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Master of lightweight structures

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German research engineer and architect Frei Otto wasawarded Pritzker Architecture Prize 2015 shortly beforehis death at the age of 89. He was a leading authority onlightweight tensile and membrane structures and foundinspiration in nature for his designs. Buildotech presentssome of his revolutionary works that brought newinnovations in structural mathematics and civil engineering.

Born in 1925, Frei Otto served asa fighter pilot in World War IIand later started experimentingwith tents for shelter, applying hisknowledge of aerodynamics tostructures. He studied architectureat the Technical University of Berlin,earned doctorate on tensionedconstructions in 1954 and in 1957founded the Development Center forLightweight Construction in Berlin,Germany. Otto believed in moderntechnology and envisioned structuresof extreme lightness and strength,which would make the optimum useof new materials like high strengthsteel cables & synthetic fabrics. Hisvision is as much alive today as it wasfifty years ago when he began torealize his first tent constructions.


Frei Otto practicedand advanced ideasof sustainability, evenbefore the word wascoined, exploring waysto use the least amountof materials and energyto enclose spaces Hewas inspired by naturalphenomena – from birds’skulls to soap bubblesand spiders’ webs.

Selected Works ofFrei Otto

The systematic research on lightweight and adaptable construction led him towards designing some outstanding lightweight tensioned structures.The idea behind his structures wererevolutionary for their time butcontinue to serve as an inexhaustiblesource of inspiration and reflection.

Space Frame: Expo 67

The West German Pavilion Roof at Expo 67 in Montreal, Canada was acompetition-winning tensile membrane design that took Otto and collaboratorRolf Gutbrod several years to develop. Thanks to careful design and a form-findingstructural engineering principle called dynamic relaxation, the structure took onlysix weeks to construct and upon completion, was the first tent ever used as anexhibition building at a world exhibition. The roof covering an area, the size of acity block comprises a steel mesh covered by a translucent plastic skin suspendedfrom eight slender steel masts of varied height, situated at irregularly intervals andsupported by steel cables anchored outside the structure. The structure cleverlyescaping from the tyranny of the box, produced a unique and beautiful interiorspace that lit through the transparent plastic and odd-shaped windows on the roof.

Umbrella: Cologne Garden Show

Of all of the themes Frei Otto has dealt with in his work, the umbrella bestillustrates the new approach to the art and science of building which he has pioneered.He developed a new umbrella form, based on the minimum surface principle.

The tension loaded membrane of the funnel-shapedumbrella was stretched under the compression-loadedbars, making it technically and structurally possible to buildvery large convertible umbrellas. In 1970, he designed suchlarge convertible umbrellas for the Federal Garden Showin Cologne. Eight such umbrellas, each with a diameter of19m and an area of 250sqm, overlapped to protect an areafor 800 spectators from the rain. The funnel-like shapedmembrane channeled the rain water to a central downpipe.When closed the membrane was protected by a spiderlikearray of flaps hinged to the top of the mast. These umbrellashad a complex telescopic system to enable the arms to beshortened along a predetermined path during the closingoperation. Activated by a pin-drive they were designed toopen and close in about three minutes. After 25 years theyare still operational. The great beauty of these lightweightstructures inspired many subsequent projects built all overthe world.

Cable Net Structure:Munich Olympic Arena

Otto designed the distinct tented roof aboveMunich’s Olympic Stadium, which hosted the ill-fated1972 Olympic Games, synonymous with the murder ofIsraeli athletes. Designed in collaboration with GuntherBehnisch, the roofing connected the park’s main programs– the natatorium, gymnasium and main stadium – with awhimsical, lightweight canopy structure that mimicked the“rhythmic protrusions” of the Swiss Alps. The cloud-like andinnovative structure was a striking departure from the harshand authoritarian appearance of previous roofing structuresand helped present a new, lighter face of Germany tothe world. Covered in acrylic glass panels, the suspendedmembrane delicately floats above the stadium and maintains views out towards the surrounding landscape. The designof the stadium was considered revolutionary with sweepingcanopies of acrylic glass stabilized by metal ropes, used onsuch a large scale for the first time.

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