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Effective Length

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Chris,

I consider the unbraced length of web members as being along the axis of the 
member from the center of the top chord to the center of the bottom chord.  
Actually, the points of lateral restraint (but no moment restraint) are where 
the roof sheathing and ceiling are nailed to the truss chord, but I am giving 
them (TPI et. al.) the benefit of the doubt.  (I do not accept TPI's 
contention that the unbraced length is less than the clear length of the web 
member.)  For chords not continuously supported laterally, I consider the 
unbraced length as the distance between lateral braces.  In the strong 
direction, I consider the unbraced length to be from panel point to panel 
point.  The effective length would be in accordance with NDS.

Hope this helps.

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

Chris Towne wrote:

. > Does anyone know of any good literature about determining effective 
. > lengths of truss members in compression?  Also, any comments from 
. > experience would be appreciated.