Allowable load on wood studs 1

[rittz]

Can we design a wood stud wall for axial stress/allowable + stress due to lateral load (wind)/allowable bending = <1 where allowable axial load = O.30E/(l/d)^2. d=least dimension of the stud and l = stud length. And Stud assuumed pin connnected. What adjustment would we make to 0.30E/l/d^2 to install solid blocking at mid height? (or oftener)ignoring the sheeting inside and out. Or allow for sheeting outside and/or inside. Thinking of wall heights 14ft to 18 ft.studs spaced 12" or 16" OC.

 

[msquared48]

If you have sheeting across the short face of the studs on both sides, then the "d" would be the depth of the stud.

I would make no change to the equation for adding any blocking midheight.

Hopefully, considering lateral deflections and possibly a gyp finish on the wall, you can use 2X8's or 2X10's for those unsupported lengths.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[rscassar]

Are these the 18' walls from your other post. I used 2x8's at 12" crs for a similar span and I imagine you should get it to work for the 20psf wind pressure.

What adjustment would we make to 0.30E/l/d^2 to install solid blocking at mid height?

I thought the whole idea to install solid blocking (nogging or noggin' as I like to call it) at 4.5' crs was to reduce the unsupported length for bending and compression?

 

[dik]

The Canadian Wood Council has an excellent free publication on the design of tall walls with a worked example... (do site search on 'tall walls') different code, but the approach is likely similar.

Dik

 

[DaveAtkins]

You should use the formula for combined stress in the NDS. It is not as simple as fa/Fa + fb/Fb.

If you have wood or gypsum sheathing on both faces of the wall, the studs are braced. There is no need for blocking in the wall (unless blocking is needed for some other reason--shear wall, for example).

DaveAtkins

 

[MiketheEngineer]

As a double check - I use a rather simple but quite helpful piece of software - BeamChek at Beamchek.com (yes - it is spelled this way). It can take into consideration almost all the variables you can think of when designing wood walls - and beams for that matter.

Last time I checked it was about $150 US. An investment that has paid for itself at least a thousand times over.

 

[rittz]

What is NDS?

 

[PSlem]

http://www.awc.org/standards/nds.html

 

[a2mfk]

Make sure you are using the proper load cases (I don't know what your structure looks like). Often the case that produces the worse case axial load on a wall is full roof and live load, which is different then the axial load during your worse case wind, which may result in a tensile axial force...