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RE: Design Guidance For Diagonal Embedded Anchors

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I haven't found any references on this subject however, we typically design
the angle with at least two (usually four but depends on congestion,
thickness of slab etc) #4 x 24" at 6"oc for an 8" long embed.  It is more
common to see four bars, two welded to the horizontal leg of the angle and
shop bent so that it has adequate concrete cover away from the angle and the
others welded to the vertical leg with at least 1" of cover to the slab
soffit.  The length of the bars helps develop the moments without relying on
the thin slab section at the edge (assuming the embed is in an elevated
slab).

I would avoid using studs as you then rely more on the moment/shear capacity
of the edge of slab.  If you do use studs you should do a shear cone
analysis (per PCA or the new ACI-Strength Design of Anchorage to Concrete
methods) and verify the strength of the support section for shear and
moment.  Unless you are using unusually large forces, the weak link is
usually (should be) the embed not the slab especially if you are designing
in Zone 4 (i.e.. with lots of boundary steel, get the dowels under the
boundary steel).  It is not unreasonable to be conservative, unless you have
thousands of embeds, as this connection (the concrete surrounding the embed)
is frequently a maintenance issue (rust, spalled concrete etc.)  You want
the embed to show signs of failure not the slab since it is cheaper to fix
an embed before the concrete around it fails.


I hope this helps

Nick Blackburn

-----Original Message-----
From: Canitz, Charles F NAB02
[mailto:Charles.F.Canitz(--nospam--at)nab02.usace.army.mil]
Sent: Wednesday, January 17, 2001 10:27 AM
To: 'seaint(--nospam--at)seaint.org'
Subject: Design Guidance For Diagonal Embedded Anchors


To all -
  I'm attempting to locate guidance for the design of diagonal(i.e.,
oriented 45 degrees relative to the horizontal) anchors welded to a corner
protection angle and embedded at the corners of CIP beams or slabs. Said
assembly is subjected to moment and shear(the assembly supports pedestrian
guardrail posts). I have the current PCA publication for strength design of
embedded anchors but it appears to only address single or group vertical
anchors located near the edge of CIP members. Any suggestions?

TIA,
Charlie Canitz