Great Achievements notable structural engineers

The School of Building Design ® By Martin Trautz, Univ.-Prof. Dr.-Ing & Lorraine Lin, Ph.D., P.E.

In , the southern city of Stuttgart is Curt Siegel (1911-2004), a hot spot for engineering innovation. With professor of statics and struc- a population of less than 600,000 inhabit- tural design at the faculty of ants, Stuttgart is the home to internation- between 1950 Tanzbrunnen Fabric Roof in Cologne, Germany. Architect: . ally renowned companies, such as Daimler and 1970, widened the spec- Courtesy of ILEK. Benz, Bosch, and Porsche. However, not trum of that discipline by only premium cars and automotive products introducing a systematic classification of load- Fritz Leonhardt were initiators and founders come from Stuttgart. The region is famous bearingCopyright structures as an additional topic of of the first special research group, SFB 64, throughout Germany for the inventiveness his lectures and as a new field of building which conducted research on longspan struc- of its people. It also gave birth to one of sciences. Siegel called this new field, which tures at the faculties of architecture and civil the most interesting modern movements in joins together static analysis of structures and engineering and was funded by the DFG (the structural engineering and architecture, the structural forms, “Tragwerklehre.” This can German Research Foundation). This research “Stuttgarter Bauschule,” also known as the be translated as “teaching on structures” or group attracted many ambitious young en- Stuttgart School of Building Design. the translation of statics and materials science gineers and architects. It also developed the To a casual observer, a key feature of the into physical objects. In 1957, together with scientific groundwork for one of the most Stuttgart School appears to be aesthetic Fritz Leonhardt (see more below), who was challenging projects planned for the 1972 and structural expression. However, hidden then the chair of concrete structures at the Olympic Games in – the stadium features which have made this possible faculty of civil engineering, Siegel organized buildings designed as a “landscape of tents” include the high technical competence of design projects for students of architecture and built of cable-net structures by Günther engineers and architects, a high degree of and structural engineering. Leonhardt recog- Behnisch (b.1922) and Frei Otto. It was also integration of both disciplines starting at nized that Siegel’s approach to “teaching on one of Jörg Schlaich’s (see more below) early the university level, precision construction structures” was instructive not only to archi- outstanding projects. Schlaich later became methods, and a desire to construct lightweight tecture students but also structural engineering well-known in his own right as a representa- structures. The faculty at the local university students, so he was instrumental in ensuring tive of the Stuttgart School, first while work- has maintained close links with regional that it became part of the engineering curricu- ing at Leonhardt’s office and then with his engineering offices; in fact, many of themagazine key lum, as well. own practice. members of the Stuttgart School have been Around this time, Leonhardt and Siegel This, then, is how the School began and simultaneouslyS universityT professorsR and fosteredU the appointment C of Frei OttoT (see developedU as a collectiveR project. To understandE partners in thriving engineering practices, more below) as the chair of lightweight it better, we need to turn to the individual which has allowed them both the resources structures and the foundation of a con- work of these founding members. to innovate new ideas and the actual projects nected institute that conducted research on to put them into practice. An important related subjects, which later became famous Founding Members condition that facilitated the flourishing of as the “Institute for Lightweight Structures” structural innovation in Stuttgart has been (IL). Frei Otto is an architect with a deep The Bridge and Tower Builder the constellation of personalities associated understanding of all things related to struc- A pioneering figure of the Stuttgart School with Stuttgart University. tures, structural forms, and development was Fritz Leonhardt (1909–1999), a very gifted of structures in nature as well and intelligent engineer who made major con- as in engineering. He special- tributions to bridge design and difficult civil ized in design of tents and engineering projects. The son of an architect, cable-net