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Re: Runway beam

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What about a vertical miter?  Long span bridges have used finger joints to 
accommodate very large expansions --- I think up to *6 feet* on the Verazanno 
Narrows bridge --- but this would be impractical on a runway beam.

With a vertical miter, you would not have a gap problem, nor would you have a 
thin section problem.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona  

Stan Mulder wrote:

. > ...the trolley wheel needs to be continuously supported. The small wheels 
. > (~5 to 6 ins diameter) also cannot move over gaps larger than about 1/8 
. > ins otherwise the gap interferes with the with the movement. The flanges 
. > also need to be perfectly level at joints. Mitring the flange tends to 
. > weaken the flange in cross bending because the wheels are close to the 
. > edges of the flange, with a impact load applied at the tip of the taper.
. >