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RE: Concrete anchorage (ACI 318-99 appendix D)

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The other limitation I am seeing the crushing of the concrete at the head.
I currently am using the table in the Note for ACI 318 published by PCA.
Most of the headed stud type anchors fail by crushing the concrete near the
head prior to yielding the anchor.  Basically, there are extremely few
conditions which actually satisfy the ductility provisions when current
anchors are used.

I think I understand the intent, but good luck actually trying to make it
work!

Any other thoughts out there?

Jake Watson, P.E.
Salt Lake City, UT

-----Original Message-----
From: Forrest Braun [mailto:fbraun(--nospam--at)bbfm.com]
Sent: Wednesday, June 25, 2003 3:09 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Concrete anchorage (ACI 318-99 appendix D)


Jake

I was hoping that there would have been some response on this issue
following your earlier post.  The IBC section 1913.3.3 (ACI D3.3.4 and
5) is indicating for seismic categories C, D, E, and F, that the anchors
are to be designed for the strength of a ductile element.  It appears
that based on these provisions, hold downs in wood shear walls will be
impossible to use since the embedment, and edge distances will not allow
capacities great enough to yield the anchor.

> Jake Watson wrote:
>
> How many people have though about the new CCD approach and its
> integration into the IBC?  Reading between the lines I have drawn the
> conclusion that the new CCD approach & the IBC wants us to begin to
> think of concrete connections the same way we think of concrete
> beams.  Connections should be designed to fail in a ductile manner.
> We are not necessarily making a better building by over-sizing
> anchors.  But instead, we should design the steel to yield before the
> concrete fails similar to a concrete beam.
>
> Am I on the right track?  How many people still just use standard
> "over-sized" connections that are strong enough, but don't fail in a
> ductile manner?  Or is this another code provision that will be
> repealed in a few code cycles?  Any thoughts?
>
> Jake Watson, P.E.
> Salt Lake City, UT

--
++++++++++++++++++++++++++
Forrest T. Braun, P.E.
BBFM Engineers, Inc.
Ph (907)274-2236
Fx (907)274-2520
Anchorage, Alaska
http://www.bbfm.com
++++++++++++++++++++++++++

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