Galloping Gertie - Aeroelastic Flutter and the Tacoma Bridge Disaster

Galloping Gertie is the nickname given to the original Tacoma Narrows Bridge, which opened on July 1, 1940 and dramatically collapsed into Puget Sound on November 7 of the same year. The suspension bridge spanned the Tacoma Narrows strait between Tacoma and the Kitsap Peninsula in the same location as the current bridges. The bridge's collapse had a lasting effect on science and engineering. In many physics textbooks the event is presented as an example of elementary forced resonance with the wind providing an external periodic frequency that matched the natural structural frequency (even though its real cause of failure was aeroelastic flutter). Its failure also boosted research in the field of bridge aerodynamics/aeroelastics which have themselves influenced the designs of all the world's great long-span bridges built since 1940.

http://en.wikipedia.org/wiki/Galloping_Gertie