Galvanized Steel

Oversized holes in galvanized members are a good idea, either before or after the steel is galvanized. If your are designing structural steel to be galvanized, here are some references:

The galvanized bolt and nut assembly must be sized to accomodate the coating thickness. The overtapping of the nt is done by the manufacturer and there is nothing special to be done by the engineer.

The hole in the connected part is not adjusted. The standard 1/16" oversize is enough to account for the thickness of the galvanizing. Increasing the standard hole size will probably end up violating the RCSC bolt code tolerances and increasing the project cost.

See these AISC references:

I spec hand wire brushed for slip critical connections

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