Form Finding Flashback: Basento Viaduct

It is unclear where the unusual shape of the Basento Viaduct (Potenza, Italy) was derived.  Some even say the thin shell concrete pedestrian bridge is shaped like the headdresses of nuns in Federico Fellini’s Italian films [1].  Regardless, the Basento Viaduct is an example of a structure designed using early form finding techniques.

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Similarity in shape between the Basento Viaduct (left) and nun’s headdress (right)      [Photo Credit [1], [2]]
Today, we rely heavily on the use of computational methods for the form finding of thin shell structures. Yet, we see existing shell structures around the world that were designed and realized before engineers had numerical technology.  Who were these extraordinary engineers and how did they generate these unique forms?

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Ash wood – catastrophe or opportunity for creativity?

Since 2002, the emerald ash bore beetle, Agrilus planipennis, has destroyed more than 20 million ash trees in the US, with only 30% of the waste timber recycled into low-end products such as mulch and firewood. High value uses could turn this “waste” material into a valuable resource and an economic opportunity, especially considering that, before the widespread development of plastics, aluminum, and carbon fiber, … Continue reading Ash wood – catastrophe or opportunity for creativity?

Sagrada Familia: the structure sometimes misunderstood

Incomplete but already a UNESCO World Heritage Site, Gaudí’s Sagrada Família towers over the city of Barcelona. Over a century in the making, the cathedral is expected to finish in the next 10-20 years.

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The cathedral’s nave has a unique and breathtaking roof geometry accompanied by rows of treelike columns.
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A spectacular amount of light filters into the nave from above.

In the form finding world, we’re often familiar with Frei Otto and Heinz Isler’s hanging methods, in which inverting a hanging model in pure tension informed the designer of the structure’s final form, which takes pure compression. While Gaudí is also known for making hanging models, a common misconception is that he embraced his hanging models as a way of determining the shape of his structures.

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Form exploration of shells in seismic areas

News broadcasts showing images of collapsed buildings, ravaged roads and torn-apart cities regularly remind us about the destructive power of earthquakes. While decades of research have greatly improved the understanding of these cataclysmic events, building professionals and researchers continuously try to adapt and employ the most sophisticated numerical methods to improve the behavior of buildings during a seismic event in order to safeguard their occupants.

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Las Manantiales Restaurant in Mexico City, a concrete shell designed by Félix Candela that behaved excellently during the 1985 Mexico City earthquake. (Image courtesy Félix and Dorothy Candela Archive, Princeton University)

Researchers at the Form-Finding Lab of Princeton University ( are exploring the design of elegant and expressive structures that can safely be employed in seismic areas. They focus on shell structures, which are very thin, curved and typically large span structures made out of wide range of materials going from steel and glass, to concrete and even bricks or mud.

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About the Form Finding Lab

By 2050, 70% of the world’s population will live in cities. Structural engineers envision, design and construct the bridges and long-span buildings those city dwellers daily depend upon daily. The construction industry is one of most resource-intensive sectors, and yet our urban infrastructure continues to be built in the massive tradition in which strength is pursued through material mass. In contrast, the research at the … Continue reading About the Form Finding Lab