TWSB: Arch Rival

For whatever reason, today from the deep recesses of my mind I recalled my last (only?) visit to the Gateway Arch in St. Louis. Back in the days before life was complicated and strange, my grandparents lived down in Missouri and my mom and I would occasionally jet down there to visit. Mostly because of Cracker Barrel, my grandpa’s set of Tinker Toys, and the Magic House, I found St. Louis to be a pretty sweet place.

But let’s get to the science. The Gateway Arch was completed in October 1965 and opened to the public in June the following year. It’s the tallest manmade monument in the States, required more stainless steel than any other project in history, and (though it doesn’t look like it) is as tall as it is wide.
According to Wikipedia, its shape is that of a catenary, not a strict parabola. A catenary is the shape that a hanging chain or cable assumes when it is supported at its ends and is acted on only by its own weight (Wiki gives the examples of a loose single-chain fence or the strands of a spider’s web).
Actually, the arch is (very similar to) an inverted catenary, as it is heavier on its ends. Architect Eero Saarinen claims the inverted was chosen over a regular catenary for aesthetic purposes—an ordinary catenary would “look too pointed.”
I actually remember watching a really fascinating building on the construction of the arch, particularly its topping out, but I can’t find the vid on YouTube or elsewhere right now. I’ll post it if I ever do find it.

More fun facts:
– In 1970, the whole arch shrunk three full inches due to cold weather.
– It is able to sway up to nine inches in one direction during high winds.
– It can withstand an earthquake. Unless the earthquake caused it to sway more than nine inches in one direction, I’m assuming.
– The windows up at the top are so small because larger windows would not be able to withstand the pressure (500+ tons) used to separate the legs of the arch in order to insert the final piece.


Cool, huh? If you’re ever in the St. Louis area, go and check it out. I was like five when I went up there and I still remember it.

One response

  1. Matt Farnsworth | Reply

    That’s definitely on my list of things I need to see.


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