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Collapse of the Tacoma Narrows Bridge, 7 November 1940

Zhigang Suo's picture

In today's class of complex analysis, my co-instructor Scott Norris was lecturing on resonance.  He mentioned a YouTube video of the Tacoma Narrows Bridge.  Also instructive is the entry of the bridge on Wikipedia


Mark E. Walter's picture

A young inventor says that the Tacoma Narrows Bridge inspired him to invent the "Windbelt" to generate electricity. 


In September, I attended IABSE (International Association for Bridge and Structural Engineering) symposium in Germany. It was interesting to see several presentations dealing with advances in computational modeling of bridge dynamics. These programs combine CFD with structural models and are becoming so powerful that can virtually eliminate wind tunnel testing, at least during the conceptual design stages.


Hope I do this right as I am new to this.

I believe the failure of
Tacoma Bridge was not due to  resonance but  due to
aerodynamic  instability  of flutter. [See Billah K.Y. and Scalan R.H. (1991) "Resonance, Tacoma Narrows Bridge Failure and Undergraduate Physics Textbooks" Am. J. Phys. Vol 59, No. 2, pp 118-124).

Flutter occurs when the
bending and torsion modes couple. In this coupled mode the 
deformation causes the aerodynamic loads to increase which in turn
causes additional deformation and the cycle grows till the stucture
breaks. Today wind tunnel testing of suspension bridges is mandatory
but was not understood in bridge design at the time Tacoma Bridge was




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