A Conversation With Frei Otto

A Conversation with

Frei Otto

Conversations:A Princeton Architectural Press series

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A Conversation with

Frei OttoJuan Mara Songel

Princeton Architectural Press | New York

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First published under the title Frei Otto: Conversacin con Juan Mara Songel by Editorial Gustavo Gili, Barcelona, Spain, in 2008.

Text Frei Otto, Juan Mara SongelSpanish edition 2008 Editorial Gustavo Gili, SL, BarcelonaEnglish edition 2010 Princeton Architectural Press, New YorkAll rights reserved Printed and bound in 201014 13 11 10 5 4 3 2 1 First edition

No part of this book may be used or reproduced in any manner without written permission from the publisher, except in the context of reviews. Every reasonable attempt has been made to identify owners of copyright. Errors or omissions will be corrected in subsequent editions.

Text sources:Original title of Frei Ottos text: Grundlagen einer Baukunst von Morgen, published in Der Architekt (October 1997): 58990.

Design: Marin BardalCover photograph: Thomas LttgeTranslation from the Spanish: Emily Tell

Editing, English edition: Nicola BednarekDesign, English edition: Paul Wagner

Special thanks to: Nettie Aljian, Bree Anne Apperley, Sara Bader, Janet Behning, Becca Casbon, Carina Cha, Tom Cho, Penny (Yuen Pik) Chu, Carolyn Deuschle, Russell Fernandez, Pete Fitzpatrick, Jan Haux, Linda Lee, Laurie Manfra, John Myers, Katharine Myers, Steve Royal, Dan Simon, Andrew Stepanian, Jennifer Thompson, Joseph Weston, and Deb Wood of Princeton Architectural Press Kevin C. Lippert, publisher

Library of Congress Cataloging-in-Publication DataOtto, Frei, 1925[Frei Otto. English]A conversation with Frei Otto / Juan Mara Songel. p. cm. (Conversations)Originally published: Frei Otto : conversacin con Juan Mara Songel. Barcelona, Spain : Editorial Gustavo Gili, 2008.ISBN 978-1-56898-884-9 (alk. paper)1. Otto, Frei, 1925Interviews. 2. ArchitectsGermanyInterviews. 3. ArchitectureGermanyHistory 20th century. I. Songel, Juan Mara. II. Otto, Frei, 1925 Grundlagen einer Baukunst von Morgen. III. Title.NA1088.O78A35 2010720.92dc22 2010007934

The Fundamentals of Future ArchitectureFrei Otto

A Conversation with Frei Otto

Frei Otto, Investigator of the Processes of Form GenerationJuan Mara Songel

Illustration Credits

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Contents

The Fundamentals ofFuture Architecture

Frei Otto | 1997

8ArchitectureThe art of building is old, as old as man the builder. Until today, it does not really require the architect. The architect has existed for about six thousand years, and the engineer builder for 150 years. For millennia, the art of building played, if not the main role, at least a fundamental role in all culturesin technology, in natural sciences, and in art. The division between art and science is relatively new. Throughout history, the architects tasks have grown and with them the specializations of all the building-related professions. The architect needed help from the detail-oriented scientist with mathematical gifts. Architecture is called the mother of the arts; the engineer is its child who now claims independence.

The Architect TodayEcological consciousnessto protect not only man, but also life as a wholeis a novelty in the area of architecture. In this regard, the knowledge of the objective evolution of forms in all areas of nature, technology, and art plays an important role; it is a field where the architect has his new great mission. If he does not know the processes of form generation, the architect lacks control over his own doing; he must understand the difference between what he does and what occurs in autonomous processes. In the area of physics he receives support from the engineer; in the humanities he lacks both the knowledge and necessary collaborators, not because of a lack of willingness to collaborate, but because those who work in the humanities are specialized, and as specialists they are not

9The Fundamentals of Future Architecture

in a position to respond to current demands and transcend the borders of the disciplines. The architect is also alone in the area of natural sciences, as the figure of the generalist scientist no longer exists. He has to act like a scientist even though he is not a scientist in the conventional sense. This is true especially for the areas of biology, ethology, and ecology.

The essence of the architects profession has remained unaltered since ancient times. The architect composes interior and exterior forms and directs their construction; he must have ideas and be an inventor; he must be able to understand and advise people; and he must act as a good diplomat and justice of the peace. In recent times changes have taken place, however. The majority of the most distinguished architects today are conductors who adapt the inventions and ideas of others in order to, on occasion, give form to something new. Nevertheless, the most important architects of our time continue to be the composers who invent new forms and structures, creating the intellectual basis to carry out new missions.

In a time like ours, oriented towards the economy, the old-style architect is considered increasingly superfluous. For the most part, he has been replaced by project managers who offer all services, including the functions of the architect and the engineer. Our engineering and architecture students frequently approach the offices of project managers for employment, thinking that they will find the origins of architecture there.

The typical autonomous architect, concerned about the primordial architecture of housing, tries to continue in the same manner as always. Today his social reputation is unjustifiably

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damaged; he is reduced to being an uncreative imitator of forms or a dreamer who designs unrealistically and cannot be entrusted with budgets and deadlines. This type of small architect desperately defends himself in light of this difficult situation, but he cannot cope with the increasingly unfair methods of job acquisition, especially when these are presented as fair under a democratic camouflage.

The New Structural EngineerIdeally, the structural engineer helps the architect with the many tasks that he must perform: he takes care of all material issues, supporting constructions and their structures, security, durability, and injury prevention, and even paved areas, glazing, application of paint, insulation, and installations. Increasingly, he calculates not only loads and forces, but also mass, areas and costs, and energy efficiency. All of this is very good.

The traditional stress analyst has turned into the multifunctional engineer. In the field of technology, the object and scope of his work must be in line with those of the architect, in all types of projects. Nevertheless, the engineers work is different from the architects, because it requires specific knowledge, models of thought, and work techniques. Todays engineer needs skills that are different from those of an architect. He must be an authentic scientist and try to understand the nature of reality through experiments and analysis.

The engineers tasks have increased considerably. A new way of thinking is required, especially in the field of ecology oriented

towards energy, that is, in the effort to save material and energy, to care for the environment, and to optimize construction.

Building Constructions are auxiliary means, not ends in themselves. For example, a bridge is a part of a human road system and its purpose is to transcend the obstacle that is imposing upon the communication between men. Constructions always have a form, and some of them even have an unmistakable shape. From the physical point of view, the best construction uses the minimum amount of energy and material. Sometimes this type of construction is especially beautiful. To build means to make architecture real on the borders of knowledge.

As strange as it may seem to the non-expert, architects and architecture students are much better at building than engineers and engineering students. The reason is evident. Architectural forms are constructions that have been optimized according to tradition. The ability to build assumes the knowledge of all architecture and construction forms, as well as their development. To build means to advance this process, to investigate, and to make. The development of buildings began over ten thousand years ago and has reached an extremely high level, but it is in no way a closed process. There are still an infinite number of open possibilities, infinite discoveries to make.

DesigningGood architects are rare, and those who can teach how to design buildings are even rarer. Teaching design as an artistic discipline

The Fundamentals of Future Architecture 11

depends both on the aptitude of the professor and that of his students. The capacity to design may be encouraged, but it cannot be taught or tested in the classic sense, through lessons or exams. Designing can only be advanced through examples. Only someone who builds masterworks can educate masters.

Surprisingly, many talented architects and engineers are self-taught, even if they were exposed during their youth to academic studies and to the dangers of receiving inadequate design education. The greatest danger of teaching design is to bury talent through the teaching of false prophets, through scientifically untenable theories, through the imposition of subjective thought models, through moral pressure towards specific formal concepts, or through the discouragement of attempts to materialize visions. Our best students search for their own path and persevere despite the inevitable conflicts with their professors.

The Works of EngineeringThe increasingly heard demand that architects must design and build houses, and engineers the so-called works of engineeringsuch as towers, bridges, canal locks, shells, and lightweight roofsdoes not lead to better houses, nor to better bridges or more beautiful pavilions.

