On Wed, 18 Mar 2009 17:17:14 -0700, Jim Lux
wrote:
Reeds don't oscillate torsionally (at least not as the dominant mode)
They're more of a fixed/free beam that oscillates in longitudinal bending.

And yet the failure mode I've most seen with them is splitting.
Perhaps this only reveals a limited experience of their failure.

The bridge was an
architectural feat, with a very delicate looking thin roadbed and much
longer than most other bridges (3rd longest when it was built, some 1500
feet longer than the Golden Gate, for instance).

You can't be third in the list to the GGB and longer both unless you
are speaking of the insignificance of approaches.

The GGB is shorter than the TNB. It was third on the list on July 1,
1940 according to Wa DoT. (Verrazano narrows was built in 1964) George
Washington was built in 31 and was 3500 ft, and was longest until 37,
when GGB was built in 37.

TNB was 5939 ft long (per Washington state DOT). GGB is 4200 ft
(wikipedia gives 5000 ft for the length of the TNB)

You have inadvertently summed in ordinary approaches. We have freeway
interchanges with more complexity. Bridge span is the significant
indicator of interest. The GGB comes in at 4200 feet suspension span,
yes, the Narrows is much shorter at 2800 suspension span.

If push came to shove about overall length over water, we, here in
Seattle, have vastly larger bridges that float. The I-90 bridge logs
in at 6620 feet, and the 520 bridge pushes that to 7578 feet. Nearby,
we have the Hood Canal bridge that is longer at 7869 feet.

I've been across all five many, many, many times, and I used to live
halfway across the bay on the way to Oakland, by way of the Bay Bridge
in Frisco. The one suspension bridge I refused to drive across is SW
of Colorado Springs, over the Royal Gorge - the highest suspension
bridge (1053 above the river below). Just standing on the approach as
a car goes over gives you the shakes (talk about harmonic coupling).

73's
Richard Clark, KB7QHC