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Qualification of the Golden Gate Bridge as Structural Art

The Golden Gate Bridge is a magnificent spectacle greeting any visitor to the city of San Francisco, rising 746 feet above the water of the San Francisco Bay. Its status as an unofficial national landmark was highlighted when it was considered for addition to the back of the California state quarter, though it lost to another design. Though it is an elegant piece of architecture and a moderately efficient design, according to modern standards of structural art, it is currently quite uneconomic. Thus it should not be considered to be a proper example of structural art, as it fails to meet all three of the citeria of structural art.

The main span of the Golden Gate Bridge

Structural Description

The plan to span the Golden Gate Straight began in August 1919, when the city's chief engineer, Michael O'Shaughnessy, began to look into the feasibility of building a bridge. No one believed that the task was possible until Joseph Baermann Strauss proposed a symmetrical cantilever-suspension design for the bridge, though it was later changed to a purely suspension design. Construction on the bridge officially began on January 5th, 1933, and the bridge span was completed on November 18th, 1936, though the road way would not be finalized until April 1937. Each of the cables passing over the entire span of the bridge and its two towers is 7,650 feet long and has a diameter of 36.375 inches, being composed of 27,572 individual wires. The suspended structure spans a total of 6,450 feet. The dead load on the structure across this distance is 21.3 kips/foot. The two towers supporting the roadway are each made of solid steel, and each main cable is made of galvanized steel wires.

Economy

The bridge connects to a major U.S. city, and is thus best compared with other structures that fulfill the same purpose and are also suspension bridges, in particular the Brooklyn and George Washington bridges. The George Washington Bridge and the Golden Gate Bridge were built in 1931 and 1937, respectively, during which years the inflation rates of the U.S. dollar were, respectively, about -8% and 2.5%. Despite the fact there was actually deflation during 1931, the George Washington Bridge ($59,000,000) still cost 24 million dollars more than the Golden Gate Bridge (35,000,000) to build. The inflation of the dollars spent on the Golden Gate Bridge means that they were actually worth less than the George Washington Bridge dollars. This stresses the frugality exhibited by Joseph Strauss when he built his bridge. However, to consider its current economy, one must consider its worth to the modern American. A good means of comparing the public utility of the three mentioned bridges is by the average daily traffic flow across each one in the last year(2011). The Golden Gate Bridge was actually the least used, with only 112,000 vehicles crossing per day, as opposed to 145,000 for the Brooklyn Bridge and a whopping 300,000 for the George Washington Bridge. While the number is still impressive, the bridge is nonetheless not as well traveled as its fellows. This is particularly important because the bridge is maintained entirely by money from tolls. In the past this money has been sufficient for repairs and repainting, with a few adjustments to the price of tolls. However,in recent years new features have been deemed necessary for the bridge. In 2001 a $122,300,000 contract was begun to carry out a seismic retrofit to prepare the structure to resist an earthquake of Richter magnitude 8.3. Also, due to the large number of suicides carried out from the bridge each year, a suicide barrier with a projected cost of $45,000,000 is being planned. Should the authority responsible for the bridge chose to raise tolls to combat these costs, the bridge's regular travellers, very likely from the city itself, will foot the bill. Considered in light of the past and the present, it is evident that the Golden Gate Bridge was an incredibly economic design at the time of its creation, but is now quite costly to the city of San Francisco, without a particularly great social utility to justify the expenses it requires.

Efficiency

The Golden Gate Bridge has a dead load of 21.3 kips/ft. Compared to the George Washington Bridge(1931), which has a load of 39.6 kips/ft, and the Brooklyn Bridge(1883), which has a load of 9.37 kips/ft, the Golden Gate Bridge is only moderately efficient. It should be noted that the Brooklyn Bridge was originally built to carry trains as well, and so would have been built with an even greater live load in mind than that of automobiles. Thus, though Strauss's bridge is more efficient than the George Washington Bridge, it is hardly noteworthy next to the Brooklyn Bridge, which was built far earlier. The given dead load for the Golden Gate Bridge is also after a redecking operation carried out in 1986, which reduced the roadway weight, though not enough to call it significantly efficient. A problem faced by the bridge due to tower design is that of increased wind load. The towers, rather than being built of individual members, are solid. This increases the surface area presented to the wind, making the wind load on the bridge greater. Were the towers designed to be more open, the bridge's overall load might have been lessened. In the end, Strauss' creation fails to stand out as a striking example of engineering.

The Golden Gate Bridge while the sea is covered by fog

Elegance

The bridge owes its elegance primarily to the unique paint scheme selected for it. This color, ‘International Orange”, makes the structure stand out from the standard tones of gray on other suspension bridges. The artificial nature of steel is partially hidden by the brilliant hue of the bridge. While the bridge lacks the imposing image that comes with masonry towers, its paint grants it a more artistic flair. Its towers aappear thinner than the masonry towers of the Brooklyn Bridge, but appear equally as strong to the eye, making the bridge seem lighter yet in no way weaker. The large spacing between the vertical cables on which the roadway rests prevents the structure from obstructing the view from the bridge, making the crossing more scenic than that of the Brooklyn Bridge, in which the web like array of diagonal stays is detrimental to the view. The view of the bridge is particularly scenic when fog rolls into the strait, when the roadway seems to float on a sea of fog. This environmental factor is a welcome addition to the bridge's beauty.

For more information on structural art: http://en.wikipedia.org/wiki/Structural_art