By now the concept of a work of engineering has become commonplace. Although I view it with scepticism, I cannot change this fact. For me there are no works of architects, engineers, or amateurs, only works of architecture, which are the ones I love and which I dont want to miss.

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ResearchThe big new ecological and biological tasks require a global and integrated way of thinking and designing, especially when dealing with works of great dimensions and significant technological components. In the majority of cases even the best architects or artistically gifted engineers are not yet capable to cope with these challenges.

Today neither architects nor engineers carry out notable research. They dont get involved with either the humanities or natural sciences. They dont even try to approach problems dealing with medicine, biology, or ethology, and they dont arrive at developments worthy of mention even in the common area of construction. Up until now, the construction industry only supports research projects that can produce short-term benefits.

To elevate the quality of construction, basic interdisciplinary research must begin at once, with long-term objectives that are passed on through many generations. Productive research must be brave! Where are the experiments, developments, and inventions that we need most? And specifically, where are the incursions to new territories? What do we architects and engineers know about man, about nature, and about the phenomenon of art?

PhilosophyA young architect, who had already designed many good buildings, once answered me in response to a question regard-ing his ethics and his understanding of nature: The philosophy of architecture has to be passed down to us by established

The Fundamentals of Future Architecture 13

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architects. We have too much work. We have no other choice than to follow the ways and the forms of our stars.

Is the philosophy of architecture really an exclusive question of the established? Shouldnt every new generation search for its own understanding of nature, man, art, architecture, through profound observations and reflections, and thus create a basis for their own creative activity? While the understanding of nature and aesthetics are the key areas of philosophy, they have so far only been traditionally considered in historic terms. In order to have a current and future understanding of nature and art, philosophy still doesnt provide any information. The architect is alone. He must look for his own ethics by himself if he doesnt want to become guilty. He can build his own aesthetics, but this causes prejudices and makes designing difficult.

Running Head Title 15

Otto in his studio, Warmbronn, Stuttgart, Germany, 2004


2004

A conversation between Frei Otto and Juan Mara Songel, held on June 7, 2004, in Frei Ottos workshop-studio in Warmbronn (Stuttgart, Germany).

Out of the rich and wide variety of aspects and possibilities of analysis that your work and thought offers, I would like to focus on the methodological, experimental, and systematizing dimensions of your work. The classic historiography of modern architecture tends to place your work in the context of architecture with greater emphasis on technology, arriving at the start of high tech. However, I think that your historical contribution would fit better within the tradition of the pioneer engineers of new materials and their search for and reflection on the resistant form, as well as within the rationalizing approaches that characterized the origins of modern architecture in the 1920s. It is well known that you have had a close and productive relationship with engineers such as Fred Severud,1 Ove Arup,2 and Ted Happold.3 What did this relationship consist of and how did it influence your career?

From 1952 to 1953 I had a close relationship with the German engineer and bridge builder Fritz Leonhardt, who has been described as practically being the inventor of television towers and with whom I did a lot of work.4 It was only later that I began to work with Ove Arup and Ted Happold.

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How did you meet these engineers and how did your relationship with them start? Well, the process was really rather simple: a project came up, some problems had to be resolved, and some contacts were established. In the case of Ove Arup, our collaboration started with our first project in Saudi Arabia (1965).5 I simultaneously started to work with Ted Happold, who was then one of the directors of the department known as Structures 3 at Ove Arups studio, and this collaboration has lasted through time. Even today I collaborate with these three firms, although my closest friends, Arup, Happold, and Leonhardt, have passed away.

Which work or what occasion gave rise to the start of your collaboration with Fritz Leonhardt?

It is a very strange story. I had studied in Berlin, and when I wrote my doctoral thesis I had already published a few things.6 Having read one of my articles published in the magazine Bauwelt, the architect Erich Schelling, winner of the bid for the Schwarzwaldhalle auditorium in Karlsruhe, wrote asking me for help as a specialist. My professor of structures and director of my doctoral thesis, Hellmuth Bickenbach, advised me to contact Fritz Leonhardt. Ultimately, we didnt carry out the work, because another engineer, Ulrich Finsterwalder, intervened, but, in reality, this building arose out of my work; that is, it all started with the Raleigh Arena, although the Karlsruhe auditorium was built

A Conversation with Frei Otto 19

beforehand: the imitation came before the original product, a rather strange situation.7

Thats when I met Fritz Leonhardt. At the time, after having just recently finished my doctoral thesis, I collaborated with Stromeyer, a tent construction company, on the entrance arch for the Federal Garden Exposition of Cologne (1957). Since then we have collaborated on different projects.

Afterwards the projects for Saudi Arabia arrived. The English engineers were better prepared, because Saudi Arabia had a historic relationship with England. Since Leonhardt didnt consider himself an ideal candidate to work in that country, we carried out these works in collaboration with the English. The relationships with Ove Arup and Ted Happold arose out of that collaboration.

What relationship did you have with the most important engineers of the twentieth century?

Eduardo Torroja: I had an epistolary relationship with him. He had studied my work a lot and invited me to a seminar that was held in Paris, which he couldnt attend because he passed away beforehand, so I never met him personally. Of course I know his famous book Philosophy of Structures in its German version (Logik der Form).8

With respect to the International Association for Shell and Spatial Structures (IASS) that Torroja founded, I had a relationship with the association but never belonged to it because I was mainly concerned with membranes and this association

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was concerned with the study of shells; only later did it also focus on membranes. It was said back then that membranes were also shells; I didnt agree, as they are two very different things: shells are shells, and membranes are membranes.

Eugne Freyssinet: I didnt know him personally, either. There was an epistolary exchange, especially between Leonhardt and Freyssinet, and of course I have studied his work.

Bernard Laffaille: I had a very intense epistolary exchange with him, and I alluded to his first works in my doctoral thesis. Laffaille had already built his first metal sheets and his hanging roofs before he had that terrible reverse with the great shell structure of the Radio Europe No. 1 broadcasting station in Luxembourg, which ruined him. I think that he never mentally or emotionally recovered from this mishap. One of his children now writes me, because there are still people from his life that keep our relationship alive, but it wasnt as intense as one would think.

Robert le Ricolais: I met him in Philadelphia, with Louis I. Kahn, when I was teaching in the United States.9 I knew his work and I think that we have mutually benefited from each other to a certain extent, but thats it.

Flix Candela: I met him in 1958, when I traveled to Mexico and he showed me his work. Fourteen days before his death he called and wanted to meet me in Paris for the exhibition LArt de lIngnieur.10 Neither one of us saw the exhibit. He had fractured


the neck of his femur and was in a bad state of health when he called me. But I used to see him frequently, as he came to visit me at the institute and at the studio many times.11 He had some difficulties, because he didnt get any jobs and couldnt go back to his profession. I tried to help him, but it wasnt possible for me, as I didnt have any work either. Once I met him in MadridCandela was born in Spain and had to go into exile due to the Spanish civil warand on a long trip he showed me the places linked to his childhood, to the city where he had been raised.

Pier Luigi Nervi: I didnt know him personally, although I knew his work. Many times I was, lets say, his competitor, especially in the bid for the Kuwait Sports City, in which Pier Luigi Nervi, Flix

Otto (on the far left) with Flix Candela (on the far right)

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Candela, and the team made up of Kenzo Tange and me were invited to participate. We were working from Tokyo and ended up winning the bid. That was the only time I competed with Nervi so directly. I hold him in very high regard, but when you are invited to bid on a project like this and you are young, you try to outdo even an authority like him. Without a doubt, Nervis buildings are masterworks.

Richard Buckminster Fuller: I knew his work and we saw each other for the first time in 1958, in St. Louis, when I was teaching at Washington University (later we met again at Southern Illinois University Carbondale). We had a long conversation, which at times became a heated but friendly discussion on wide-span

Otto (left) with Richard Buckminster Fuller


constructions, especially wide-span grid shells. Later he traveled frequently to Germany and came to visit me at the institute and we spoke about biology, especially ordinary biology and about the professor Johann-Gerhard Helmcke of the Technical University of Berlin. When he saw Helmckes works, especially the radiolarian and diatomic stereomicroscopic images, he stood up and wanted to grab them! It was very funny. He was amazed when he saw how animate nature was faster at inventing than he was.

