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RE: MISC: Reality Check - Dumb Question

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Thanks Jeff, I agree with you completely on this. It is most desirable to locate anchors within the limits of the shearwall for exactly the reason that you indicated - to prevent installation of an opening which may break the plate and reduce the capacity of the plate connection in the line of each shear wall.
In the field, however, I find that it is not always as I designed the connection and my underlying concern is "should I require a retrofit of epoxy anchors or recalculate the total installed anchors to see if I am within my demand from adjacent walls". BTW, one issue that I think you will agree with is that the capacity of anchors installed between plate discontinuities (such as door openings) should be greater than the demand of the walls in that area. Therefore, having six anchors on one side of an opening and only two on the other does no good when the side with two has a hefty shear wall with a demand greater than the capacity of the two anchors.
Thanks for your response.
Dennis
 
-----Original Message-----
From: Jeff Smith [mailto:smthengr(--nospam--at)sirius.com]
Sent: Saturday, February 14, 1998 9:41 AM
To: seaoc(--nospam--at)seaoc.org
Subject: Re: MISC: Reality Check - Dumb Question

I have run across this situation before, that is if I understand your situation. As mentioned, anchor bolts should be installed to all fndn sill plates with two min per piece of sill. So for your 4' panel you could possibly have no anchors within the shearwall, that is, between holdowns (if needed). If the sill plate is continuous each side of the shear wall, then the required anchors could resist shear outside the shearwall. However, my intuition says it would be best to always have the required anchors with in the shear panel. What if someone puts a door right next to your shearwall in the future, it would seem perfectly OK since it would not appear to be effecting the shear wall.
 
As a side note:
Even with no calculated shear load there is a potential vertical component of seismic forces and out of plane forces. BTW I always specify "BP" washers for both sill plate anchors and holdown stud bolts in zone 3 and 4. IMHO anchor bolts are an inexpensive item to specify above code minimums. Field overdrilled sill holes and ratty PT sill plates in addition to the dynamic and impact earthquake loads convince me to be conservative with anchor bolts. For this reason I don't think taking a 1/3 increase in values are a good idea. I also I don't count the holdown as the first anchor and the first anchor should be 6" from the holdown anchor. For short sections of wall it is best to specify the *number* of anchors in addition to the spacing. Occasionally I hear some grumbling from contractors, but I have little sympathy if it was on the bid or pricing drawings.
 
Regards,
Jeff Smith
Anchor Bolt Nazi