Though AISC requires +1/16" oversized holes for bolts, shop drawings for weldments (angle ledgers, etc) being attached to concrete with post-installed anchors often come back with +1/8" or +3/16" oversized holes proposed, presumedly so they'll have more tolerance for installation. Are +1/16" tolerances a reasonable expectation for the contractor? Are +1/8" holes permitted by code, or is there any research saying a +1/8" hole will provide acceptable load sharing with adjacent anchors (especially for weldments with several anchors in close proximity)?
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Hole Size in Steel for Post-Installed Anchors
- Thread starter WAstruc10
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Lomarandil
Structural
In my experience, +1/16" is not reasonable for most contractors installing a post-installed anchor. Some anchors may not even fit a standard hole.
Apparently, AISC 2016 will list the standard hole size for 1" or larger bolts as the bolt diameter + 1/8" instead of +1/16" -- so at least for larger anchors, there seems to be some plausibility to letting anchor ductility solve the issue for you.
If that doesn't work, I'd treat it the same as an anchor bolt group on a base plate -- either provide extra so you can justify that some of the anchors will not bear on the weldment and carry anchor shear, or specify field welded plate washers if your installation is critical enough.
Apparently, AISC 2016 will list the standard hole size for 1" or larger bolts as the bolt diameter + 1/8" instead of +1/16" -- so at least for larger anchors, there seems to be some plausibility to letting anchor ductility solve the issue for you.
If that doesn't work, I'd treat it the same as an anchor bolt group on a base plate -- either provide extra so you can justify that some of the anchors will not bear on the weldment and carry anchor shear, or specify field welded plate washers if your installation is critical enough.
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