RCDC consider 0.4% reinforcement for column minimum reinforcement by default. Is there any clause in IS code to reduce column minimum reinforcement from 0.8% to 0.4%?
As per code, Min As = 0.8% of the required C/s area of the column. RCDC follows the same.
RCDC internally calculates the c/s area required for the Maximum Pu and then takes 0.8% of the Required c/s area.
The 0.4% mentioned on the reinforcement setting form is used to calculate the Asmin with the Provided c/s area of the column.
Finally the Asmin is considered as Max (0.8*Required c/s area of column, 0.4*Provided c/s area of column) where the required c/s area of column is calculated in RCDC internally with Max Pu.