different requirements and backgroundsnumber of solution has been studied and built for this purposInnovation is this field is a challenge: new solutions areextremely severe and, most of the time,

Fig. 65: Emergency tent Fig.

b. APPLICATION IN EMERGENCY

Sheltering systems used in post-emergency occasions have some specific features that can vary according to the environmental conditions or the kind of emergency they have to face. Anyway, mentioned in the paragraphs above, twthey should be useful in all the stages and also whencharacteristics lower the standards of the dweluse products that aren’t thought to be housing such as facilities for parades or meetings, facilitieswarehouses fit perfectly the requirement of fast setting and reuse.those two features and more traditional characteristics ofthe right balance is not an easy task. Lightweight architecture is a step methods because it is fast to set up and reusable by definition. generates drawbacks that should be carefully foreseen and taken into account.

20 Richardson P., 2009 21 Claudi de Saint Mihiel C., 2003


These solution are far to be comfortable or luxury: only efficiency matters.of the development in these kind of structures.

Fig. 63: Walking house by N55 2008 Fig. 64: Instant housing

It responds to an urgent need of protection and safety, following natural disasters or war emergencies, . Main goal is to provide an immediate response to the crisis

economical and technical issues. Solutions offered in this case need to be simple, effective and ready to assemble; they should be fast to set up, easy to maintain and repair, easy to deal with in all the phases of the emergencyproduct should provide the higher level of comfort in relation with the resources available:

should be carefully considered before their application They should be high-tech in concept and low tech in solutions (materials, ass

should make people feel safe and the population should recognizeact that these solutions should be designed and adapt

with different requirements and backgrounds: form children to grandpas from educated to number of solution has been studied and built for this purpose but only few of them have been applied in real life.

a challenge: new solutions are highly required but the process of application of new systems is too slow.

Fig. 66: Fold Flat Shelter by Lippmann A. 2010 Fig. 67:

b. APPLICATION IN EMERGENCY

emergency occasions have some specific features that can vary according to the or the kind of emergency they have to face. Anyway, among the other features already

wo properties are more important than others: they should be easy to set up and useful in all the stages and also when the emergency has passed (reusable)

of the dwelling and that’s the reason why, sometimes, as use products that aren’t thought to be housing such as any exhibition pavilion, temporary roof, covering of sport

or parades or meetings, facilities for tourism or for the army etc: containers, exhibition stanperfectly the requirement of fast setting and reuse. To assure a certain living standard, a balance between

more traditional characteristics of a dwelling (like comfort, appeal, usability)the right balance is not an easy task. Lightweight architecture is a step ahead compared to other building construction

t up and reusable by definition. On the other hand, the application of this solution generates drawbacks that should be carefully foreseen and taken into account. Starting from this consideration,


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These solution are far to be comfortable or luxury: only efficiency matters. Innovation is the core

Instant housing by Baumann W. 2008.

It responds to an urgent need of protection and safety, following natural disasters or war emergencies, offering to the crisis dealing with social,

simple, effective and ready to assemble; they easy to deal with in all the phases of the emergency. The final

resources available: it should be cost effective. before their application due to the low know how

tech in concept and low tech in solutions (materials, assemblage). the population should recognize them as “their

should be designed and adapt and satisfy different users : form children to grandpas from educated to illiterate. A incredible

e but only few of them have been applied in real life. the process of application of new systems is

: Expandable containers

emergency occasions have some specific features that can vary according to the among the other features already

: they should be easy to set up and (reusable) 21. These two basic

sometimes, as emergency shelter, NGOs exhibition pavilion, temporary roof, covering of sport centres,

ontainers, exhibition stands, info points, To assure a certain living standard, a balance between

(like comfort, appeal, usability) is required. To find compared to other building construction

On the other hand, the application of this solution Starting from this consideration, the


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focus on this section will be not only those designs that were thought for emergency but also some the “temporary-by-choice-structures” (c.f. 6.) because the author thinks they can inspire new possible solutions. 7. Analysis of advantages and drawbacks of the application of lightweight structures in emergency

It is evident that not many foldable or expandable structures have been applied in emergency yet. On the contrary, a lot of projects have been produced. Lightweight and ultra-lightweight constructions give their best when they have to be applied in case of lack of time of set up and when transportation is an issue. What’s the reason why these kinds of structures are not applied that much in emergency occasions? The author believes that the distrust of lightweight structures comes from a lack of knowledge in general. Architects, engineers but also volunteers and public opinion are not used to deal with the new principles that lightweight architecture offers. In front of such a kind of structures, people are astonish and impressed but, anyway, these structures are far away to be generally accepted in everyday life. In addition, sometimes in the past, lightweight systems have been presented as the easiest answer in too many occasions. Utopias of the 70s and 80s fascinated architects and engineers but, at that time, technical solutions and materials were not able to fulfil the performances of those futuristic designs. Starting from the tremendous gap between design and final product, the belief of a sustainable, fast, transportable, flexible living environment disappeared. People still have in mind early experiments in which the dream of lightness and innovation wasn’t fulfilled at all. Moreover, the appeal of those structures was far away to the beauty of the designs and concepts developed at that time.