Eladio Dieste: Unfortunately, I didnt meet him personally, although once a joint talk was planned at the Accademia di Architettura in Mendrisio, Switzerland, coinciding with a joint publication on our work.12 However, the occasion didnt arise. His work is magnificent, and I would have loved to meet him. Although his work was introduced very late in Europe, a former student of mine, Rainer Barthel, currently a professor at the Technical University in Munich, knew his work very well and disseminated it in Germany.

You have had a close relationship with Heinz Isler, isnt that right?

I have had a long relationship with Isler. He collected many of my developments and trials with models, but applied them specifically to building with reinforced concrete shell structures. He has also been very active in the Structural Morphology Group of the IASS.

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Have you had any type of relationship with this group? What do you think of its activities?

Fritz Leonhardt, Jrg Schlaich, and Heinz Isler had very active roles in this group. I would also have liked to participate if they had invited me, although, on the other hand, I am happy it didnt happen as these types of activities require a lot of work. Nevertheless, I have participated in debates with these colleagues, and I cannot judge to what extent they have been able to benefit the IASS work. In any event, the IASS has been an important organization and perhaps it was due to lethargy or idleness that I havent been more active. I already had enough work from setting up my own institute.

Perhaps we could now address the link between your work and the rationalizing approaches of German architecture from the 1920s. Your father was a member of the Deutsche Werkbund, and names such as Walter Gropius and Erich Mendelsohn were discussed in his studio.

Yes, he had a very active role in the Deutsche Werkbund and personally knew Erich Mendelsohn, although Im not sure if he ever met Walter Gropius.

Did you meet Walter Gropius?

I met Walter Gropius, Mies van der Rohe, Frank Lloyd Wright, Erich Mendelsohn, and Fred Severud (this last person thanks


to Eero Saarinen) during a long study trip to the United States between 1950 and 1951. I continued developing relationships with some of them until their deaths, especially Walter Gropius and Mies van der Rohevery important and beautiful relationships for me.

What were the importance and influence of these relationships based on?

On the clarity of the ideas of the modern movement. For more than a decade I was president of the Weissenhofsiedlung Society of Stuttgart and I also participated in the internal discussions of the Deutsche Werkbund and of the Congrs International dArchitecture Moderne (CIAM) after returning from the prisoner of war camp.

During these discussions, for example, Wassili and Hans Luckhardt, two pioneers of modern architecture, informed me in detail about the fights and arguments arising in Germany about two opposing trendsone of them linked to the imaginary and to the current green movement. The roots of Wassili and Hans Luckhardt, Hans Poelzig, and Erich Mendelsohn went beyond the limits of the classical modern movement; this has interested me a lot: why and how at the end of the 1920s one of the two trends continued to exist while this fantasy architecture, which I have called proto-green, suffered a set-back. It was something very calculated and was mainly due to the strong influence of Le Corbusier.

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Later I had the opportunity to work in Berlin with the son of Hans Poelzig, Peter Poelzig. I know about the architectonic debate during the 1920s, both from my parents and from the conversations I had after World War II with the survivors of this generation.

There are perhaps two ideas in your work that we could relate to German architecture from the 1920s. One of them would be the experimental methodology of the Bauhausof Josef Alberss preliminary course, with his experiments on paper, folds, curvaturesand the exploration of the relationship between form and material.

I met Albers when he taught a seminar at Yale University during my stay in the United States in 1960, but I was more interested in Walter Gropius. Gropius came to visit me in Berlin when Gropiusstadt was being built (at the time I was still living in Berlin although I was already teaching in Stuttgart, so it must have been between 1965 and 1966).13 During that visit he told me that I was the only one who continued working in the line he had established, mainly because I did not start from any formal approaches but searched for the future architectural form through experiments. I could almost say that Gropius was a passionate enthusiast of my work (which was reciprocal) and he was very well informed of what I did, something that I ignored, perhaps seeing in this the only future path. All that really impressed me.


So he considered you to be an authentic successor of the Bauhaus methodology?

Yes, we could say a continuator of its fundamental principles. Gropius didnt want architecture based on form, but architecture based on natural sciences. Mies van der Rohe was another world, and, although we understood each other very well, he tended more towards creation, elaboration, or construction of form; he designed architectonic forms. Gropius didnt search for form but for the essential, the substantial. That is the difference between these two greatly successful characters with very different paths.

I went to Mies van der Rohes studio in Chicago when they were working on the Neue Nationalgalerie in Berlin. He was already very sick at the time, and his collaborators asked me for my opinion, because it seemed that Mies had requested it. So I made some observations about the museum project, because I felt that some changes needed to be made. In order to support the big roof slab, only four pillars had been put in the middle point of the sides of the roof, so the overhanging corners tended to suffer severe deformation. I proposed they put at least two pillars on each side, that is, to support the roof on a total of eight pillars, and that is how it was done. I met Mies van der Rohe for the last time in Berlin a few weeks before his death, when the roof was being assembled, and he was very happy with the decision of the pillars. The two of us have followed our own careers in complete harmony.

Mies van der Rohe didnt get to see the Neue Nationalgalerie finished, and on the day of the inauguration I saw Walter Gropius

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for the last time, because he was at the ceremony. These are small insignificant anecdotes, but interesting for the history of architecture.

Did you meet Gropius during the long study trip to the United States that you took between 1950 and 1951?

Well, not directly. We had written each other, as he had helped me out with some letters of introduction to Richard Neutra and Erich Mendelsohn when I was studying at the University of Virginia; thanks to him I was able to meet all of these people. I met him personally later, in Germany, although he had already seen my work long beforehand. I was also in his studio in the United States when I took that trip, but he wasnt there at the time.

Do you think that having known the experimental methodology of the Bauhaus influenced you?

The truth is that I knew little, as I hadnt studied what the Bauhaus had done, nor Johannes Itten and Maximilian Debus; I learned all this much later. I must say that it didnt really influence me; I have followed my own path. Even the influence of Antoni Gaud came much later, when I had already done investigations with models in the prisoner of war camp that could be considered Gaudan, without even having known Gaud. One can follow this path simply based on logic, especially when it comes to inverting structures that function by traction so they function by compression. I learned this from an engineer


friend in the prisoner camp who was in my work group. The possibility of developing vaults through catenary inversion is something very simple that has been known from the time of Robert Hooke and Isaac Newton. It was later when I studied Gauds work.

So I endeavored to learn how force diagrams are represented, that is, graphic statics. When you focus on these things, you realize that the same forms are independently present in graphic statics whether they are structures that work by compression, tension, or bending. The difference lies in the preceding sign. So the fact that identical vaults of hung forms can be generated through graphic statics is something that I already knew from my time in the prisoner camp, specifically towards the end of 1945.

On occasion you have shared your experience in your fathers workshop, when he soaked a cloth in plaster and hung it, so that once dried it could be inverted.

Yes, it was simply part of a sculptors work. It was there when I tried to build these inverted forms for the first time, and even today I continue to play with this: a marvelous toy.

Your efforts to systematize also connect to the rationalizing approaches of German architecture from the 1920s: Walter Gropius produced a large number of spatial combinations starting from modular elements of large dimensions; Alexander Klein explored types of housing starting from the possible variations of plans;

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and Hermann Muthesius saw an expression of the essential and even the immaterial in types. In your case, your system sketches seem to take a step forward in these rationalizing approaches.

