Shear Key Design
Shear Key Design
(OP)
Greetings all,
I need to design a base plate connection for a column that is subject to high values of shear. I´m having trouble finding a reasonable solution by only accounting for friction+shear on anchor bolts. For that reason i will need to use a shear key welded to the base plate in order to increase the resistance of the connection.
My question is: do you think it is acceptable to account the contribution of the friction + shear on the anchor bolts + resistance of the shear key on the calculation of the shear resistance of the connection? Or do i need to only work with friction+shear on anchor bolts or friction+shear key
Thanks a lot for the help.
I need to design a base plate connection for a column that is subject to high values of shear. I´m having trouble finding a reasonable solution by only accounting for friction+shear on anchor bolts. For that reason i will need to use a shear key welded to the base plate in order to increase the resistance of the connection.
My question is: do you think it is acceptable to account the contribution of the friction + shear on the anchor bolts + resistance of the shear key on the calculation of the shear resistance of the connection? Or do i need to only work with friction+shear on anchor bolts or friction+shear key
Thanks a lot for the help.






RE: Shear Key Design
Or you can embed plates into the top surface of the concrete and use welded vertical tabs on the sides of the base plate to take the shear down into the embeds.
I think AISC's stance is to minimize shear on anchor rods....we use them all the time but when the shear is high we go with an external load path instead of the bolts.
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RE: Shear Key Design
Can you elaborate on the second method that you described? English is not my first language and i did not understand it very well.
Thanks a lot.
RE: Shear Key Design
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RE: Shear Key Design
RE: Shear Key Design
RE: Shear Key Design
RE: Shear Key Design
@JAE: great detail. I've used a version with a single, solid embed plate below the the column which is inferior from a concrete placement standpoint. This is much better. There is something about this style of connection that I've had a hard time resolving however. It seems to me that, despite the fact that the shear and tension reside in different anchors, all of the anchors contribute force to the same concrete breakout cone. How have you been handling that?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Shear Key Design
In one case we used steel tubes stretching between columns with anchors along the tube length. This works well except where the design includes doors through the wall.
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RE: Shear Key Design
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Shear Key Design
RE: Shear Key Design
Plus getting good fill with non-shrink grout around it is a concern as well.
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RE: Shear Key Design
I like the concept. But, I am not thrilled with the one-side fillet welds on the shear tab plates with prying/bending on the weld axis. But there many are ways to alleviate my concerns - calc the weld to justify or modify the detail a little.
RE: Shear Key Design
What I mean is, there is surely a method that has been suggested, promoted and used in our industry for calculating how much shear key is needed....or conversely...what a specific shear key with depth, width, etc. provides in terms of capacity. However, under App. D our world has been turned upside down by the much lower capacities provided today vs. older bolt tables and capacities previously used.
I am just wondering if something similar applies to shear keys as it is a sort of "wide" bolt breakout that would occur with large shear forces in a formed key. Especially if the column has uplift on it during major shear events...i.e. no confinement of the concrete in front of the key.
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RE: Shear Key Design
See this thread for my version of JAE's detail that I use when conditions permit: Link
Is this still a concern given that the shear would be directed out of the page?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Shear Key Design
However, the paper summary cautions that these results, tests, and recommendations do not include enough tests to establish proper phi factors for use in design - only raw formulaic equations for Rn capacities.
I guess you could still use 0.75 or something but you'd be on your own with that.
But they do seem to approach the shear key design similar to Appendix D in ACI 318.
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RE: Shear Key Design
RE: Shear Key Design