SPS0010.1177/0266351116642071International Journal of Space StructuresGoldsmith 642071research-article2016

Original Article

International Journal of Space Structures 6–­1 The physical modeling legacy of © The Author(s) 2016 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0266351116642071 Nicholas Goldsmith1,2 sps.sagepub.com

Abstract Physical modeling as a developmental iterative process was one of the primary legacies of Frei Otto in his quest for a formfinding design tool. Exploring first hand knowledge of his sketching, and then incremental physical modeling techniques, we look at Otto’s global approach to problem solving through design. Numerous actual projects of Otto including the BP Dyce in Scotland and the KOCOMMAS project in are described in terms of this process as a better way of understanding his approach. A comparison of the formfinding and shape making approach to design is examined. In contrast to Otto’s physical modeling, digital modeling & parametric approaches are also investigated to show Otto`s influence and evolution in contemporary modeling of complex surface , but also to point out the seismic change that is presently occurring in the architectural profession.

Keywords Physical modeling, formfinding, shape making, biomimetics, soap films, finite element analysis,

I first worked for Frei Otto at his Institute of Lightweight Structures (IL) at the University of proofreading texts in English, but after a month or so, I think Frei could see that I really wanted to be involved with the design pro- cess, so he asked me in 1975 whether I wanted to work with him on a tent project celebrating the start of the British Petroleum (BP) oil pumping rigs in the British sec- tor of the North Sea near Aberdeen, Scotland. This project arrived at Otto’s studio in the autumn of 1975 via Ted Happold who at the time was the head of Structures 3 at Ove Arup Engineers and requested Frei to help in the Figure 1. BP Dyce Tent shown in Hyde Park for the Queen’s design of a membrane canopy for the opening ceremony. It 25th Jubilee. was a cover for 3300 m2 and had to be ready for fabrication in 6 weeks. Naturally, I jumped at the opportunity and moved to his Atelier Warmbronn studio in the Black Forest before we completed our work. The modeling techniques where I parked myself for the next 2.5 years, working on included stretch membranes initially, but developed into every project that came through the door. fixed woven membranes to better understand the hand pat- Prior to the rapid digital form-finding programs that are terning of the edges (Figure 1). This was my first experi- widely used today and with such a limited time to design ence with Frei’s design approach of selecting a physical this structure, Frei had us work on this BP project with the modeling technique to simulate a method design parameters of using a “hump tent” approach. With the spring-loaded “hump tent” approach, we could assume 1Senior Principal, FTL Design Engineering Studio, New York, USA a shape could be made from flat unpatterned cloth with 2Adjunct Professor of , Planning and Preservation, only allowing patterning to occur along the edges. The fab- Columbia University New York, USA ric was a minimally coated cotton material which allowed Corresponding author: for a high-angle deformation in the fibers to create curva- Nicholas Goldsmith, FTL Design Engineering Studio,44 East 32nd ture of the surfaces. Using this approach, it allowed work Street, New York, NY 10016, USA. to proceed in a fast-track manner, so fabrication could start Email: [email protected]  (International Journal of Space Structures 0(0 2

(and in this case, primarily an installation approach)—a method he used time and time again. Because it predated digital modeling, the physical mod- eling process was the ultimate design tool. We built soap film models, hanging chain models, tensile fabric models made of stretch fabrics, and some without stretch which we patterned. We made inflatable forms, cable nets, and deployable models all as an iterative design tool and not as a visualization of a finished design. Models started out as very crude elements and through a series of iterations became sophisticated analytical tools. Working in this pro- cess was an extraordinary lesson because each modeling technology was reflective of the structural intelligence of different technologies: the soap film for tensile membranes and the hanging chain form Figure 2. Utzon’s competition drawing for the Sydney Opera for compressive arch and shell structures. This was the House. essence of form-finding through physical modeling.1 The tent was completed by 3 November 1975 arriving days before the opening ceremony. In the 18th century, naturalists started a movement which arose from a desire to understand the “universal laws of form” in order to explain observed forms of living organisms. Although it did not have much traction at the time, during the early 20th century pioneers such as D’Arcy Wentworth Thompson expanded these notions to create a modern understanding that there are universal laws which arise from fundamental math and physics and that reflect the growth and form in biological systems. Thompson worked on the correlation between natural forms and mathematical models and showed similarities Figure 3. Otto’s soap film conoid. between such things as jellyfish forms and drops of liquid. His book, On Growth and Form, became an important developed natural forms. As Frei once told me about way-finder in the study of nature and was instrumental in using the form-finding process, “The architect is acting the later emergence of the field of biomimetics and had a more as a midwife than God the creator.” great influence on Frei.2 He saw that model-making A clear example of the different approaches between allowed the possibility to “both gain a direct appreciation shape-making and form-finding is seen below in two of the scientific equations describing nature, and to develop images: the first is a drawing from Jørn Utzon’s initial an understanding of materials, structure and form that design of the Sydney Opera House, where he generated the made it possible to create new structures.”3 curved shapes using a ruler in a bench vise (Figure 2); Traditionally, in the architectural design process, there is an and the second image shows a soap film model of a mini- underlying belief that the design process is a rational linear one mal surface where all the is equal across the entire which it is not and that the heroic architect is somehow acting surface (Figure 3). This minimal surface translates directly like God the creator which he actually is not, but it makes into a with no fabric wrinkling and equal for good copy and reinforces the writer Ayn Rand’s4 romanti- stresses throughout. The drawing of Utzon is an organic cized image of the architect in her novel, The Fountainhead. shape that looks efficient but actually is in and This traditional approach fosters more a shape-making design took massive amounts of engineering manipulations to approach based on personal visualizations rather than a form- realize these unique shapes into a built form. Ove Arup and finding one, where natural systems are based on processes and his firm which engineered these concrete shells treated it coordination arises out of interactions between components of as a problem-solving exercise in a traditional architect/ these seemingly disordered systems. engineer relationship, although through their creative In the form-finding process, the designer looks at pro- problem solving Arup was able to develop the use of epoxy cesses in nature to uncover ways in which to organize his resins to bond thin joints of pre-cast concrete units.5 or her building project. It is a study into the capability of The second image of the soap film model of Frei Otto discovering optimum form and dynamic adaptability. was used for understanding the shape of a conoid form for The beauty of the form does not have to be designed; a tensile structure which he used in his design of inverted rather it becomes an emergent property from the umbrellas. All points on this surface have equal tension Goldsmith 3

