SPS0010.1177/0266351116642071International Journal of Space StructuresGoldsmith 642071research-article2016 Original Article International Journal of Space Structures 1 –6 The physical modeling legacy of Frei Otto © 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 Tent in Scotland and the KOCOMMAS project in Saudi Arabia 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 geometries, 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, geometry I first worked for Frei Otto at his Institute of Lightweight Structures (IL) at the University of Stuttgart 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 construction 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 Architecture, 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] 2 International Journal of Space Structures 0(0) (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 minimal surface for tensile membranes and the hanging chain catenary 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 steel 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 tension 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 tensile structure 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 bending 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.