On 06/09/2018 06:56 PM, Dean Hoffman wrote:
Do I have it right that something shaped like an inverted airplane
wing
is put under the bridges now to minimize wind effect?

I don't know about that but they do pay a lot more attention to the wind
effect:

http://www.blwtl.uwo.ca/Public/WindE...OnBridges.aspx

https://en.wikipedia.org/wiki/Tacoma...idge_Puget.jpg

That's the replacement and it hasn't fallen into the Sound (yet).

https://en.wikipedia.org/wiki/Tacoma...ws_Bridge1.gif

That's the original. The new one appears to have a lot more truss work
under the deck. That was one difference between that and the Golden Gate
or George Washington, both of which are longer. The trusses for the
Tacoma bridge were enclosed in concrete and split the airflow rather
than just letting it blow through.

For trivia, Robert Resnick was a professor at RPI so we of course used
the Resnick & Halliday physics text. Resnick's explanation at the time
was natural resonance like the old marching soldiers breaking cadence
when crossing a bridge. Later research points to a more complex answer.

Science can't even get it right when saying why a bridge fell down Of
course in that same textbook it assumed the coefficient of friction
could not exceed 1, which limited the times for, say, a quarter mile.
Our TA, who drove a Corvette and was a car nut, took great glee in
pointing out the fuel dragsters were beating that theoretical limit.
Back to the drawing board on that one too.