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RE: big dig structural failure - epoxy anchors overhead supporting gravity

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Mark Swingle wrote:
 
According to my recollection, I never met, worked for, or worked with ONE SINGLE engineer who would specify anchors grouted with epoxy to be used in an overhead application supporting gravity loads. "
 
Personally, I have sometimes used chemical anchors in overhead applications in the past - actually, I previously felt that properly installed chemical anchors were superior to expansion anchors for such applications if fire hazard was not a significant concern (e.g, in a liquid-containing structure). 
 
Cast-in-place anchors clearly would be the first choice but may not always be practical.  Expansion anchors that rely on friction make me nervous - especially if any dynamic load effects may be possible.  Do you really want to rely on friction to resist constant direct tension loads in overhead applications?  Undercut anchors probably would be a better choice.
 
It would appear quite likely that these epoxy grouted anchors were not "properly installed".  I've also heard horror stories of expansion anchors that were not properly installed and that could not resist the intended design load.  Blaming the problem solely on the fact that chemical anchors were used seems rather short sighted.  I look forward to hearing what forensic investigation turns up on this issue - I may then have to change my practice for overhead conditions.  
 
 
Bill Sherman