Fig. 68: Instant city, Archigram

On the other hand, in the last twenty years, the material science developments and the continuous transfer of

knowledge, for example, from sailing and sport industry to architecture, offered better and lighter materials with higher performances from any points of view. Therefore, nowadays, new systems, technologies and solutions are available and, in most of the cases, they can come through the old limits. Anyway, the risk of going too far should be avoided: especially in case of emergency, solutions should fulfil strict standards and rules. Sometimes lightweight constructions perform well, some other times they don’t at all. The worst mistake would be to push one technology when it is not ready or if there is no reasons to apply it. That’s why, there are so much differences between the temporary solutions “by choice” and the one that can be applied “in emergency”. Anyway, contamination is possible and would benefit the humanitarian sector as a whole.

The goal of this paragraph is to show if some lightweight technologies are ready to give their benefits in humanitarian relief too. Below is a list of possible advantages and drawbacks due to the applications of lightweight structures in case of emergency. They are divided in macro areas.

Advantages: Disadvantages: Set up

1. Lightness 2. Transportability 3. Fast to built/dismantle 4. Self scaffolding 5. Simple material/elements involved

Structural limits

1. Safety doubts/risk 2. Limited/low load bearing capacity 3. Stability 4. Connection and details: can be weak points

Usability

6. Adaptability/modularity 7. Appealing structures 8. Visible and distinct structures 9. Possible implementation with local materials 10. Second or third use possible

Control of internal comfort

5. Low thermal insulation 6. Low acoustic insulation (privacy) Design and layouts

7. High cost of design (low know how) 8. Restrictions in shape (height-width relation) Acceptance

9. Specific know how for mounting and repairing 10. Social acceptance of shapes and materials


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Advantages of the application of lightweight architecture in emergency are well known. The list on the left side is basically the resume of the theory showed in part a: lightweight constructions clearly shows features that match the requirements to be applied in post disaster occasions. The advantages presented are specific of lightweight constructions and they are of great benefit for the field of emergency. They can be shorted in two main areas: advantages related to the very first phase (the set up) and advantages related to the life cycle of those systems (usability). The first category of advantages is strictly connected with the rapidity of the mounding phase: the faster the better but keeping in mind the quality of the product and its life cycle. Therefore, from the second category, two main advantages relies in the possibility to implement the basic structure with local materials (point n° 9) and the opportunity to reuse those structures for a second or third purposes (point n° 10), when the emergency has passed. If refugees could deal with the materials and the technologies applied, giving their contribution too, their quality of life would improve faster. Not many words should be spent to explain how much the impact of these features would benefit the population. Reader may refers to bibliography if necessary.

On the other hand, the list of disadvantages has to be carefully discussed and investigated: the goal of this paragraph is to show the limit of this kind of structures but also to highlight which are the possible fields of improvement and main focuses of the future development. Anyway, most of the disadvantages listed here affect traditional structure too. They can be divided into four main areas: 1) structural limits, 2) control of internal comfort , 3) design and form problems and 4) acceptance of the technology provided. Let’s analyse all four topic separately.

7.1. Structural limits

Public opinion consider lightweight and special structures unsafe. That’s a general attitude that comes from the lack of knowledge about the behaviour of these structures under loading. Tensile structures are safe as traditional ones and, sometimes, even more: in case of collapsing, for example, large deformations appear in advance showing any possible risk (that’s definitely the case of pneumatic structures, for example, if overpressure decrease). Moreover, the weight of a single element is usually not dangerous for the guests even if they are under the structure at the moment of the collapse. Anyway, their rigidity is much less compared to traditional systems and that’s why shivering and movements are present under strong wind: that’s something people should get used to. Membranes or other fabric elements are considered the weak points. That’s only true in the cases in which membrane collaborates to the stability of the whole systems (cf. 5.): in these cases, if any element brakes (not only fabric but cables or struts too), the stability of the whole systems is damaged. Collapsing of structures can be shorted in two macro areas: collapsing due to natural factors (e.g. wind or earthquakes) or due to human factors (e.g. design error, attack or vandalism). In the first case the whole structure collaborate contrasting the external forces. A well design of shapes, details and good manufacture can produce, for example, tents who are able to withstand incredibly heavy wind loads. The current knowledge and materials available lowered this risk of collapse almost to zero. Considering human factors, design errors are possible but rare. They appear when unpredictable loading conditions arise or when information are not available (for example experience about soil composition). Concerning vandalism or attacks, it is for sure a problem that has to be solved from the design phase. Fabrics and cables are considered the weakest points because of their thin section. Anyway fabric can be punctured or cut only due to heavy contact with sharp elements: it is really rare it would happen accidentally. In the worst cases, small cut (10-20 cm) into fabric doesn’t mean that the structure will collapse: in case of pneumatic structures, systems are usually designed to compensate the loss of air through air blower. In addition, tensile structure are designed to avoid tear propagation. In the case of cables, they are, most of the time, made of steel: special pincers are required to cut them. Anyway, vandalism should be taken into consideration avoiding a direct contact of people to the weakest points of the structure. That’s difficult and, sometimes, impossible.