structures, and had Leonhardt was born in Stuttgart and studied at already established a research the and Purdue Uni- laboratory for lightweight struc- versity. During his stay in the United States, he tures in . hitchhiked across the country to study Ameri- These individuals formed the can long-span bridges and high-rise buildings. “critical mass” needed to ex- After returning from the United States, tend the type of research Leonhardt accepted a job in 1935 working conducted on the basics of for the German Highway Building Authority. structures, lightweight struc- There he was given the opportunity to build tures, structural detailing, and the first German suspension bridge near natural structures for which Cologne (Autobahnbrücke Köln-Rodenkirchen), the Stuttgart School became which became the longest span in Europe at famous. In 1969, Frei Otto and that time. Museum of Daimler-Benz, Stuttgart Germany. Engineer: . Courtesy of Christian Richters, Münster, Germany. continued on next page

STRUCTURE magazine 61 April 2008 In 1953, he founded his own engineering in his hometown. The “Stuttgart Television practice together with Wolfhardt Andrä (1914- Tower” became a standard for many televi- 1996). The Leonhardt-Andrä Partnership sion towers in the world, and also an icon (LAP) later became the most renowned en- of Stuttgart. Leonhardt also developed the gineering firm in Germany. One of their first concept for cable-stayed bridge design that projects was the development of standardized was first put into practice in Düsseldorf over telecommunication towers for the German the Rhine River in 1957. Positive acceptance Postal Authority. In contrast to the steel of his design led to two more bridge projects, ® structures traditionally used for this structure which became two additional cable-stayed type, Leonhardt designed a tower in pre- structures in Leonhardt’s veritable collection stressed concrete, which he first constructed of bridges – later known as the “Düsseldorf Bridge Family.” The planning and building of the Munich Olympic Stadium roofs as cable- net structures is further evidence of Leonhardt’s versatility and engineering competence. During his career, Leonhardt developed new The Düsseldorf Bridge Family, Germany. Engineer: systems for long-span suspension and cable- Fritz Leonhardt. Courtesy of SAA. stayed bridgesCopyright with improved aerodynamic stability that were more economical than From Natural Structures traditional bridge designs. He also pioneered to Lightweight Structures new systems and construction methods for Frei Otto (b.1925) was born the son of prestressed concrete, including long-span a sculptor in Saxony. His early interest in prestressed concrete bridges. He is the author gliders and flight led him to develop an of Bridges: Aesthetics and Design (1982), a interest in lightweight design. Otto started classic book on bridge design. His greatest his studies in architecture in Berlin and won ambition was to build a long-span mono- a scholarship for a stay in the United States. cable bridge, a suspension bridge with just one There he met and was influenced by several suspension cable. Unfortunately, Leonhardt architects who had left Germany to escape was not able to fulfill this wish, which was Hitler’s regime, including , Stuttgart Television Tower, Germany. Engineer: left for others to pursue. , and Ludwig Mies van der Fritz Leonhardt. Courtesy of M. Ladner. Rohe. He went on to complete an innovative dissertation entitled The Hanging Roof (1954), which later became a standard work for Earn CEUs tents and tension structures. In 1952, Otto Take advantage of founded his architectural office in Berlin, magazine2 post-conference seminars: which evolved into a research center for the S T R U C1. Building designT studyU of lightweight structures.R In 1961,E he AND founded a research group for biology and 2. Slab-on-ground architecture at Berlin University, which design investigated and compared natural structures FREE to with architectural structures. conference attendees With the founding of the Institute for ($275 value) Lightweight Structures (IL) in Stuttgart, Otto finally gained the solid research plat- form needed to pursue his broad, multi- www.STRUCTUREmag.org Attend the 7th annual PTI technical . . . disciplinary vision of natural structures, bionics, lightweight structures, forming CONFERENCE AND EXHIBITION processes, structural forms and textures, and reconstruction of historical design May 4 - 6, 2008 methods. A series of forty-one delightful Held concurrently with the 2008 Concrete Bridge Conference. and