Figure 4. King’s Office initial model.

Figure 5. Council of Ministers developed model.

One day in Atelier when we were in the early design pro- cess of all three buildings, Frei sketched his thoughts and design approach to me as a way of understanding the nature of tree structures and how they could become the support of a lattice shell. The first sketch below shows one tree with tension and compression lines, its support, and its canopy. The second sketch shows two or three trees which to him were basically the same approach. The third sketch shows two trees with a small lattice shell spanning between them and the Gaudi process of using element nets to develop forms with gravity models. The fourth shows six trees with a highly developed gridshell which was the basis of the Figure 6. Majlis Al Shura. design for the COM structure (Figure 7). This idea of start- ing with the simplest element and then adding each time one because of the modeling technique used, hence no wrin- new step until it became complex and highly articulated was kling of the membrane and even stresses throughout. The an approach Frei was fond of and a great learning experi- lines on the surface were projected using a wire grid. ence. It applies first to a structural type rather than a particu- In tandem with this form-finding modeling design pro- lar architectural site-specific project in Riyadh. cess, Otto had an amazing skill of being able to see the This basic premise was used for the other two struc- design issues from a 10,000-m perspective and slowly tures as well. The KO was also a six-sided geometry using hone in on a particular design. He would layer the com- an elongated lattice shell form which became difficult as plexity into the design with each additional step, segueing some of the elements kept going into compression. We from geometry into detail and back out again. had to adjust the lengths of the different element links An example of this process was in the design of a new until the entire dome was in tension. The final dome was government complex for the Kingdom of Saudi Arabia in for the Majlis or Parliament which used a seven-sided Riyadh called King’s Office, Council of Ministers, and geometry, again with tree structures supporting a shallow Majlis Al Shura (KOCOMMAS) which began in 1975 and bowl for the seating with suspended balconies and a high continued until 1982 when King Khalid passed away. It lattice shell dome using glass and shading elements which was to be a government center including a King’s Office became the subject of much research. Should they be (KO; Figure 4), a Council of Ministers (COM) building pyramidal or domical, should the shading be linear or (Figure 5) and a new Parliament (Majlis Al Shura; Figure rotational? (Figure 8). 6). Otto with the Architect Rolf Gutbrod and partners and Tree-form projects have been used as a way of minimiz- the engineering firms of Arup and BuroHappold collabo- ing large spans with the churches of Antonio Gaudi such as rated in developing the project. Frei concentrated his the Sagrada Familia or the Colònia Güell chapel where energy on the design of the three main buildings which large dimensions are broken up into a series of discrete were domical elements. He conceived them as unique lat- spaces using tree elements. More recently, this can be seen tice gridshell structures supported by a substructure of tree at the Stuttgart Airport in , completed in the 1990s. supports which also supported the floors. We also have had gridshells from Otto’s groundbreaking  (International Journal of Space Structures 0(0 4

Figure 7. Sketches by Frei Otto showing the development of tree and lattice shell ideas.

Figure 8. Studies for different shading systems on the KOCOMMAS project at Atelier Warmbronn.

