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Re: Anchoring in seismic zones

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Select anchors that have passed seismic testing.  ICBO ES seismic testing is 
done in unreinforced concrete.  If the concrete is going to crack at the 
anchor location due to the applied seismic load, this will happen during 
testing and the anchor will probably not pass the test requirements.  Epoxy 
adhesive anchors may even strengthen the area at the anchor location (18000 
psi compressive, 5000 psi tensile strength) and cause the cracking to stay in 
the very low tensile strength concrete-just an idea.

Howard



-----Original Message-----

From: Jan Hermanek [mailto:herzmi(--nospam--at)hotmail.com]

Sent: Tuesday, May 15, 2001 8:44 AM

To: seaint(--nospam--at)seaint.org

Subject: Anchoring in seismic zones





Dear Sirs,


I have a question about anchoring to the concrete.


Our structures are connected to the concrete by chemical or short mechanical


anchors. My question is about anchoring in seismic zones. Chemical anchors 

are not suitable for cracked concrete. In Europe they are not recommended 

because during seismic event concrete cracks. But in the USA I've seen 

evaluation documents for chemical anchors. There you can find that those 

anchors are not suitable for cracked concrete but they are allowed to resist


seismic forces and some document allows even increasing of allowable 

stresses (extra 33% up). I have also understood that mechanical anchors in 

seismic zones are not really welcomed in USA.

Thank you for any suggestion to this topic.


What should I do then to fulfill criteria accepted by US building officials?


Jan Hermanek



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