Yes, I have tried to systematize for the purpose of placing a bit of order in this almost infinite range of possibilities. It happened when I began to teach in the Hochschule fr Gestaltung in Ulm, my first teaching experience. The first time I was asked to teach a class was to replace Matthew Nowicki at the School of Architecture at North Carolina State University in Raleigh, but I couldnt accept, as I was very busy here. Later I was invited to the universities of St. Louis, Yale, Berkeley, and the Massachusetts Institute of Technology (MIT), as well as Harvard. I believed that it was necessary to introduce a certain systematization; without it, how could one address teaching from such a vast field? The teaching commitment demanded a certain order, but, at the same time, I also had to address or take into account both the issues of extension and concentration; I had to concentrate on some places to be able to put forward real advances towards the future, something that interests me more than making history. I have always considered the attention to history the responsibility of my specialist colleagues, and in the institute there has always been at least one collaborator, assistant, or professor who has seriously dealt with this issue, specifically Rainer Graefe, Eda Schaur, and Berthold Burkhardt. I have also paid attention to it, but it is not a field of work that I have felt as my own, because I believe that it is not possible to create the future with history


alone. Of course, its important to learn history, but my job is to work for the future.

Naturally, the role of your system sketches is very important not only for classifying and organizing, but also for inventing new possibilities.

Yes, because one discovers things that have not been studied extensively yet, and then the gaps can be filled; I call this the systematic method of invention, but its only a method. The process through which one thing is combined with another can be done very systematically, and I have developed an entire series of inventions that have their origin in this combinatorial analysis. But the truly important things did not arise from that method, but largely from fortuitous or casual observations made during experiments, some of which were planned in a completely systematic style. I have always combined systematic experimentation with the fortuitous or casual, where chance plays a role; if something is accidentally discovered, it would be stupid to reject it simply because it doesnt fit within the systematization. I am convinced that one cant invent anything by working only systematically.

Therefore its necessary to develop a capacity to perceive and appreciate that which arises casually.

Yes, and to constantly observe. In the first place, to observe the forms of inanimate nature and to see what happens, because

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Experimental structures developed in the seminar on lightweight

structures led by Otto in 1958 at Washington University,

St. Louis, Missouri

Two-dimensional objects. Classification of forms according to Otto

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forms of animate nature, which I have also studied, are much more complex, almost impenetrable and opaque.

Now I would like to address the start of your experimental methodology, the origins of your permanent principles: the principles of lightweight construction, of anti-funicular inversion, of form generation starting from autonomous processes. Your experience as a glider pilot, the construction of models, and your apprenticeship as a stonemason appear as important initial experiences.

All of these things happened a long time ago, and I dont believe they are important, because each person follows a specific individual path in life. Who would be interested in reliving it? Its possible for others to find it interesting, but I dont think it is.

Perhaps the unstoppable drive for inventing and combining is important.

Ever since I was a child it has been a pastime and an obsession; I always had to be inventing something, and I built the strangest inventions, which didnt have anything to do with architecture.

One-, two-, and three-dimensional hollow bodies. Drawings by Otto.


When I was seven or eight years old, I invented inline skates, which are so common today. It is something very logical, which is in the air, but its silly to carry it out too soon, before the right moment arrives. An invention always has to arise at the right time and place and with the right people; if all these conditions arent present, the invention fails.

In your experience as a pilot you also mention the fuselage design for a one-person plane as a grid shell.

Yes, I arrived at grid shells through building fuselages of gliders and not by constructing buildings. So I began to focus on grid shells, and when I started to concentrate on the inversion of forms, all of this seemed completely logical and automatic to me.

During your stay in the prisoner camp in Chartres, France, important early experiences also took place, such as the construction of some small vaults and your study to optimize the arrangement of railroad tracks in order to build a lattice bridge.

Back then I already knew about the possibilities of graphic statics, so it wasnt enough for me to just design a lattice construction and calculate it afterwards. I thought that a form could also be generated starting from statics, and beginning from there I developed what I called a natural lattice. It was much later when I found out that a German architect and engineer, Georg Laves, had used the same method around

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1820 or 1830; a bridge of his still stands in Hanover, which is almost identical to the one I designed. Therefore, my study didnt deal with anything special but was rather a logical process for reaching a form starting from statics, because my head cant wrap around the idea of drawing something and doing the calculations afterwards. This always works; everything can be calculatedtoday according to the theory of elasticity, and back then through graphic statics, but in principle there is no difference.

Despite having two different methods, the problem deals with optimization.

Yes, it deals with form generation starting from a series of physical and calculation processes, beginning with those that generate forms already optimized from the start or that can be optimized through small steps following a repetitive process. I have been focusing more on those processes that contain an optimization from the beginning, like soap bubbles, minimum surfaces, and fluid forms, which, being very sensitive, can only exist in very few forms. Based on those, we found a universe of infinite possibilities. The membranes of soap bubbles have infinite forms.

Nevertheless, the computer is currently an important tool for form optimization and generation. To what extent are all those physical experiments and tests with models necessary?


The computer can only calculate what is already conceptually inside of it; you can only find what you look for in computers. Nevertheless, you can find what you havent searched for with free experimentation. If, for example, you do experiments with liquids, the infinite possibilities are restricted to only those forms that can be built with the surface stresses of the liquids, that is, those that tend to form minimum surfaces. If this process is done with the computer and this criterion is eliminated, then you obtain surfaces with different stresses, surfaces with bending moments, shear stress, etc; you can do an infinite amount of things. As an architect, or as an artist, I can demonstrate that any sculpture can be built. I calculate the sculpture with the computer and I adapt its dimensions, thicknesses, or reinforcing steel bars in concrete according to the resulting static calculation; that is, I dont find forms, but I create forms. The computer only acts as if it has found the forms. If we keep in mind that an infinite amount of forms could be created this way, the person sitting in front of the computer has really created them and not just found them.

Its a serious problem that the majority of those who work only with computers today are incapable of seeing, because to think of infinite possibilities is tremendously difficult. One can think of everything, one can calculate everything using the computer. It can be said that the computer has created this form, but I think thats a lie because the artist or the mathematician who is behind the computer has created it by using calculation methods to obtain something that he likes, that speaks to his artistic sensibility. I reject the lie that says that the computer

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Graphic representation of the minimum surface formed by soap film

and supported by a loop, obtained through computer calculation.

Elevation and plan.

has found everything, because new inventions cant arise from it; you only get what you have already placed inside it.

In fact, everything is created in our brain, a computer that is much more efficient and can do better combinations, although inexactly and imprecisely and frequently slowly, but its capable of doing it. Those who only trust calculations done on the computer are the foolish ones in our profession.

I must add that since 1965 all of my buildings have been calculated with the computer. This is only natural and does not need to be questioned, because its common practice today.

The relevancy of trials with models in the search for form also relates to teaching objectives, as a didactic tool.

It actually deals with something very different, because the transmission of knowledge to the student is very difficult, but I still want to tell you something else. We are treading in dangerous waters here; right now I am confronted with a problem in a study Im doing regarding the stability of high buildings, specifically shells and vaults, which can suddenly collapse. Are current computer programs good enough to prevent the sudden collapses without prior warning? My answer is no. This is something that makes me nervous, because not too long ago in Parisand previously in Moscow and even before that three times in Germanysome shells that had been correctly calculated with computers, had used all of the necessary paraphernalia, and had been checked, suddenly collapsed. The politicians always ask for those responsible, but they cant

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blame the engineers in these cases, because they used correctly designed programs according to the theory of elasticity.

We ask ourselves why the great master builders of medieval vaultsand Antoni Gaud as wellwere able to build stable structures without having all of the current methods of calculating at their disposal, and why today these mistakes are made even though we have this enormous computational arsenal. The mistakes are made among professionals, students, or imitators who make things without having really understood them, and it seems as though the models of stability have not been sufficiently studied in depth.

The question is how we should proceed given the fact that we have always had two methods available to us. Therefore Fritz Leonhardt and Ove Arup created their own laboratories and I created my institute in Stuttgart. Leonhardt founded a second institute of model statics in 1964, and I created and directed a department for the construction of models in London for Ove Arup. During those same years, specifically in 1965, calculations by computers began to be applied. Arup had realized that it wasnt enough to trust the calculations because there could be phenomena that could not be explained.

The most interesting phenomenon is the buckling of superficial structures. At what moment does a piece of paper buckle? [Frei Otto places a piece of paper vertically on the table.] Pay attention to this phenomenon. The paper doesnt deteriorate; its kept intact. This type of buckling, described by Euler, happens in an environment where we cant talk about stress, as there is no stress, only a bit of dead load


and nothing more. If you take a look at Eulers formula, youll see that he started from the basis that the deformation can start with a circular figure, and therefore the famous appears. How is buckling generated? To tell you the truth, from trials.