Limited bearing capacity has also to be discussed. Lightweight and especially temporary structure are systems designed to match specific loading criteria rather than, as architecture in general, to resist the worst possible condition that may only happen once in their lifetime. To obtain high level of bearing capacity with lightweight structures is possible but, most of the time, there is no reason to go for it. High bearing capacity means unreasonable higher stresses (or higher pressure in case of inflatable) that lead to bigger section of materials and/or bigger mass (in case of foundation, for example). Moreover, higher risks of failure or damages are there if forces are intense. The best design is the one calibrates forces within the structure to satisfy safety standards with a sustainable use of materials and redundancies.

Connection and details can be weak points. Lightweight structures relies their behaviours on the performances of their details and connections. That’s the reason why the best, stronger, durable materials should be used. Stress and deformations focuses in these areas thus, their design can’t be done roughly on site, especially in case of emergency,


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when the lack of time would lead to mistakes. Joints and connections are affected by several external agents: they are weather-beaten; they occurs several cycles of mounding/dismounting phases; they could suffer long periods of storages where moistures or constant pressure can be applied to the elements. Metal elements are one of the most suitable solutions due to their resistance to external agents and their structural performances.

7.2. Control of internal comfort

To assure thermal and acoustic insulation, mass is necessary. On the contrary lightweight constructions are systems were, by definition, the use of materials is minimized. In relation with thermal comfort, smart design should take into account natural systems to cool down or keep shelters warm (e.g. natural ventilation or avoiding moisture). Combination of different layers is the easiest way to improve thermal comfort. Sun shading devices together with waterproof layers are required. Combination of lightweight materials with massive systems are possible too. Local materials like water, leaves or ground can also be considered and used. Concerning thermal insulation, a series of studies about winterized tent are available in literature22.

On the other hand, sound insulation system of lightweight structure is still an issue and it hasn’t been studied deeply yet. Anyway, sound insulation can be crucial for refuges to feel safe and “at home” during the displacement period. Fabric finishing materials have low performances in terms of airborne sound insulation. Better performances can be obtained by the application of non woven mattresses in combination with aluminium or lead sheets. The results are flexible but heavier and thicker finishing materials.

7.3. Design and form problems

The design of lightweight construction is crucial for the success of the structure itself. Structures are mainly pre fabricated and then assembled on site. Thus, not many changes can be done in the mounting phase and that’s the reason why everything should be carefully checked before being transported on site. Know how about the structural behaviour of lightweight structures is technical and it is not diffuse among architects and engineers. Specific software are required for form finding and structure analysis. Improvising is definitely to avoid, especially in emergency field. Some design and structural systems present restrictions in shape too. For example, sometimes, dimension of the structure are linked and related to each other (that the case of arcade construction). Another example concern the behaviour under wind load: since different shapes reacts differently, some configuration can’t be applied in windy areas. Tie-back cables can be an issue too: they can’t be avoided and, sometimes, they produce restrictions in the usability of the structure itself. Safety problems can arise from them since they are out of the perimeter of the structure itself and they are, in some cases, not visible at the first sight.

7.4. Acceptance

Social acceptance is the most complex issue concerning lightweight constructions. If technical problems can be solved in a well defined period of time (even if, in some cases, solutions are not sustainable), social acceptance requires time and effort and, sometimes, can’t be solved at all. Ethical issues arise when a so called “developed country” offers a “ready to use” technical solution, for example, in a “third world countries”. How should NGOs deal with the consequence of the application of alien technologies into local environments? On the other hand, mounting and maintenance phases are both crucial in this respect. Material used plays the key role in the success of the solution: familiar material can be substitute, repaired and reuse locally also when the emergency has passed. On the contrary, alien material, should be repaired or maintained by external contractors who should deal with the emergency phase only. The fast achievement of a self sustainable condition for the population affected by an emergency is the mayor goal of the humanitarian relief. Steel and aluminium materials are the perfect examples and lightweight constructions the perfect application about social acceptance. Special structures, even if designed as simple as possible, need components that should have a certain level of accuracy. On the contrary, if masts (for the structures) or foundation systems can be built locally, it is difficult to find alternatives to hinges, turnbuckles, tie-back systems, iron cables, stakes or eyelets; materials should be mainly out of metal too. Anyway, the majority of these aliments are so simple that can be found almost in any place where hardware shops are available. Of course, quality and durability should be controlled.

22 Shelter cluster, 2004


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8. Foldable and expandable systems for emergency As mention in paragraph 1, considering structures that are provided within the very first phase after the emergency

has occurred and looking at the definition of lightweight architecture of paragraph three, three different solutions offering foldable or expandable features have been pointed out. The first one concerns containers, characterized by a consistent inner volume (the habitat); the second one concern kit systems, when the building is constructed from simple factory-made elements transported in a really small package and then quickly assembled on site; the third one concerns a fully integrate but compactable system that is easy to transport and usually deployed or dry assembled on site. Even if all three categories can have foldable characteristics, the lightest structures in terms of weight, are mainly part of the second and third category; but as we have learnt, weight can’t be the only parameter of analysis.

Chronologically, the first solution appear to be the oldest. The first design for emergency based on foldable or expandable principles was the “Emergency housing” by Jenneret and Prouvè, from the mid of the 40s, designed for the population affected by the second world war. It is a mobile unit on wheels. A fix central core hosts the kitchen and the sanitation systems. Both on right and left side, the unit can enlarge its volume thanks to hinged and sliding walls. This project looks still modern and, unfortunately, most of the solution still in use right now didn’t learn much from this experience. A similar technology was developed by professor Rudolph in “dwelling for married students”, University of Virginia, (1967).

