 29-Apr-2004, 07:57 AM
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| | Dodgy Old Bugger  Karma +/- Power: 61 Karma:  (70) | | Local Time: 05:15 AM Local Date: 07-Sep-2008
Join Date: Feb 2004 Age: 40 Posts: 516 | |
 re: The Hikoi ... Sparkle's rant for the day
Quote: Originally posted by kall@Apr 29 2004, 09:47 AM
Quote:
Bridges have a "natural frequency." When the wind blows or people cross the bridge at a rhythm that matches this frequency, the force can cause the bridge to vibrate. This phenomenon is called resonance, and the frequency is called resonant frequency. Soldiers are taught to march across a bridge out-of-step, so they won't create vibrations that tap into the bridge's resonant frequency. In extreme cases, the vibrations can cause a bridge to collapse, as happened when the driving force of the wind caused the collapse of the Tacoma Narrows Bridge in Washington State in 1940.
| | Regarding bridges and their frequency, it could be worse.... LONDON (Reuters) - London's Millennium Bridge will reopen to the public without a wobble or a ceremony on Friday, the structure's engineers say.
Queen Elizabeth opened the 350-meter pedestrian bridge on June 10, 2000, but local authorities shut it down on June 12 after people walking across the bridge made it shake so much that some felt seasick. |
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