One of the most important methods was the method, a coefficient by which the stresses increase when the form is slender. All engineers have been using the coefficient for decades; linear equations can be calculated with it, creating a multiplier generated from very simple trials. Two of my professors of structuresone of whom was responsible for drafting the German building regulations in the 1930sexplained to me in detail that coefficients had been found that could be applied to multiply stresses in order to be able to use this elastic stress model.

But why do the buildings fall if they havent received more load than planned in either case? They collapse despite being intact. In the case of tensions this isnt important, as the building is balanced until it returns to being stable; in the area of compressions, when the building buckles, it suddenly collapses. This sudden collapse is very dangerous and, although I lack detailed information and only know what has been said in the press and on television, the last two big accidents in France and Moscow concerned glazed grid shells, with an undoubtedly inadequate form. They werent shells without bending stresses; if they exceed a certain deformation, they become unstable. My question is: where are the computer calculations that can prevent this phenomenon?

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When we built the pavilion for the Federal Garden Exposition in Mannheim (1975), in collaboration with the office of Arup and Happold, we also did a static analysis with models, which provided a greater approximation of reality. Although they are simple, these structures can be adjusted and, above all, they allow the danger that can arise to be detected. This is something that many people do today.

Shells are often built too thinly; it is thought that in shell structures one can obtain stability through the section and not through stiffening on the surface. These are the problems we are currently working on, and in my opinion, computational analysis is not enough. Perhaps it will be in the future when adequate methods are found, but so far I have not seen any that are good enough.

What this means is that there is an open field for new generations, but it would be absurd for them to think that they can be pure theoretical physicists. Everything that we build is applied physics and statics is a part of physics. In fact, the dynamic in buildings today must be currently thought out with more precision as every building becomes deformed with the application of loads. What happens when buildings become deformed and the instability that this deformation can produce are rarely analyzed. In my opinion, this still requires a generation of engineers who are more precise in calculating, on the one hand, and on the other, verification in the physical reality.

The problem is that, once built, buildings are not checked, because there is no possible verification. In a concrete building the way in which the calculated stresses are distributed cant be


verified, but in my membrane buildings they can. The stresses can be measured in a membrane and in a cable, but not in brick or concrete buildings. Variations in stress can be measured by placing meters but not the stress itself. The problem consists in establishing where the zero point is.

It is a delicate and important issue. To tell you the truth, all stress analyses done so far have been imprecise. To say that stress in buildings can be calculated is not true, because these calculations are only approximate methods. Precisely calculating the stress does not make much sense because precision beyond 10 percent cant be obtained. It actually isnt really necessary anyway, because we dont even know the loads. Who knows what the loads of wind or snow are? The current generation of

Above and opposite: Interior of the pavilion for the Federal Garden

Exposition in Mannheim, Germany, 1975

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youth does not concern itself with loads; it takes them from a purely theoretical formula. I have not been successful either in motivating my collaborators to really reflect and worry about the loads of snow or wind on buildings or about the difficulty involving trials with models in this respect.

Therefore, its not known what happens to buildings from a physical point of view. So the question would consist of learning more about this unknown reality, and for this we have two methods available. On the one hand calculus; on the other hand, verification in the buildings themselves or experimental verification through models, as some results can already be obtained in models, but not from the building itself. A suspension bridge cant be built and the stress in the cables measured


afterwards, without having done prior calculations, because if I detect an error, its very expensive to fix it. In many constructions, a subsequent supplemental reinforcement isnt feasible, especially if the construction has collapsed as happened recently in Paris.

Some engineers question the transfer to reality of the results obtained from trials with models. What is verified as valid on a small scale doesnt necessarily hold true on a large scale.

Hanging model of the pavilion for the Federal Garden Exposition in

Mannheim, Germany, 1975

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There are very simple physical rules and formulas. It is no doubt necessary to know the laws of the models themselves if they are used to measure stresses or forces. We build models to know the form and, once obtained, we also build models to know what happens inside. Without a doubt, the most interesting models are those that generate forms optimized by the models type of construction; herein lies the specificity of my work. The first point is to build models that produce physical forms, to demonstrate later, through another type of model, that these forms can be built.

Geometric model


German Pavilion for the Universal Exposition in Montreal, Canada,

1967 (with Rolf Gutbrod)

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If we take the example of the roofs for the Olympic Stadium of Munich, an important leap of scale was taken with respect to the previous experience of the German Pavilion for the Universal Exposition in Montreal (1967).

The Munich stadium is bigger, but the spans were more or less the same, so the two buildings are very similar and are built with very similar methods: with steel cables and minimum surfaces, if as such we understand the smallest surfaces within a frame or the biaxial surface stresses. In both cases they were very similar.

Olympic Stadium of Munich, Germany, 196772 (with Gnter Behnisch)


The calculations for the Montreal building were done on a computer using a very simple method. In the case of Munich, the sports pavilion was more complicated. While we calculated the pool in the same way as the Montreal project, we arrived at the stadium design through a combination of calculations using a computer and construction of models.

What more can you do to control a project than rely on these two pillars? You can build models to generate the form and later verify the stresses in the models and in reality. In the case of Munich we measured the real stresses in each cable; it is probably the first building where we really know what happens inside. We also know the dangers that can arise from overloads and what happens in the structure when we overload it.

I would like to return to the important question, which engineers ask, about the leap from small to large scale, especially in relation to models that generate forms.

Its very simple. If, for example, you have a model of the same form and material, and you apply loads in the same way, its deformations are linear with respect to the real building. This is the fundamental condition. The point is to only verify if the model fulfills this condition. The models necessary to obtain this condition are frequently very expensive. If concrete is concerned, it is very difficult, because concrete cant be reduced in size so easily, and all of the models components must be reduced in size. Reducing a grain of aggregate at a 1:100 scale is very difficult, but it is possible. The question would be with what level

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of precision the model can be built. Nevertheless, doesnt even a simple paper model like those that Eduardo Torroja made show the dangers that can arise precisely through instability? Naturally, yes. So in this case its not necessary to build such an expensive model.

This is a question that can only be answered in each particular case. The fundamental principles of experimentation with models are known; therefore, the question of whether it can be verified or not is not in doubt. Of course it can! And it should be. Are the calculations safe enough to allow us to limit ourselves to only calculating? On the one hand, we have experimental physics, on the other hand, theoretical physics. No theoretical physicist, despite the fact that he can reach new knowledge through reflection and mathematics, dares to publish or reveal the results of his work if he hasnt verified them through trials. Albert Einstein arrived at his famous formula of the theory of relativity starting from the results of experiments; later he performed calculations and afterwards the verification process took place. It is not very professional, in fact it is simply frivolous, to make new knowledge public without verification. In my opinion some current computer programs used to calculate structures dont have a physical verification process, therefore buildings can collapse and kill people today, transforming engineers into killers (though it wont reach this extreme, because no bad intentions could be attributed to them, aside from stupidity). Many engineers today are foolish for using computer programs superficially, and for not being cautious enough.


The question is verifying the underlying theory in the program.

Naturally, this is the job of the stress analyst supervising the structural design process who must always use different methods; some are simple methods, but others are not so simple. In reality, at least one small trial with models must be done, because on occasion very primitive trials with models may force one to see something unfeasible. But often trials arent carried out at all, because people believe that the amazing computer program guarantees enough safety. This is wrongful thinking.

Its interesting to observe that the pioneers of engineering of the twentieth century, such as Robert Maillart, Eduardo Torroja, Eugne Freyssinet, and others, also made these physical verifications, although each one in his own style.

Yes, and they have each had a work collapse; now I remem- ber a case of Freyssinet and Laffaille. Once one of my professors drew the vital career of a good engineer for us in class; at the beginning the line went up and later there was an inflection, which coincided with some collapse. Its an unspoken issue, because otherwise the engineer would be judged and impris-oned. On the other hand, without these trials there is no knowledge, so risks have to be taken; the question is if the homicide is from imprudence or from stupidity.