Fig. 69: Emergency housing: front and section by Jenneret and Prouvè, 1945 Fig. 70: Dwelling for married students by Rudolph 1967

Other dwellings based on the same concepts have been developed by Alberto Rosselli (1972), by Spadolini (1983)

and by Kenzo Tange for the pilgrims of Muna. In the last case, core rigid elements (services) were connected by concertina systems (rooms): several configuration and aggregations were possible in contrast with the rigid layout of other traditional container solutions.

Fig. 71: Expandable dwelling, Rosselli, 1972 Fig. 72: Foldable container, Spadolini, 1983 Fig. 73: Dwelling for Pilgrims, Kenzo Tange

More recent development of the container system are “Su-si” (1996) and “Fred” (1999) transportable buildings by

Kaufmann & Rüf. Both are transportable buildings that can be used as simple dwelling, studio, office space or home addition and in any “emergency”. The design makes relocation or expansion as quick and fast as possible. Units are transported on site by a truck and erected using a mobile crane: it takes five hours to be mounted for the 50 m2 of “Su-si” and two hours for the 18 m2 of “Fred”. A more recent example is the IKEA refugee housing (2005) in which the whole systems folds up in thanks to his “shrimp” system in a quarter of a shipping container and can be set up on site in less than one hour.


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Fig. 74: Su-si by Kaufmann & Rüf, 1996 Fig. 75: Fred by Kaufmann & Rüf, 1999 Fig. 76: S.H.R.I.M.P design by IKEA, 2007

Apart from few exceptions, already since the beginning of the 80s became clear how architecture made of fully prefabricated systems was nothing more than utopia: a massive use of such a solution, it would have generated an artificial and unsustainable landscape. That’s the reason why searcher and architects adapted the container approach pushing the idea to design several and different units (one for each function) and focused on the aggregation of these different parts, as spontaneous architecture is.

At the same time, the affirmation of compactable systems (second solution) began. Fast set up and flexible delivery methods were at the basis of the concept of Feature Systems which designed in 1989 a umbrella-like shelter for emergency application. The structure could be transported attached to any truck thanks to its wheels. Twelve people could erect the structure in 30 minutes according to the designers, simply pulling apart a series of metal struts. Mounting phase was simplified combining the set up of the load bearing structure together with the system of pretension of the covering membrane.

Fig. 77: Delivery by plane o truck Fig. 78: Mounting phase Fig. 79: final shape

From the mid of the 80s, new shelter kits approach (second solution) have been developed. The idea was to

provide the population with simple and standardized material to be assembled easily and fast with local labour. Learning from the experiences of temporary exhibition, one of the most famous pavilion, based on the repetition of simple components, was the “IBM travelling pavilion” (1982) by Renzo Piano and Peter Rice. The pavilion consisted in 85 m long and 480 m2. The structure was based on a suspended steel floor that contained a hollow space for services. A series of free-standing three-pin arches was attached to this floating platform. The layout was simple but effective and a sense of lightness and transparency were fully achieved. The projects was deeply influenced by a series of studies carried out by Piano about “Basic shelters” (1964) for temporary and emergency occasions. These designs focused on the modularity of the elements and their details and each of them was deeply studied and carefully optimized in terms of weight and usability.

Fig. 80: IBM pavilion by Piano R., Fig. 81: IBM pavilion, details Fig. 82: Basic shelters by Piano R., 1964

In the field of emergency, the most famous case of shelter kits is the “Paper Log House” by Shigeru Ban for the

earthquake of Kobe in 1995 together with some other experiences from the same architect like the “paper partition system” designed after the earthquakes of Fukuoka in 2005. On this path, a really new promising design is the Übershelter by Rafael Smith. The goal of this project was to offer something more than an emergency shelter but a solution that could provide victims with a more personal place to live. As result, Übershelter can be a basic shelter bit it


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also have the capabilities to upgrade and implement modern infrastructures. It can be shipped flat to speed up the transportation and all components are designed modular and collapsible to facilitate the transportation phase. In the same category, “Emergency housing project” is also innovative: it is based on a self supporting modular steel frame to allow great flexibility in layout and covering.

Fig. 83: Übershelter: assembling phase by Smith R., (2010) Fig. 84: Emergency housing project (2010)

Shelters are the main focus of the humanitarian relief but services and facilities are essential too. Talking about

education, “School wheel” project offer the simplest and faster technology to set up a temporary classroom everywhere in few minutes: one big blackboard on wheels, a roll up awning and few chairs are enough to offer a place where to study and meet. In the case of hospital or other medical units, rigid expandable elements are preferable because they can integrate medical infrastructures. Thus, temporary hospital are usually designed within containers and, in the case of “mobile hospital”, expandable partitions can make the volume three times bigger.

