The Millennium Bridge and Its Construction - Essay Example

The Millennium Bridge is located in London, exactly linked to St.Paul`s Cathedral with the Tate Modern Gallery. It was opened to the public on 10 June 2000. This bridge was designed by Norman Foster and was considered to be a passing solution for 80,000 to 100,000 people. Unfortunately, after only two days of its opening, the Millennium Bridge had to be closed from the function on 12 June 2000. The problem was a degree of movement in which sideways movements occurred when a large amount of people were crossing. Analyzing the particular problems, this report identifies what happened when there were movements on the Millennium Bridge.

The phenomenon that happened in the Millennium Bridge was rather serious.

In a view, the phenomenon was like a swaying bridge as a fairground ride.

As it had been observed, the movements that occurred on the Millennium Bridge were caused by Synchronous Lateral Excitation. In this case, small sideways oscillations happened because of the natural sway motion of people walking; it in turn caused people who passed the bridge to sway in step, which made the amplitude of the bridge oscillations increase and reinforced the effect continuously. When it occurred, the worst movement was on the central span where the deck moved by up to 70mm. What a dramatic swaying that had made people who passed shocked.

The solutions that had been done to analyze the phenomenon were mostly used tests. Crowd tests were implemented on the bridge deck. In July 2000, 100 people were used in the first test. The purpose of the first test was to devise a load model for the dynamic forces created by people when they were walking. To apply this, the bridge was equipped to measure movements, and a proportion of the crowd was fitted with heel sensors to measure the precise timing of their steps. Following the first test, December 2000 was chosen to be the second time to implement a test. The second test involved 275 people who were used to load test a prototype installation of the proposed solution in reducing the movement of the bridge. Moreover, as it was observed, there are two fundamental ways to limit dynamic excitation; they are to stiffen the structure so the frequency of the bridge and our footsteps no longer match, and add damping to absorb the energy.

All around the world, dampers can be used in bridges and buildings, particularly in areas prone to earthquakes. Furthermore, dampers have another benefit in that most of them could be beneath or within the structure. Therefore, it can be hidden from public view.