31/07/2019
BASIC RULES FOR DESIGN OF COLUMN:
The basic rules for designing of columns are listed below:
A. LONGITUDINAL STEEL:
1. The cross-sectional area of longitudinal steel in a column shall not be less than 0.8 and not more than 6% of the gross-sectional area of the column.
In places where bars from a column below have to be lapped with those in the column to be designed, the maximum percentage of steel should not exceed 4%.
2. The diameter of longitudinal bars should not be less than 12 mm and should not be more than 50 mm.
3. Round columns and columns having helical binders should have at least bars.
4. The minimum cover of concrete to the outside of longitudinal bars shall be 4 cm or the diameter of the bar whichever is greater. In case where the maximum dimension of a column does not exceed 20 cm and the diameter of the longitudinal bars does not exceed 12 mm, the cover of 2.5 cm may be used.
5. Where it is necessary to splice the longitudinal bars, the bars shall overlap for a distance of not less than 24 times the diameter of the smallest bar.
6. The spacing of bars measured along the periphery of the column shall not exceed 300 mm.