Fig. 85: School wheel, Atelier Bow-Wow, 2006 Fig. 86: Mobile hospital by Kukil Han, 2011 Fig. 87: Mobile hospital: four modules Membrane and fabric should be folded too. That seems obvious and easy but, if large structures are involved, that’s not always an easy task. Micro tent, easy to store within a backpack are possible (life tent is an example). On the contrary, in the case of double or three layer shelter, especially if they are made in one piece only, weight matters. “Life cube” tries to avoid this problem integrating a smart transportation system of the packaging of the shelter (two metal ring attached to the box, that work as a wheel) and using all the elements of the packaging as components for the shelter itself: in this case, the sides of the cube are used as suspended floor of the tent.

Fig. 88: Life tent by Ostrowski D., 2010

Fig. 89: Life cube, Conner M., 2009 Fig. 90: Life cube: packaging

9. Tensegrity systems and emergency

Tensegrity structures are definitely the most fascinating systems but their applications in emergency is still a dream due to some intrinsic limitation. That’s why some of the problems concerning tensegrity structures, will, probably, never come to a solution. Advantages of tensegrity are several but even if they are the most lightweight system compared to other structures with similar resistance, too many problems would arise in the case of application in emergency occasion. One of the advantages derives from the fact that they don’t depend on gravity due to their self-stability, so they don’t need to be anchored or leaned on any surface and thus, the systems are stable in any positions.


Moreover they can be joined in a modular way: egrids or conglomerates made of the same or different fefficient because, as the components in compression are discontinuous, they only work locallycompression is located in specific and short lines of action, so they athis discontinuity in compression, they don’t suffer torque at all.

Anyway, at the moment this report was written, tdome” based on the equilibrium of vertical rigid elements in a net of cables stretched within a rigiddefined a relatively fast system of set up for his dome (especially in the case of the Olympic gymnastic arena of Seoul (1988)crew of skilled workers with the coordination of the best engineerrequire simplicity: that’s definitely not the case of tensegrity, design point of view, bar congestion remains

Learning from the properties of thereally simple but stiff structures in an easy wayFolly Dock EXPO in Rotterdam (2007)overpressure. Like in tensegrity, cables are stressed curvature of the inflatable itself, reducing thwas designed by the author. The goal was to obtain a rigid double layered inflatable dome based on the tensegrity principle. Further studies have to be conduct to test the stability of the system.

Fig. 91: The Cloud by Frantzen Architecten (2007)

10. Inflatable and tensairity® Inflatable structures are really promising when transportation and time of set up are issues.

small volume and they don’t need much effort in the set up. On the contrary, they require air blower and their shapes are usually squat and limited. The most advanced example of inflated architecmobile, rectangular, meeting and exhibiconsists in three main elements: 1) air-muscles; 2) air-filled flat panel walls; building are “active” structural members that can be automatically loosened or tightened depending on external wind pressure. Anyway, Airtecture is an exceptioninnovative and nothing really new popped up since the first applications.

Fig. 94: Airtecure hall (1999)

A big step in the development of inflatable technology could be

tensairity® because it can combine advantages of pneumatic structurepressure. Moreover, general doubts about the safety of pneumatic (in case of deflation) are avoided because tensairityincludes steel elements, dimensioned to withstand


Moreover they can be joined in a modular way: elemental tensegrity modules can be joined in order to create masts, grids or conglomerates made of the same or different figures. In addition, from a structural point of view, they are really

s the components in compression are discontinuous, they only work locallycompression is located in specific and short lines of action, so they are not subject to high buckling loads and,this discontinuity in compression, they don’t suffer torque at all.

Anyway, at the moment this report was written, the only application in architecture wasum of vertical rigid elements in a net of cables stretched within a rigid

system of set up for his dome (especially considering the large span invoin the case of the Olympic gymnastic arena of Seoul (1988), the mounting phase was crucial and crew of skilled workers with the coordination of the best engineers available. On the contrary

icity: that’s definitely not the case of tensegrity, especially when spans are large. of view, bar congestion remains the key issue that has to be solved.

the tensegrity systems and combining them with pneumatiin an easy way. That’s the case of “the cloud” designed by Fran

Dock EXPO in Rotterdam (2007). In this case, the compressed struts have been substituted by the air in ables are stressed within a net of tension (the membrane)

, reducing the stresses in the membrane. Based on the same principleThe goal was to obtain a rigid double layered inflatable dome based on the tensegrity

principle. Further studies have to be conduct to test the stability of the system.

Architecten (2007) Fig. 92: The cloud, inner view Fig. 93

are really promising when transportation and time of set up are issues. small volume and they don’t need much effort in the set up. On the contrary, they require air blower and their shapes

The most advanced example of inflated architecture is the Airtecture Hall (1999): it mobile, rectangular, meeting and exhibition space that uses a number of innovative high-pressure stru

-filled-y-shaped columns, tensioned by cables and a series of linear pneumatic filled flat panel walls; 3) and air filled roof beams. The pneumatic muscles that help

structural members that can be automatically loosened or tightened depending on external wind exception. Most of inflatable technology applied in emergency are far away to be

innovative and nothing really new popped up since the first applications.

Fig. 95: Airtecure hall, muscles’ connection

ment of inflatable technology could be done by the promising researches aboutt can combine advantages of pneumatic structures reducing the section of the air beam at low

about the safety of pneumatic (in case of deflation) are avoided because tensairitydimensioned to withstand the permanent loads also in the case of loss of pressure.