innovative books numbered “IL 1” to Conference highlights: Conference topics: “IL 41” chronicle the work of Frei Otto ❍ Trade exhibits ❍ Committee ❍ Bridges ❍ Evaluation & and his Stuttgart-based institute. ❍ Seminars meetings ❍ Slab-on-ground repair In contrast to his outstanding reputation as ❍ Technical foundations ❍ Innovative ADVERTISEMENT – For Advertiser ADVERTISEMENT Information, visit ❍ 2008 design awards a researcher, Otto’s constructed work as an ❍ Product/software demos presentations ❍ Building design technologies architect/engineer is not as comprehensive. ❍ “Ask the Expert” panels ❍ Field issues However, the projects where Otto has been FORREGISTRATION & DETAILS involved are almost all extraordinary, and Voice: 6 0 2 . 8 7 0 . 7 5 4 0 w w w. p o s t - t e n s i o n i n g . o r g therefore very popular. Together with Peter Strohmeier, the owner of a tent construction C ONFERENCE L OCATION HYATT REGENCY AT UNION STATION company, Otto developed the first tents with ST. LOUIS, MISSOURI anticlastic form (i.e. double curvature similar ©2008—Post-Tensioning Institute to a saddle), which were built for garden

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Inside_Cover_Outside_Cover_Perfe1 1 3/4/2008 11:13:32 AM high chimney driven by the temperature differential between the ground and atmo- sphere. Schlaich-Bergermann Partnership’s second project was the Hoogly Bridge near Calcutta, which they took over from LAP and then completed. This cable-stayed bridge was specially designed for ease of construction by requiring riveting rather ® than welding, which made it ideal for a developing country like India. Additionally, Schlaich extended a series of extraordinary footbridges in and around Stuttgart, which Cable-net clad with timber at the Institute for were variations on suspension bridges, cable- Lightweight Structures and Conceptual Design stayed designs, and bridge designs corre- (ILEK), University of Stuttgart. Architect: Frei sponding to the flow of forces. Otto. Courtesy of ILEK. Power Plant Manzanares, Spain. Engineer: Jörg Professor Schlaich’s strength is invention and architects from the Stuttgart School have Schlaich. Courtesy of SBP, Stuttgart. and the realization of ideas, as his constructed stood on the shoulders of giants. Schlaich projects clearly demonstrate. In 1974, Schlaich considers himself a disciple of Leonhardt. exhibitions and outdoor festivals. The most Copyright was appointed the chair of concrete structures He has mentored many other engineers, who famous ones were constructed in in and the successor to Fritz Leonhardt at Stuttgart worked as researchers at his institute at Stuttgart 1955 and Cologne in 1957 (Tanzbrunnen). University. Schlaich has been able to make many University, then later became practitioners Appropriately, the Institute of Lightweight of Otto’s ideas real, such as gridshells enclosing and lecturers in structural engineering and Structures is housed in an experimental a swimming hall (Schwimmhalle Neckarsulm), related disciplines at various universities in building, an early cable-net structure similar to the History Museum (Museum für Germany. Many of Otto’s disciples became the German Pavilion for Expo ‘67 in Hamburgische Geschichte), and an ice rink scientists, professors, and teachers, such as or the roofs of the Munich stadium. In 1975, roof with an arch stabilized by a cable-net in Ewald Bubner (b. 1932) at the University of Otto was a consultant for an innovative Munich. More recent projects include adaptive Essen, Berthold Burkhardt (b.1941) at the timber grid structure with a pneumatic-like bridges, such as a foldable bridge near Kiel in University of Braunschweig, and Bernd Baier form designed as the roof of a multi-purpose Northern Germany and a suspension bridge (b.1943) at the University of Essen. Another hall for ’s Garden Exhibition. with a variable opening near Duisburg. Today, example is Mahmud Bodo Rasch (b.1943), The great aviary at the Munich Animal Schlaich collaborates with many famous who converted to Islam and now is the most Park (Großvolière München-Hellabrunn) architects, including , Rafael important planner of lightweight structures is characteristic of the architectural designs Vinoly, Thomas Herzog, and Volkwin Marg. and tents in the Arabic world, including for of Frei Otto. It is a large, light, cable-net One of his most famous projects, the Twin the Great Mosque at Mecca. structure covering more than 54,000 square- Towers Memorial, is in . Among the next generation of engineers feet (5,000 square-meters). Recent consultingmagazine who have studied and worked