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re: high uplift base plate connections

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What others have mentioned previously on this list, and what I have done in the past, is to rely on a different mechanism to develop your uplift force outside of ACI Appendix D. This can include many methods such as:

- lapping threaded rods attached to the base plate with rebar in the footing, developing tension via lap splices, welds, or mechanical means

-using weldable rebar attached to the base plate/columns and developing it via lap splices with footing rebar

-embedding a steel plate or other structural member into the footing and relying on upward punching shear and reinforcement in the shear zone of the footing to transfer the uplift force. The steel plate would be attached to the base plate via threaded rods or other mechanical means

-helical or auger piles with all-thread connections to the base plate; use of lap splices in the case of auger piles

-also, I forgot the proper name, but with very high uplift forces local bending in the base plate is likely a concern. You may have to connect the threaded rods or whatever your anchorage method is directly to your column with a reinforced local connection. That way the base plate is only in compression and is not used in resisting the uplift.


I am sure others have some I may have left out. At extremely high pullout forces it becomes almost a bridge-dead-man anchor situation, and some of those methods of tensile anchorage may be studied. Or something from the post-tension industry. Way outside my field of expertise…



Andrew Kester, PE

Orlando, FL