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All of this belongs to the same tradition of the great builders, engineers, and architectspioneer masters whose sense of the physical was always well developed.

Since the separation between engineers and architects took place, its always been the architects who have been more concerned with the qualitative vision and the meticulous study of buildings and structures, while the engineers have focused on calculations; both focuses are necessary. I place myself both on the side of the engineers and on the side of the architects; for me there is no separation. All possible separation is erroneous, because experimental physics is as necessary as theoretical physics; its not about separating but about integrating.

The problem of inventing structures is something very different, as even today it is considered a mental job. One cant invent new structures by sitting in front of a computer, because the computer shows only the infinite possibilities of what has already been invented. In reality, its not necessary to invent anything new, because the computer can already do it all. Nevertheless, there is an infinite amount of possible inventions that we must carry out, although it seems that we dont need to invent any more and that all the construction projects of the world can be solved through the existing repertoire.

We have already talked about the validity of models in the search for form, and now Id like to return to the systematization of forms and structures. Every generation of architects has posed this problem, which


seems to be a permanent objective: to obtain a globalizing systematization of the infinite variety of forms and structures, in spite of being aware of the impossibility of reaching a definitive systematization. Why set the objective of obtaining a classification of an infinite variety of forms?

I have by no means set this objective for myself. The infinite cant be completely placed in order. But for teaching purposes, to orient students, one can start with simple things before introducing them to the complex world of the infinite; this is the reason for the order of structures, but it doesnt constitute any vital objective.

In your criteria of classifying forms and structures you follow a globalizing approach that includes not only artificial objects but also those from natureyour search for common principles. Other systematizations of formssuch as those of Paul Klee or Iakov Chernikhovseem more abstract, more geometric, perhaps more influenced by the artistic vanguards of the first third of the twentieth century, while your criteria reflect your search for a close relationship between form and strength.

I think youre referring to the possible influence of the formal inventions of classical modern architecture or of painting on my work. Naturally I know, among others, Piet Mondrian; I dont know whether he has influenced my work or not: both yes and no.

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Yes, if you are referring to inventing additive structures, but no, if youre referring to experiments with physical processes.

The previous question was directed more towards the origins of your criteria for systematization. For example, I wonder if the categories positive form, negative form, cavities, and hollow bodies proceed perhaps from experiments with pneumatic structures; or if the criteria peaks and depressions, borders, or corners have their origin perhaps in your experience with networks or tents.

No, they were merely logical considerations, and I dont believe any type of theory has been able to influence me there.

Lets talk about the Mannheim pavilion, which in its time achieved the greatest span in a grid shell. How do you value this work in its scale, transcending the limits of grid shell spans, as proof of the potential that this type of structure has to bridge large spans? Once you mentioned how this very flexible grid structure was transformed into a very consistent grid shell. I was really amazed at being able to build this work, a structure that, on the other hand, supported a load test that we carried out well. The building is still standing and soon it will turn thirty years old, if Im not mistaken. Its the work Ive been the most afraid of; the most audacious work that really went


beyond my knowledge back then and perhaps even my current knowledge.

Im very grateful to Ove Arup and Ted Happold and their studios for their collaboration. The structure was correctly calculated, but we knew and had a feeling of the difficulties it could have. I must be thankful that it has never had to support excessive loads, which could have destroyed it. Originally, the pavilion was supposed to remain only during the Federal Garden Exposition. It was allowed to continue standing there but surely one day it will be taken down. Nevertheless, the older it gets, the more anxious I become. I dont know what I should do: Should I warn the owner that it would be better to tear it down so that I can sleep better?

In the project for the governmental center (KOCOMMAS) in Riyadh (Saudi Arabia), you proposed a grid shell with a hexagonal mesh on branched supports. Could these supports be considered a step forward in the development of a type of grid shell support that is more in line with the principle of antifunicular inversion? Why a hexagonal mesh and not a quadrilateral one, as in classic grid shells?

Very simply said, because I wanted to try out this type of mesh.

For some physical reason?

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Because it makes sense to find out what happens with a hexagonal mesh. The majority of the grid shells occurring in animate nature are hexagonal, although the quadrilateral ones are easier to build. With this project, which was never built, I learned to avoid hexagonal meshes: they are very dangerous and expensive because the knots require extraordinary care. They lack safe points, because no element crosses them continuously, other than in the Mannheim pavilion. In hexagonal meshes, bars bump into each other, loosing the continuity after the knot; in triangular meshes, the bars can cross the knots continuously,

Model of the project for a governmental center (KOCOMMAS) in

Riyadh, Saudi Arabia


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Model of the project for

a governmental center

(KOCOMMAS) in Riyadh,

Saudi Arabia

but the meshes have different sizes, and a grid shell made of a triangular mesh cant be developed on a plane. Consequently, quadrilateral meshes have the advantage of bars that cross the knots continuously and permit simple construction. Hexagonal meshes are more difficult; in a work that Im developing now, some engineers want to use triangular or hexagonal meshes (triangular meshes are in reality camouflaged hexagonal meshes) and are surprised that I dont support them.

In Riyadh I wanted to use this type of mesh in order to study how they functioned, and I had the best engineering office in the world at my disposal. When one experiments, one should count on the best collaborators. I havent even built my magnificent branched supports yet; there are some in the Stuttgart airport, but they arent mine. Nevertheless, they are very good imitations of our project in Saudi Arabia, and it could be said that they are proof that what I proposed is feasible; at least they are still standing.

You have referred to some current issues regarding your work with engineers. How do you see the role of the architect and the engineer today?

As far as I can see, what I find odd today is that not being a physicist or a natural scientist, I really have to consult on natural sciences, on questions that have no longer anything to do with current architecture, but that in fact have always had something to do with historical architecture, from the middle ages up to modern times. At the moment architects voluntarily dont want to

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have anything to do with natural sciences, but I think they make a serious mistake because construction is applied natural science.

The architect doesnt realize this fact and leaves this part to the engineers; in my case, I have to ask the engineers to go back to being authentic natural scientists, and they in turn frequently leave this part to the computer programs. However, being an authentic scientist requires the development and verification of everything according to criteria inherent to natural sciences,

Stuttgart airport, passenger terminal, Gerkan, Marg und Partner, with

Klaus Staratzke and Jrgen Hillmer, 1991


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which means at least double verification and therefore the verification of that which has been calculated.

So contemporary building engineering has gone back to being provincial and has really drifted away from centers of thought; its very far from the scientific area of human thought, while during another period it was at the top, when architects were the vanguard physicists who built the highest buildings and made the greatest experiments. Today both architects and structural engineers have ceased being top-notch scientists. This is my complaint, and Im not alone; both the old Ove Arup and Fritz Leonhardt thought similarly, as well as Stefan Polnyi.14 Its a disgrace that the engineering profession has been converted into something so frivolous, which limits itself to the application of a few formulas; its not enough.

I also wanted to ask you about your current works and projects, such as the project for the Stuttgart 21 Central Station.

In this station we have exactly the same problems that I just referred to. We have been working on this project for more than six years and still dont know if it will be carried out. Im already counting on the fact that I will never see the station finished for biological reasons, as Im seventy-nine years old; the station has an execution period of twelve years, and I dont think it will take less than twenty, because there are always delays. Even so, Im not giving up hope of being able to see it built.

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How do you see the role of the institute that you founded as a center of education in the field of lightweight construction? Could it be said that the institute has created a school of thought, which has educated an entire generation of engineers and architects?