with Schlaich, activities include the Japanese Pavilion for the Werner Sobek (b.1953) is probably the WorldS inT , GermanyR – a UNext GenerationC T U R E best known. He studied civil engineering bamboo structure designed by the Japanese No school would be a school without and architecture in Stuttgart and benefited architect . disciples. Many of today’s influential engineers from the multi-disciplinary approach taught Shells and Structural Machines Jörg Schlaich (b.1934) was born the son of a Lutheran minister and studied engineering at the University of Stuttgart, Technical University of Berlin, and Case Western visit ADVERTISEMENT Information, – For Advertiser Reserve University in Cleveland, Ohio. Schlaich became a protégé of Leonhardt with his research work on concrete structures. In 1963, he joined the office of Leonhardt-Andrä Partnership (LAP) and eventually became a partner, where he worked as a designer on many innovative projects. He was responsible for the design of a widespan concrete shell covering a swimming hall in Hamburg, several www.STRUCTUREmag.org bridges, and also footbridges constructed of special structures. In 1980, Schlaich established his own en- gineering practice with Rudolf Bergermann (b.1941). They started with an extraordi- nary project in Spain – the planning of a thermodynamic powerplant powered by air traveling through a 660-foot (200 meter)

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Inside_Cover_Outside_Cover_Perfe1 1 2/26/2008 11:18:22 AM was merged with a large institute headed expanded its reputation, first nationally by Schlaich to form the new “Institute for within Germany, then throughout and Lightweight Structures and Conceptual beyond Europe to North America, Asia, Design” (ILEK). Together with the German- and the Middle East. This includes the American architect Helmut Jahn, Sobek United States – where many of its founding planned and designed the new airport in members, such as Leonhardt, Otto, and . Daimler-Benz’s new museum in Schlaich, studied as young men and found Stuttgart is likely his most exciting recent some of their early inspiration.▪ ® project, which he developed with the Dutch architect Ben van Berkel. The building has a complicated free-form architectural design that required even more complex engineering. Univ.-Prof. Dr.-Ing. Martin Trautz is Head Jan Knippers (b.1962) is another of of the Chair for Structures and Structural Schlaich’s disciples. He studied in Berlin Design at the Faculty of Architecture at Folding bridge near Kiel, Germany. Engineer: Jörg and was later backed by Schlaich at Stuttgart Aachen University (RWTH Aachen) in Schlaich. Courtesy of M. Winzenburg. University and worked in Schlaich’s office. Germany. He also heads his own engineering consulting practice in /Main and there – the direct result of the educational Knippers is a specialist in the design and Aachen. Professor Trautz earned his Ph.D. infrastructure put in place by Leonhardt and analysis ofCopyright gridshells. He is responsible for the from Stuttgart University and has worked the other professors. As both a structural design of the Kiel Folding Bridge, a movable with many of the individuals mentioned engineer and architect, Sobek has developed bridge in the German state of Schleswig- in this article. He may be reached at strong collaborative relationships with Holstein. In 2001, he took over the chair [email protected]. architects, which has made him one of the formerly occupied by Curt Siegel and few internationally recognized structural founded his own practice. His most famous Lorraine Lin, Ph.D., P.E. was a guest engineers. Sobek started as an engineer project is a beautiful curved glass enclosure researcher at the Institute of Lightweight in Schlaich’s office, where he designed for the company Peek & Cloppenburg in Structures (IL), University of Stuttgart a pneumatic roof for the Roman arena Cologne, which he designed with Pritzker in 1995, where she conducted research in Nimes, . He opened his own Prize-winning architect . on natural tension structures. She holds engineering practice in Stuttgart in 1992 graduate degrees from UC Berkeley in and was appointed in 1995 the successor Conclusion structural engineering and the Graduate to Frei Otto as the director of the Institute The Stuttgart School of Building Design School of Design at Harvard University. for Lightweight Structures (IL), which has increasingly extended its influence and S T Rmagazine ADVERTISEMENTU – For Advertiser Information,C visit www.STRUCTUREmag.org T U R E

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