Waiting for the fog to clear at Wroclaw airport after two good days at the IASS symposium here. Yesterday featured three special sessions on Nervi, and I was honored to be part of the proceedings. The papers’ range was good evidence that Nervi’s career was remarkably broad in its achievements, as architects, engineers, scholars, and preservationists all had something interesting to say. Marco Nervi, Pier Luigi’s grandson and the President of the Pier Luigi Nervi Project talked about that group’s work to raise awareness of Nervi’s career and the current state of his works, and the afterparty showed off the exhibition that the Project has assembled in Wroclaw’s architecture museum. The exhibition is truly extraordinary—a collection of drawings, photographs, videos, and new physical models that show how the buildings and structures demonstrate static and constructive principles. The venue, in a 15th century hall adjacent to one of the city’s historic churches, provided a good tectonic contrast to Nervi’s work (in addition to an ace wine bar…)
My paper was on the formwork methods used to construct Nervi’s famous variable section piers and how these related to the economic conditions that would have permeated any jobsite in Italy in the 1950s and early 1960s. Italy’s construction industry was dominated during the decade by small firms—there were none of the large conglomerates that were forming in Germany, say, or the U.S. As a result, most building in the country was based on an artisanal model (think Scarpa, for example). The large projects that Nervi designed would have suffered from the lack of large-scale mobilization, equipment, and fabrication that other economies enjoyed. And, at the same time, massive labor migration meant that cities like Rome or Turin had a surplus of unskilled labor even as skilled workers were in higher and higher demand.
So, my working hypothesis is that Nervi & Bartoli won the competitions they did based on their ability to wring as much sophistication and efficiency out of simple construction processes as they could. The curved formwork for these piers, for instance, produced complex shapes that were based on very simple construction algorithms. By using ruled surfaces that could a) be drawn with nothing more than straightedges and a compass at the drawing board, and b) be constructed using only metal jigs and thin, twisted timber boards on the jobsite, the firm was able to limit the amount of metalwork required to a few simple frames. Laborers could then be instructed to perform a fairly simple task—twist a board so that it lays up against its neighbor, twist it so that it fits into the widely spaced stack of metal jigs, and then nail the board into each jig to make it hold the twist. Once you’ve twisted and nailed all the boards, you set the reinforcing, fill the thing with concrete, and voila—you have a set of elegantly curved surfaces formed out of simple materials and processes.
You also have a pretty efficient column form, if you’ve done things right. Two graduate students from Cambridge and Harvard presented another paper on these piers, but focused as much on their structural performance as their construction. Their work showed that Nervi’s shapes create an ideal set of column cross sections based on the need for movement or stability at the ends (rectangular, circular, or cross-shaped plans, depending on what you need to do), and maximum moment of inertia/radius of gyration at the midpoint, which helps prevent buckling. This is a hunch I’ve had for a while, but good to see that there’s some engineering to actually back it up. (Did our presentations both have essentially the same animation showing how the geometry of a typical Nervi pier gets developed? They did).
Fortunately the papers are all collected and published in the current, just-released issue of the IASS Journal (requires membership, but worth it…) Good reading while waiting for a turboprop to Warsaw, which is an hour-and-a-half late and counting…
[UPDATE: despite that threatening sky, made it back to Rome only an hour late, thanks to an assist from the Alitalia counter staff in Warsaw…my travel luck is the same the world over.]