Influence would be a more adequate word, but only among a small circle. The institute has generated knowledge, which was published and which makes up a body of general knowledge, although its not applied. The institute today doesnt exist as it did before, as it now works in other areas under the direction of my successor, Werner Sobek, who is undoubtedly a leader in his field. The work that I carried out at the institute doesnt have any continuity, although there are people from other institutes throughout the world who still do similar work. I founded the Institut fr Leichte Flchentragwerke (IL: Institute for Lightweight Structures) and I must say that, unfortunately, I also brought it to an end. My successor hasnt continued in the same direction, because the university didnt want to continue working in this way. They thought that I had strayed too far, and they wanted to go back to doing real things with their feet on the ground. The question about my institute is a question pertaining to history, not the present, given the fact that the areas in which I used to work arent studied anymore. Today they dont work anymore on the development of lightweight surface structures at the institute, although the term lightweight construction continues to appear in the official name of the center. Now they focus primarily on fillings and lattice webs or panels and energy


problems, glazing, etc.issues that are also important, but dont have anything to do with lightweight surface structures.

You were the director of the institute until 1991.

Until March 31, 1991, to be exact. On April 1, I retired.

But books from the collection Mitteilungen (Communications) are still being published. The institute continues selling the old ones, and two more have appeared since I left. The most recent one, Diatomeen 2, is a beautiful book about diatoms, which are also grid shells.15

My most important publication was included in the series Form, Kraft, Masse (Form, force, mass) and appeared after I retired.16 As emeritus professor of the institute I am still

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Exterior of the IL, Stuttgart

Interior of the IL, Stuttgart

responsible for the publications. Now the institute has other priorities, because the university and the faculty wanted it that way, why not?

The book that you are referring to addresses principles of lightweight construction, right?

Yes, its really a summary of my knowledge in the field of lightweight construction. The book includes many of the questions I have asked myself, questions about model equations, for example, as well as the deduction of my simple formula on the minimum consumption for the construction of houses.

The BIC.

Yes, the BIC deals with finding out about and evaluating the mass consumption of different elements such as fibers, which are the elements with the greatest load capacity, for the purpose of investigating the lightest possible construction of a housea question already raised by my old friend Richard Buckminster Fuller, who claimed that in order to know the efficiency of a house it only had to be weighed. I said to him that it was necessary to know at least its spans and volume. I found the answer to the questions of volume and mass in the simple formula that I have included in the book.

In the publications of the institute some of your collaborators appear time and again, for example

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Rainer Graefe, Berthold Burkhardt, Ewald Bubner, Gernot Minke, and Rob Krier.

Graefe lives in Innsbruck. Berthold Burkhardt is professor and vice-rector of the Technical University of Braunschweig. Ewald Bubner was a professor in Essen and retired a little while ago. Gernot Minke has not had much contact with the institute. He addressed an issue that we had already addressed in the institute and made it his own: the structures of earth, sand, clay, etc. He used to be a professor in the Gesamthochschule Kassel and has also already retired. Rob Krier worked in my Warmbronn studio and also did the project for my house and studio, his first constructed building. Now he lives in Berlin and for a long time was a professor in Vienna.

In the case of Rob Krier, dont you find the subsequent transformation of his formal universe strange?

Many architects have been marked by their education. Their professors told them, You are an architect, so sit down and design something; then build it. While I tell them, Lets not draw anything, lets just look for the unknown. Some, like Krier, want to finally see their vision of an architect carried through, to design something. Krier is a very emotional man. His conferences are a show, an explosion of energy. I told him that a city couldnt be designed, that a city can only be left to develop by itself; he felt very differently and claimed that a city should always be in a position to be designed. A few years ago I congratulated him on


Kirchsteigfeld, the town he built near Potsdam Drewitz, outside of Berlin. He had everything he needed in this project, and finally he has seen his great wish of building a city come true, so for him there is nothing bigger than building a city. Its a question of desires, and therefore he strayed from the path that I proposed to him. Im not so interested in designing houses as if I were a sculptor but rather in finding out how they should be and how they can generate themselves. This is the difference between us, although I personally admire Krier very much.

Does the book you are currently preparing already have a title?

It will be titled Das Netz der lebenden Wesen (Networks in live beings) and perhaps it will appear in 2005, although it could also be titled Das Netz der lebenden Natur (Networks in animate nature).17 One of the chapters relates to Richard Buckminster Fullers work, but the rest focuses on the work of the German biologists Johann-Gerhard Helmcke and Ulrich Kull, of Stuttgart, and of Adolf Seilacher of Tbingen, and on the SFB 230 investigation program, focused on natural structures, which lasted more than fifteen years. Officially, the program was deemed completed in 1995, but it actually finished when I retired in 1991.

In fact, the book has two parts, one referring to systems of roads and infrastructures and the other referring to networks that exist in animate nature. The book investigates the origin of forms and how networks in animate nature developedthat is, the beginnings of life, its evolution, its aspect, etc. Its the most

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difficult text Ive ever written; it has little to do with classifications and systematizations but rather presents the fundamental idea that all forms of animate nature owe their existence to water-filled fiber systems.

Could you tell me more about your upcoming publications?

Im working on another book about the issue of occupation and connection.18 It deals with topographic and connection systems, that is, systems of highways and railroad lines, but also systems of force or of energy: force pathway networks and normal road networks. To some extent, its a collection of issues concerning unplanned settlements based on Eda Schaurs doctoral thesis.19 It explores how road networks are developed from an energetic point of view, road networks of man and animals, but also other systems. Volumes 49 and 50 of the institutes Konzepte (concepts) collection are a preview of the manuscript and have served as preliminary material for the book.

And what about the book titled Verzweigungen (branching structures)?20

Actually, one of my collaborators, Jrgen Hennicke, who still works in the institute, should have written this book, but unfortunately he hasnt finished this work yet. And I havent had the necessary energy to finish it, either, as I have been more focused on biological subjects.


What can you tell me about your work on the principle of pneumatic structures?

It deals with the concept of pneumatic structures, which has been introduced to the institute thanks to the biologists. I have actually substituted the concept of pneu for hydro, as pneu and pneuma mean air in Greek, and I am actually talking about elements filled with water in animate nature. What aspect and strength do they have? How do their forms originate? The most interesting result is that, without exception, all forms of naturefrom a microbe to a whale, to an elephant, or a redwood treehave a unique constructive principle, just one, with a range of around forty billion variants. It also deals with a new interpretation of the genetic principle, which not only researches atoms but also the underlying concept of large molecular grids. I continue to believe that the direct imitation of objects of ani-mate nature for the construction of buildings is an erroneous path. What we should do is study the objects of animate nature and measure them with equivalent scales, because the principles of form generation are very similar in some areas. For example, in the field of pneumatic structures supported by air, that is, the authentic pneus, the principles are similar to those of animate nature, although not identical. Its not very scientific to take nature as a model; nature cant be imitated because its very complex. In principle it seems very simple but it is actually very complicated and should not be interpreted mistakenly. People say that I focus on biology only to create new architecture, but thats not true. I am just very curious to know what nature is.

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Could you go into more detail about your trials and constructions with models, and about their forms and materials?

In regard to these issues there are no limits for me. Depending on the type of problem posed one has to invent the methods of experiment. In experiments one can use string, water, egg yolk, or anything else; the important thing is to be able to extract knowledge based on the results. The best trials with models dont cost much.

Could you give a concrete example of a model?

In recent years we have built four models, which relate to the Stuttgart station. Here, in this workshop-studio in Warmbronn, we have about three hundred models made with very different construction methods; for each concrete problem we find a new specific method.

I will only talk about a small part of what we have done, as a lot has already been published. The most important thing of all is to do the appropriate experiment. I used to do very complicated experiments, as I didnt dare, nor did I have the knowledge, to extract results based on simple experiments. In order to verify the stability of a shell from a simple paper model, a lot of knowledge is needed, and the more knowledge you have, the simpler the verification will be. The models have been useful for me both as a way to create new things and to verify them.


Hanging model, stiffened and inverted, of the Stuttgart 21 Central

Station in Stuttgart, Germany

In the case of the models for the Stuttgart station, I realized that my colleagues didnt understand what a curve of constant curvature was, therefore I had to make some models, among them some made in parts, to show this characteristic. I had to make my colleagues understand that introducing a concentrated load on a surface structure can be resolved without large peaks in stress arising, if the load is transmitted through a cable in the form of a loop. I found this form in my experiments, I didnt invent it; its a curve of constant curvature. It starts from a flat surface with a perfect circle; its something that is related to the circle, a circle that revolves around a longitudinal axis. Its a figure that has absolute geometric precision. A model of this type doesnt have anything to do with the statics of models; its purely geometric and didactic.

