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Re: IBC Section 1908.1.16 is a bugger

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IIRC, D.3.3.4 and D.3.3.5 in Appendix D require that there is ductile failure, otherwise the anchorage is not permitted.  The idea behind the 2.5 factor is if you can provide enough overstrength in the anchorage that there is little chance of failure, you don't have to have a ductile connection.  Think equipment bracing anchors on a shallow slab.

If you are doing hold downs, how about using a smaller diameter rod that will get ductile faulure, and put a plate washer in the seat of the hold down.  We see this all of the time with our DUC Undercut anchors for tilt up retrofits.


Howard Silverman, PE
Anchoring Systems and Field Engineer Manager
USP Structural Connectors

-----Original Message-----
From: Bill Allen <t.w.allen(--nospam--at)>
To: seaint(--nospam--at)
Sent: Fri, 30 Jan 2009 11:15 am
Subject: RE: IBC Section 1908.1.16 is a bugger

Yes, I am in California.
I am referring to structural components, specifically hold downs in residential shear walls in remodels.
One plan checker I am currently dealing with won't even let me use 2,500 psi concrete. The Simpson program will not work for 2,000 psi concrete. I don't think the plan checker could tell me the difference between 2,000 psi concrete and 2,500 psi concrete except for a number in a specification. Both are uninspected.
I asked him if he knew where the 2.5 factor came from. He said "Yes. It came from the code".
Yes, he's a S.E.
T. William (Bill) Allen, S.E.
Consulting Structural Engineers
V (949) 248-8588 F(949) 209-2509
-----Original Message-----
From: john yang [mailto:jeongidea(--nospam--at)]
Sent: Friday, January 30, 2009 10:43 AM
Subject: Re: IBC Section 1908.1.16 is a bugger
I know 2.5 factor killing especially non-structural component case.  I don't know you are in California or not. However, In California Building Code,  we have some relaxation for non-structural component members.  If your are located in California,  see 1908A.1.47.

On Fri, Jan 30, 2009 at 10:26 AM, Bill Allen <t.w.allen(--nospam--at)> wrote:
Now that new construction is slowing down, I wonder how big of a role this will play in the remodel world.
Does anyone know the source of the 2.5 factor mentioned in the modification to ACI 318 Appendix D.3.3.5? It seems rather arbitrary to me. But, what do I know?
T. William (Bill) Allen, S.E.
Consulting Structural Engineers
V (949) 248-8588 F(949) 209-2509