Wood Shear Wall without Holdowns 2

[vandede427]

Has anyone ever designed a wood shear wall to use the anchor bolts for shear and uplift resistance? I belive the analysis in determining each bolt's uplift force would be similar to a concrete or masonry shear wall. Any tips on the analysis of the compression block? Also, are there problems with the sill plate in this approach concerning not having a piece of hardware nailed/screwed/bolted to the tension chord?

 

[KBVT]

I have designed shear walls w/o anchors at the tension chord where the dead load was great enough to resist any overturning created by the applied lateral force. I have not however utilized typical spaced anchor bolts to resist uplift, and I don't think it would be an advisable solution.

 

[msquared48]

The anchor bolts are meant to take the shear, not the uplift. To do this would get into cross-grain bending of the sill plate which is not allowed. Plus, the connection of the end stud(s)to the plate, exclusive of the plywood, would have to be developed. Not a good idea. Additional thought - usually the sill plate material is not the best for bending strength either. Just don't do it, in spite of any contractors' "years of doing this". That's just plain BS.

As mentioned previiously, if the shearwall is long and is a bearing wall that is lightly loaded in shear, chances are good that holddowns will not be needed.

Mike McCann
MMC Engineering

 

[MiketheEngineer]

I believe IBC/IRC does NOT allow this...

Other than mentioned above

 

[vandede427]

Thanks for the responses guys. I used to practice struct eng in Florida, so calling out a bunch of holdowns never got questioned. But I live and work in Alabama now and of course construction practice are different from region to region. I'm just trying to find a way to reduce the amount of holdown hardware, safely resist the applied loads, and still meet code detailing requirements.

I found in the prescriptive requirements of the IRC Commentary that states the holdown is connected to the tension chord. I did not find in IBC Commentary where is states the same thing, only that the holdown is "typically" done this way.

I agree with the point about the sill material being of lesser quality, but I'm not sure about the cross-grain bending point. Doesn't the panel stiffen the connection of the tension chord to the sill plate enough so that the plate doesn't go into any weak-axis bending? Also, you said it wasn't allowed, where does the code say that?

This particular bldg is not a residence so I am using the IBC. And it seems that so many times in our profession we are left to our own interpration of the code, but I would always like to double-check the fine print to eliminate that need to interpret.

 

[boo1]

Portal Frame Bracing Without Hold-Down Devices
Details for APA-developed portal frame wall bracing to help provide segments as narrow as 16 inches that can be counted toward the overall bracing percentage required by the International Residential Code (IRC). (Form J740 - 6 pages)

or Whole House Wall Bracing, Form G440,

http://www.apawood.org/level_b.cfm?content=pub_main