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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This is a 1/15-sized reproduction of Gaudí’s hanging model for the Colònia Güell church found in the Museum of the cathedral.
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“There exists in the world not a single vertical column (although in many cases they were intended to be vertical): the nature of things requires a certain amount of inclination, which means that one only has to agree over by what amount the column should incline.” — Gaudí. Crypt of the Colònia Güell church for which Gaudí experimented with his hanging model. Photo by Maria Rosa Ferre

Gaudí did use hanging models to aid in the design of one of his structures– the Colònia Güell church; however, this incomplete project served mostly as an experiment. In truth, Gaudí was skeptical of the hanging model as a means of determining architectural form:

“Claiming that from the threads arise the architectural shapes is infantile, since they only represent a way of verifying stability, which one needs at a convenient moment. However, before stability, other things have to be satisfied: (space) capacity, lighting, sanitary requirements, etc.”

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Ruled surfaces are curved surfaces created from straight lines. Gaudí took advantage of these geometries throughout the Sagrada Família. (Felix Candela was another Spanish– Spanish-Mexican, though, to be exact– architect who favored these geometries.) This model is found in the Museum below the cathedral.

Rather than the traditional forms of Gothic arches, catenaries, or even circular arcs, Gaudí embraced conic sections and ruled geometries.

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The hyperboloid is just one of the ruled structures Gaudí used in his structure, in this case to provide light into the nave. This model and accompanying mirror are found in the Museum below the cathedral.
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Repetition of these geometries in the interior has a pleasing effect.

The result is the grand and awe-inspiring structure that we can visit today.

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Despite some common misconceptions, the Sagrada Família was not in fact modeled using the hanging chain model.

This post quotes, paraphrases, and takes inspiration from Jos Tomlow’s “Gaudí’s reluctant attitude towards the inverted catenary,” published by the Institution of Civil Engineers.

Author and images: Demi Fang ’17


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