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Tension capacity of Anchor bolts at Wood Frame Construction

Tension capacity of Anchor bolts at Wood Frame Construction

I am trying to find out the pull-out (tension) capacity of 1/2" dia. anchor bolt w/ 12" embedment into the concrete (I have 2x6 cont. P.T. sill plate over concrete basement wall). Where can I find this information? Does NDS manual has this information? I could not find it in NDS though. I would appreciate your help on this.

FYI: This is wood frame construction. I am designing a house for overturning.

RE: Tension capacity of Anchor bolts at Wood Frame Construction

Just calc a 45 degree shear plane through the foundation wall based on f'c of the concrete - 2000 psi minimum - and divide the result by 4.  That would yield around 2200# for a 6" wall, 1/3 more for an 8" wall.  

I would rotohammer and epoxy in a separate A36 all-thread anchor though, relying more on what I know than what I don't know.

Hopefully you intend to anchor directly to the bolt and not put the sill plate in cross grain bending...

Mike McCann
MMC Engineering

RE: Tension capacity of Anchor bolts at Wood Frame Construction


Thanks for the prompt response. For more info, the anchor bolts will be installed while pouring concrete for basement wall (8" thick). This is not post installed case. And the sill plate is on the top of the wall.

I am  not sure your answer does apply in my case.

RE: Tension capacity of Anchor bolts at Wood Frame Construction

If you are trying to engineer anchor bolts, sizes and depths also look at the appropriate bulding codes.

There have been some very questionable prescriptive requirements that could cause mush closer spacing than you would think. They were changed because of one type of foundation, but apply to all foundation anchor bolts. Some jurisdictions have eliminated that portion of the code until the newer version is released.


RE: Tension capacity of Anchor bolts at Wood Frame Construction

Based on ACI 318-05, a headed bolt would have a tensile capacity of 4,074 lbs (controled by pull-out) assuming 1 1/2" edge distance and cracked concrete non-seismic conditions.  A "L" bolt would only have a capacity of 1,180 lbs (controled by pull-out) assuming the same thing.  ACI doen't like "L" and "J" bolts anymore.  You should use this code to calculate your concrete anchorages, don't trust my numbers, the NCAA is distracting my calcs.

RE: Tension capacity of Anchor bolts at Wood Frame Construction

2500 psi concrete...

RE: Tension capacity of Anchor bolts at Wood Frame Construction

Usually anchor bolts are used to resist shear, not uplift.  That is generally done with holddowns - embedded straps, HD's and the like.  To use the anchor bolt in tension, some form of hardware would have to be attached to it and nailed, screwed, or bolted off to the shearwall end column.

Other than trying to save hardware and money, is there another reason you have not mentioned why you do not want to use a standard holddown?

Mike McCann
MMC Engineering

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