Information AboutAngers Bridge |
| CATEGORIES ABOUT ANGERS BRIDGE | |
| bridges in france | |
| bridge disasters | |
| angers | |
| bridge | |
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DYNAMIC FAILURE OF BRIDGES As a result of the bridge's collapse, marchers now break step when crossing bridges. Ironically, crowds of people that don't intend to march often start walking in step to match the swaying of the bridge and maintain their balance. The problem is caused by transfer of momentum from the pedestrians to the bridge structure, causing Resonance . The same problem occurred in 2000 at the recently completed Millennium Bridge (London) , when over 600 people walked across the bridge, causing lateral vibrations. The problem was corrected by installing large dampers to absorb the vibrations, and change the Natural Frequency of the structure. Torsional oscillations caused the catastrophic failure of the Tacoma Narrows Bridge in 1940, when winds blowing at about 40 mph were enough to induce resonance. The Torsional waves induced by aerodynamic Flutter of the deck, grew in Amplitude until the deck failed, and it fell into the waters below. RESULTS The disaster led France to abandon suspension bridges for many years. There had been similar failures elsewhere, such as that at Yarmouth in England in May 1845, when 79 people were killed by the fall of the main deck. The fall of the Angers bridge rased serious questions over the integrity of suspension bridges, and some engineers (like John A. Roebling ) used reinforced decks in future structures such as the Brooklyn Bridge . REFERENCES
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