Timber Pile Section Verification (resisting moment vs computed moment) 2

[pelelo]

Engineers,

I am performing a timber pile design. Similar to the steel pile design, after i compute my lateral moment (LPILE) and make sure that the lateral deflection is adequate, i compare the steel pile resisting moment (f'y and section modulus) against the computed moment (LPILE), if resisting is greater than the computed moment, then the section is ok.

I understand the same procedure should be followed for timber piles. However, Does anyone knows where to get the section modulus of timber piles?, In my case, i plan to use the southern pine specie, 8 inches diameter at the butt and 7 inches diameter at the tip, with a lenght of 20 ft.

I have been trying to look for tables, similar to the steel profiles, but haven't found anything. The Timber pile design and construction manual is somewhat vague at this.

Please advise,

 

[SlideRuleEra]

Does anyone knows where to get the section modulus of timber piles?

Calculate it.
The cross section of a timber pile approximates a circle.
Section Modulus of a circle (axis of moments through the center) = pi x R³ / 4.
If you want to be conservative, use the tip diameter for the calcs.
If you need section modulus at a specific location on the pile, interpolate the diameter between the tip and butt. Timber piles have a fairly constant taper.

BTW, timber pile specs usually specify the circumference 3 ft. from the butt, not actually at the butt. Of course, diameter is easily calculated from circumferance This is to allow for the way trees tend to enlarge near the stump.

http://www.SlideRuleEra.net

 

[oldestguy]

This is unbelievable. A basic calculation for an engineer Shows what use of computers has left us.

 

[GeoEnvGuy]

section modulus of rectangle = bd²/6