Archi
Pier Luigi Nervi (Video Coming Soon)
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Architectural modernist movement leader Walter Gropius famously said that “Architecture begins where engineering ends” but one master builder challenged that statement 20 years before it was uttered. Pier Luigi Nervi was a builder, engineer, and architect whose revolutionary use of reinforced concrete blurred the line between the three professions to the point of indistinguishability.
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Nervi was born in 1891 and though his buildings and writings in the first half of the twentieth century are often overshadowed by the modernist starchitects also active at that time his contributions to architectural history hold many lessons we can learn about the relationship between architecture, engineering, and construction, as well as the nature and role of materials in architecture.
Vitruvius, author of the famous 10 Books on Architecture from the beginning of the common era described the three core principles of architecture as Firmitas, Utilitas, and Venustas; roughly translatable to Strength, Utility, and Beauty. Nervi was more successful than perhaps any other builder to date at realizing the ideal mix of these three principles.
The engineer, architect, and builder knew better than anyone else in his time how the natural properties of structural materials, specifically reinforced concrete, could be best utilized to create elegant architecture informed by engineering. Nervi’s solution for good architectural design was to follow the instructions of the material’s physical properties, he strove to create beautiful architecture as a product of good engineering, or as he put it:
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"A structure that does not follow the simplest and most efficient schemes…will only with great difficulty achieve good aesthetic expression.”
- Nervi, Aesthetics and Technology in Building, 1965
In 1939 Pier Luigi Nervi filed a patent application for what he called “prefabbricazione strutturale” or structural prefabrication, a building technique that others soon dubbed the Nervi Method. The method involved designing structures that could be broken down into small, lightweight, and repeatable pieces. These pieces could be fabricated in a controlled environment with industrial efficiency and precision rather than being forced to conform to the requirements inherent to the conventional process of building all of these pieces in their final position. Once complete the pieces were lifted into place and joined to their neighbours by casting a concrete node thus rendering the final structure monolithic.
Nervi proved that structural prefabrication was an effective method for simplifying the construction process and minimizing material waste in all types of projects. In Italy at the time Nervi was building, lumber was an expensive commodity and since the Nervi method drastically reduced the need for formwork and scaffolding it became a very economical technique. From a design standpoint, the method worked best with symmetrical buildings and encouraged the use of repeating elements which added an aesthetic of simple and functional continuity to many of Nervi’s projects.
The Nervi Method was used to reduce costs for many of Nervi’s projects and to enable the construction of amazing structures that would have been completely infeasible with conventional construction methods.
Another major invention of Nervi's was ferrocement also known as thin-shell concrete, it was used by Nervi in almost every one of his major projects following his patent application in 1943. The material is essentially a variant of reinforced concrete that uses layers of steel mesh instead of the conventional tensile reinforcement of steel bars; this new combination of steel and concrete enabled the creation of structures that were thinner, lighter, and often less expensive than those previously possible.
Prior to the invention of ferrocement, concrete structures were massive and relied on bulk for accomplishing structural feats. Nervi was able to eliminate this dependency on mass without compromising the strength of his structures by concentrating instead on the form. A section of the “wave” as Nervi called it; it is an economical, repeatable ferrocement form that Nervi used in many projects to minimize the material requirements of a structure while maintaining the strength. The technique is akin to corrugated steel sheets or cardboard and is so effective that Nervi was able to reduce the concrete mass even further by perforating the roof with large windows, allotting to them nearly a third of the entire surface area of some of his vaults. Thus ferrocement structures could be strong not in bulk, as its precedents were, but in form; an elegant engineering solution that produced a unique architectural product.
Prior to the invention of ferrocement, concrete structures were massive and relied on bulk for accomplishing structural feats. Nervi was able to eliminate this dependency on mass without compromising the strength of his structures by concentrating instead on the form. A section of the “wave” as Nervi called it; it is an economical, repeatable ferrocement form that Nervi used in many projects to minimize the material requirements of a structure while maintaining the strength. The technique is akin to corrugated steel sheets or cardboard and is so effective that Nervi was able to reduce the concrete mass even further by perforating the roof with large windows, allotting to them nearly a third of the entire surface area of some of his vaults. Thus ferrocement structures could be strong not in bulk, as its precedents were, but in form; an elegant engineering solution that produced a unique architectural product.
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Nervi used ferrocement for its technical advantages but the material led to creation of awe-inspiring forms that are considered by many to be great works of architecture. The invention of the buttress allowed medieval architects to create churches of unprecedented lightness, in both senses of the word, Nervi’s invention of ferrocement and his ingenious techniques for applying it allowed him to accomplish lightness of his own, and on an even grander scale.
The final invention of Nervi's that we will discuss is isostatic ribbing. Just as Louis Kahn famously interpreted a bricks yearning to be an arch, Nervi too interpreted the desires of his material of choice when he proclaimed that:
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"Reinforced concrete beams lose the rigidity of wooden beams or of metal shapes and ask to be molded according to the line of the bending moments”
- Nervi, Aesthetics and Technology in Building, 1965
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As an engineer, Nervi understood the importance of the physical properties of materials and he strove to follow the instructions that nature had written. In 1949 he patented an idea for a floor with “isostatic ribbing” which accomplished just that. Nervi analyzed slab systems to determine the direction of the principle bending moments throughout and aligned concrete ribs according to these bending moments. In an ideal system, this technique would result in a slab whose internal stresses were uniform throughout thus optimizing the material use by avoiding wasteful over-engineering. Nervi’s analytical methods were not perfect as he was working in a time when they lacked the computational powers to conduct the precise calculations required to produce an accurate simulation of these systems, his approximations however were an excellent first attempt at interpreting the nature of materials and pushing the architectural zeitgeist in a more logical direction regarding structural design.
Nervi's isostatic ribs show how great buildings come not from expensive materials and ornamentation, but from the simple, elegant union of architecture and engineering. This philosophy ensures that even a building whose function is mundane and utilitarian can be beautiful; even a factory can be a great work of architecture.
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He was an engineer, a builder, and an architect and his portfolio of work reflects his respect for all three of these professions; he was able to create beautiful pieces of architecture based on logical engineering principles and he even invented the building practices that allowed them to be built in an economically feasible manner. This expertise produced buildings featuring fantastic vaults, impressive domes, and unorthodox slabs which were nothing like the works of his contemporaries and to this day stand as a testament to holistic design that unites architecture, engineering, and construction; achieving Firmitas, Utilitas, and Venustas
