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.
From: Jan Hermanek [mailto:herzmi(--nospam--at)hotmail.com]
Sent: Tuesday, May 15, 2001 8:44 AM
Subject: Anchoring in seismic zones
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?
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