Posted on 06/04/2022 11:48:45 AM PDT by American Number 181269513
Our lives are inevitably bound by and shaped by the structures around us. We live in them, calling them homes; we go through them, calling them tunnels; we move on them or thanks to them, calling them roads, or bridges.
Salginatobelbrücke designed by Robert Maillart, 1930
The bridge has a particularly interesting function: it connects two places in a more complex way than a road does. The bridge helps to elevate the passenger, allowing them to move above a body of water, a valley, or a three-dimensional urban labyrinth of roads and crossings.
But apart from being a beacon of utility, good structures must also be efficiently built, and display some form of beauty or elegance. Satisfying this triad requires a mastery of the material, a deep knowledge of the building site and an artistic touch, which is why great structures, which satisfy all three are often given the grand label of Structural Art.
Can structures be appreciated in the same way art can?
The word “artwork” usually connotes a small object, be it a painting, a sculpture, or a bespoke piece of clothing. But could that definition be exploded in scale? Could something as large and monumental as a bridge be considered an “artwork”?
In short, yes.
In his book The Tower and the Bridge, David P. Billington provides a three-part definition of Structural Art, appropriately named the three dimensions of structure and they are as follows:
1- Efficient. An efficient structure should withstand the force of gravity, wind, its own weight, and of its users (e.g. cars and people), while using the least amount of material. As Billington puts it, efficiency is “the delicate balance between thinness and safety”.
2 - Economical. It must be economically viable and supported by stakeholders or the planning authority. Again, we see a balancing act, with one extreme being cheap and wasteful and the other being expensive and inviable.
3 - Elegant. An elegant structure must complement its surroundings while displaying a symbolic and expressive power.
The Salginatobel Bridge came into existence because of a bridge competition organised by the Schiers municipal council, Switzerland in 1928. Out of the 19 designs, this one was the most economically viable one. While economy was a big factor in the decision making, this design ultimately won because of how well it balanced Economy, Efficiency and Elegance.
Efficiency through innovation in Structural Engineering
The form of the Salginatobel bridge was influenced by two structural ideas coming together in one project. The main shape of the bridge is a catenary, it’s connected to the ground using its three-hinged arch system, both of which will be briefly explained below:
The Catenary
A catenary shape is one that a chain makes when you hang it between two points. It’s the most efficient shape for that specific length of chain and that specific distance between the points it is hung from.
When inverted horizontally, a highly efficient bridge arch shape is obtained, further illustrated in the diagram below:
The Three-Hinged Arch
During the year, the temperature fluctuates, causing the concrete to heat up and cool down repeatedly. Like most other materials, reinforced concrete thermally expands and contracts, which can cause the formation of cracks if not dealt with properly.
The use of the hinges allows for the thermal expansion of the material during temperature fluctuations. As the reinforced concrete expands and contracts throughout the year, the hinges provide extra space for movement, thus preventing the formation of cracks in the concrete. The use of the three-hinged arch system greatly improved the longevity of the structure.
But is it Structural Art or just Structural Engineering?
With the technical explanations above, it has clearly been shown that for its time, the Salginatobel Bridge was a feat of engineering. But what makes it museum-worthy?
Just like a great artwork has to resonate with the viewer, transporting them to an alternative dimension, and offering a glimpse into the mind of the artist, so does great structural art.
The horizontality of the bridge beautifully juxtaposes the verticality of the ravine it is cutting through, a near-permanent reminder of man’s ruthless conquering of Nature.
But it cuts through in an honest way: the bridge does not try to conceal the material it is made of, it does not pretend to be biomimetic for the show, it very clearly delineates itself from the green fir trees growing below it and beyond it. Yet, the only thing it touches is the powerful and permanent mountainside, the immovable rock, from which concrete is partially made.
The bridge touches the mountains lightly, with the curved members tapering off in section width as they come nearer the base. The form of the bridge is a physical representation of the force which flows through it. The arch is the thinnest at either end and thickens in between, which reflects the shape of its bending moment diagram, a diagram showing how much bending force is experienced by different parts of the structure.
The bridge is a symbol of utility, and through its form, it creates a permanent link between its structure and the philosophy it implies.
Concluding thoughts
Ultimately, as a student of structural engineering, I slowly built up the ability to delineate bad structures from good ones and good structures from great ones. This, in my opinion, is an example of a great structure. Efficiency, Economy and Elegance are the reasons why I think this bridge deserves to be put in an art museum.
Very nice, but that would have to be an awfully big museum.
later
later
Galloping Gertie, Tacoma, WA. Never went over it, have been on the new bridge many times.
Brusio Spiral Viaduct, Switzerland, 1908; Kawazu Nanadaru Loop Bridge, Japan, 1982
That’s the one I believe they called Galloping Gertie
It needs to scrub it’s hands before picking up that bridge.
Don’t know who has been crossing it.
Incidentally, a very similar bridge still stands on the southern coast of Maine.
I lived in the North Bay area (Benicia) for 22 years. I never got tired of the view (while driving west) as one exits the Caldecott Tunnell. Before you are the Oakland Bay Bridge and in the distance the Golden Gate.
As horrible as SF is, in many ways, it is a beautiful natural setting for a city.
It’s been said anyone can design a bridge that won’t fall down.
The trick is to design a bridge that barely won’t fall down.
People make a good living driving others over our Bay Bridge in Maryland:
https://www.insideedition.com/6448-is-this-the-scariest-bridge-in-america
lol Galloping Gerdy (sp?)
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