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Re: IBC Section 1908.1.16 is a bugger

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However, by code, you have to prove the failure mode is not in the brittle failure and this is not limited to steel anchor only.  Therefore, if the failure happens in the concrete like breakout, pullout and so on, 2.5 factor should be applied.  2.5 factor is kind of safety factor to ensure that, when the brittle failure mode is governed, the material is in the elastic range.

For example, if I use very strong anchor (high capacity anchor), the concrete pullout strength will be governed.  Therefore, regardless of anchor type or material, 2.5 factor should be applied.

In contrary, if I use relatively weak anchor and the anchor capacity is governed "not concrete", 2.5 factor may be eliminated. 

Thanks.

John Yang

On Tue, Feb 3, 2009 at 7:41 AM, Larry Hauer <lhauer(--nospam--at)live.com> wrote:
Bill,
 
I haven't gotten any "post installed" anchors in concrete to work using the 2.5 increase per CBC 1908.1.16, so I am falling back on the definition of "Ductile Steel Element" from page 379 of the ACI which states that ASTM A307 "shall be considered ductile." The way I read ACI Sec. D.3.3.4, the A307 threaded rod, (for epoxy applications), or anchor bolt would meet the criteria of this section, (I hope).
 
Larry Hauer S.E.




From: t.w.allen(--nospam--at)cox.net
To: seaint(--nospam--at)seaint.org
Subject: IBC Section 1908.1.16 is a bugger
Date: Fri, 30 Jan 2009 10:26:36 -0800



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.

ALLEN DESIGNS

Consulting Structural Engineers
 
V (949) 248-8588 F(949) 209-2509

 



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