Multihalle Mannheim6 for the Bundesgartenschau in 1975, but here, based on the physical modeling process surround- ing him and the understanding derived from this, Otto was developing new forms and geometries and then forced to develop new technologies to solve them. In developing the gridshells for these designs, we used hexagonal, pentago- nal, and even octagonal geometries to map the different forms. Frei studied how the steel pipes which were the ele- ments of this geometry could have threaded connections which could elongate to allow for the imprecision of avail- able building technologies (Figure 9). After working for Otto, the actual modeling techniques we used later on were ones developed by Frei. Granted, he was absorbing techniques from the masters that went before such as Gaudi with his hanging chain structures Figure 9. Adjustable connection concept for the and photographic measurements, but he modified them KOCOMMAS project designed at Atelier Warmbronn. for his own use and special vision, and these techniques still stand today. An example of this is a sketch showing As we moved more into the digital world of design, how to develop bundled tube elements in a hanging chain many of these “analog” optimization techniques became model (Figure 10). replicated with form-finding programs which can both If you are developing a membrane structure, cutting up optimize shapes and analyze them too. Finite element pro- pantyhose and pre-stretching it on a wooden frame and grams such as EZ, Form-Finder, Tensyl-suite, NDM, and then applying it over your columns, valley, and ridge others digitally optimize boundaries and shapes in a form- cables, it is still an invaluable tool. finding process and perform analysis on the structures Goldsmith 5

shapes and forms based on calculations and a diversity which expands our imagination. The designer has become in a sense a computer programmer, defining parameters and writing algorithms. In a similar manner to the histori- cal approach, the designer begins with rough models based on small number of parameters and quickly refines it as the design becomes more resolved. The transfer of the development of geometry from humans to computers is still in its nascent phase, but has the ability to com- pletely change our design process. As David Ross Scheer points out in his book, The Death of Drawing,

Human geometry is based on concepts. Euclid built his geometry on a set of concepts which he called “Common Notions” or axioms. These are ideas that we intuitively feel to be true, such as the “whole is greater than the part.” Concepts like this are universal.

He goes on to say that

Computers, on the other hand, do not use concepts; they Figure 10. Bundled tube modeling techniques, sketch by Frei perform calculations on quantities. To use computers to Otto. perform geometric operations, humans had to translate concepts into programs that produce a shape that corresponds being described. This is today the commonplace approach, to a concept. Thus we say that computers plot a shape, i.e., but still requires designer input whether in sketch form, ini- they calculate a series of points that approximates it when tial physical modeling, or using rendering programs such as appropriately displayed. A shape in a computer is entirely Rhino. From the basic form, an optimization can be per- defined by the process by which it is generated.7 formed using a mixture of traditional and digital tools. This is in a sense a hybrid design process employing both com- Scheer posits that through the development of ideas putational tools with drawings and physical models. It is from our imagination, our drawing of them, and subse- quicker than the pure analog process used by Otto, but it quent building of them through construction, we mediate also allows for second-rate forms to be built because many between an ideal world and the built world through draw- designers conflate the designing part of the process with the ing. With the loss of drawing and development of compu- drafting portion (computer-aided design (CAD) modeling). tational design, our paradigms dramatically change. Unlike drawing, the first digital sketch of a CAD design has The problem with the form-finding process moving for- the same degree of exactitude as the final version which ward in this new environment is that the knowledge base lends an aura of finality to the drawing process and discour- about the craft of building can be easily lost since the new ages any experimentation. The necessary time used in the computer-based geometries are generated outside this spe- analog approach allows one to study the design in a manner cialized craft. When I visit architectural offices now to con- that is not available in this hybrid approach. Models that sult on lightweight structures, there is a plethora of forms used to take weeks have evolved into models that take days, but no material or detailing sense that corresponds to this as and as such, the reflection time has been constricted. Clients the computational process is devoid of materiality. demand tighter time schedules in the process because their Otto’s father was a sculptor, and in his development, the time is money which only accelerates this movement. In a materiality was a critical part of his design process. His sense from Otto’s perspective, the ease of present-day modeling techniques were each based on a material. We form-finding and analysis is actually problematic. He once used stretch fabric for tensile structures, hanging chains told me that computers were like cows: “you feed them for lattice shells, soap films for pneumatics, and folding good grass and you get good milk.” systems for deployables. How do we now integrate this Now, however, this paradigm is changing, and the abil- knowledge into the parametric process? ity of designers to treat computation as a medium in itself The legacy of Frei’s work serves as the necessary bridge is now challenging this hybrid model. We are now seeing to get from there to here. The knowledge accrued from with the introduction of parametric modeling and compu- hours of study and reflection on the physical form is hard tational design where the forms are generated from cho- to replicate with digital processes. Inherent in the physical sen parameters generally with little concern to the modeling process is a longer concentration on the form, materiality of building. However, we are seeing new scale, and proportion that cannot be duplicated with  (International Journal of Space Structures 0(0 6 boundary wireframe and surface modeling. Hours go by References and days go by and slowly the structure unfolds, whereas 1. IL 25. In: Siegfried Gass (ed) Experimente—experiments: with digital modeling, within minutes complex forms can Mitteilungen des Instituts für Leichte Flächentragwerke be derived. The different scale of time involved I think is (IL). Stuttgart, Institut fur leichte Flachentragwerke, Federal noticeable in the end result and one of the reasons with a Republic of Germany, 1990. historical perspective Frei’s designs today look so timeless 2. Thompson D. On growth and form. Cambridge: Cambridge and appropriate as they did when they were built. Charles University Press, 1917. Eames, one of the great industrial designers of the 20th 3. Walker D and Addis B. 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