Correct Answer - Option 3 : 300 mm
Concept:
As per IS 456: 2000, clause 26.5.3.1,
Longitudinal reinforcement in a column:
Spacing:
The spacing of longitudinal bars measured along the periphery of the column shall not exceed 300 mm.
Percentage of steel:
The cross-sectional area of longitudinal reinforcement shall be not less than 0.8% nor more than 6% of the gross cross-sectional area of the column.
The minimum diameter of longitudinal reinforcement bars:
The main longitudinal reinforcement bars used in the column shall not be less than 12 mm in diameter.
The minimum number of longitudinal bar:
The minimum number of the longitudinal bar provided in the column shall be
- four in rectangular columns
- six in circular columns
Helical reinforcement:
A reinforced concrete column having helical reinforcement shall have at least six-bar of longitudinal reinforcement within the helical reinforcement.
