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Re: Cracked Concrete?
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Cracked Concrete?
- From: Steve Gordin <sgordin(--nospam--at)sgeconsulting.com>
- Date: Thu, 25 Feb 2010 11:47:21 -0800
I wonder how this construction marvel was detected.
Steve Gordin SE
Harold Sprague wrote:
under my desk as I write this is an epoxy all thread bolt 1" diameter
with 10" embedment. It pulled out from concrete under a static load
that was markedly lower than advertised. There was no cone because
there was little bond to the concrete. The epoxy bonded well to the
all thread. The problem was the prep of the concrete. I am very
cautious when it comes to epoxy bolts.
I would agree that it should be considered cracked unless otherwise
Always look at the ESR's and make them part of the special inspection.
Regards, Harold Sprague
Date: Tue, 23 Feb 2010 21:10:02 -0800
Subject: Re: Cracked Concrete?
Cracked concrete needs to be considered "in the region of concrete
where analysis indicates cracking at service load levels" (ACI 318-05
D.6.2.7). In other words, for example, when it can be shown by
rational analysis that stresses in the foundation will not exceed the
tension resistance of non-reinforced concrete, concrete may be
I design a lot of epoxy anchors, and did some research on the issue.
Based on my conversations with HILTI and Simpson, there are no recorded
cases of the seismic failure of the epoxy anchor bolts - even those
designed/installed 20 years ago. Without "bodies", and with the code
giving us clear guidance - why over-design?
IMO, the engineer needs to either demonstrate that the section is not
cracked, or to use the cracked concrete properties.
Steve Gordin SE
Tim Rudolph wrote:
I am looking at a submittal to
replace 16 misplaced anchor bolts for a 38 ft diameter 16 ft tall
bolted steel water tank in Seismic demand D area Old Zone 4 . The
engineer submitted a epoxy anchorage of a 3/4" all thread rod with a 6"
embedment for a 4500 lb tension only load in a grade beam 18"wide 24"
deep with #5 stirrups @ 18"oc and 6 # 5 long bars inside the stirrups
around the ring. (there are 26 of the 3/4" dia anchor bolts @ 4'7" oc
spacing around the grade beam) They called out for the Simpson SET-EP
epoxy and they used the anchor system calc software. now the question
- The engineer did not select that the concrete was cracked. Should I
consider this foundation grade beam an element that requires a cracked
section anchor solution?
Tim Rudolph PE
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