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lemental tensegrity modules can be joined in order to create masts, point of view, they are really

s the components in compression are discontinuous, they only work locally. This means that the subject to high buckling loads and, due to

e was the so called “Geiger um of vertical rigid elements in a net of cables stretched within a rigid closed ring. Geiger

span involved) but, for example crucial and it was carried out by a

On the contrary, emergency occasion when spans are large. In addition, from the

with pneumatic, it is possible to obtain Frantzen Architecten for the

been substituted by the air in within a net of tension (the membrane) and thus, they brakes the

. Based on the same principle, Turtle Tent (2009) The goal was to obtain a rigid double layered inflatable dome based on the tensegrity

Fig. 93: Turtle tent by Maffei (2009)

are really promising when transportation and time of set up are issues. They can be packed in small volume and they don’t need much effort in the set up. On the contrary, they require air blower and their shapes

Airtecture Hall (1999): it is a pressure structural systems. It

shaped columns, tensioned by cables and a series of linear pneumatic and air filled roof beams. The pneumatic muscles that help to stretch the

structural members that can be automatically loosened or tightened depending on external wind Most of inflatable technology applied in emergency are far away to be

Fig. 96: Muscles

e by the promising researches about section of the air beam at low

about the safety of pneumatic (in case of deflation) are avoided because tensairity® also in the case of loss of pressure.


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Even though the tensairity® systems is highly effective, combining cables and struts around the air chamber, some of the advantages of pneumatic systems are lost. In fact, the author believe that the steel girder coupled with the air beam is the weak point in this construction principle. First of all, the maximum length of the steel girder is bounded by the way of transportation and by the length the industry can provide. Secondly, tensairity® beam can be dismantled but it can’t be folded as any pneumatic element anymore. Thankfully, really new researches23 proved the possibility to substitute the steel girder with a collapsible element thus the total element can be folded and stored in a simple box. In this way, it would be possible to transport the whole element in a much smaller volume reducing cost and time.

Fig. 97: Garage Park Montreaux, 2004 Fig. 98: Observatory Tenerife, 2008 Fig. 99: Planchamps Skiers bridge, 2006

Moreover, the set up of inflatable structures remains fast and simple and no cranes neither scaffolds are required. Examples of this application can be found in the “garage park” of Motreux, (2004) and in the observatory of Tenerife (2008). Huge spans are the best application for tensairity® structures: temporary infrastructures like roads or bridges can be set up in few hours. That’s the case of the “Planchamps Skiers bridge” (2005) of 56 m span.

Some recent studies demonstrated that beams are not the only structural elements that can be done with tensairity®. arches and mattresses are also possible. Tents and community shelter can be some of the applications.

Fig. 100: Tensairity® arch Fig. 101: Ten m span tensairity® arch (2010) Fig. 102: Spider tent by Maffei (2011)

11. Details and materials Details and materials in lightweight structures are, as it was already discussed, crucial. The application and

selection of the right material in emergency occasions is even a bigger challenge. Materials and their arrangements should not only be selected according to their structural and durability properties but also considering the availability on site and the possibilities to maintain and repair them when the emergency has passed. Material used in foldable and lightweight architecture can be grouped in two parts according to the role they have in the shelter: 1) structural materials (e.g. membranes, masts, cables and connections) and 2) finishing elements (e.g. membranes, thin plates, shading devices, walls, floors etc). In both categories, coated fabrics are usually the most common materials when a folding system is involved. Anyway, as we saw in paragraph 8, some expandable and foldable modular solutions do not include membranes at all. That’s, for example, the case of container solutions.

Fig. 103: Different kinds of swaged sockets

23 De Laet L., Luchsinger R., 2010


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Even if “structure-free” systems are possible (pneumatic structures), in most of the cases, fabrics are coupled with rigid frames. These are usually a combination of bars or thin plates. Structural bars or plates for foldable structures are usually made of steel or aluminium. They need to be rigid, strong and lightweight. Any damage at any of the elements of the structure would spoil the whole folding system. Hinges should be carefully designed too but they remain the weakest points. They should find the right balance between resistance and lightness within the smallest possible volume.

Fig. 104: Sheltering, Grupo Estran Fig. 105: Deployment by Grupo Estran Fig. 106: Flying mast

Details of lightweight constructions are either really simple like tie back cables or corner plates or quite complex,

in the case of fling masts but all of them should be carefully designed. Their role is to pre-stress, to stabilize and to keep the membrane attached to the structure. Considering hinges, for example, due to the cinematic of the parts, they should be designed taking into consideration the accommodation of the membrane not only at the packed and fully-deployed configuration but during the whole process of deployment too. That was one of the goals of De Laet, designing the hinges for a tensairity® beam.

Fig. 107: Hinges for tensairity® foldable beam by De Laet L. Fig. 108: Design of the hinge system by De Laet L.

Moreover, details should be flexible in a sense that they should be able to accommodate different elements in

several ways. Simplicity has to be included too: in case of emergency, when the lack of time is an issue, the advantage of using the same connection for different purposes would incredibly speed up the set up phase and would allow local labour to collaborate in the construction activity. In this sense, metal element can be easily fixed and repaired with common tools and that’s one for the reason why they can be applied. Some examples of well known connections of lightweight structures can be find below. All of them are schemes and can be detailed in different ways according to the needs.

