ACI 10.8

[joemarch]

In my old ACI 318-89 section 10.8.4 it states that a compression member with a larger cross section than required, a reduced effective Ag may be reduced to 1/2 to determine minimum reinforcing. Won't this be the case in every axially loaded column? I guess I don't know if I totally have understood this section??

 

[WillisV]

Joemarch,

I believe the intent of this section is to allow you to use 0.5% minimum column reinforcing rather than the typical 1% minimum reinforcing when you have a column size that is dictated by other factors (architecture, matching beam widths framing in, etc) than load. Typically, efficiently sized columns for the loads on them would not meet this section and would require a minimum of 1% reinforcing. If, however, a larger column is required than truly necessary 0.5% minimum reinforcing may be used provided that the column strength is still adequate for the actual loads using a reduced cross sectional area of the column.