Transcript lmb wobble-1.ppt

The London Millennium Bridge
Wobble
Group 12
Contents
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Description
Problem
Explanation
Solution
Questions
Bridge Description
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Shallow
suspension bridge
Deck supported by
cables
Prefabricated steel
V-brackets
Problem
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Opened 10th June 2000
80,000 to 100,000 people
Unexpected sideways movements
Closed 12th June 2000
Explanation
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Oscillating pattern of forces
Vertical and lateral forces
Spread feet apart to regain balance
“Lock-in” phenomenon
Motion further amplified
“Synchronous lateral excitation”
Explanation
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Excitation increases with movement
Damping capacity remains constant
Lateral force increases
Lateral force becomes greater than
damping force
SLE occurs
Explanation
Solution
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Add passive
damping
Increase resistance
to vibration
Greater pedestrian
load
Reopened Feb. 2002
Thank You
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Any questions?