Fig. 109: Corner plate apart from fabric

Fig. 110: Corner plate clamped to fabric & adjustable cables

Fig. 111: Clamped edge with plate

Fig. 112: Double hinged base plate for cable

Fig. 113: Ball & socket mast base plate

As one can notice at first sight, details, if well dimensioned and designed, are usually quite small compared to the size of the shelter itself. On the contrary, they can easily become too heavy and large to be effective in terms on transportability and setting up. Some good example are offered in “emergency house project” where one single joint can accommodate several struts or in the “fast set up” by Ferrino where hinges and tensioners are coupled together.


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Fig. 114: Emergency house project: detail of joint Fig. 115: detail - fast set up tent by Ferrino Fig. 116: detail - fast set up tent by Ferrino Steel profiles in lightweight constructions derive from two different forming processes: hot laminated steel and cold formed steel (CFS). The first case is traditionally the most common one; all special elements are produced in this way. On the other hand, nowadays, the coupling of membranes with aluminium profiles is growing and it opens new scenarios for a larger application of CFS steel profiles too. new designs and structures require lighter profiles with complex section. That’s the case of ETFE cushions and other special clamping systems. Sheltering would benefit by the use of profiles of this kind too.

Fig. 117: Aluminum clamping plate for ETFE cushion Fig. 118: Aluminum clamping profile with cable

12. Building processes: design, stocking, delivery and mounting phase Lightweight structures differ from traditional architecture not only regarding to the five concepts mentioned in

paragraph 1 but also considering some of the steps of the building process: design, stocking, delivery and mounting phase are four of them and should be considered more into detail.

In the case of membrane structures, from the design point of view, specific know how and computational tools (e.g. form finding and specific structural analysis software) are required. Design can’t be improvised and specific skills are necessary, especially in the case of large structures. Anyway, having few basic principles in mind and looking at well know solutions, safe and high quality design can be selected to be applied in specific contexts. Moreover, design of lightweight construction does not end when the element is produced. Stocking, delivery and mounting phase should be designed since the very beginning and should be the main input to guide the product development.

Comparing lightweight structure with traditional architecture, delivery and mounting phase are definitely easier and faster in the first case. When transportation is an issue, only extremely lightweight and compact systems can be the solution. Success of the delivery phase is strictly related with folding and packaging strategy of the stoking phase. Starting from the design, it should be taken into account how a certain structure can be packed and kept in a standard packaged volume. Moreover, materials and elements should be designed and selected to stand forces and external agents (e.g. moisture) in the packed configuration too. That’s why foldable structures should be designed to be stored in a packed configuration maybe for some months or even years and, at the time when an emergency occurs, they should be fully operative and ready to be used. Membrane is the weakest part in this respect because it can undergo damages during the stocking phase. That’s the reason why the folding process should be tested and controlled in advance to define the final configuration without producing unsustainable stresses or permanent damages in the material.

Fig. 119: packaging of 2” tent by Quechua Fig. 120: sketch of 2” tent system by Quechua Fig. 121: packaging phase of 3” tent by Malamoo


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Camping tent shows the most advanced solutions in this field: deployability, packaging and storage features are highly developed to offer compact, fast and simple products easy to handle for everybody. Mounting phase, as in the example showed above, is, most of the time, reduced to two or three simple movements.

c. CONCLUSIONS 13. Key words

Foldable and expandable structures showed clearly their benefits in application in case of emergency. Anyway, as all experts in the fields know, “the” perfect shelter doesn’t exist and that’s the same for “the” perfect technology. That’s the reason why, it would be a tremendous error to consider foldable and expandable structures the “easy” solution to every complex issue in humanitarian relief. They can’t be an easy solution because emergency is always complex by definition and any solutions have to take into considerations many factors. In addition, each emergency is unique (e.g. considering the climate, the culture and the kind of hazard occurred) thus, an effective response can’t be done with standard products. As we saw in part b., lightweight system offer advantages for some specific applications but, at the same time, they generate disadvantages that should be considered and, if possible, prevented.

Five different keywords, derived from the analysis of this report, can identify the main features that any foldable/expandable structures should have to be applied in emergency. Moreover, these words can be the starting points for future researches and developments in the field.

13.1 Simplicity

As suggested in chapter 11, simplicity is the concept that links all five definitions presented in chapter 1. Simplicity implies the use of few elements, materials and connectors without any redundant parts: less material (in terms of number and mass) means effectiveness of the solution, velocity in the mounting phase, lightness in the transportation and easiness in handling by any actors at any stages of the emergency. Foldable and expandable structures are usually more complex that other lightweight constructions. They make use of moving elements (e.g. rotation of hinges, sliding of walls) and collapsible devices (concertina, scissor or telescopic systems) but each of them should be intuitive in use and deigned to resist unpredictable loading conditions because the integrity of the whole structure and its usability derives from the resistance of any elements. Recent shelter projects learnt from camping solutions and give their best in terms of portability and fast set up.

