Column Reinforcement Requirement

 

There are two kinds of reinforcement in a column; Longitudinal and transverse reinforcement. The purpose of transverse reinforcement is to hold the vertical bars in a position providing lateral support so that individual bars cannot buckle outwards and split the concrete. Transverse reinforcement does not contribute to the strength of a column. Below are the requirements that must be satisfied in the reinforcement concrete column per code.

1.   The minimum area of cross section of longitudinal bars must be at least 0.8% of the gross sectional area of the column.

2.    The maximum area of cross section of longitudinal bars must not exceed 6% of the gross sectional area of the column.

3.    In any column that has a larger cross sectional area than that required to support the load, the minimum percentage steel must be based on the area of concrete required to resist the direct stress and not on the actual area.

4.    The bar should not be less than 12 mm in diameter so that it is sufficiently rigid to stand up straight in the column forms during fixing and concreting.

5.    The minimum number of longitudinal bars must be 4 in rectangular column and 6 in circular column.

6.    A reinforced concrete column having helical reinforcement must have at least 6 bars of longitudinal reinforcement within the helical reinforcement and must be in contact with helical reinforcement. Also equidistant around its inner circumference.

7.    Spacing of longitudinal bars measured along the periphery of a column should not exceed 300 mm.

8.    In case of pedestals, in which the longitudinal reinforcement is not taken into account in strength calculations, nominal longitudinal reinforcement should not be less than 0.15% of the cross sectional area. A pedestal is a compression member whose effective height does not exceed three times the least lateral dimension.