There is another case of a hexagonal mesh model, which we didnt make to be built in this exact form, but to show that when parts converging on the knots form equal angles that are less than 120, the surface has uniform stresses, because only then can a knot be formed. Naturally, I can build this form with absolute precision using soap film. The form of soap film lasts only a few seconds, before it disappears, so I cant show it to anyone. In this hexagonal mesh model the form is not so exact but it is longer lasting; if I try to make something rigid or long lasting, then I cease to be exact.

There are many other types of models, like those for verifying stability, which are the most difficult to build. This model is built so the supports can be removed piece by piece; if its truly a vault, then it will remain standing, as though it were built with stones.


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Model submitted in the bid for the Stuttgart 21 Central Station in

Stuttgart, Germany

Isaac Newton and Robert Hooke already proposed the theory that the forces of a hanging form are the same as those of an upright form, a theory that I have checked myself through trials with models. When I was still a student, I built a model of an inverted catenary in which I could vary the line of the arch, although only to a certain limit. If this limit is exceeded, that is, if the line of pressures exceeds this limit, then the arch imme-diately collapses, which means that I need a specific thickness in the arch. Another type of model is used to see how a body is elastically deformed.

We started the Stuttgart project with the idea of a hang-ing roof that would be extended over the excavated hole in the ground. The pointed support with a loop appeared again, and after many intermediate steps I built this other model, which became rigid while it hung and was later inverted (see page 72). A very important step had to be taken to obtain this. The rest of the models that we made for the Stuttgart station performed specific functions, like this one (see pages 7475), which we made to show the interior space, and to help the architect and the promoter win the bid.

The biggest model shows the whole station in its exact location seen from below. There is a rule: if something flexible can be built in the model, then it can be photographed or mea-sured directly. Therefore, photogrammetry or direct measuring apparatuses can be used to calculate it afterwards, following a repetitive process without the need to generate the form using the computer, because it can basically be done by hand. We developed the pattern of the roof of the German Pavilion in

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Montreal by hand and later we did the calculations using a computer, a novelty back then. The swimming pool pavilion and the Olympic Stadium of Munich were also done by hand.

Lets return to the explanation of the curves of constant cur-vature. People know what a circle is, but there are also, among other curves of constant curvature, the spiral and helicoidal lines. We have tried to learn about these types of curves extensively.

Did you make the model only with a metallic strip with the ends connected?

Yes, it is that simple. Of course, it has to be controlled and reviewed. You can also make an unequal curve, but only the exact curve of constant curvature provides infinite possibilities. You can make a bigger or smaller circle by varying the radius just as you can make the curves bigger or smaller. If you modify the connection, then infinite possibilities arise. The discussion on the concept of the infinite is extremely important. The majority of architects dont understand that there are infinite possibilities for architecture in the future. There are no limits.

One of the most fascinating documents that I have got here is a computer calculation of the formula of the minimum surface made by my collaborators Bodo Rasch, Jrgen Bradatsch, and Bernhard Gawenat. The calculations were also made with the formulas of an old collaborator of mine, Eberhard Haug, the first assistant in my studio who now works in France designing bodies for automobiles. In these documents they represented the minimum surfacethat is, the same surface that we can


produce with soap filmwith the computer program, with different variants.

Did you arrive at these formulas through your experiments with soap bubbles?

Yes, it was in 1961. It was very simple: we hang soap film, we let a string fall, we break the film remaining inside the string, and then a perfect circle is generated; afterwards, we take the string, we try to pull it outside, and then this minimum surface is generated. Now it can be calculated, but for more than forty years it was impossible to calculate it. I have not waited for it to be calculated in order to build it. The formula is really very complicated, and we dont even have it completely finished now, because the program develops it according to a repetitive process. Its fantastic to see the precision used to arrive at this.

There is an important question here: whether one should build a structure only if it can be calculated. For example, the thin concrete shells used by Robert Maillart for his bridges were forms that were impossible to exactly calculate in his time.

Yes, and it has its advantages and disadvantages. Fortunately, there have been engineers such as Fritz Leonhardt who have shared this way of thinking, and we have built things that were incalculable.

Eduardo Torroja also.

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Yes, he too. I have said to some engineers that although not everything can be calculated, we can do very precise experiments with models, and knowing the formulas of the laws inherent in the models, I can and have the right to verify bridges, shells, and lattices with carefully built models. Fritz Leonhardt built very complicated bridges with forms that had never been built before. The only possibility he had in the 1950s was to build models, taking a sheet of aluminum or glass and measuring the deformations the loads produced. Later one can rely on the critical stresses in concrete again, do trials, and build the bridge. If the deformation under the dead weight is also verified and if it is possible to check the cracking, then there is some safety and it can be built. Today students think that they cant build if they dont have an adequate computer program. They dont realize that often its safer to build with the old methods. This has been a problem for the last three decades; I am from the old school.

In my opinion, forgetting about experiences and determining factors can be very dangerous. People dont think about why some buildings have been standing for centuries and continue to be stable, while nowadays a well-calculated structure suddenly collapses. The majority of the collapses today concern grid shellsthe type of structures I have worked onbecause people dont act carefully enough.

Here is a model that was built inverted.

Was it planned to be built of stone?

No, the model was meant only to show the form. But it could be built with stone. All the elements of the Stuttgart station could be


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built as if it were a stone vault. We built the model inverted, with small wood blocks hung by string, and then this form appears; once one knows the form, its easy to calculate.

The issue of the hexagonal mesh again.

Its a hexagonal mesh because we wanted to build it like a closed shell. In the field of simple compressions, if there is no bending, the hexagon can be used. I can easily collect all of the forces in a hexagonal mesh in concrete, but not so much in steel and wood because steel bars are thin and long, and wood, although it works better than steel, contains fibers. Nevertheless, concrete is a surface structure, and to obtain a form that has the most uniform stresses possible, one can use a ribbed shell or a continuous shell. The verification can be done more easily with the hexagon, because I can verify the uniformity of stresses and easily transform a catenary network into a concrete shell. This is one method to find the form of a concrete shell through the construction of models.

The Stuttgart station could be built both as a concrete shell and as a ribbed stone shell. This type of vault was built during the gothic period, although without the hole, which wasnt known then. I studied the presence of holes in shells and the fact that they dont collapse, after the war.

Do you make any models with traditional materials?

Yes, everything here deals with the field of stability. You can make models with a set of blocks. My father was a sculptor


Hanging and inverted hexagonal mesh model of the Stuttgart 21

Central Station in Stuttgart, Germany

and stonemason (like my grandfather) and was very interested in medieval stonework, in finding out how vaults were built so they wouldnt collapse, as neither Hooke nor Newton had yet existed then, nor current mathematics or computer programs; nevertheless, people knew how to build. In my opinion, we have all this knowledge today, but we dont take advantage of it, so I try to convey it.

I analyzed the Pantheon in Rome, because I wanted to find out what horizontal action (earthquake) would make the Pantheon collapse, and with the help of some very simple models we obtained an approximate result: a third of the force of gravity. Therefore, we can deduce that during the last eighteen hundred years Rome has not experienced any earthquake with a greater intensity than that. In the trial with models we can destroy the object. We have verified the behavior of the Stuttgart station in light of an earthquake and we know exactly at what point it becomes unstable. Any construction becomes unstable if an earthquake takes place; the question is to find out what magnitude it must reach.

The safest construction is the pneumatic structure, as earthquakes dont destroy it. What everyone considers the most unstable constructive form is in fact the most stable; the less mass a form has, the more stable it will be.

The most stable construction is the one that doesnt exist or has already collapsed. I always said to my students that a collapsed building is the most stable; the standing building has a degree of instability. The question is to know what magnitude exterior actions must have to make it collapse. In principle,

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every building is unstable; all architecture tries to do is to temporarily make stable what

A Conversation With Frei Otto

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