reference design values for round timber cross sections

[tmoesabi]

How does one determine reference design values for timber members such as 6" or 12" diameter poles. the members are NOT being used in a pile application. Rather, I have 12" diam. columns with 6" diam. bracing members.

thanks

 

[dhengr]

Tmoesabi:

“Standard on the Design and Construction of Log Structures,” ICC 400-2007, by American National Standard, is a good place to start. Also, “Log Program Technical Guide,” by Timber Products Inspection, Inc., (phone 770/922-8000). Logs are surprisingly effective, since we do so little to screw up the orientation of the grain at the extreme fiber, by cutting them up into littler pieces.

 

[tmoesabi]

dhengr,

great references, thanks alot

 

[TLHS]

The Canadian Code has some direction in CSA O86-01 (not the current version since I don't do much work in wood). Basically they say to take strength as 80% of the strength of select structural grade and for bending you treat it like the square of equal cross section, which seems fairly conservative to me. There are some further requirements about shape and similar things. With compression you treat it like any other member.

 

[JoshPlumSE]

I'm looking at the 2001 NDS, though I'm pretty sure the newer version has a similar provision.

Section 3.7.3 Round Columns:
"The design of a column of round cross section shall be based on the design calculations for a square column of the same cross-sectional area and having the same degree of taper. Design values and special design provisions for round timbers poles and piles are provided in Chapter 6".

Therefore, that gives us the design procedure.... Re-reading your post,leads me to believe that you are probably more interested in tabulated stress values Fb, Fc, et cetera.

 

[dik]

If you are using poles that are 12" dia, you may consider graded utility poles. They are often designed for an outer fibre flexural stress of 5 or 6 ksi.

Dik