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RE: Rod bracing

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I have an interesting article from Caltrans where they describe how they
tightened eyebars on an old steel bridge.  

Basically they taped a pencil to the eyebar, pushed the eyebar outward by
hand, let it go, then placed a pad of paper over the pencil and recorded the
resulting "sine curve" by moving the paper over the oscillating pencil.
>From this graph they got the frequency, then they used an equation out of
Timoshenko relating natural frequency to axial load.

Accurate? Who knows.  Seems like it would be a good way to compare relative
tightness of adjacent rods. 

-----Original Message-----
From: Greatorex, Alan R ERDC [mailto:agreatx(--nospam--at)]
Sent: Wednesday, February 09, 2000 9:04 AM
To: 'seaint(--nospam--at)'
Subject: RE: Rod bracing

		-----Original Message-----
		From:	MSSROLLO(--nospam--at) [mailto:MSSROLLO(--nospam--at)]
		Sent:	Wednesday, February 09, 2000 11:21 AM
		To:	seaint(--nospam--at)
		Subject:	Re: Rod bracing

		The same thing happens when the temperature goes up on 
		elongates..on the other hand..when it goes down..the rod
gets tighter..

		This would be true regardless of how well it is

		Ron Martin

	Yes, but, IMHY, that would only occur if the frame were held at a
constant temperature while the rod is cooled or heated. The other
possibility is that the coefficients of thermal expansion for the rods and
the frame are different, but that difference would have to be significant.

Alan Greatorex
72 Lyme Road
Hanover, NH 03755-1290