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Re: Cracked Concrete?

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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 considered non-cracked. 

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
Irvine CA

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