Fig. 122: Nido by Cuello A., 2010 Fig. 123: Sanctuary by Kim J. and co., 2007 Fig. 124: Lightweight emergency shelter by Warram P., 2007

13.2 Fairness

Lightweight and foldable solutions are usually lighter compared to traditional systems. Anyway, as we saw in paragraph 2.1 mass is not the only variable to define the “weight” of the solution. Mass is crucial from the thermal and sound insulation point of view; also from the structural one, mass is the easiest way to prevent architecture, for example, to be blown away by the wind forces. Sometimes mass is required and that’s why the application of lightweight system should compensate this lack in terms of stability, privacy and considering the comfort too. Sometimes, lightweight structures are not able, by themselves, to assure the requirements of inner comfort. Or, in some other cases, lightweight systems need complex and/or heavy foundations or coats that spoil the optimization of the material used. Big issues arise in cases in which smart solutions are applied only partially or in the wrong way. That’s the case of some of the experiments that tried to apply tensegrity in architecture. To match the architectural requirements, the efficiency of the pure concept is, most of the time, lost. As a result, product doesn’t offer the advantages of the system itself and the final product is maybe just more complex and expensive than a traditional solution. Looking in the cases when temporality is “by choice”, it is easier to find projects that can fully offer the efficiency of foldable architecture. That’s even more easy in the case of pure structural elements. A good example is


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Paddington Foldable bridge in which the structural and architectural image of the bridge come together (e.g. handrails are part of the system of hinges).

Fig. 125: Rolling Bridge by Thomas Heatherwick (2004) 13.3 All embracing

The decision about the application of lightweight systems in emergency should be based on an all embracing approach. Shelter by themselves can’t be the only focus: transportation methods and all the complementary devices (e.g. furniture or services) should be considered too as they are equally important in terms of “weight”. If, on one hand, containers or other fully integrated systems offers a ready to use solution, foldable and expandable systems (especially of the second and third categories out of the ones showed in paragraph 8) need additional devices to be fully operative. To compare different solutions is not the aim of this report but, a careful consideration of needs should be done. Even if roof and floor are considered the two most important facilities that have to be provided in case of emergency, they are not an home by themselves, especially in the case of long displacement.

Fig. 126. Priorities for humanitarian assistance (NRC Shelter Handbook, 2009)

13.4 Identity

Emergency shelters should be, first of all, a new home, although temporary, for refugees. Most of the time, in lightweight construction the structural side prevails on the architectural (welcoming) part. That’s an issue that affect many of the designs that are developed every day. It seems that technology prevails an that’s maybe one of the reason why expandable and foldable structure are not usually applied in emergency. Forms, layout and materials all collaborate to the identity of the new home that have to be accepted and identified as home by the users. In this respect, an advantage of lightweight architecture in generals derives from the concept of temporality: everything is transportable and adaptable means that it allow future developments and radical changes. Design that allow a certain degree of personalization and the possibility of improvements during time are usually well accepted by the local population.

13.5 Safety/reliability

Lightweight and foldable system are safe as other traditional technology. Moreover, due to its structural system, in case of collapsing, large deformations occurs before any crash can happen, thus inhabitants have time to leave the building. That’s the case of pneumatic structures: in case of loss of pressure, the process of deflations takes several minutes or, sometimes, hours. It the really rare cases of fast collapsing, materials and elements are usually so light that people don’t get injured if everything falls apart.

On the contrary, due to the flexibility of the connections and the material involved, foldable and lightweight structures in general behave efficiently in case of earthquakes or storms. In these cases the structures would shake, move and deform absorbing the external forces without losing their stability.

14. Innovation Osaka Expo of 1970 was the milestone for lightweight architecture. In that moment, renovation and innovation

were applied in the field of temporary construction: new construction systems, new shapes but also new technology were investigated. It was a turning point in which all the world finally realised that membrane structure could easily host human life and activities. The idea of sustainable architecture was also taken into account. In fact, almost all pavilions have been easily removed at the end of the period of the exhibition. However, after that moment, engineers and companies focused their attention on the improvement of material performances. Architect, on the other hand, didn’t focus on further investigation about lightweight structures’ forms and applications. As a result, the most


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innovative tensile pavilion after the Osaka ones come out after 30 years: it is the Festo Airtecture Hall, now more than ten years old. Tensairity® remains the only new principle but architects are not used to apply it in their designs.

In the author’s ideas, lightweight structures require a fundamental and deep renovation to finally spread out into everyday life. On one hand, time seems to be ready because material and technology development are improving faster and faster every year and also software for structural analysis and form-finding are now available and they are much more user-friendly compared to the ones of some years ago. On the other hand, forms, concepts and applications of lightweight structures seem to be the same since decades.

And this is even more true in the case of application in emergency. Solutions seems to be there but on field applications are rare. That’s because innovative technology can’t pass into use without general adoption by the building industry, NGOs, and all the actors that works in the humanitarian sector. The architectural profession needs to be aware of such developments and be able to recognize their value and the relevance to the life projects to which they are asked to find solutions. Genuine innovative research is risky, both in term of the success or failure of the project objectives but also in terms of money expended for an unquantifiable return, particularly if the results do not find a valuable market. But, in the case of emergency, errors means death.

It is interesting to see how many new projects about sheltering devices in case of emergency can be found on the net. Ideas an inspirations are around but the step between a concept and a fully working product in not an easy task. And it is even more complex in the case of application in the field of emergency.

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Roberto Maffei Ultra light weight foldable sheltering systems

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