December 01, 2009

Engineering is All Around Us

As I stated in my last entry, I drove to St. Louis for the Thanksgiving holiday. This week I would like to share some of the engineering marvels that I saw. What do you think about when someone mentions the city, St. Louis? For many the answer is the Gateway Arch. Another answer might be the St. Louis Cardinals which is more than acceptable (Go Redbirds!) but for the purposes of this article I will avoid discussing the latter.




During the visit back to my hometown, I promised myself that I would go up into the arch, and even though it stands 630 feet at the top, I’m not afraid of heights so I was undeterred. Before I share my feelings on the experience I want to give you all the specs of the arch as they are quite impressive.




Referencing what I just said, the arch stands 630 feet high above the Mississippi River, and was built to represent the 1803-1890 westward expansion that made St. Louis the gateway to the West. A lot of buildings are really tall, even taller than the arch, but the feature that sets this building apart from the rest is its shape. The arch is shaped exactly as its name suggests, like an arch. To explain, if you took the McDonald’s golden arches and cut them down the middle symmetrically, you would have two of the building that I am describing.

In more technical terms, the arch is the shape of an inverted catenary curve. A catenary curve is the shape that a necklace makes when you hold it at both ends. The equation for the catenary curve is




Where k is the y-intercept and cosh is the hyperbolic cosine. (consult Dr. Traum for a detailed explanation) The arch’s legs are the same distance apart as the height, 630 feet. The arch is incredibly strong, able to withstand wind gusts up to 150 mph. The structure just bends to compensate for the high winds. Believe it or not, the engineer designed the building to bend this way, and I promise that I could feel the building swaying as I was at the top.




Once a man tried to land his parachute onto the top of the arch, he was successful initially, but then fell off after landing…I will let you fill in the blank on whichever adjective you choose to describe this guy. The real point that I’m trying to make here is that my studies here at UNT have opened my eyes to the endless possibilities of engineering. What started as a simple tour of a national monument quickly turned into a study and appreciation of an amazing chapter of American engineering history. My challenge to you is this: start to observe things around you and ask yourself, “How was this made?”, or “How does it work?” I assure you that the answers to these questions are found within a solid engineering education that can be achieved at the University of North Texas.