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RE: ACI 318 App D, and wedge anchors

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In one existing residential remodel job, I  utilized a bracket that placed the post-installed mechanical anchors in shear on the face of the foundation wall and was able to meet the requirements in a retrofit situation. 


I have wondered about presenting the case that in wood construction, if the anchors are sized such that the shear chord nailing fails prior to developing the concrete breakout force in the anchor, you have essentially provided a ductile yielding connected element.  As such, you have met the ACI provisions.  This assumes that nail pullout is a ductile failure mechanism, which in the case of cyclical seismic forces, I believe this argument is valid, at least based on the high R-value permitted to be used in design.  The problem with this is QA/QC and making sure the contractor does not over-nail the chord and force the weak link back to the anchor.   




From: Rhkratzse(--nospam--at) [mailto:Rhkratzse(--nospam--at)]
Sent: Thursday, July 31, 2008 10:01 AM
To: Jared Keyser; Seaint(--nospam--at)
Subject: Re: ACI 318 App D, and wedge anchors


In a message dated 7/31/08 10:02:24 AM, jkeyser(--nospam--at) writes:

or avoid post-installed anchors entirely if possible.

In other words, completely *prohibit* the improvement of the earthquake strength and safety of existing structures, except with (often prohibitively expensive) new foundation construction.

I'm thinking mainly of single-family homes, where many owners are willing to invest a "reasonable" amount in anchor bolts and plywood, but not an order of magnitude more in a whole new foundation.

Ralph Hueston Kratz, S.E.
Richmond CA USA

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