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Millennium Arch

Millennium Arch

Millennium Gate museum

Structure Information

The millennium gate bridge is located on 17th street in Atlantic station which is a popular mixed-use development in midtown Atlanta.  Construction began in 2005 and was opened to the public on July 4th 2008.Image result for millennium arch atlanta

Figure 1: Millennium Arch

This structure was funded by the National Monuments Foundation because they wanted to honor the rich history of Atlanta. Back in the mid-1800s Atlanta was known as the gate city because the rail system that ran through the city was the first to connect the east coast to the western United States. The National Monuments Foundation thought it was fitting to build an actual gate in the heart of Atlanta to honor fast growing city. The design of the arch came to be through an international competition which was judged by some of the most respected architects of the time.  [1]

Historical Significance

This structure was not an innovative structural engineering design. The arch was perfected by the ancient Greeks back in 470 BC. There has been plenty of Arch monuments that have been built around the United States and around the world like the Titus Arch in Rome and the Washington Square Arch, in New York’s Washington Square. [1]

Cultural Significance

Atlantic Station today is a highly populated area in Atlanta which is known for is retail, high density apartments and tall office buildings. It was not always like this. Back in the early 1900s the Atlanta Hoop factory was founded here where they made cotton bale ties and barrel hoops. With the advancement of technology steel was in high demand and the factory switched its focus to steel and became known as the Atlantic Steel Mill. It finally closed in the 90s and was abandoned.  The steel mill created a lot of hazardous waste and because it was abandoned no one ever cleaned up the waste properly. This became a huge road block for developers whose hopes were to transform this area into a huge retail area to try to improve and grow Atlanta. The EPA determined that this area was too harmful to build here where families would live. Experts came up with a plan to remove and also burry most of the waste along with other methods.

This development became a huge success by accelerating the growth of Atlanta which is now one of the fastest growing cities of it size. People from Atlanta have enjoyed this monument as it sits in a park where people can sit and reflect in such a beautiful place

Structural Art

Billington would definitely not consider the Millennium Arch as structural art. One could say that the load path is clear and is a very elegant looking structure but that is about it. There was no new technology developed in the design of this monument, the arch outdates the ancient Greeks. Also, the economy and politics didn’t really add any constraints to this project to effect its final design.

Structural Analysis

I had a difficult time finding the exact dimensions of this arch so I had to make a few assumptions. I do know that the total height of the arch is 100 ft tall. Based on this I assumed the length of the arch is 35 ft long and 20 feet 12 feet high. The structure is made of lime stone which ways 150lb/ft3 so I made an assumption that the distributed load along the top of the arch is 184 kip/ft.  Please see Figure below.

 

Figure 2: Loads Applied

To calculate the reaction of this arc, I first summed the forces in the y direction of the entire structure. I did this because there is a symmetric load across the arch so the two reactions will equal each other. I got both of the y reactions to equal 3220 kips. Then to find the x reactions I cut the arch in half where the arch is at its tallest height which is 12 ft. At that maximum point there is no internal force in the y direction.  I took the Moment about C and got the x value to equal 2348 kips. IF you look at the entire arch again and sum forces in the x, you will notice that the x values on both side of the arch will equal the same value.

The reason this structure works well is that the top of this arch corbeled. This allows the weight from the top of the structure to get evenly distributed across the arch without collapsing. The forces flow from the arch to the columns it sits on and into the the ground.

Personal Response. 

This arch has always stood out to me but I never had the chance to actually go and visit before. Getting to see it up cloase and person I got see how much detail went into this monument. I really does show how rich Atlanta’s history is and and just how important this area really sparked the immense growth in the A.T.L

 

 

references

Referecnces

  1. http://thegatemuseum.org/history/
  2. http://www.atlanticstation.com/history